diff --git a/ext/cpp-httplib/httplib.h b/ext/cpp-httplib/httplib.h
index 28746000c..dfdd260ab 100644
--- a/ext/cpp-httplib/httplib.h
+++ b/ext/cpp-httplib/httplib.h
@@ -1,14 +1,14 @@
 //
 //  httplib.h
 //
-//  Copyright (c) 2023 Yuji Hirose. All rights reserved.
+//  Copyright (c) 2024 Yuji Hirose. All rights reserved.
 //  MIT License
 //
 
 #ifndef CPPHTTPLIB_HTTPLIB_H
 #define CPPHTTPLIB_HTTPLIB_H
 
-#define CPPHTTPLIB_VERSION "0.12.2"
+#define CPPHTTPLIB_VERSION "0.15.3"
 
 /*
  * Configuration
@@ -82,6 +82,10 @@
 #define CPPHTTPLIB_FORM_URL_ENCODED_PAYLOAD_MAX_LENGTH 8192
 #endif
 
+#ifndef CPPHTTPLIB_RANGE_MAX_COUNT
+#define CPPHTTPLIB_RANGE_MAX_COUNT 1024
+#endif
+
 #ifndef CPPHTTPLIB_TCP_NODELAY
 #define CPPHTTPLIB_TCP_NODELAY false
 #endif
@@ -141,11 +145,11 @@ using ssize_t = long;
 #endif // _MSC_VER
 
 #ifndef S_ISREG
-#define S_ISREG(m) (((m)&S_IFREG) == S_IFREG)
+#define S_ISREG(m) (((m) & S_IFREG) == S_IFREG)
 #endif // S_ISREG
 
 #ifndef S_ISDIR
-#define S_ISDIR(m) (((m)&S_IFDIR) == S_IFDIR)
+#define S_ISDIR(m) (((m) & S_IFDIR) == S_IFDIR)
 #endif // S_ISDIR
 
 #ifndef NOMINMAX
@@ -160,10 +164,6 @@ using ssize_t = long;
 #define WSA_FLAG_NO_HANDLE_INHERIT 0x80
 #endif
 
-#ifndef strcasecmp
-#define strcasecmp _stricmp
-#endif // strcasecmp
-
 using socket_t = SOCKET;
 #ifdef CPPHTTPLIB_USE_POLL
 #define poll(fds, nfds, timeout) WSAPoll(fds, nfds, timeout)
@@ -172,9 +172,15 @@ using socket_t = SOCKET;
 #else // not _WIN32
 
 #include <arpa/inet.h>
-#ifndef _AIX
+#if !defined(_AIX) && !defined(__MVS__)
 #include <ifaddrs.h>
 #endif
+#ifdef __MVS__
+#include <strings.h>
+#ifndef NI_MAXHOST
+#define NI_MAXHOST 1025
+#endif
+#endif
 #include <net/if.h>
 #include <netdb.h>
 #include <netinet/in.h>
@@ -187,6 +193,7 @@ using socket_t = SOCKET;
 #endif
 #include <csignal>
 #include <pthread.h>
+#include <sys/mman.h>
 #include <sys/select.h>
 #include <sys/socket.h>
 #include <sys/un.h>
@@ -207,6 +214,7 @@ using socket_t = int;
 #include <condition_variable>
 #include <cstring>
 #include <errno.h>
+#include <exception>
 #include <fcntl.h>
 #include <fstream>
 #include <functional>
@@ -223,6 +231,9 @@ using socket_t = int;
 #include <string>
 #include <sys/stat.h>
 #include <thread>
+#include <unordered_map>
+#include <unordered_set>
+#include <utility>
 
 #ifdef CPPHTTPLIB_OPENSSL_SUPPORT
 #ifdef _WIN32
@@ -237,7 +248,6 @@ using socket_t = int;
 
 #ifdef _MSC_VER
 #pragma comment(lib, "crypt32.lib")
-#pragma comment(lib, "cryptui.lib")
 #endif
 #elif defined(CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN) && defined(__APPLE__)
 #include <TargetConditionals.h>
@@ -259,10 +269,8 @@ using socket_t = int;
 #include <iostream>
 #include <sstream>
 
-#if OPENSSL_VERSION_NUMBER < 0x1010100fL
-#error Sorry, OpenSSL versions prior to 1.1.1 are not supported
-#elif OPENSSL_VERSION_NUMBER < 0x30000000L
-#define SSL_get1_peer_certificate SSL_get_peer_certificate
+#if OPENSSL_VERSION_NUMBER < 0x30000000L
+#error Sorry, OpenSSL versions prior to 3.0.0 are not supported
 #endif
 
 #endif
@@ -321,7 +329,7 @@ struct scope_exit {
   explicit scope_exit(std::function<void(void)> &&f)
       : exit_function(std::move(f)), execute_on_destruction{true} {}
 
-  scope_exit(scope_exit &&rhs)
+  scope_exit(scope_exit &&rhs) noexcept
       : exit_function(std::move(rhs.exit_function)),
         execute_on_destruction{rhs.execute_on_destruction} {
     rhs.release();
@@ -344,6 +352,81 @@ struct scope_exit {
 
 } // namespace detail
 
+enum StatusCode {
+  // Information responses
+  Continue_100 = 100,
+  SwitchingProtocol_101 = 101,
+  Processing_102 = 102,
+  EarlyHints_103 = 103,
+
+  // Successful responses
+  OK_200 = 200,
+  Created_201 = 201,
+  Accepted_202 = 202,
+  NonAuthoritativeInformation_203 = 203,
+  NoContent_204 = 204,
+  ResetContent_205 = 205,
+  PartialContent_206 = 206,
+  MultiStatus_207 = 207,
+  AlreadyReported_208 = 208,
+  IMUsed_226 = 226,
+
+  // Redirection messages
+  MultipleChoices_300 = 300,
+  MovedPermanently_301 = 301,
+  Found_302 = 302,
+  SeeOther_303 = 303,
+  NotModified_304 = 304,
+  UseProxy_305 = 305,
+  unused_306 = 306,
+  TemporaryRedirect_307 = 307,
+  PermanentRedirect_308 = 308,
+
+  // Client error responses
+  BadRequest_400 = 400,
+  Unauthorized_401 = 401,
+  PaymentRequired_402 = 402,
+  Forbidden_403 = 403,
+  NotFound_404 = 404,
+  MethodNotAllowed_405 = 405,
+  NotAcceptable_406 = 406,
+  ProxyAuthenticationRequired_407 = 407,
+  RequestTimeout_408 = 408,
+  Conflict_409 = 409,
+  Gone_410 = 410,
+  LengthRequired_411 = 411,
+  PreconditionFailed_412 = 412,
+  PayloadTooLarge_413 = 413,
+  UriTooLong_414 = 414,
+  UnsupportedMediaType_415 = 415,
+  RangeNotSatisfiable_416 = 416,
+  ExpectationFailed_417 = 417,
+  ImATeapot_418 = 418,
+  MisdirectedRequest_421 = 421,
+  UnprocessableContent_422 = 422,
+  Locked_423 = 423,
+  FailedDependency_424 = 424,
+  TooEarly_425 = 425,
+  UpgradeRequired_426 = 426,
+  PreconditionRequired_428 = 428,
+  TooManyRequests_429 = 429,
+  RequestHeaderFieldsTooLarge_431 = 431,
+  UnavailableForLegalReasons_451 = 451,
+
+  // Server error responses
+  InternalServerError_500 = 500,
+  NotImplemented_501 = 501,
+  BadGateway_502 = 502,
+  ServiceUnavailable_503 = 503,
+  GatewayTimeout_504 = 504,
+  HttpVersionNotSupported_505 = 505,
+  VariantAlsoNegotiates_506 = 506,
+  InsufficientStorage_507 = 507,
+  LoopDetected_508 = 508,
+  NotExtended_510 = 510,
+  NetworkAuthenticationRequired_511 = 511,
+};
+
 using Headers = std::multimap<std::string, std::string, detail::ci>;
 
 using Params = std::multimap<std::string, std::string>;
@@ -373,6 +456,7 @@ class DataSink {
   DataSink &operator=(DataSink &&) = delete;
 
   std::function<bool(const char *data, size_t data_len)> write;
+  std::function<bool()> is_writable;
   std::function<void()> done;
   std::function<void(const Headers &trailer)> done_with_trailer;
   std::ostream os;
@@ -383,7 +467,7 @@ class DataSink {
     explicit data_sink_streambuf(DataSink &sink) : sink_(sink) {}
 
   protected:
-    std::streamsize xsputn(const char *s, std::streamsize n) {
+    std::streamsize xsputn(const char *s, std::streamsize n) override {
       sink_.write(s, static_cast<size_t>(n));
       return n;
     }
@@ -465,6 +549,7 @@ struct Request {
   MultipartFormDataMap files;
   Ranges ranges;
   Match matches;
+  std::unordered_map<std::string, std::string> path_params;
 
   // for client
   ResponseHandler response_handler;
@@ -476,8 +561,7 @@ struct Request {
 
   bool has_header(const std::string &key) const;
   std::string get_header_value(const std::string &key, size_t id = 0) const;
-  template <typename T>
-  T get_header_value(const std::string &key, size_t id = 0) const;
+  uint64_t get_header_value_u64(const std::string &key, size_t id = 0) const;
   size_t get_header_value_count(const std::string &key) const;
   void set_header(const std::string &key, const std::string &val);
 
@@ -509,14 +593,14 @@ struct Response {
 
   bool has_header(const std::string &key) const;
   std::string get_header_value(const std::string &key, size_t id = 0) const;
-  template <typename T>
-  T get_header_value(const std::string &key, size_t id = 0) const;
+  uint64_t get_header_value_u64(const std::string &key, size_t id = 0) const;
   size_t get_header_value_count(const std::string &key) const;
   void set_header(const std::string &key, const std::string &val);
 
-  void set_redirect(const std::string &url, int status = 302);
+  void set_redirect(const std::string &url, int status = StatusCode::Found_302);
   void set_content(const char *s, size_t n, const std::string &content_type);
   void set_content(const std::string &s, const std::string &content_type);
+  void set_content(std::string &&s, const std::string &content_type);
 
   void set_content_provider(
       size_t length, const std::string &content_type, ContentProvider provider,
@@ -573,7 +657,7 @@ class TaskQueue {
   TaskQueue() = default;
   virtual ~TaskQueue() = default;
 
-  virtual void enqueue(std::function<void()> fn) = 0;
+  virtual bool enqueue(std::function<void()> fn) = 0;
   virtual void shutdown() = 0;
 
   virtual void on_idle() {}
@@ -581,7 +665,8 @@ class TaskQueue {
 
 class ThreadPool : public TaskQueue {
 public:
-  explicit ThreadPool(size_t n) : shutdown_(false) {
+  explicit ThreadPool(size_t n, size_t mqr = 0)
+      : shutdown_(false), max_queued_requests_(mqr) {
     while (n) {
       threads_.emplace_back(worker(*this));
       n--;
@@ -591,13 +676,17 @@ class ThreadPool : public TaskQueue {
   ThreadPool(const ThreadPool &) = delete;
   ~ThreadPool() override = default;
 
-  void enqueue(std::function<void()> fn) override {
+  bool enqueue(std::function<void()> fn) override {
     {
       std::unique_lock<std::mutex> lock(mutex_);
+      if (max_queued_requests_ > 0 && jobs_.size() >= max_queued_requests_) {
+        return false;
+      }
       jobs_.push_back(std::move(fn));
     }
 
     cond_.notify_one();
+    return true;
   }
 
   void shutdown() override {
@@ -647,6 +736,7 @@ class ThreadPool : public TaskQueue {
   std::list<std::function<void()>> jobs_;
 
   bool shutdown_;
+  size_t max_queued_requests_ = 0;
 
   std::condition_variable cond_;
   std::mutex mutex_;
@@ -658,6 +748,82 @@ using SocketOptions = std::function<void(socket_t sock)>;
 
 void default_socket_options(socket_t sock);
 
+const char *status_message(int status);
+
+std::string get_bearer_token_auth(const Request &req);
+
+namespace detail {
+
+class MatcherBase {
+public:
+  virtual ~MatcherBase() = default;
+
+  // Match request path and populate its matches and
+  virtual bool match(Request &request) const = 0;
+};
+
+/**
+ * Captures parameters in request path and stores them in Request::path_params
+ *
+ * Capture name is a substring of a pattern from : to /.
+ * The rest of the pattern is matched agains the request path directly
+ * Parameters are captured starting from the next character after
+ * the end of the last matched static pattern fragment until the next /.
+ *
+ * Example pattern:
+ * "/path/fragments/:capture/more/fragments/:second_capture"
+ * Static fragments:
+ * "/path/fragments/", "more/fragments/"
+ *
+ * Given the following request path:
+ * "/path/fragments/:1/more/fragments/:2"
+ * the resulting capture will be
+ * {{"capture", "1"}, {"second_capture", "2"}}
+ */
+class PathParamsMatcher : public MatcherBase {
+public:
+  PathParamsMatcher(const std::string &pattern);
+
+  bool match(Request &request) const override;
+
+private:
+  static constexpr char marker = ':';
+  // Treat segment separators as the end of path parameter capture
+  // Does not need to handle query parameters as they are parsed before path
+  // matching
+  static constexpr char separator = '/';
+
+  // Contains static path fragments to match against, excluding the '/' after
+  // path params
+  // Fragments are separated by path params
+  std::vector<std::string> static_fragments_;
+  // Stores the names of the path parameters to be used as keys in the
+  // Request::path_params map
+  std::vector<std::string> param_names_;
+};
+
+/**
+ * Performs std::regex_match on request path
+ * and stores the result in Request::matches
+ *
+ * Note that regex match is performed directly on the whole request.
+ * This means that wildcard patterns may match multiple path segments with /:
+ * "/begin/(.*)/end" will match both "/begin/middle/end" and "/begin/1/2/end".
+ */
+class RegexMatcher : public MatcherBase {
+public:
+  RegexMatcher(const std::string &pattern) : regex_(pattern) {}
+
+  bool match(Request &request) const override;
+
+private:
+  std::regex regex_;
+};
+
+ssize_t write_headers(Stream &strm, const Headers &headers);
+
+} // namespace detail
+
 class Server {
 public:
   using Handler = std::function<void(const Request &, Response &)>;
@@ -702,6 +868,7 @@ class Server {
   bool remove_mount_point(const std::string &mount_point);
   Server &set_file_extension_and_mimetype_mapping(const std::string &ext,
                                                   const std::string &mime);
+  Server &set_default_file_mimetype(const std::string &mime);
   Server &set_file_request_handler(Handler handler);
 
   Server &set_error_handler(HandlerWithResponse handler);
@@ -718,6 +885,8 @@ class Server {
   Server &set_socket_options(SocketOptions socket_options);
 
   Server &set_default_headers(Headers headers);
+  Server &
+  set_header_writer(std::function<ssize_t(Stream &, Headers &)> const &writer);
 
   Server &set_keep_alive_max_count(size_t count);
   Server &set_keep_alive_timeout(time_t sec);
@@ -765,9 +934,14 @@ class Server {
   size_t payload_max_length_ = CPPHTTPLIB_PAYLOAD_MAX_LENGTH;
 
 private:
-  using Handlers = std::vector<std::pair<std::regex, Handler>>;
+  using Handlers =
+      std::vector<std::pair<std::unique_ptr<detail::MatcherBase>, Handler>>;
   using HandlersForContentReader =
-      std::vector<std::pair<std::regex, HandlerWithContentReader>>;
+      std::vector<std::pair<std::unique_ptr<detail::MatcherBase>,
+                            HandlerWithContentReader>>;
+
+  static std::unique_ptr<detail::MatcherBase>
+  make_matcher(const std::string &pattern);
 
   socket_t create_server_socket(const std::string &host, int port,
                                 int socket_flags,
@@ -778,16 +952,16 @@ class Server {
   bool routing(Request &req, Response &res, Stream &strm);
   bool handle_file_request(const Request &req, Response &res,
                            bool head = false);
-  bool dispatch_request(Request &req, Response &res, const Handlers &handlers);
-  bool
-  dispatch_request_for_content_reader(Request &req, Response &res,
-                                      ContentReader content_reader,
-                                      const HandlersForContentReader &handlers);
+  bool dispatch_request(Request &req, Response &res,
+                        const Handlers &handlers) const;
+  bool dispatch_request_for_content_reader(
+      Request &req, Response &res, ContentReader content_reader,
+      const HandlersForContentReader &handlers) const;
 
-  bool parse_request_line(const char *s, Request &req);
+  bool parse_request_line(const char *s, Request &req) const;
   void apply_ranges(const Request &req, Response &res,
-                    std::string &content_type, std::string &boundary);
-  bool write_response(Stream &strm, bool close_connection, const Request &req,
+                    std::string &content_type, std::string &boundary) const;
+  bool write_response(Stream &strm, bool close_connection, Request &req,
                       Response &res);
   bool write_response_with_content(Stream &strm, bool close_connection,
                                    const Request &req, Response &res);
@@ -806,21 +980,23 @@ class Server {
   bool read_content_core(Stream &strm, Request &req, Response &res,
                          ContentReceiver receiver,
                          MultipartContentHeader multipart_header,
-                         ContentReceiver multipart_receiver);
+                         ContentReceiver multipart_receiver) const;
 
   virtual bool process_and_close_socket(socket_t sock);
 
+  std::atomic<bool> is_running_{false};
+  std::atomic<bool> done_{false};
+
   struct MountPointEntry {
     std::string mount_point;
     std::string base_dir;
     Headers headers;
   };
   std::vector<MountPointEntry> base_dirs_;
-
-  std::atomic<bool> is_running_{false};
-  std::atomic<bool> done_{false};
   std::map<std::string, std::string> file_extension_and_mimetype_map_;
+  std::string default_file_mimetype_ = "application/octet-stream";
   Handler file_request_handler_;
+
   Handlers get_handlers_;
   Handlers post_handlers_;
   HandlersForContentReader post_handlers_for_content_reader_;
@@ -831,18 +1007,22 @@ class Server {
   Handlers delete_handlers_;
   HandlersForContentReader delete_handlers_for_content_reader_;
   Handlers options_handlers_;
+
   HandlerWithResponse error_handler_;
   ExceptionHandler exception_handler_;
   HandlerWithResponse pre_routing_handler_;
   Handler post_routing_handler_;
-  Logger logger_;
   Expect100ContinueHandler expect_100_continue_handler_;
 
+  Logger logger_;
+
   int address_family_ = AF_UNSPEC;
   bool tcp_nodelay_ = CPPHTTPLIB_TCP_NODELAY;
   SocketOptions socket_options_ = default_socket_options;
 
   Headers default_headers_;
+  std::function<ssize_t(Stream &, Headers &)> header_writer_ =
+      detail::write_headers;
 };
 
 enum class Error {
@@ -860,17 +1040,19 @@ enum class Error {
   UnsupportedMultipartBoundaryChars,
   Compression,
   ConnectionTimeout,
+  ProxyConnection,
 
   // For internal use only
   SSLPeerCouldBeClosed_,
 };
 
-std::string to_string(const Error error);
+std::string to_string(Error error);
 
 std::ostream &operator<<(std::ostream &os, const Error &obj);
 
 class Result {
 public:
+  Result() = default;
   Result(std::unique_ptr<Response> &&res, Error err,
          Headers &&request_headers = Headers{})
       : res_(std::move(res)), err_(err),
@@ -893,13 +1075,13 @@ class Result {
   bool has_request_header(const std::string &key) const;
   std::string get_request_header_value(const std::string &key,
                                        size_t id = 0) const;
-  template <typename T>
-  T get_request_header_value(const std::string &key, size_t id = 0) const;
+  uint64_t get_request_header_value_u64(const std::string &key,
+                                        size_t id = 0) const;
   size_t get_request_header_value_count(const std::string &key) const;
 
 private:
   std::unique_ptr<Response> res_;
-  Error err_;
+  Error err_ = Error::Unknown;
   Headers request_headers_;
 };
 
@@ -1059,16 +1241,21 @@ class ClientImpl {
   bool send(Request &req, Response &res, Error &error);
   Result send(const Request &req);
 
-  size_t is_socket_open() const;
+  void stop();
 
-  socket_t socket() const;
+  std::string host() const;
+  int port() const;
 
-  void stop();
+  size_t is_socket_open() const;
+  socket_t socket() const;
 
   void set_hostname_addr_map(std::map<std::string, std::string> addr_map);
 
   void set_default_headers(Headers headers);
 
+  void
+  set_header_writer(std::function<ssize_t(Stream &, Headers &)> const &writer);
+
   void set_address_family(int family);
   void set_tcp_nodelay(bool on);
   void set_socket_options(SocketOptions socket_options);
@@ -1117,6 +1304,7 @@ class ClientImpl {
   void set_ca_cert_path(const std::string &ca_cert_file_path,
                         const std::string &ca_cert_dir_path = std::string());
   void set_ca_cert_store(X509_STORE *ca_cert_store);
+  X509_STORE *create_ca_cert_store(const char *ca_cert, std::size_t size) const;
 #endif
 
 #ifdef CPPHTTPLIB_OPENSSL_SUPPORT
@@ -1145,14 +1333,14 @@ class ClientImpl {
   // Also, shutdown_ssl and close_socket should also NOT be called concurrently
   // with a DIFFERENT thread sending requests using that socket.
   virtual void shutdown_ssl(Socket &socket, bool shutdown_gracefully);
-  void shutdown_socket(Socket &socket);
+  void shutdown_socket(Socket &socket) const;
   void close_socket(Socket &socket);
 
   bool process_request(Stream &strm, Request &req, Response &res,
                        bool close_connection, Error &error);
 
   bool write_content_with_provider(Stream &strm, const Request &req,
-                                   Error &error);
+                                   Error &error) const;
 
   void copy_settings(const ClientImpl &rhs);
 
@@ -1177,6 +1365,10 @@ class ClientImpl {
   // Default headers
   Headers default_headers_;
 
+  // Header writer
+  std::function<ssize_t(Stream &, Headers &)> header_writer_ =
+      detail::write_headers;
+
   // Settings
   std::string client_cert_path_;
   std::string client_key_path_;
@@ -1239,7 +1431,8 @@ class ClientImpl {
   Result send_(Request &&req);
 
   socket_t create_client_socket(Error &error) const;
-  bool read_response_line(Stream &strm, const Request &req, Response &res);
+  bool read_response_line(Stream &strm, const Request &req,
+                          Response &res) const;
   bool write_request(Stream &strm, Request &req, bool close_connection,
                      Error &error);
   bool redirect(Request &req, Response &res, Error &error);
@@ -1258,7 +1451,7 @@ class ClientImpl {
       const std::string &content_type);
   ContentProviderWithoutLength get_multipart_content_provider(
       const std::string &boundary, const MultipartFormDataItems &items,
-      const MultipartFormDataProviderItems &provider_items);
+      const MultipartFormDataProviderItems &provider_items) const;
 
   std::string adjust_host_string(const std::string &host) const;
 
@@ -1431,16 +1624,21 @@ class Client {
   bool send(Request &req, Response &res, Error &error);
   Result send(const Request &req);
 
-  size_t is_socket_open() const;
+  void stop();
 
-  socket_t socket() const;
+  std::string host() const;
+  int port() const;
 
-  void stop();
+  size_t is_socket_open() const;
+  socket_t socket() const;
 
   void set_hostname_addr_map(std::map<std::string, std::string> addr_map);
 
   void set_default_headers(Headers headers);
 
+  void
+  set_header_writer(std::function<ssize_t(Stream &, Headers &)> const &writer);
+
   void set_address_family(int family);
   void set_tcp_nodelay(bool on);
   void set_socket_options(SocketOptions socket_options);
@@ -1497,6 +1695,7 @@ class Client {
                         const std::string &ca_cert_dir_path = std::string());
 
   void set_ca_cert_store(X509_STORE *ca_cert_store);
+  void load_ca_cert_store(const char *ca_cert, std::size_t size);
 
   long get_openssl_verify_result() const;
 
@@ -1556,6 +1755,7 @@ class SSLClient : public ClientImpl {
   bool is_valid() const override;
 
   void set_ca_cert_store(X509_STORE *ca_cert_store);
+  void load_ca_cert_store(const char *ca_cert, std::size_t size);
 
   long get_openssl_verify_result() const;
 
@@ -1564,7 +1764,7 @@ class SSLClient : public ClientImpl {
 private:
   bool create_and_connect_socket(Socket &socket, Error &error) override;
   void shutdown_ssl(Socket &socket, bool shutdown_gracefully) override;
-  void shutdown_ssl_impl(Socket &socket, bool shutdown_socket);
+  void shutdown_ssl_impl(Socket &socket, bool shutdown_gracefully);
 
   bool process_socket(const Socket &socket,
                       std::function<bool(Stream &strm)> callback) override;
@@ -1608,15 +1808,9 @@ inline void duration_to_sec_and_usec(const T &duration, U callback) {
   callback(static_cast<time_t>(sec), static_cast<time_t>(usec));
 }
 
-template <typename T>
-inline T get_header_value(const Headers & /*headers*/,
-                          const std::string & /*key*/, size_t /*id*/ = 0,
-                          uint64_t /*def*/ = 0) {}
-
-template <>
-inline uint64_t get_header_value<uint64_t>(const Headers &headers,
-                                           const std::string &key, size_t id,
-                                           uint64_t def) {
+inline uint64_t get_header_value_u64(const Headers &headers,
+                                     const std::string &key, size_t id,
+                                     uint64_t def) {
   auto rng = headers.equal_range(key);
   auto it = rng.first;
   std::advance(it, static_cast<ssize_t>(id));
@@ -1628,14 +1822,14 @@ inline uint64_t get_header_value<uint64_t>(const Headers &headers,
 
 } // namespace detail
 
-template <typename T>
-inline T Request::get_header_value(const std::string &key, size_t id) const {
-  return detail::get_header_value<T>(headers, key, id, 0);
+inline uint64_t Request::get_header_value_u64(const std::string &key,
+                                              size_t id) const {
+  return detail::get_header_value_u64(headers, key, id, 0);
 }
 
-template <typename T>
-inline T Response::get_header_value(const std::string &key, size_t id) const {
-  return detail::get_header_value<T>(headers, key, id, 0);
+inline uint64_t Response::get_header_value_u64(const std::string &key,
+                                               size_t id) const {
+  return detail::get_header_value_u64(headers, key, id, 0);
 }
 
 template <typename... Args>
@@ -1665,21 +1859,106 @@ inline ssize_t Stream::write_format(const char *fmt, const Args &...args) {
 inline void default_socket_options(socket_t sock) {
   int yes = 1;
 #ifdef _WIN32
-  setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, reinterpret_cast<char *>(&yes),
-             sizeof(yes));
+  setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
+             reinterpret_cast<const char *>(&yes), sizeof(yes));
   setsockopt(sock, SOL_SOCKET, SO_EXCLUSIVEADDRUSE,
-             reinterpret_cast<char *>(&yes), sizeof(yes));
+             reinterpret_cast<const char *>(&yes), sizeof(yes));
 #else
 #ifdef SO_REUSEPORT
-  setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, reinterpret_cast<void *>(&yes),
-             sizeof(yes));
+  setsockopt(sock, SOL_SOCKET, SO_REUSEPORT,
+             reinterpret_cast<const void *>(&yes), sizeof(yes));
 #else
-  setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, reinterpret_cast<void *>(&yes),
-             sizeof(yes));
+  setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
+             reinterpret_cast<const void *>(&yes), sizeof(yes));
 #endif
 #endif
 }
 
+inline const char *status_message(int status) {
+  switch (status) {
+  case StatusCode::Continue_100: return "Continue";
+  case StatusCode::SwitchingProtocol_101: return "Switching Protocol";
+  case StatusCode::Processing_102: return "Processing";
+  case StatusCode::EarlyHints_103: return "Early Hints";
+  case StatusCode::OK_200: return "OK";
+  case StatusCode::Created_201: return "Created";
+  case StatusCode::Accepted_202: return "Accepted";
+  case StatusCode::NonAuthoritativeInformation_203:
+    return "Non-Authoritative Information";
+  case StatusCode::NoContent_204: return "No Content";
+  case StatusCode::ResetContent_205: return "Reset Content";
+  case StatusCode::PartialContent_206: return "Partial Content";
+  case StatusCode::MultiStatus_207: return "Multi-Status";
+  case StatusCode::AlreadyReported_208: return "Already Reported";
+  case StatusCode::IMUsed_226: return "IM Used";
+  case StatusCode::MultipleChoices_300: return "Multiple Choices";
+  case StatusCode::MovedPermanently_301: return "Moved Permanently";
+  case StatusCode::Found_302: return "Found";
+  case StatusCode::SeeOther_303: return "See Other";
+  case StatusCode::NotModified_304: return "Not Modified";
+  case StatusCode::UseProxy_305: return "Use Proxy";
+  case StatusCode::unused_306: return "unused";
+  case StatusCode::TemporaryRedirect_307: return "Temporary Redirect";
+  case StatusCode::PermanentRedirect_308: return "Permanent Redirect";
+  case StatusCode::BadRequest_400: return "Bad Request";
+  case StatusCode::Unauthorized_401: return "Unauthorized";
+  case StatusCode::PaymentRequired_402: return "Payment Required";
+  case StatusCode::Forbidden_403: return "Forbidden";
+  case StatusCode::NotFound_404: return "Not Found";
+  case StatusCode::MethodNotAllowed_405: return "Method Not Allowed";
+  case StatusCode::NotAcceptable_406: return "Not Acceptable";
+  case StatusCode::ProxyAuthenticationRequired_407:
+    return "Proxy Authentication Required";
+  case StatusCode::RequestTimeout_408: return "Request Timeout";
+  case StatusCode::Conflict_409: return "Conflict";
+  case StatusCode::Gone_410: return "Gone";
+  case StatusCode::LengthRequired_411: return "Length Required";
+  case StatusCode::PreconditionFailed_412: return "Precondition Failed";
+  case StatusCode::PayloadTooLarge_413: return "Payload Too Large";
+  case StatusCode::UriTooLong_414: return "URI Too Long";
+  case StatusCode::UnsupportedMediaType_415: return "Unsupported Media Type";
+  case StatusCode::RangeNotSatisfiable_416: return "Range Not Satisfiable";
+  case StatusCode::ExpectationFailed_417: return "Expectation Failed";
+  case StatusCode::ImATeapot_418: return "I'm a teapot";
+  case StatusCode::MisdirectedRequest_421: return "Misdirected Request";
+  case StatusCode::UnprocessableContent_422: return "Unprocessable Content";
+  case StatusCode::Locked_423: return "Locked";
+  case StatusCode::FailedDependency_424: return "Failed Dependency";
+  case StatusCode::TooEarly_425: return "Too Early";
+  case StatusCode::UpgradeRequired_426: return "Upgrade Required";
+  case StatusCode::PreconditionRequired_428: return "Precondition Required";
+  case StatusCode::TooManyRequests_429: return "Too Many Requests";
+  case StatusCode::RequestHeaderFieldsTooLarge_431:
+    return "Request Header Fields Too Large";
+  case StatusCode::UnavailableForLegalReasons_451:
+    return "Unavailable For Legal Reasons";
+  case StatusCode::NotImplemented_501: return "Not Implemented";
+  case StatusCode::BadGateway_502: return "Bad Gateway";
+  case StatusCode::ServiceUnavailable_503: return "Service Unavailable";
+  case StatusCode::GatewayTimeout_504: return "Gateway Timeout";
+  case StatusCode::HttpVersionNotSupported_505:
+    return "HTTP Version Not Supported";
+  case StatusCode::VariantAlsoNegotiates_506: return "Variant Also Negotiates";
+  case StatusCode::InsufficientStorage_507: return "Insufficient Storage";
+  case StatusCode::LoopDetected_508: return "Loop Detected";
+  case StatusCode::NotExtended_510: return "Not Extended";
+  case StatusCode::NetworkAuthenticationRequired_511:
+    return "Network Authentication Required";
+
+  default:
+  case StatusCode::InternalServerError_500: return "Internal Server Error";
+  }
+}
+
+inline std::string get_bearer_token_auth(const Request &req) {
+  if (req.has_header("Authorization")) {
+    static std::string BearerHeaderPrefix = "Bearer ";
+    return req.get_header_value("Authorization")
+        .substr(BearerHeaderPrefix.length());
+  }
+  return "";
+}
+
 template <class Rep, class Period>
 inline Server &
 Server::set_read_timeout(const std::chrono::duration<Rep, Period> &duration) {
@@ -1720,6 +1999,7 @@ inline std::string to_string(const Error error) {
     return "Unsupported HTTP multipart boundary characters";
   case Error::Compression: return "Compression failed";
   case Error::ConnectionTimeout: return "Connection timed out";
+  case Error::ProxyConnection: return "Proxy connection failed";
   case Error::Unknown: return "Unknown";
   default: break;
   }
@@ -1733,10 +2013,9 @@ inline std::ostream &operator<<(std::ostream &os, const Error &obj) {
   return os;
 }
 
-template <typename T>
-inline T Result::get_request_header_value(const std::string &key,
-                                          size_t id) const {
-  return detail::get_header_value<T>(request_headers_, key, id, 0);
+inline uint64_t Result::get_request_header_value_u64(const std::string &key,
+                                                     size_t id) const {
+  return detail::get_header_value_u64(request_headers_, key, id, 0);
 }
 
 template <class Rep, class Period>
@@ -1790,7 +2069,7 @@ void hosted_at(const std::string &hostname, std::vector<std::string> &addrs);
 
 std::string append_query_params(const std::string &path, const Params &params);
 
-std::pair<std::string, std::string> make_range_header(Ranges ranges);
+std::pair<std::string, std::string> make_range_header(const Ranges &ranges);
 
 std::pair<std::string, std::string>
 make_basic_authentication_header(const std::string &username,
@@ -1810,6 +2089,9 @@ std::string trim_copy(const std::string &s);
 void split(const char *b, const char *e, char d,
            std::function<void(const char *, const char *)> fn);
 
+void split(const char *b, const char *e, char d, size_t m,
+           std::function<void(const char *, const char *)> fn);
+
 bool process_client_socket(socket_t sock, time_t read_timeout_sec,
                            time_t read_timeout_usec, time_t write_timeout_sec,
                            time_t write_timeout_usec,
@@ -1886,7 +2168,7 @@ class decompressor {
 
 class nocompressor : public compressor {
 public:
-  virtual ~nocompressor() = default;
+  ~nocompressor() override = default;
 
   bool compress(const char *data, size_t data_length, bool /*last*/,
                 Callback callback) override;
@@ -1896,7 +2178,7 @@ class nocompressor : public compressor {
 class gzip_compressor : public compressor {
 public:
   gzip_compressor();
-  ~gzip_compressor();
+  ~gzip_compressor() override;
 
   bool compress(const char *data, size_t data_length, bool last,
                 Callback callback) override;
@@ -1909,7 +2191,7 @@ class gzip_compressor : public compressor {
 class gzip_decompressor : public decompressor {
 public:
   gzip_decompressor();
-  ~gzip_decompressor();
+  ~gzip_decompressor() override;
 
   bool is_valid() const override;
 
@@ -1972,6 +2254,29 @@ class stream_line_reader {
   std::string glowable_buffer_;
 };
 
+class mmap {
+public:
+  mmap(const char *path);
+  ~mmap();
+
+  bool open(const char *path);
+  void close();
+
+  bool is_open() const;
+  size_t size() const;
+  const char *data() const;
+
+private:
+#if defined(_WIN32)
+  HANDLE hFile_;
+  HANDLE hMapping_;
+#else
+  int fd_;
+#endif
+  size_t size_;
+  void *addr_;
+};
+
 } // namespace detail
 
 // ----------------------------------------------------------------------------
@@ -2003,7 +2308,7 @@ inline bool from_hex_to_i(const std::string &s, size_t i, size_t cnt,
   val = 0;
   for (; cnt; i++, cnt--) {
     if (!s[i]) { return false; }
-    int v = 0;
+    auto v = 0;
     if (is_hex(s[i], v)) {
       val = val * 16 + v;
     } else {
@@ -2014,7 +2319,7 @@ inline bool from_hex_to_i(const std::string &s, size_t i, size_t cnt,
 }
 
 inline std::string from_i_to_hex(size_t n) {
-  const char *charset = "0123456789abcdef";
+  static const auto charset = "0123456789abcdef";
   std::string ret;
   do {
     ret = charset[n & 15] + ret;
@@ -2025,7 +2330,7 @@ inline std::string from_i_to_hex(size_t n) {
 
 inline size_t to_utf8(int code, char *buff) {
   if (code < 0x0080) {
-    buff[0] = (code & 0x7F);
+    buff[0] = static_cast<char>(code & 0x7F);
     return 1;
   } else if (code < 0x0800) {
     buff[0] = static_cast<char>(0xC0 | ((code >> 6) & 0x1F));
@@ -2064,8 +2369,8 @@ inline std::string base64_encode(const std::string &in) {
   std::string out;
   out.reserve(in.size());
 
-  int val = 0;
-  int valb = -6;
+  auto val = 0;
+  auto valb = -6;
 
   for (auto c : in) {
     val = (val << 8) + static_cast<uint8_t>(c);
@@ -2112,6 +2417,11 @@ inline bool is_valid_path(const std::string &path) {
     // Read component
     auto beg = i;
     while (i < path.size() && path[i] != '/') {
+      if (path[i] == '\0') {
+        return false;
+      } else if (path[i] == '\\') {
+        return false;
+      }
       i++;
     }
 
@@ -2196,7 +2506,7 @@ inline std::string decode_url(const std::string &s,
   for (size_t i = 0; i < s.size(); i++) {
     if (s[i] == '%' && i + 1 < s.size()) {
       if (s[i + 1] == 'u') {
-        int val = 0;
+        auto val = 0;
         if (from_hex_to_i(s, i + 2, 4, val)) {
           // 4 digits Unicode codes
           char buff[4];
@@ -2207,7 +2517,7 @@ inline std::string decode_url(const std::string &s,
           result += s[i];
         }
       } else {
-        int val = 0;
+        auto val = 0;
         if (from_hex_to_i(s, i + 1, 2, val)) {
           // 2 digits hex codes
           result += static_cast<char>(val);
@@ -2260,16 +2570,30 @@ inline std::string trim_copy(const std::string &s) {
   return s.substr(r.first, r.second - r.first);
 }
 
+inline std::string trim_double_quotes_copy(const std::string &s) {
+  if (s.length() >= 2 && s.front() == '"' && s.back() == '"') {
+    return s.substr(1, s.size() - 2);
+  }
+  return s;
+}
+
 inline void split(const char *b, const char *e, char d,
                   std::function<void(const char *, const char *)> fn) {
+  return split(b, e, d, (std::numeric_limits<size_t>::max)(), std::move(fn));
+}
+
+inline void split(const char *b, const char *e, char d, size_t m,
+                  std::function<void(const char *, const char *)> fn) {
   size_t i = 0;
   size_t beg = 0;
+  size_t count = 1;
 
   while (e ? (b + i < e) : (b[i] != '\0')) {
-    if (b[i] == d) {
+    if (b[i] == d && count < m) {
       auto r = trim(b, e, beg, i);
       if (r.first < r.second) { fn(&b[r.first], &b[r.second]); }
       beg = i + 1;
+      count++;
     }
     i++;
   }
@@ -2345,6 +2669,97 @@ inline void stream_line_reader::append(char c) {
   }
 }
 
+inline mmap::mmap(const char *path)
+#if defined(_WIN32)
+    : hFile_(NULL), hMapping_(NULL)
+#else
+    : fd_(-1)
+#endif
+      ,
+      size_(0), addr_(nullptr) {
+  open(path);
+}
+
+inline mmap::~mmap() { close(); }
+
+inline bool mmap::open(const char *path) {
+  close();
+
+#if defined(_WIN32)
+  hFile_ = ::CreateFileA(path, GENERIC_READ, FILE_SHARE_READ, NULL,
+                         OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
+
+  if (hFile_ == INVALID_HANDLE_VALUE) { return false; }
+
+  size_ = ::GetFileSize(hFile_, NULL);
+
+  hMapping_ = ::CreateFileMapping(hFile_, NULL, PAGE_READONLY, 0, 0, NULL);
+
+  if (hMapping_ == NULL) {
+    close();
+    return false;
+  }
+
+  addr_ = ::MapViewOfFile(hMapping_, FILE_MAP_READ, 0, 0, 0);
+#else
+  fd_ = ::open(path, O_RDONLY);
+  if (fd_ == -1) { return false; }
+
+  struct stat sb;
+  if (fstat(fd_, &sb) == -1) {
+    close();
+    return false;
+  }
+  size_ = static_cast<size_t>(sb.st_size);
+
+  addr_ = ::mmap(NULL, size_, PROT_READ, MAP_PRIVATE, fd_, 0);
+#endif
+
+  if (addr_ == nullptr) {
+    close();
+    return false;
+  }
+
+  return true;
+}
+
+inline bool mmap::is_open() const { return addr_ != nullptr; }
+
+inline size_t mmap::size() const { return size_; }
+
+inline const char *mmap::data() const {
+  return static_cast<const char *>(addr_);
+}
+
+inline void mmap::close() {
+#if defined(_WIN32)
+  if (addr_) {
+    ::UnmapViewOfFile(addr_);
+    addr_ = nullptr;
+  }
+
+  if (hMapping_) {
+    ::CloseHandle(hMapping_);
+    hMapping_ = NULL;
+  }
+
+  if (hFile_ != INVALID_HANDLE_VALUE) {
+    ::CloseHandle(hFile_);
+    hFile_ = INVALID_HANDLE_VALUE;
+  }
+#else
+  if (addr_ != nullptr) {
+    munmap(addr_, size_);
+    addr_ = nullptr;
+  }
+
+  if (fd_ != -1) {
+    ::close(fd_);
+    fd_ = -1;
+  }
+#endif
+  size_ = 0;
+}
 inline int close_socket(socket_t sock) {
 #ifdef _WIN32
   return closesocket(sock);
@@ -2354,7 +2769,7 @@ inline int close_socket(socket_t sock) {
 }
 
 template <typename T> inline ssize_t handle_EINTR(T fn) {
-  ssize_t res = false;
+  ssize_t res = 0;
   while (true) {
     res = fn();
     if (res < 0 && errno == EINTR) { continue; }
@@ -2399,7 +2814,7 @@ inline ssize_t select_read(socket_t sock, time_t sec, time_t usec) {
   return handle_EINTR([&]() { return poll(&pfd_read, 1, timeout); });
 #else
 #ifndef _WIN32
-  if (sock >= FD_SETSIZE) { return 1; }
+  if (sock >= FD_SETSIZE) { return -1; }
 #endif
 
   fd_set fds;
@@ -2427,7 +2842,7 @@ inline ssize_t select_write(socket_t sock, time_t sec, time_t usec) {
   return handle_EINTR([&]() { return poll(&pfd_read, 1, timeout); });
 #else
 #ifndef _WIN32
-  if (sock >= FD_SETSIZE) { return 1; }
+  if (sock >= FD_SETSIZE) { return -1; }
 #endif
 
   fd_set fds;
@@ -2458,7 +2873,7 @@ inline Error wait_until_socket_is_ready(socket_t sock, time_t sec,
   if (poll_res == 0) { return Error::ConnectionTimeout; }
 
   if (poll_res > 0 && pfd_read.revents & (POLLIN | POLLOUT)) {
-    int error = 0;
+    auto error = 0;
     socklen_t len = sizeof(error);
     auto res = getsockopt(sock, SOL_SOCKET, SO_ERROR,
                           reinterpret_cast<char *>(&error), &len);
@@ -2490,7 +2905,7 @@ inline Error wait_until_socket_is_ready(socket_t sock, time_t sec,
   if (ret == 0) { return Error::ConnectionTimeout; }
 
   if (ret > 0 && (FD_ISSET(sock, &fdsr) || FD_ISSET(sock, &fdsw))) {
-    int error = 0;
+    auto error = 0;
     socklen_t len = sizeof(error);
     auto res = getsockopt(sock, SOL_SOCKET, SO_ERROR,
                           reinterpret_cast<char *>(&error), &len);
@@ -2537,7 +2952,7 @@ class SocketStream : public Stream {
   size_t read_buff_off_ = 0;
   size_t read_buff_content_size_ = 0;
 
-  static const size_t read_buff_size_ = 1024 * 4;
+  static const size_t read_buff_size_ = 1024l * 4;
 };
 
 #ifdef CPPHTTPLIB_OPENSSL_SUPPORT
@@ -2666,7 +3081,7 @@ socket_t create_socket(const std::string &host, const std::string &ip, int port,
 #ifndef _WIN32
   if (hints.ai_family == AF_UNIX) {
     const auto addrlen = host.length();
-    if (addrlen > sizeof(sockaddr_un::sun_path)) return INVALID_SOCKET;
+    if (addrlen > sizeof(sockaddr_un::sun_path)) { return INVALID_SOCKET; }
 
     auto sock = socket(hints.ai_family, hints.ai_socktype, hints.ai_protocol);
     if (sock != INVALID_SOCKET) {
@@ -2735,17 +3150,27 @@ socket_t create_socket(const std::string &host, const std::string &ip, int port,
 #endif
 
     if (tcp_nodelay) {
-      int yes = 1;
-      setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, reinterpret_cast<char *>(&yes),
-                 sizeof(yes));
+      auto yes = 1;
+#ifdef _WIN32
+      setsockopt(sock, IPPROTO_TCP, TCP_NODELAY,
+                 reinterpret_cast<const char *>(&yes), sizeof(yes));
+#else
+      setsockopt(sock, IPPROTO_TCP, TCP_NODELAY,
+                 reinterpret_cast<const void *>(&yes), sizeof(yes));
+#endif
     }
 
     if (socket_options) { socket_options(sock); }
 
     if (rp->ai_family == AF_INET6) {
-      int no = 0;
-      setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, reinterpret_cast<char *>(&no),
-                 sizeof(no));
+      auto no = 0;
+#ifdef _WIN32
+      setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY,
+                 reinterpret_cast<const char *>(&no), sizeof(no));
+#else
+      setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY,
+                 reinterpret_cast<const void *>(&no), sizeof(no));
+#endif
     }
 
     // bind or connect
@@ -2804,7 +3229,7 @@ inline bool bind_ip_address(socket_t sock, const std::string &host) {
   return ret;
 }
 
-#if !defined _WIN32 && !defined ANDROID && !defined _AIX
+#if !defined _WIN32 && !defined ANDROID && !defined _AIX && !defined __MVS__
 #define USE_IF2IP
 #endif
 
@@ -2860,7 +3285,7 @@ inline socket_t create_client_socket(
 #ifdef USE_IF2IP
           auto ip_from_if = if2ip(address_family, intf);
           if (ip_from_if.empty()) { ip_from_if = intf; }
-          if (!bind_ip_address(sock2, ip_from_if.c_str())) {
+          if (!bind_ip_address(sock2, ip_from_if)) {
             error = Error::BindIPAddress;
             return false;
           }
@@ -2888,13 +3313,14 @@ inline socket_t create_client_socket(
 #ifdef _WIN32
           auto timeout = static_cast<uint32_t>(read_timeout_sec * 1000 +
                                                read_timeout_usec / 1000);
-          setsockopt(sock2, SOL_SOCKET, SO_RCVTIMEO, (char *)&timeout,
-                     sizeof(timeout));
+          setsockopt(sock2, SOL_SOCKET, SO_RCVTIMEO,
+                     reinterpret_cast<const char *>(&timeout), sizeof(timeout));
 #else
           timeval tv;
           tv.tv_sec = static_cast<long>(read_timeout_sec);
           tv.tv_usec = static_cast<decltype(tv.tv_usec)>(read_timeout_usec);
-          setsockopt(sock2, SOL_SOCKET, SO_RCVTIMEO, (char *)&tv, sizeof(tv));
+          setsockopt(sock2, SOL_SOCKET, SO_RCVTIMEO,
+                     reinterpret_cast<const void *>(&tv), sizeof(tv));
 #endif
         }
         {
@@ -2902,13 +3328,14 @@ inline socket_t create_client_socket(
 #ifdef _WIN32
           auto timeout = static_cast<uint32_t>(write_timeout_sec * 1000 +
                                                write_timeout_usec / 1000);
-          setsockopt(sock2, SOL_SOCKET, SO_SNDTIMEO, (char *)&timeout,
-                     sizeof(timeout));
+          setsockopt(sock2, SOL_SOCKET, SO_SNDTIMEO,
+                     reinterpret_cast<const char *>(&timeout), sizeof(timeout));
 #else
           timeval tv;
           tv.tv_sec = static_cast<long>(write_timeout_sec);
           tv.tv_usec = static_cast<decltype(tv.tv_usec)>(write_timeout_usec);
-          setsockopt(sock2, SOL_SOCKET, SO_SNDTIMEO, (char *)&tv, sizeof(tv));
+          setsockopt(sock2, SOL_SOCKET, SO_SNDTIMEO,
+                     reinterpret_cast<const void *>(&tv), sizeof(tv));
 #endif
         }
 
@@ -3008,18 +3435,20 @@ inline constexpr unsigned int operator"" _t(const char *s, size_t l) {
 
 } // namespace udl
 
-inline const char *
+inline std::string
 find_content_type(const std::string &path,
-                  const std::map<std::string, std::string> &user_data) {
+                  const std::map<std::string, std::string> &user_data,
+                  const std::string &default_content_type) {
   auto ext = file_extension(path);
 
   auto it = user_data.find(ext);
-  if (it != user_data.end()) { return it->second.c_str(); }
+  if (it != user_data.end()) { return it->second; }
 
   using udl::operator""_t;
 
   switch (str2tag(ext)) {
-  default: return nullptr;
+  default: return default_content_type;
+
   case "css"_t: return "text/css";
   case "csv"_t: return "text/csv";
   case "htm"_t:
@@ -3072,76 +3501,6 @@ find_content_type(const std::string &path,
   }
 }
 
-inline const char *status_message(int status) {
-  switch (status) {
-  case 100: return "Continue";
-  case 101: return "Switching Protocol";
-  case 102: return "Processing";
-  case 103: return "Early Hints";
-  case 200: return "OK";
-  case 201: return "Created";
-  case 202: return "Accepted";
-  case 203: return "Non-Authoritative Information";
-  case 204: return "No Content";
-  case 205: return "Reset Content";
-  case 206: return "Partial Content";
-  case 207: return "Multi-Status";
-  case 208: return "Already Reported";
-  case 226: return "IM Used";
-  case 300: return "Multiple Choice";
-  case 301: return "Moved Permanently";
-  case 302: return "Found";
-  case 303: return "See Other";
-  case 304: return "Not Modified";
-  case 305: return "Use Proxy";
-  case 306: return "unused";
-  case 307: return "Temporary Redirect";
-  case 308: return "Permanent Redirect";
-  case 400: return "Bad Request";
-  case 401: return "Unauthorized";
-  case 402: return "Payment Required";
-  case 403: return "Forbidden";
-  case 404: return "Not Found";
-  case 405: return "Method Not Allowed";
-  case 406: return "Not Acceptable";
-  case 407: return "Proxy Authentication Required";
-  case 408: return "Request Timeout";
-  case 409: return "Conflict";
-  case 410: return "Gone";
-  case 411: return "Length Required";
-  case 412: return "Precondition Failed";
-  case 413: return "Payload Too Large";
-  case 414: return "URI Too Long";
-  case 415: return "Unsupported Media Type";
-  case 416: return "Range Not Satisfiable";
-  case 417: return "Expectation Failed";
-  case 418: return "I'm a teapot";
-  case 421: return "Misdirected Request";
-  case 422: return "Unprocessable Entity";
-  case 423: return "Locked";
-  case 424: return "Failed Dependency";
-  case 425: return "Too Early";
-  case 426: return "Upgrade Required";
-  case 428: return "Precondition Required";
-  case 429: return "Too Many Requests";
-  case 431: return "Request Header Fields Too Large";
-  case 451: return "Unavailable For Legal Reasons";
-  case 501: return "Not Implemented";
-  case 502: return "Bad Gateway";
-  case 503: return "Service Unavailable";
-  case 504: return "Gateway Timeout";
-  case 505: return "HTTP Version Not Supported";
-  case 506: return "Variant Also Negotiates";
-  case 507: return "Insufficient Storage";
-  case 508: return "Loop Detected";
-  case 510: return "Not Extended";
-  case 511: return "Network Authentication Required";
-
-  default:
-  case 500: return "Internal Server Error";
-  }
-}
-
 inline bool can_compress_content_type(const std::string &content_type) {
   using udl::operator""_t;
 
@@ -3218,7 +3577,7 @@ inline bool gzip_compressor::compress(const char *data, size_t data_length,
     data += strm_.avail_in;
 
     auto flush = (last && data_length == 0) ? Z_FINISH : Z_NO_FLUSH;
-    int ret = Z_OK;
+    auto ret = Z_OK;
 
     std::array<char, CPPHTTPLIB_COMPRESSION_BUFSIZ> buff{};
     do {
@@ -3262,7 +3621,7 @@ inline bool gzip_decompressor::decompress(const char *data, size_t data_length,
                                           Callback callback) {
   assert(is_valid_);
 
-  int ret = Z_OK;
+  auto ret = Z_OK;
 
   do {
     constexpr size_t max_avail_in =
@@ -3276,16 +3635,12 @@ inline bool gzip_decompressor::decompress(const char *data, size_t data_length,
     data += strm_.avail_in;
 
     std::array<char, CPPHTTPLIB_COMPRESSION_BUFSIZ> buff{};
-    while (strm_.avail_in > 0) {
+    while (strm_.avail_in > 0 && ret == Z_OK) {
       strm_.avail_out = static_cast<uInt>(buff.size());
       strm_.next_out = reinterpret_cast<Bytef *>(buff.data());
 
-      auto prev_avail_in = strm_.avail_in;
-
       ret = inflate(&strm_, Z_NO_FLUSH);
 
-      if (prev_avail_in - strm_.avail_in == 0) { return false; }
-
       assert(ret != Z_STREAM_ERROR);
       switch (ret) {
       case Z_NEED_DICT:
@@ -3298,7 +3653,7 @@ inline bool gzip_decompressor::decompress(const char *data, size_t data_length,
       }
     }
 
-    if (ret != Z_OK && ret != Z_STREAM_END) return false;
+    if (ret != Z_OK && ret != Z_STREAM_END) { return false; }
 
   } while (data_length > 0);
 
@@ -3367,7 +3722,7 @@ inline bool brotli_decompressor::decompress(const char *data,
     return 0;
   }
 
-  const uint8_t *next_in = (const uint8_t *)data;
+  auto next_in = reinterpret_cast<const uint8_t *>(data);
   size_t avail_in = data_length;
   size_t total_out;
 
@@ -3437,6 +3792,9 @@ inline bool parse_header(const char *beg, const char *end, T fn) {
   }
 
   if (p < end) {
+    auto key_len = key_end - beg;
+    if (!key_len) { return false; }
+
     auto key = std::string(beg, key_end);
     auto val = compare_case_ignore(key, "Location")
                    ? std::string(p, end)
@@ -3526,11 +3884,7 @@ inline bool read_content_without_length(Stream &strm,
   uint64_t r = 0;
   for (;;) {
     auto n = strm.read(buf, CPPHTTPLIB_RECV_BUFSIZ);
-    if (n < 0) {
-      return false;
-    } else if (n == 0) {
-      return true;
-    }
+    if (n <= 0) { return true; }
 
     if (!out(buf, static_cast<size_t>(n), r, 0)) { return false; }
     r += static_cast<uint64_t>(n);
@@ -3566,7 +3920,7 @@ inline bool read_content_chunked(Stream &strm, T &x,
 
     if (!line_reader.getline()) { return false; }
 
-    if (strcmp(line_reader.ptr(), "\r\n")) { return false; }
+    if (strcmp(line_reader.ptr(), "\r\n") != 0) { return false; }
 
     if (!line_reader.getline()) { return false; }
   }
@@ -3576,7 +3930,7 @@ inline bool read_content_chunked(Stream &strm, T &x,
   // Trailer
   if (!line_reader.getline()) { return false; }
 
-  while (strcmp(line_reader.ptr(), "\r\n")) {
+  while (strcmp(line_reader.ptr(), "\r\n") != 0) {
     if (line_reader.size() > CPPHTTPLIB_HEADER_MAX_LENGTH) { return false; }
 
     // Exclude line terminator
@@ -3595,8 +3949,8 @@ inline bool read_content_chunked(Stream &strm, T &x,
 }
 
 inline bool is_chunked_transfer_encoding(const Headers &headers) {
-  return !strcasecmp(get_header_value(headers, "Transfer-Encoding", 0, ""),
-                     "chunked");
+  return compare_case_ignore(
+      get_header_value(headers, "Transfer-Encoding", 0, ""), "chunked");
 }
 
 template <typename T, typename U>
@@ -3611,14 +3965,14 @@ bool prepare_content_receiver(T &x, int &status,
 #ifdef CPPHTTPLIB_ZLIB_SUPPORT
       decompressor = detail::make_unique<gzip_decompressor>();
 #else
-      status = 415;
+      status = StatusCode::UnsupportedMediaType_415;
       return false;
 #endif
     } else if (encoding.find("br") != std::string::npos) {
 #ifdef CPPHTTPLIB_BROTLI_SUPPORT
       decompressor = detail::make_unique<brotli_decompressor>();
 #else
-      status = 415;
+      status = StatusCode::UnsupportedMediaType_415;
       return false;
 #endif
     }
@@ -3634,7 +3988,7 @@ bool prepare_content_receiver(T &x, int &status,
         };
         return callback(std::move(out));
       } else {
-        status = 500;
+        status = StatusCode::InternalServerError_500;
         return false;
       }
     }
@@ -3662,7 +4016,7 @@ bool read_content(Stream &strm, T &x, size_t payload_max_length, int &status,
         } else if (!has_header(x.headers, "Content-Length")) {
           ret = read_content_without_length(strm, out);
         } else {
-          auto len = get_header_value<uint64_t>(x.headers, "Content-Length");
+          auto len = get_header_value_u64(x.headers, "Content-Length", 0, 0);
           if (len > payload_max_length) {
             exceed_payload_max_length = true;
             skip_content_with_length(strm, len);
@@ -3672,7 +4026,10 @@ bool read_content(Stream &strm, T &x, size_t payload_max_length, int &status,
           }
         }
 
-        if (!ret) { status = exceed_payload_max_length ? 413 : 400; }
+        if (!ret) {
+          status = exceed_payload_max_length ? StatusCode::PayloadTooLarge_413
+                                             : StatusCode::BadRequest_400;
+        }
         return ret;
       });
 } // namespace detail
@@ -3720,6 +4077,8 @@ inline bool write_content(Stream &strm, const ContentProvider &content_provider,
     return ok;
   };
 
+  data_sink.is_writable = [&]() -> bool { return strm.is_writable(); };
+
   while (offset < end_offset && !is_shutting_down()) {
     if (!strm.is_writable()) {
       error = Error::Write;
@@ -3764,6 +4123,8 @@ write_content_without_length(Stream &strm,
     return ok;
   };
 
+  data_sink.is_writable = [&]() -> bool { return strm.is_writable(); };
+
   data_sink.done = [&](void) { data_available = false; };
 
   while (data_available && !is_shutting_down()) {
@@ -3814,6 +4175,8 @@ write_content_chunked(Stream &strm, const ContentProvider &content_provider,
     return ok;
   };
 
+  data_sink.is_writable = [&]() -> bool { return strm.is_writable(); };
+
   auto done_with_trailer = [&](const Headers *trailer) {
     if (!ok) { return; }
 
@@ -3898,7 +4261,8 @@ inline bool redirect(T &cli, Request &req, Response &res,
   new_req.path = path;
   new_req.redirect_count_ -= 1;
 
-  if (res.status == 303 && (req.method != "GET" && req.method != "HEAD")) {
+  if (res.status == StatusCode::SeeOther_303 &&
+      (req.method != "GET" && req.method != "HEAD")) {
     new_req.method = "GET";
     new_req.body.clear();
     new_req.headers.clear();
@@ -3910,7 +4274,8 @@ inline bool redirect(T &cli, Request &req, Response &res,
   if (ret) {
     req = new_req;
     res = new_res;
-    res.location = location;
+
+    if (res.location.empty()) { res.location = location; }
   }
   return ret;
 }
@@ -3957,14 +4322,34 @@ inline bool parse_multipart_boundary(const std::string &content_type,
   if (pos == std::string::npos) { return false; }
   auto end = content_type.find(';', pos);
   auto beg = pos + strlen(boundary_keyword);
-  boundary = content_type.substr(beg, end - beg);
-  if (boundary.length() >= 2 && boundary.front() == '"' &&
-      boundary.back() == '"') {
-    boundary = boundary.substr(1, boundary.size() - 2);
-  }
+  boundary = trim_double_quotes_copy(content_type.substr(beg, end - beg));
   return !boundary.empty();
 }
 
+inline void parse_disposition_params(const std::string &s, Params &params) {
+  std::set<std::string> cache;
+  split(s.data(), s.data() + s.size(), ';', [&](const char *b, const char *e) {
+    std::string kv(b, e);
+    if (cache.find(kv) != cache.end()) { return; }
+    cache.insert(kv);
+
+    std::string key;
+    std::string val;
+    split(b, e, '=', [&](const char *b2, const char *e2) {
+      if (key.empty()) {
+        key.assign(b2, e2);
+      } else {
+        val.assign(b2, e2);
+      }
+    });
+
+    if (!key.empty()) {
+      params.emplace(trim_double_quotes_copy((key)),
+                     trim_double_quotes_copy((val)));
+    }
+  });
+}
+
 #ifdef CPPHTTPLIB_NO_EXCEPTIONS
 inline bool parse_range_header(const std::string &s, Ranges &ranges) {
 #else
@@ -3975,9 +4360,9 @@ inline bool parse_range_header(const std::string &s, Ranges &ranges) try {
   if (std::regex_match(s, m, re_first_range)) {
     auto pos = static_cast<size_t>(m.position(1));
     auto len = static_cast<size_t>(m.length(1));
-    bool all_valid_ranges = true;
+    auto all_valid_ranges = true;
     split(&s[pos], &s[pos + len], ',', [&](const char *b, const char *e) {
-      if (!all_valid_ranges) return;
+      if (!all_valid_ranges) { return; }
       static auto re_another_range = std::regex(R"(\s*(\d*)-(\d*))");
       std::cmatch cm;
       if (std::regex_match(b, e, cm, re_another_range)) {
@@ -4022,11 +4407,6 @@ class MultipartFormDataParser {
   bool parse(const char *buf, size_t n, const ContentReceiver &content_callback,
              const MultipartContentHeader &header_callback) {
 
-    // TODO: support 'filename*'
-    static const std::regex re_content_disposition(
-        R"~(^Content-Disposition:\s*form-data;\s*name="(.*?)"(?:;\s*filename="(.*?)")?(?:;\s*filename\*=\S+)?\s*$)~",
-        std::regex_constants::icase);
-
     buf_append(buf, n);
 
     while (buf_size() > 0) {
@@ -4059,18 +4439,54 @@ class MultipartFormDataParser {
             break;
           }
 
-          static const std::string header_name = "content-type:";
           const auto header = buf_head(pos);
-          if (start_with_case_ignore(header, header_name)) {
-            file_.content_type = trim_copy(header.substr(header_name.size()));
+
+          if (!parse_header(header.data(), header.data() + header.size(),
+                            [&](std::string &&, std::string &&) {})) {
+            is_valid_ = false;
+            return false;
+          }
+
+          static const std::string header_content_type = "Content-Type:";
+
+          if (start_with_case_ignore(header, header_content_type)) {
+            file_.content_type =
+                trim_copy(header.substr(header_content_type.size()));
           } else {
+            static const std::regex re_content_disposition(
+                R"~(^Content-Disposition:\s*form-data;\s*(.*)$)~",
+                std::regex_constants::icase);
+
             std::smatch m;
             if (std::regex_match(header, m, re_content_disposition)) {
-              file_.name = m[1];
-              file_.filename = m[2];
-            } else {
-              is_valid_ = false;
-              return false;
+              Params params;
+              parse_disposition_params(m[1], params);
+
+              auto it = params.find("name");
+              if (it != params.end()) {
+                file_.name = it->second;
+              } else {
+                is_valid_ = false;
+                return false;
+              }
+
+              it = params.find("filename");
+              if (it != params.end()) { file_.filename = it->second; }
+
+              it = params.find("filename*");
+              if (it != params.end()) {
+                // Only allow UTF-8 enconnding...
+                static const std::regex re_rfc5987_encoding(
+                    R"~(^UTF-8''(.+?)$)~", std::regex_constants::icase);
+
+                std::smatch m2;
+                if (std::regex_match(it->second, m2, re_rfc5987_encoding)) {
+                  file_.filename = decode_url(m2[1], false); // override...
+                } else {
+                  is_valid_ = false;
+                  return false;
+                }
+              }
             }
           }
           buf_erase(pos + crlf_.size());
@@ -4108,9 +4524,9 @@ class MultipartFormDataParser {
           buf_erase(crlf_.size());
           state_ = 1;
         } else {
-          if (dash_crlf_.size() > buf_size()) { return true; }
-          if (buf_start_with(dash_crlf_)) {
-            buf_erase(dash_crlf_.size());
+          if (dash_.size() > buf_size()) { return true; }
+          if (buf_start_with(dash_)) {
+            buf_erase(dash_.size());
             is_valid_ = true;
             buf_erase(buf_size()); // Remove epilogue
           } else {
@@ -4143,7 +4559,6 @@ class MultipartFormDataParser {
 
   const std::string dash_ = "--";
   const std::string crlf_ = "\r\n";
-  const std::string dash_crlf_ = "--\r\n";
   std::string boundary_;
   std::string dash_boundary_crlf_;
   std::string crlf_dash_boundary_;
@@ -4230,28 +4645,32 @@ inline std::string to_lower(const char *beg, const char *end) {
   return out;
 }
 
-inline std::string make_multipart_data_boundary() {
+inline std::string random_string(size_t length) {
   static const char data[] =
       "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
 
   // std::random_device might actually be deterministic on some
   // platforms, but due to lack of support in the c++ standard library,
   // doing better requires either some ugly hacks or breaking portability.
-  std::random_device seed_gen;
+  static std::random_device seed_gen;
 
   // Request 128 bits of entropy for initialization
-  std::seed_seq seed_sequence{seed_gen(), seed_gen(), seed_gen(), seed_gen()};
-  std::mt19937 engine(seed_sequence);
+  static std::seed_seq seed_sequence{seed_gen(), seed_gen(), seed_gen(),
+                                     seed_gen()};
 
-  std::string result = "--cpp-httplib-multipart-data-";
+  static std::mt19937 engine(seed_sequence);
 
-  for (auto i = 0; i < 16; i++) {
+  std::string result;
+  for (size_t i = 0; i < length; i++) {
     result += data[engine() % (sizeof(data) - 1)];
   }
-
   return result;
 }
 
+inline std::string make_multipart_data_boundary() {
+  return "--cpp-httplib-multipart-data-" + detail::random_string(16);
+}
+
 inline bool is_multipart_boundary_chars_valid(const std::string &boundary) {
   auto valid = true;
   for (size_t i = 0; i < boundary.size(); i++) {
@@ -4304,48 +4723,96 @@ serialize_multipart_formdata(const MultipartFormDataItems &items,
     body += item.content + serialize_multipart_formdata_item_end();
   }
 
-  if (finish) body += serialize_multipart_formdata_finish(boundary);
+  if (finish) { body += serialize_multipart_formdata_finish(boundary); }
 
   return body;
 }
 
-inline std::pair<size_t, size_t>
-get_range_offset_and_length(const Request &req, size_t content_length,
-                            size_t index) {
-  auto r = req.ranges[index];
+inline bool range_error(Request &req, Response &res) {
+  if (!req.ranges.empty() && 200 <= res.status && res.status < 300) {
+    ssize_t contant_len = static_cast<ssize_t>(
+        res.content_length_ ? res.content_length_ : res.body.size());
 
-  if (r.first == -1 && r.second == -1) {
-    return std::make_pair(0, content_length);
-  }
+    ssize_t prev_first_pos = -1;
+    ssize_t prev_last_pos = -1;
+    size_t overwrapping_count = 0;
+
+    // NOTE: The following Range check is based on '14.2. Range' in RFC 9110
+    // 'HTTP Semantics' to avoid potential denial-of-service attacks.
+    // https://www.rfc-editor.org/rfc/rfc9110#section-14.2
+
+    // Too many ranges
+    if (req.ranges.size() > CPPHTTPLIB_RANGE_MAX_COUNT) { return true; }
 
-  auto slen = static_cast<ssize_t>(content_length);
+    for (auto &r : req.ranges) {
+      auto &first_pos = r.first;
+      auto &last_pos = r.second;
 
-  if (r.first == -1) {
-    r.first = (std::max)(static_cast<ssize_t>(0), slen - r.second);
-    r.second = slen - 1;
+      if (first_pos == -1 && last_pos == -1) {
+        first_pos = 0;
+        last_pos = contant_len;
+      }
+
+      if (first_pos == -1) {
+        first_pos = contant_len - last_pos;
+        last_pos = contant_len - 1;
+      }
+
+      if (last_pos == -1) { last_pos = contant_len - 1; }
+
+      // Range must be within content length
+      if (!(0 <= first_pos && first_pos <= last_pos &&
+            last_pos <= contant_len - 1)) {
+        return true;
+      }
+
+      // Ranges must be in ascending order
+      if (first_pos <= prev_first_pos) { return true; }
+
+      // Request must not have more than two overlapping ranges
+      if (first_pos <= prev_last_pos) {
+        overwrapping_count++;
+        if (overwrapping_count > 2) { return true; }
+      }
+
+      prev_first_pos = (std::max)(prev_first_pos, first_pos);
+      prev_last_pos = (std::max)(prev_last_pos, last_pos);
+    }
   }
 
-  if (r.second == -1) { r.second = slen - 1; }
+  return false;
+}
+
+inline std::pair<size_t, size_t>
+get_range_offset_and_length(Range r, size_t content_length) {
+  assert(r.first != -1 && r.second != -1);
+  assert(0 <= r.first && r.first < static_cast<ssize_t>(content_length));
+  assert(r.first <= r.second &&
+         r.second < static_cast<ssize_t>(content_length));
+
   return std::make_pair(r.first, static_cast<size_t>(r.second - r.first) + 1);
 }
 
-inline std::string make_content_range_header_field(size_t offset, size_t length,
-                                                   size_t content_length) {
+inline std::string make_content_range_header_field(
+    const std::pair<size_t, size_t> &offset_and_length, size_t content_length) {
+  auto st = offset_and_length.first;
+  auto ed = st + offset_and_length.second - 1;
+
   std::string field = "bytes ";
-  field += std::to_string(offset);
+  field += std::to_string(st);
   field += "-";
-  field += std::to_string(offset + length - 1);
+  field += std::to_string(ed);
   field += "/";
   field += std::to_string(content_length);
   return field;
 }
 
 template <typename SToken, typename CToken, typename Content>
-bool process_multipart_ranges_data(const Request &req, Response &res,
+bool process_multipart_ranges_data(const Request &req,
                                    const std::string &boundary,
                                    const std::string &content_type,
-                                   SToken stoken, CToken ctoken,
-                                   Content content) {
+                                   size_t content_length, SToken stoken,
+                                   CToken ctoken, Content content) {
   for (size_t i = 0; i < req.ranges.size(); i++) {
     ctoken("--");
     stoken(boundary);
@@ -4356,50 +4823,51 @@ bool process_multipart_ranges_data(const Request &req, Response &res,
       ctoken("\r\n");
     }
 
-    auto offsets = get_range_offset_and_length(req, res.body.size(), i);
-    auto offset = offsets.first;
-    auto length = offsets.second;
+    auto offset_and_length =
+        get_range_offset_and_length(req.ranges[i], content_length);
 
     ctoken("Content-Range: ");
-    stoken(make_content_range_header_field(offset, length, res.body.size()));
+    stoken(make_content_range_header_field(offset_and_length, content_length));
     ctoken("\r\n");
     ctoken("\r\n");
-    if (!content(offset, length)) { return false; }
+
+    if (!content(offset_and_length.first, offset_and_length.second)) {
+      return false;
+    }
     ctoken("\r\n");
   }
 
   ctoken("--");
   stoken(boundary);
-  ctoken("--\r\n");
+  ctoken("--");
 
   return true;
 }
 
-inline bool make_multipart_ranges_data(const Request &req, Response &res,
+inline void make_multipart_ranges_data(const Request &req, Response &res,
                                        const std::string &boundary,
                                        const std::string &content_type,
+                                       size_t content_length,
                                        std::string &data) {
-  return process_multipart_ranges_data(
-      req, res, boundary, content_type,
+  process_multipart_ranges_data(
+      req, boundary, content_type, content_length,
       [&](const std::string &token) { data += token; },
       [&](const std::string &token) { data += token; },
       [&](size_t offset, size_t length) {
-        if (offset < res.body.size()) {
-          data += res.body.substr(offset, length);
-          return true;
-        }
-        return false;
+        assert(offset + length <= content_length);
+        data += res.body.substr(offset, length);
+        return true;
       });
 }
 
-inline size_t
-get_multipart_ranges_data_length(const Request &req, Response &res,
-                                 const std::string &boundary,
-                                 const std::string &content_type) {
+inline size_t get_multipart_ranges_data_length(const Request &req,
+                                               const std::string &boundary,
+                                               const std::string &content_type,
+                                               size_t content_length) {
   size_t data_length = 0;
 
   process_multipart_ranges_data(
-      req, res, boundary, content_type,
+      req, boundary, content_type, content_length,
       [&](const std::string &token) { data_length += token.size(); },
       [&](const std::string &token) { data_length += token.size(); },
       [&](size_t /*offset*/, size_t length) {
@@ -4411,13 +4879,13 @@ get_multipart_ranges_data_length(const Request &req, Response &res,
 }
 
 template <typename T>
-inline bool write_multipart_ranges_data(Stream &strm, const Request &req,
-                                        Response &res,
-                                        const std::string &boundary,
-                                        const std::string &content_type,
-                                        const T &is_shutting_down) {
+inline bool
+write_multipart_ranges_data(Stream &strm, const Request &req, Response &res,
+                            const std::string &boundary,
+                            const std::string &content_type,
+                            size_t content_length, const T &is_shutting_down) {
   return process_multipart_ranges_data(
-      req, res, boundary, content_type,
+      req, boundary, content_type, content_length,
       [&](const std::string &token) { strm.write(token); },
       [&](const std::string &token) { strm.write(token); },
       [&](size_t offset, size_t length) {
@@ -4426,18 +4894,6 @@ inline bool write_multipart_ranges_data(Stream &strm, const Request &req,
       });
 }
 
-inline std::pair<size_t, size_t>
-get_range_offset_and_length(const Request &req, const Response &res,
-                            size_t index) {
-  auto r = req.ranges[index];
-
-  if (r.second == -1) {
-    r.second = static_cast<ssize_t>(res.content_length_) - 1;
-  }
-
-  return std::make_pair(r.first, r.second - r.first + 1);
-}
-
 inline bool expect_content(const Request &req) {
   if (req.method == "POST" || req.method == "PUT" || req.method == "PATCH" ||
       req.method == "PRI" || req.method == "DELETE") {
@@ -4471,7 +4927,7 @@ inline std::string message_digest(const std::string &s, const EVP_MD *algo) {
   std::stringstream ss;
   for (auto i = 0u; i < hash_length; ++i) {
     ss << std::hex << std::setw(2) << std::setfill('0')
-       << (unsigned int)hash[i];
+       << static_cast<unsigned int>(hash[i]);
   }
 
   return ss.str();
@@ -4564,7 +5020,7 @@ inline bool retrieve_root_certs_from_keychain(CFObjectPtr<CFArrayRef> &certs) {
 
 inline bool add_certs_to_x509_store(CFArrayRef certs, X509_STORE *store) {
   auto result = false;
-  for (int i = 0; i < CFArrayGetCount(certs); ++i) {
+  for (auto i = 0; i < CFArrayGetCount(certs); ++i) {
     const auto cert = reinterpret_cast<const __SecCertificate *>(
         CFArrayGetValueAtIndex(certs, i));
 
@@ -4707,7 +5163,7 @@ inline bool parse_www_authenticate(const Response &res,
         s = s.substr(pos + 1);
         auto beg = std::sregex_iterator(s.begin(), s.end(), re);
         for (auto i = beg; i != std::sregex_iterator(); ++i) {
-          auto m = *i;
+          const auto &m = *i;
           auto key = s.substr(static_cast<size_t>(m.position(1)),
                               static_cast<size_t>(m.length(1)));
           auto val = m.length(2) > 0
@@ -4724,20 +5180,6 @@ inline bool parse_www_authenticate(const Response &res,
   return false;
 }
 
-// https://stackoverflow.com/questions/440133/how-do-i-create-a-random-alpha-numeric-string-in-c/440240#answer-440240
-inline std::string random_string(size_t length) {
-  auto randchar = []() -> char {
-    const char charset[] = "0123456789"
-                           "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
-                           "abcdefghijklmnopqrstuvwxyz";
-    const size_t max_index = (sizeof(charset) - 1);
-    return charset[static_cast<size_t>(std::rand()) % max_index];
-  };
-  std::string str(length, 0);
-  std::generate_n(str.begin(), length, randchar);
-  return str;
-}
-
 class ContentProviderAdapter {
 public:
   explicit ContentProviderAdapter(
@@ -4782,7 +5224,7 @@ inline void hosted_at(const std::string &hostname,
     const auto &addr =
         *reinterpret_cast<struct sockaddr_storage *>(rp->ai_addr);
     std::string ip;
-    int dummy = -1;
+    auto dummy = -1;
     if (detail::get_ip_and_port(addr, sizeof(struct sockaddr_storage), ip,
                                 dummy)) {
       addrs.push_back(ip);
@@ -4802,10 +5244,11 @@ inline std::string append_query_params(const std::string &path,
 }
 
 // Header utilities
-inline std::pair<std::string, std::string> make_range_header(Ranges ranges) {
+inline std::pair<std::string, std::string>
+make_range_header(const Ranges &ranges) {
   std::string field = "bytes=";
   auto i = 0;
-  for (auto r : ranges) {
+  for (const auto &r : ranges) {
     if (i != 0) { field += ", "; }
     if (r.first != -1) { field += std::to_string(r.first); }
     field += '-';
@@ -4924,7 +5367,7 @@ inline void Response::set_redirect(const std::string &url, int stat) {
     if (300 <= stat && stat < 400) {
       this->status = stat;
     } else {
-      this->status = 302;
+      this->status = StatusCode::Found_302;
     }
   }
 }
@@ -4943,13 +5386,22 @@ inline void Response::set_content(const std::string &s,
   set_content(s.data(), s.size(), content_type);
 }
 
+inline void Response::set_content(std::string &&s,
+                                  const std::string &content_type) {
+  body = std::move(s);
+
+  auto rng = headers.equal_range("Content-Type");
+  headers.erase(rng.first, rng.second);
+  set_header("Content-Type", content_type);
+}
+
 inline void Response::set_content_provider(
     size_t in_length, const std::string &content_type, ContentProvider provider,
     ContentProviderResourceReleaser resource_releaser) {
   set_header("Content-Type", content_type);
   content_length_ = in_length;
   if (in_length > 0) { content_provider_ = std::move(provider); }
-  content_provider_resource_releaser_ = resource_releaser;
+  content_provider_resource_releaser_ = std::move(resource_releaser);
   is_chunked_content_provider_ = false;
 }
 
@@ -4959,7 +5411,7 @@ inline void Response::set_content_provider(
   set_header("Content-Type", content_type);
   content_length_ = 0;
   content_provider_ = detail::ContentProviderAdapter(std::move(provider));
-  content_provider_resource_releaser_ = resource_releaser;
+  content_provider_resource_releaser_ = std::move(resource_releaser);
   is_chunked_content_provider_ = false;
 }
 
@@ -4969,7 +5421,7 @@ inline void Response::set_chunked_content_provider(
   set_header("Content-Type", content_type);
   content_length_ = 0;
   content_provider_ = detail::ContentProviderAdapter(std::move(provider));
-  content_provider_resource_releaser_ = resource_releaser;
+  content_provider_resource_releaser_ = std::move(resource_releaser);
   is_chunked_content_provider_ = true;
 }
 
@@ -5010,7 +5462,7 @@ inline SocketStream::SocketStream(socket_t sock, time_t read_timeout_sec,
       write_timeout_sec_(write_timeout_sec),
       write_timeout_usec_(write_timeout_usec), read_buff_(read_buff_size_, 0) {}
 
-inline SocketStream::~SocketStream() {}
+inline SocketStream::~SocketStream() = default;
 
 inline bool SocketStream::is_readable() const {
   return select_read(sock_, read_timeout_sec_, read_timeout_usec_) > 0;
@@ -5120,6 +5572,99 @@ inline socket_t BufferStream::socket() const { return 0; }
 
 inline const std::string &BufferStream::get_buffer() const { return buffer; }
 
+inline PathParamsMatcher::PathParamsMatcher(const std::string &pattern) {
+  // One past the last ending position of a path param substring
+  std::size_t last_param_end = 0;
+
+#ifndef CPPHTTPLIB_NO_EXCEPTIONS
+  // Needed to ensure that parameter names are unique during matcher
+  // construction
+  // If exceptions are disabled, only last duplicate path
+  // parameter will be set
+  std::unordered_set<std::string> param_name_set;
+#endif
+
+  while (true) {
+    const auto marker_pos = pattern.find(marker, last_param_end);
+    if (marker_pos == std::string::npos) { break; }
+
+    static_fragments_.push_back(
+        pattern.substr(last_param_end, marker_pos - last_param_end));
+
+    const auto param_name_start = marker_pos + 1;
+
+    auto sep_pos = pattern.find(separator, param_name_start);
+    if (sep_pos == std::string::npos) { sep_pos = pattern.length(); }
+
+    auto param_name =
+        pattern.substr(param_name_start, sep_pos - param_name_start);
+
+#ifndef CPPHTTPLIB_NO_EXCEPTIONS
+    if (param_name_set.find(param_name) != param_name_set.cend()) {
+      std::string msg = "Encountered path parameter '" + param_name +
+                        "' multiple times in route pattern '" + pattern + "'.";
+      throw std::invalid_argument(msg);
+    }
+#endif
+
+    param_names_.push_back(std::move(param_name));
+
+    last_param_end = sep_pos + 1;
+  }
+
+  if (last_param_end < pattern.length()) {
+    static_fragments_.push_back(pattern.substr(last_param_end));
+  }
+}
+
+inline bool PathParamsMatcher::match(Request &request) const {
+  request.matches = std::smatch();
+  request.path_params.clear();
+  request.path_params.reserve(param_names_.size());
+
+  // One past the position at which the path matched the pattern last time
+  std::size_t starting_pos = 0;
+  for (size_t i = 0; i < static_fragments_.size(); ++i) {
+    const auto &fragment = static_fragments_[i];
+
+    if (starting_pos + fragment.length() > request.path.length()) {
+      return false;
+    }
+
+    // Avoid unnecessary allocation by using strncmp instead of substr +
+    // comparison
+    if (std::strncmp(request.path.c_str() + starting_pos, fragment.c_str(),
+                     fragment.length()) != 0) {
+      return false;
+    }
+
+    starting_pos += fragment.length();
+
+    // Should only happen when we have a static fragment after a param
+    // Example: '/users/:id/subscriptions'
+    // The 'subscriptions' fragment here does not have a corresponding param
+    if (i >= param_names_.size()) { continue; }
+
+    auto sep_pos = request.path.find(separator, starting_pos);
+    if (sep_pos == std::string::npos) { sep_pos = request.path.length(); }
+
+    const auto &param_name = param_names_[i];
+
+    request.path_params.emplace(
+        param_name, request.path.substr(starting_pos, sep_pos - starting_pos));
+
+    // Mark everythin up to '/' as matched
+    starting_pos = sep_pos + 1;
+  }
+  // Returns false if the path is longer than the pattern
+  return starting_pos >= request.path.length();
+}
+
+inline bool RegexMatcher::match(Request &request) const {
+  request.path_params.clear();
+  return std::regex_match(request.path, request.matches, regex_);
+}
+
 } // namespace detail
 
 // HTTP server implementation
@@ -5131,69 +5676,72 @@ inline Server::Server()
 #endif
 }
 
-inline Server::~Server() {}
+inline Server::~Server() = default;
+
+inline std::unique_ptr<detail::MatcherBase>
+Server::make_matcher(const std::string &pattern) {
+  if (pattern.find("/:") != std::string::npos) {
+    return detail::make_unique<detail::PathParamsMatcher>(pattern);
+  } else {
+    return detail::make_unique<detail::RegexMatcher>(pattern);
+  }
+}
 
 inline Server &Server::Get(const std::string &pattern, Handler handler) {
-  get_handlers_.push_back(
-      std::make_pair(std::regex(pattern), std::move(handler)));
+  get_handlers_.emplace_back(make_matcher(pattern), std::move(handler));
   return *this;
 }
 
 inline Server &Server::Post(const std::string &pattern, Handler handler) {
-  post_handlers_.push_back(
-      std::make_pair(std::regex(pattern), std::move(handler)));
+  post_handlers_.emplace_back(make_matcher(pattern), std::move(handler));
   return *this;
 }
 
 inline Server &Server::Post(const std::string &pattern,
                             HandlerWithContentReader handler) {
-  post_handlers_for_content_reader_.push_back(
-      std::make_pair(std::regex(pattern), std::move(handler)));
+  post_handlers_for_content_reader_.emplace_back(make_matcher(pattern),
+                                                 std::move(handler));
   return *this;
 }
 
 inline Server &Server::Put(const std::string &pattern, Handler handler) {
-  put_handlers_.push_back(
-      std::make_pair(std::regex(pattern), std::move(handler)));
+  put_handlers_.emplace_back(make_matcher(pattern), std::move(handler));
   return *this;
 }
 
 inline Server &Server::Put(const std::string &pattern,
                            HandlerWithContentReader handler) {
-  put_handlers_for_content_reader_.push_back(
-      std::make_pair(std::regex(pattern), std::move(handler)));
+  put_handlers_for_content_reader_.emplace_back(make_matcher(pattern),
+                                                std::move(handler));
   return *this;
 }
 
 inline Server &Server::Patch(const std::string &pattern, Handler handler) {
-  patch_handlers_.push_back(
-      std::make_pair(std::regex(pattern), std::move(handler)));
+  patch_handlers_.emplace_back(make_matcher(pattern), std::move(handler));
   return *this;
 }
 
 inline Server &Server::Patch(const std::string &pattern,
                              HandlerWithContentReader handler) {
-  patch_handlers_for_content_reader_.push_back(
-      std::make_pair(std::regex(pattern), std::move(handler)));
+  patch_handlers_for_content_reader_.emplace_back(make_matcher(pattern),
+                                                  std::move(handler));
   return *this;
 }
 
 inline Server &Server::Delete(const std::string &pattern, Handler handler) {
-  delete_handlers_.push_back(
-      std::make_pair(std::regex(pattern), std::move(handler)));
+  delete_handlers_.emplace_back(make_matcher(pattern), std::move(handler));
   return *this;
 }
 
 inline Server &Server::Delete(const std::string &pattern,
                               HandlerWithContentReader handler) {
-  delete_handlers_for_content_reader_.push_back(
-      std::make_pair(std::regex(pattern), std::move(handler)));
+  delete_handlers_for_content_reader_.emplace_back(make_matcher(pattern),
+                                                   std::move(handler));
   return *this;
 }
 
 inline Server &Server::Options(const std::string &pattern, Handler handler) {
-  options_handlers_.push_back(
-      std::make_pair(std::regex(pattern), std::move(handler)));
+  options_handlers_.emplace_back(make_matcher(pattern), std::move(handler));
   return *this;
 }
 
@@ -5231,6 +5779,11 @@ Server::set_file_extension_and_mimetype_mapping(const std::string &ext,
   return *this;
 }
 
+inline Server &Server::set_default_file_mimetype(const std::string &mime) {
+  default_file_mimetype_ = mime;
+  return *this;
+}
+
 inline Server &Server::set_file_request_handler(Handler handler) {
   file_request_handler_ = std::move(handler);
   return *this;
@@ -5272,7 +5825,6 @@ inline Server &Server::set_logger(Logger logger) {
 inline Server &
 Server::set_expect_100_continue_handler(Expect100ContinueHandler handler) {
   expect_100_continue_handler_ = std::move(handler);
-
   return *this;
 }
 
@@ -5296,6 +5848,12 @@ inline Server &Server::set_default_headers(Headers headers) {
   return *this;
 }
 
+inline Server &Server::set_header_writer(
+    std::function<ssize_t(Stream &, Headers &)> const &writer) {
+  header_writer_ = writer;
+  return *this;
+}
+
 inline Server &Server::set_keep_alive_max_count(size_t count) {
   keep_alive_max_count_ = count;
   return *this;
@@ -5331,8 +5889,7 @@ inline Server &Server::set_payload_max_length(size_t length) {
 
 inline bool Server::bind_to_port(const std::string &host, int port,
                                  int socket_flags) {
-  if (bind_internal(host, port, socket_flags) < 0) return false;
-  return true;
+  return bind_internal(host, port, socket_flags) >= 0;
 }
 inline int Server::bind_to_any_port(const std::string &host, int socket_flags) {
   return bind_internal(host, 0, socket_flags);
@@ -5366,7 +5923,7 @@ inline void Server::stop() {
   }
 }
 
-inline bool Server::parse_request_line(const char *s, Request &req) {
+inline bool Server::parse_request_line(const char *s, Request &req) const {
   auto len = strlen(s);
   if (len < 2 || s[len - 2] != '\r' || s[len - 1] != '\n') { return false; }
   len -= 2;
@@ -5407,7 +5964,7 @@ inline bool Server::parse_request_line(const char *s, Request &req) {
     size_t count = 0;
 
     detail::split(req.target.data(), req.target.data() + req.target.size(), '?',
-                  [&](const char *b, const char *e) {
+                  2, [&](const char *b, const char *e) {
                     switch (count) {
                     case 0:
                       req.path = detail::decode_url(std::string(b, e), false);
@@ -5430,7 +5987,10 @@ inline bool Server::parse_request_line(const char *s, Request &req) {
 }
 
 inline bool Server::write_response(Stream &strm, bool close_connection,
-                                   const Request &req, Response &res) {
+                                   Request &req, Response &res) {
+  // NOTE: `req.ranges` should be empty, otherwise it will be applied
+  // incorrectly to the error content.
+  req.ranges.clear();
   return write_response_core(strm, close_connection, req, res, false);
 }
 
@@ -5486,11 +6046,11 @@ inline bool Server::write_response_core(Stream &strm, bool close_connection,
     detail::BufferStream bstrm;
 
     if (!bstrm.write_format("HTTP/1.1 %d %s\r\n", res.status,
-                            detail::status_message(res.status))) {
+                            status_message(res.status))) {
       return false;
     }
 
-    if (!detail::write_headers(bstrm, res.headers)) { return false; }
+    if (!header_writer_(bstrm, res.headers)) { return false; }
 
     // Flush buffer
     auto &data = bstrm.get_buffer();
@@ -5508,7 +6068,6 @@ inline bool Server::write_response_core(Stream &strm, bool close_connection,
       if (write_content_with_provider(strm, req, res, boundary, content_type)) {
         res.content_provider_success_ = true;
       } else {
-        res.content_provider_success_ = false;
         ret = false;
       }
     }
@@ -5533,15 +6092,16 @@ Server::write_content_with_provider(Stream &strm, const Request &req,
       return detail::write_content(strm, res.content_provider_, 0,
                                    res.content_length_, is_shutting_down);
     } else if (req.ranges.size() == 1) {
-      auto offsets =
-          detail::get_range_offset_and_length(req, res.content_length_, 0);
-      auto offset = offsets.first;
-      auto length = offsets.second;
-      return detail::write_content(strm, res.content_provider_, offset, length,
-                                   is_shutting_down);
+      auto offset_and_length = detail::get_range_offset_and_length(
+          req.ranges[0], res.content_length_);
+
+      return detail::write_content(strm, res.content_provider_,
+                                   offset_and_length.first,
+                                   offset_and_length.second, is_shutting_down);
     } else {
       return detail::write_multipart_ranges_data(
-          strm, req, res, boundary, content_type, is_shutting_down);
+          strm, req, res, boundary, content_type, res.content_length_,
+          is_shutting_down);
     }
   } else {
     if (res.is_chunked_content_provider_) {
@@ -5598,7 +6158,7 @@ inline bool Server::read_content(Stream &strm, Request &req, Response &res) {
     const auto &content_type = req.get_header_value("Content-Type");
     if (!content_type.find("application/x-www-form-urlencoded")) {
       if (req.body.size() > CPPHTTPLIB_FORM_URL_ENCODED_PAYLOAD_MAX_LENGTH) {
-        res.status = 413; // NOTE: should be 414?
+        res.status = StatusCode::PayloadTooLarge_413; // NOTE: should be 414?
         return false;
       }
       detail::parse_query_text(req.body, req.params);
@@ -5617,10 +6177,11 @@ inline bool Server::read_content_with_content_receiver(
                            std::move(multipart_receiver));
 }
 
-inline bool Server::read_content_core(Stream &strm, Request &req, Response &res,
-                                      ContentReceiver receiver,
-                                      MultipartContentHeader multipart_header,
-                                      ContentReceiver multipart_receiver) {
+inline bool
+Server::read_content_core(Stream &strm, Request &req, Response &res,
+                          ContentReceiver receiver,
+                          MultipartContentHeader multipart_header,
+                          ContentReceiver multipart_receiver) const {
   detail::MultipartFormDataParser multipart_form_data_parser;
   ContentReceiverWithProgress out;
 
@@ -5628,7 +6189,7 @@ inline bool Server::read_content_core(Stream &strm, Request &req, Response &res,
     const auto &content_type = req.get_header_value("Content-Type");
     std::string boundary;
     if (!detail::parse_multipart_boundary(content_type, boundary)) {
-      res.status = 400;
+      res.status = StatusCode::BadRequest_400;
       return false;
     }
 
@@ -5664,7 +6225,7 @@ inline bool Server::read_content_core(Stream &strm, Request &req, Response &res,
 
   if (req.is_multipart_form_data()) {
     if (!multipart_form_data_parser.is_valid()) {
-      res.status = 400;
+      res.status = StatusCode::BadRequest_400;
       return false;
     }
   }
@@ -5683,17 +6244,26 @@ inline bool Server::handle_file_request(const Request &req, Response &res,
         if (path.back() == '/') { path += "index.html"; }
 
         if (detail::is_file(path)) {
-          detail::read_file(path, res.body);
-          auto type =
-              detail::find_content_type(path, file_extension_and_mimetype_map_);
-          if (type) { res.set_header("Content-Type", type); }
           for (const auto &kv : entry.headers) {
-            res.set_header(kv.first.c_str(), kv.second);
+            res.set_header(kv.first, kv.second);
           }
-          res.status = req.has_header("Range") ? 206 : 200;
+
+          auto mm = std::make_shared<detail::mmap>(path.c_str());
+          if (!mm->is_open()) { return false; }
+
+          res.set_content_provider(
+              mm->size(),
+              detail::find_content_type(path, file_extension_and_mimetype_map_,
+                                        default_file_mimetype_),
+              [mm](size_t offset, size_t length, DataSink &sink) -> bool {
+                sink.write(mm->data() + offset, length);
+                return true;
+              });
+
           if (!head && file_request_handler_) {
             file_request_handler_(req, res);
           }
+
           return true;
         }
       }
@@ -5789,13 +6359,14 @@ inline bool Server::listen_internal() {
 #ifdef _WIN32
         auto timeout = static_cast<uint32_t>(read_timeout_sec_ * 1000 +
                                              read_timeout_usec_ / 1000);
-        setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, (char *)&timeout,
-                   sizeof(timeout));
+        setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO,
+                   reinterpret_cast<const char *>(&timeout), sizeof(timeout));
 #else
         timeval tv;
         tv.tv_sec = static_cast<long>(read_timeout_sec_);
         tv.tv_usec = static_cast<decltype(tv.tv_usec)>(read_timeout_usec_);
-        setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, (char *)&tv, sizeof(tv));
+        setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO,
+                   reinterpret_cast<const void *>(&tv), sizeof(tv));
 #endif
       }
       {
@@ -5803,17 +6374,22 @@ inline bool Server::listen_internal() {
 #ifdef _WIN32
         auto timeout = static_cast<uint32_t>(write_timeout_sec_ * 1000 +
                                              write_timeout_usec_ / 1000);
-        setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO, (char *)&timeout,
-                   sizeof(timeout));
+        setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO,
+                   reinterpret_cast<const char *>(&timeout), sizeof(timeout));
 #else
         timeval tv;
         tv.tv_sec = static_cast<long>(write_timeout_sec_);
         tv.tv_usec = static_cast<decltype(tv.tv_usec)>(write_timeout_usec_);
-        setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO, (char *)&tv, sizeof(tv));
+        setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO,
+                   reinterpret_cast<const void *>(&tv), sizeof(tv));
 #endif
       }
 
-      task_queue->enqueue([this, sock]() { process_and_close_socket(sock); });
+      if (!task_queue->enqueue(
+              [this, sock]() { process_and_close_socket(sock); })) {
+        detail::shutdown_socket(sock);
+        detail::close_socket(sock);
+      }
     }
 
     task_queue->shutdown();
@@ -5829,7 +6405,7 @@ inline bool Server::routing(Request &req, Response &res, Stream &strm) {
   }
 
   // File handler
-  bool is_head_request = req.method == "HEAD";
+  auto is_head_request = req.method == "HEAD";
   if ((req.method == "GET" || is_head_request) &&
       handle_file_request(req, res, is_head_request)) {
     return true;
@@ -5895,17 +6471,17 @@ inline bool Server::routing(Request &req, Response &res, Stream &strm) {
     return dispatch_request(req, res, patch_handlers_);
   }
 
-  res.status = 400;
+  res.status = StatusCode::BadRequest_400;
   return false;
 }
 
 inline bool Server::dispatch_request(Request &req, Response &res,
-                                     const Handlers &handlers) {
+                                     const Handlers &handlers) const {
   for (const auto &x : handlers) {
-    const auto &pattern = x.first;
+    const auto &matcher = x.first;
     const auto &handler = x.second;
 
-    if (std::regex_match(req.path, req.matches, pattern)) {
+    if (matcher->match(req)) {
       handler(req, res);
       return true;
     }
@@ -5915,18 +6491,18 @@ inline bool Server::dispatch_request(Request &req, Response &res,
 
 inline void Server::apply_ranges(const Request &req, Response &res,
                                  std::string &content_type,
-                                 std::string &boundary) {
+                                 std::string &boundary) const {
   if (req.ranges.size() > 1) {
-    boundary = detail::make_multipart_data_boundary();
-
     auto it = res.headers.find("Content-Type");
     if (it != res.headers.end()) {
       content_type = it->second;
       res.headers.erase(it);
     }
 
-    res.headers.emplace("Content-Type",
-                        "multipart/byteranges; boundary=" + boundary);
+    boundary = detail::make_multipart_data_boundary();
+
+    res.set_header("Content-Type",
+                   "multipart/byteranges; boundary=" + boundary);
   }
 
   auto type = detail::encoding_type(req, res);
@@ -5937,16 +6513,17 @@ inline void Server::apply_ranges(const Request &req, Response &res,
       if (req.ranges.empty()) {
         length = res.content_length_;
       } else if (req.ranges.size() == 1) {
-        auto offsets =
-            detail::get_range_offset_and_length(req, res.content_length_, 0);
-        auto offset = offsets.first;
-        length = offsets.second;
+        auto offset_and_length = detail::get_range_offset_and_length(
+            req.ranges[0], res.content_length_);
+
+        length = offset_and_length.second;
+
         auto content_range = detail::make_content_range_header_field(
-            offset, length, res.content_length_);
+            offset_and_length, res.content_length_);
         res.set_header("Content-Range", content_range);
       } else {
-        length = detail::get_multipart_ranges_data_length(req, res, boundary,
-                                                          content_type);
+        length = detail::get_multipart_ranges_data_length(
+            req, boundary, content_type, res.content_length_);
       }
       res.set_header("Content-Length", std::to_string(length));
     } else {
@@ -5965,28 +6542,22 @@ inline void Server::apply_ranges(const Request &req, Response &res,
     if (req.ranges.empty()) {
       ;
     } else if (req.ranges.size() == 1) {
-      auto offsets =
-          detail::get_range_offset_and_length(req, res.body.size(), 0);
-      auto offset = offsets.first;
-      auto length = offsets.second;
+      auto offset_and_length =
+          detail::get_range_offset_and_length(req.ranges[0], res.body.size());
+      auto offset = offset_and_length.first;
+      auto length = offset_and_length.second;
+
       auto content_range = detail::make_content_range_header_field(
-          offset, length, res.body.size());
+          offset_and_length, res.body.size());
       res.set_header("Content-Range", content_range);
-      if (offset < res.body.size()) {
-        res.body = res.body.substr(offset, length);
-      } else {
-        res.body.clear();
-        res.status = 416;
-      }
+
+      assert(offset + length <= res.body.size());
+      res.body = res.body.substr(offset, length);
     } else {
       std::string data;
-      if (detail::make_multipart_ranges_data(req, res, boundary, content_type,
-                                             data)) {
-        res.body.swap(data);
-      } else {
-        res.body.clear();
-        res.status = 416;
-      }
+      detail::make_multipart_ranges_data(req, res, boundary, content_type,
+                                         res.body.size(), data);
+      res.body.swap(data);
     }
 
     if (type != detail::EncodingType::None) {
@@ -6025,12 +6596,12 @@ inline void Server::apply_ranges(const Request &req, Response &res,
 
 inline bool Server::dispatch_request_for_content_reader(
     Request &req, Response &res, ContentReader content_reader,
-    const HandlersForContentReader &handlers) {
+    const HandlersForContentReader &handlers) const {
   for (const auto &x : handlers) {
-    const auto &pattern = x.first;
+    const auto &matcher = x.first;
     const auto &handler = x.second;
 
-    if (std::regex_match(req.path, req.matches, pattern)) {
+    if (matcher->match(req)) {
       handler(req, res, content_reader);
       return true;
     }
@@ -6050,15 +6621,10 @@ Server::process_request(Stream &strm, bool close_connection,
   if (!line_reader.getline()) { return false; }
 
   Request req;
-  Response res;
 
+  Response res;
   res.version = "HTTP/1.1";
-
-  for (const auto &header : default_headers_) {
-    if (res.headers.find(header.first) == res.headers.end()) {
-      res.headers.insert(header);
-    }
-  }
+  res.headers = default_headers_;
 
 #ifdef _WIN32
   // TODO: Increase FD_SETSIZE statically (libzmq), dynamically (MySQL).
@@ -6068,7 +6634,7 @@ Server::process_request(Stream &strm, bool close_connection,
   if (strm.socket() >= FD_SETSIZE) {
     Headers dummy;
     detail::read_headers(strm, dummy);
-    res.status = 500;
+    res.status = StatusCode::InternalServerError_500;
     return write_response(strm, close_connection, req, res);
   }
 #endif
@@ -6078,14 +6644,14 @@ Server::process_request(Stream &strm, bool close_connection,
   if (line_reader.size() > CPPHTTPLIB_REQUEST_URI_MAX_LENGTH) {
     Headers dummy;
     detail::read_headers(strm, dummy);
-    res.status = 414;
+    res.status = StatusCode::UriTooLong_414;
     return write_response(strm, close_connection, req, res);
   }
 
   // Request line and headers
   if (!parse_request_line(line_reader.ptr(), req) ||
       !detail::read_headers(strm, req.headers)) {
-    res.status = 400;
+    res.status = StatusCode::BadRequest_400;
     return write_response(strm, close_connection, req, res);
   }
 
@@ -6109,7 +6675,7 @@ Server::process_request(Stream &strm, bool close_connection,
   if (req.has_header("Range")) {
     const auto &range_header_value = req.get_header_value("Range");
     if (!detail::parse_range_header(range_header_value, req.ranges)) {
-      res.status = 416;
+      res.status = StatusCode::RangeNotSatisfiable_416;
       return write_response(strm, close_connection, req, res);
     }
   }
@@ -6117,22 +6683,22 @@ Server::process_request(Stream &strm, bool close_connection,
   if (setup_request) { setup_request(req); }
 
   if (req.get_header_value("Expect") == "100-continue") {
-    auto status = 100;
+    int status = StatusCode::Continue_100;
     if (expect_100_continue_handler_) {
       status = expect_100_continue_handler_(req, res);
     }
     switch (status) {
-    case 100:
-    case 417:
+    case StatusCode::Continue_100:
+    case StatusCode::ExpectationFailed_417:
       strm.write_format("HTTP/1.1 %d %s\r\n\r\n", status,
-                        detail::status_message(status));
+                        status_message(status));
       break;
     default: return write_response(strm, close_connection, req, res);
     }
   }
 
-  // Rounting
-  bool routed = false;
+  // Routing
+  auto routed = false;
 #ifdef CPPHTTPLIB_NO_EXCEPTIONS
   routed = routing(req, res, strm);
 #else
@@ -6144,7 +6710,7 @@ Server::process_request(Stream &strm, bool close_connection,
       exception_handler_(req, res, ep);
       routed = true;
     } else {
-      res.status = 500;
+      res.status = StatusCode::InternalServerError_500;
       std::string val;
       auto s = e.what();
       for (size_t i = 0; s[i]; i++) {
@@ -6162,17 +6728,29 @@ Server::process_request(Stream &strm, bool close_connection,
       exception_handler_(req, res, ep);
       routed = true;
     } else {
-      res.status = 500;
+      res.status = StatusCode::InternalServerError_500;
       res.set_header("EXCEPTION_WHAT", "UNKNOWN");
     }
   }
 #endif
-
   if (routed) {
-    if (res.status == -1) { res.status = req.ranges.empty() ? 200 : 206; }
+    if (res.status == -1) {
+      res.status = req.ranges.empty() ? StatusCode::OK_200
+                                      : StatusCode::PartialContent_206;
+    }
+
+    if (detail::range_error(req, res)) {
+      res.body.clear();
+      res.content_length_ = 0;
+      res.content_provider_ = nullptr;
+      res.status = StatusCode::RangeNotSatisfiable_416;
+      return write_response(strm, close_connection, req, res);
+    }
+
     return write_response_with_content(strm, close_connection, req, res);
   } else {
-    if (res.status == -1) { res.status = 404; }
+    if (res.status == -1) { res.status = StatusCode::NotFound_404; }
+
     return write_response(strm, close_connection, req, res);
   }
 }
@@ -6272,7 +6850,7 @@ inline socket_t ClientImpl::create_client_socket(Error &error) const {
   // Check is custom IP specified for host_
   std::string ip;
   auto it = addr_map_.find(host_);
-  if (it != addr_map_.end()) ip = it->second;
+  if (it != addr_map_.end()) { ip = it->second; }
 
   return detail::create_client_socket(
       host_, ip, port_, address_family_, tcp_nodelay_, socket_options_,
@@ -6297,7 +6875,7 @@ inline void ClientImpl::shutdown_ssl(Socket & /*socket*/,
          socket_requests_are_from_thread_ == std::this_thread::get_id());
 }
 
-inline void ClientImpl::shutdown_socket(Socket &socket) {
+inline void ClientImpl::shutdown_socket(Socket &socket) const {
   if (socket.sock == INVALID_SOCKET) { return; }
   detail::shutdown_socket(socket.sock);
 }
@@ -6322,7 +6900,7 @@ inline void ClientImpl::close_socket(Socket &socket) {
 }
 
 inline bool ClientImpl::read_response_line(Stream &strm, const Request &req,
-                                           Response &res) {
+                                           Response &res) const {
   std::array<char, 2048> buf{};
 
   detail::stream_line_reader line_reader(strm, buf.data(), buf.size());
@@ -6330,9 +6908,9 @@ inline bool ClientImpl::read_response_line(Stream &strm, const Request &req,
   if (!line_reader.getline()) { return false; }
 
 #ifdef CPPHTTPLIB_ALLOW_LF_AS_LINE_TERMINATOR
-  const static std::regex re("(HTTP/1\\.[01]) (\\d{3})(?: (.*?))?\r\n");
-#else
   const static std::regex re("(HTTP/1\\.[01]) (\\d{3})(?: (.*?))?\r?\n");
+#else
+  const static std::regex re("(HTTP/1\\.[01]) (\\d{3})(?: (.*?))?\r\n");
 #endif
 
   std::cmatch m;
@@ -6344,7 +6922,7 @@ inline bool ClientImpl::read_response_line(Stream &strm, const Request &req,
   res.reason = std::string(m[3]);
 
   // Ignore '100 Continue'
-  while (res.status == 100) {
+  while (res.status == StatusCode::Continue_100) {
     if (!line_reader.getline()) { return false; } // CRLF
     if (!line_reader.getline()) { return false; } // next response line
 
@@ -6492,15 +7070,31 @@ inline bool ClientImpl::handle_request(Stream &strm, Request &req,
 
   if (!ret) { return false; }
 
+  if (res.get_header_value("Connection") == "close" ||
+      (res.version == "HTTP/1.0" && res.reason != "Connection established")) {
+    // TODO this requires a not-entirely-obvious chain of calls to be correct
+    // for this to be safe.
+
+    // This is safe to call because handle_request is only called by send_
+    // which locks the request mutex during the process. It would be a bug
+    // to call it from a different thread since it's a thread-safety issue
+    // to do these things to the socket if another thread is using the socket.
+    std::lock_guard<std::mutex> guard(socket_mutex_);
+    shutdown_ssl(socket_, true);
+    shutdown_socket(socket_);
+    close_socket(socket_);
+  }
+
   if (300 < res.status && res.status < 400 && follow_location_) {
     req = req_save;
     ret = redirect(req, res, error);
   }
 
 #ifdef CPPHTTPLIB_OPENSSL_SUPPORT
-  if ((res.status == 401 || res.status == 407) &&
+  if ((res.status == StatusCode::Unauthorized_401 ||
+       res.status == StatusCode::ProxyAuthenticationRequired_407) &&
       req.authorization_count_ < 5) {
-    auto is_proxy = res.status == 407;
+    auto is_proxy = res.status == StatusCode::ProxyAuthenticationRequired_407;
     const auto &username =
         is_proxy ? proxy_digest_auth_username_ : digest_auth_username_;
     const auto &password =
@@ -6571,7 +7165,7 @@ inline bool ClientImpl::redirect(Request &req, Response &res, Error &error) {
   } else {
     if (next_scheme == "https") {
 #ifdef CPPHTTPLIB_OPENSSL_SUPPORT
-      SSLClient cli(next_host.c_str(), next_port);
+      SSLClient cli(next_host, next_port);
       cli.copy_settings(*this);
       if (ca_cert_store_) { cli.set_ca_cert_store(ca_cert_store_); }
       return detail::redirect(cli, req, res, path, location, error);
@@ -6579,7 +7173,7 @@ inline bool ClientImpl::redirect(Request &req, Response &res, Error &error) {
       return false;
 #endif
     } else {
-      ClientImpl cli(next_host.c_str(), next_port);
+      ClientImpl cli(next_host, next_port);
       cli.copy_settings(*this);
       return detail::redirect(cli, req, res, path, location, error);
     }
@@ -6588,7 +7182,7 @@ inline bool ClientImpl::redirect(Request &req, Response &res, Error &error) {
 
 inline bool ClientImpl::write_content_with_provider(Stream &strm,
                                                     const Request &req,
-                                                    Error &error) {
+                                                    Error &error) const {
   auto is_shutting_down = []() { return false; };
 
   if (req.is_chunked_content_provider_) {
@@ -6616,32 +7210,32 @@ inline bool ClientImpl::write_request(Stream &strm, Request &req,
   // Prepare additional headers
   if (close_connection) {
     if (!req.has_header("Connection")) {
-      req.headers.emplace("Connection", "close");
+      req.set_header("Connection", "close");
     }
   }
 
   if (!req.has_header("Host")) {
     if (is_ssl()) {
       if (port_ == 443) {
-        req.headers.emplace("Host", host_);
+        req.set_header("Host", host_);
       } else {
-        req.headers.emplace("Host", host_and_port_);
+        req.set_header("Host", host_and_port_);
       }
     } else {
       if (port_ == 80) {
-        req.headers.emplace("Host", host_);
+        req.set_header("Host", host_);
       } else {
-        req.headers.emplace("Host", host_and_port_);
+        req.set_header("Host", host_and_port_);
       }
     }
   }
 
-  if (!req.has_header("Accept")) { req.headers.emplace("Accept", "*/*"); }
+  if (!req.has_header("Accept")) { req.set_header("Accept", "*/*"); }
 
 #ifndef CPPHTTPLIB_NO_DEFAULT_USER_AGENT
   if (!req.has_header("User-Agent")) {
     auto agent = std::string("cpp-httplib/") + CPPHTTPLIB_VERSION;
-    req.headers.emplace("User-Agent", agent);
+    req.set_header("User-Agent", agent);
   }
 #endif
 
@@ -6650,23 +7244,23 @@ inline bool ClientImpl::write_request(Stream &strm, Request &req,
       if (!req.is_chunked_content_provider_) {
         if (!req.has_header("Content-Length")) {
           auto length = std::to_string(req.content_length_);
-          req.headers.emplace("Content-Length", length);
+          req.set_header("Content-Length", length);
         }
       }
     } else {
       if (req.method == "POST" || req.method == "PUT" ||
           req.method == "PATCH") {
-        req.headers.emplace("Content-Length", "0");
+        req.set_header("Content-Length", "0");
       }
     }
   } else {
     if (!req.has_header("Content-Type")) {
-      req.headers.emplace("Content-Type", "text/plain");
+      req.set_header("Content-Type", "text/plain");
     }
 
     if (!req.has_header("Content-Length")) {
       auto length = std::to_string(req.body.size());
-      req.headers.emplace("Content-Length", length);
+      req.set_header("Content-Length", length);
     }
   }
 
@@ -6706,7 +7300,7 @@ inline bool ClientImpl::write_request(Stream &strm, Request &req,
     const auto &path = url_encode_ ? detail::encode_url(req.path) : req.path;
     bstrm.write_format("%s %s HTTP/1.1\r\n", req.method.c_str(), path.c_str());
 
-    detail::write_headers(bstrm, req.headers);
+    header_writer_(bstrm, req.headers);
 
     // Flush buffer
     auto &data = bstrm.get_buffer();
@@ -6734,12 +7328,10 @@ inline std::unique_ptr<Response> ClientImpl::send_with_content_provider(
     ContentProvider content_provider,
     ContentProviderWithoutLength content_provider_without_length,
     const std::string &content_type, Error &error) {
-  if (!content_type.empty()) {
-    req.headers.emplace("Content-Type", content_type);
-  }
+  if (!content_type.empty()) { req.set_header("Content-Type", content_type); }
 
 #ifdef CPPHTTPLIB_ZLIB_SUPPORT
-  if (compress_) { req.headers.emplace("Content-Encoding", "gzip"); }
+  if (compress_) { req.set_header("Content-Encoding", "gzip"); }
 #endif
 
 #ifdef CPPHTTPLIB_ZLIB_SUPPORT
@@ -6800,10 +7392,9 @@ inline std::unique_ptr<Response> ClientImpl::send_with_content_provider(
       req.content_provider_ = detail::ContentProviderAdapter(
           std::move(content_provider_without_length));
       req.is_chunked_content_provider_ = true;
-      req.headers.emplace("Transfer-Encoding", "chunked");
+      req.set_header("Transfer-Encoding", "chunked");
     } else {
       req.body.assign(body, content_length);
-      ;
     }
   }
 
@@ -6864,7 +7455,8 @@ inline bool ClientImpl::process_request(Stream &strm, Request &req,
   }
 
   // Body
-  if ((res.status != 204) && req.method != "HEAD" && req.method != "CONNECT") {
+  if ((res.status != StatusCode::NoContent_204) && req.method != "HEAD" &&
+      req.method != "CONNECT") {
     auto redirect = 300 < res.status && res.status < 400 && follow_location_;
 
     if (req.response_handler && !redirect) {
@@ -6909,24 +7501,6 @@ inline bool ClientImpl::process_request(Stream &strm, Request &req,
     }
   }
 
-  if (res.get_header_value("Connection") == "close" ||
-      (res.version == "HTTP/1.0" && res.reason != "Connection established")) {
-    // TODO this requires a not-entirely-obvious chain of calls to be correct
-    // for this to be safe. Maybe a code refactor (such as moving this out to
-    // the send function and getting rid of the recursiveness of the mutex)
-    // could make this more obvious.
-
-    // This is safe to call because process_request is only called by
-    // handle_request which is only called by send, which locks the request
-    // mutex during the process. It would be a bug to call it from a different
-    // thread since it's a thread-safety issue to do these things to the socket
-    // if another thread is using the socket.
-    std::lock_guard<std::mutex> guard(socket_mutex_);
-    shutdown_ssl(socket_, true);
-    shutdown_socket(socket_);
-    close_socket(socket_);
-  }
-
   // Log
   if (logger_) { logger_(req, res); }
 
@@ -6935,13 +7509,14 @@ inline bool ClientImpl::process_request(Stream &strm, Request &req,
 
 inline ContentProviderWithoutLength ClientImpl::get_multipart_content_provider(
     const std::string &boundary, const MultipartFormDataItems &items,
-    const MultipartFormDataProviderItems &provider_items) {
-  size_t cur_item = 0, cur_start = 0;
+    const MultipartFormDataProviderItems &provider_items) const {
+  size_t cur_item = 0;
+  size_t cur_start = 0;
   // cur_item and cur_start are copied to within the std::function and maintain
   // state between successive calls
   return [&, cur_item, cur_start](size_t offset,
                                   DataSink &sink) mutable -> bool {
-    if (!offset && items.size()) {
+    if (!offset && !items.empty()) {
       sink.os << detail::serialize_multipart_formdata(items, boundary, false);
       return true;
     } else if (cur_item < provider_items.size()) {
@@ -6954,12 +7529,13 @@ inline ContentProviderWithoutLength ClientImpl::get_multipart_content_provider(
       }
 
       DataSink cur_sink;
-      bool has_data = true;
+      auto has_data = true;
       cur_sink.write = sink.write;
       cur_sink.done = [&]() { has_data = false; };
 
-      if (!provider_items[cur_item].provider(offset - cur_start, cur_sink))
+      if (!provider_items[cur_item].provider(offset - cur_start, cur_sink)) {
         return false;
+      }
 
       if (!has_data) {
         sink.os << detail::serialize_multipart_formdata_item_end();
@@ -7078,14 +7654,15 @@ inline Result ClientImpl::Get(const std::string &path, const Params &params,
   if (params.empty()) { return Get(path, headers); }
 
   std::string path_with_query = append_query_params(path, params);
-  return Get(path_with_query.c_str(), headers, progress);
+  return Get(path_with_query, headers, std::move(progress));
 }
 
 inline Result ClientImpl::Get(const std::string &path, const Params &params,
                               const Headers &headers,
                               ContentReceiver content_receiver,
                               Progress progress) {
-  return Get(path, params, headers, nullptr, content_receiver, progress);
+  return Get(path, params, headers, nullptr, std::move(content_receiver),
+             std::move(progress));
 }
 
 inline Result ClientImpl::Get(const std::string &path, const Params &params,
@@ -7094,12 +7671,13 @@ inline Result ClientImpl::Get(const std::string &path, const Params &params,
                               ContentReceiver content_receiver,
                               Progress progress) {
   if (params.empty()) {
-    return Get(path, headers, response_handler, content_receiver, progress);
+    return Get(path, headers, std::move(response_handler),
+               std::move(content_receiver), std::move(progress));
   }
 
   std::string path_with_query = append_query_params(path, params);
-  return Get(path_with_query.c_str(), headers, response_handler,
-             content_receiver, progress);
+  return Get(path_with_query, headers, std::move(response_handler),
+             std::move(content_receiver), std::move(progress));
 }
 
 inline Result ClientImpl::Head(const std::string &path) {
@@ -7201,7 +7779,7 @@ inline Result ClientImpl::Post(const std::string &path, const Headers &headers,
   const auto &content_type =
       detail::serialize_multipart_formdata_get_content_type(boundary);
   const auto &body = detail::serialize_multipart_formdata(items, boundary);
-  return Post(path, headers, body, content_type.c_str());
+  return Post(path, headers, body, content_type);
 }
 
 inline Result ClientImpl::Post(const std::string &path, const Headers &headers,
@@ -7214,7 +7792,7 @@ inline Result ClientImpl::Post(const std::string &path, const Headers &headers,
   const auto &content_type =
       detail::serialize_multipart_formdata_get_content_type(boundary);
   const auto &body = detail::serialize_multipart_formdata(items, boundary);
-  return Post(path, headers, body, content_type.c_str());
+  return Post(path, headers, body, content_type);
 }
 
 inline Result
@@ -7423,9 +8001,7 @@ inline Result ClientImpl::Delete(const std::string &path,
   req.headers = headers;
   req.path = path;
 
-  if (!content_type.empty()) {
-    req.headers.emplace("Content-Type", content_type);
-  }
+  if (!content_type.empty()) { req.set_header("Content-Type", content_type); }
   req.body.assign(body, content_length);
 
   return send_(std::move(req));
@@ -7458,13 +8034,6 @@ inline Result ClientImpl::Options(const std::string &path,
   return send_(std::move(req));
 }
 
-inline size_t ClientImpl::is_socket_open() const {
-  std::lock_guard<std::mutex> guard(socket_mutex_);
-  return socket_.is_open();
-}
-
-inline socket_t ClientImpl::socket() const { return socket_.sock; }
-
 inline void ClientImpl::stop() {
   std::lock_guard<std::mutex> guard(socket_mutex_);
 
@@ -7488,6 +8057,17 @@ inline void ClientImpl::stop() {
   close_socket(socket_);
 }
 
+inline std::string ClientImpl::host() const { return host_; }
+
+inline int ClientImpl::port() const { return port_; }
+
+inline size_t ClientImpl::is_socket_open() const {
+  std::lock_guard<std::mutex> guard(socket_mutex_);
+  return socket_.is_open();
+}
+
+inline socket_t ClientImpl::socket() const { return socket_.sock; }
+
 inline void ClientImpl::set_connection_timeout(time_t sec, time_t usec) {
   connection_timeout_sec_ = sec;
   connection_timeout_usec_ = usec;
@@ -7536,6 +8116,11 @@ inline void ClientImpl::set_default_headers(Headers headers) {
   default_headers_ = std::move(headers);
 }
 
+inline void ClientImpl::set_header_writer(
+    std::function<ssize_t(Stream &, Headers &)> const &writer) {
+  header_writer_ = writer;
+}
+
 inline void ClientImpl::set_address_family(int family) {
   address_family_ = family;
 }
@@ -7575,9 +8160,7 @@ inline void ClientImpl::set_proxy_digest_auth(const std::string &username,
   proxy_digest_auth_username_ = username;
   proxy_digest_auth_password_ = password;
 }
-#endif
 
-#ifdef CPPHTTPLIB_OPENSSL_SUPPORT
 inline void ClientImpl::set_ca_cert_path(const std::string &ca_cert_file_path,
                                          const std::string &ca_cert_dir_path) {
   ca_cert_file_path_ = ca_cert_file_path;
@@ -7589,9 +8172,34 @@ inline void ClientImpl::set_ca_cert_store(X509_STORE *ca_cert_store) {
     ca_cert_store_ = ca_cert_store;
   }
 }
-#endif
 
-#ifdef CPPHTTPLIB_OPENSSL_SUPPORT
+inline X509_STORE *ClientImpl::create_ca_cert_store(const char *ca_cert,
+                                                    std::size_t size) const {
+  auto mem = BIO_new_mem_buf(ca_cert, static_cast<int>(size));
+  if (!mem) { return nullptr; }
+
+  auto inf = PEM_X509_INFO_read_bio(mem, nullptr, nullptr, nullptr);
+  if (!inf) {
+    BIO_free_all(mem);
+    return nullptr;
+  }
+
+  auto cts = X509_STORE_new();
+  if (cts) {
+    for (auto i = 0; i < static_cast<int>(sk_X509_INFO_num(inf)); i++) {
+      auto itmp = sk_X509_INFO_value(inf, i);
+      if (!itmp) { continue; }
+
+      if (itmp->x509) { X509_STORE_add_cert(cts, itmp->x509); }
+      if (itmp->crl) { X509_STORE_add_crl(cts, itmp->crl); }
+    }
+  }
+
+  sk_X509_INFO_pop_free(inf, X509_INFO_free);
+  BIO_free_all(mem);
+  return cts;
+}
+
 inline void ClientImpl::enable_server_certificate_verification(bool enabled) {
   server_certificate_verification_ = enabled;
 }
@@ -7655,7 +8263,7 @@ bool ssl_connect_or_accept_nonblocking(socket_t sock, SSL *ssl,
                                        U ssl_connect_or_accept,
                                        time_t timeout_sec,
                                        time_t timeout_usec) {
-  int res = 0;
+  auto res = 0;
   while ((res = ssl_connect_or_accept(ssl)) != 1) {
     auto err = SSL_get_error(ssl, res);
     switch (err) {
@@ -7718,7 +8326,7 @@ inline SSLSocketStream::SSLSocketStream(socket_t sock, SSL *ssl,
   SSL_clear_mode(ssl, SSL_MODE_AUTO_RETRY);
 }
 
-inline SSLSocketStream::~SSLSocketStream() {}
+inline SSLSocketStream::~SSLSocketStream() = default;
 
 inline bool SSLSocketStream::is_readable() const {
   return detail::select_read(sock_, read_timeout_sec_, read_timeout_usec_) > 0;
@@ -7736,7 +8344,7 @@ inline ssize_t SSLSocketStream::read(char *ptr, size_t size) {
     auto ret = SSL_read(ssl_, ptr, static_cast<int>(size));
     if (ret < 0) {
       auto err = SSL_get_error(ssl_, ret);
-      int n = 1000;
+      auto n = 1000;
 #ifdef _WIN32
       while (--n >= 0 && (err == SSL_ERROR_WANT_READ ||
                           (err == SSL_ERROR_SYSCALL &&
@@ -7769,7 +8377,7 @@ inline ssize_t SSLSocketStream::write(const char *ptr, size_t size) {
     auto ret = SSL_write(ssl_, ptr, static_cast<int>(handle_size));
     if (ret < 0) {
       auto err = SSL_get_error(ssl_, ret);
-      int n = 1000;
+      auto n = 1000;
 #ifdef _WIN32
       while (--n >= 0 && (err == SSL_ERROR_WANT_WRITE ||
                           (err == SSL_ERROR_SYSCALL &&
@@ -7824,8 +8432,9 @@ inline SSLServer::SSLServer(const char *cert_path, const char *private_key_path,
 
     // add default password callback before opening encrypted private key
     if (private_key_password != nullptr && (private_key_password[0] != '\0')) {
-      SSL_CTX_set_default_passwd_cb_userdata(ctx_,
-                                             (char *)private_key_password);
+      SSL_CTX_set_default_passwd_cb_userdata(
+          ctx_,
+          reinterpret_cast<void *>(const_cast<char *>(private_key_password)));
     }
 
     if (SSL_CTX_use_certificate_chain_file(ctx_, cert_path) != 1 ||
@@ -7933,7 +8542,7 @@ inline SSLClient::SSLClient(const std::string &host, int port,
 
   detail::split(&host_[0], &host_[host_.size()], '.',
                 [&](const char *b, const char *e) {
-                  host_components_.emplace_back(std::string(b, e));
+                  host_components_.emplace_back(b, e);
                 });
 
   if (!client_cert_path.empty() && !client_key_path.empty()) {
@@ -7954,7 +8563,7 @@ inline SSLClient::SSLClient(const std::string &host, int port,
 
   detail::split(&host_[0], &host_[host_.size()], '.',
                 [&](const char *b, const char *e) {
-                  host_components_.emplace_back(std::string(b, e));
+                  host_components_.emplace_back(b, e);
                 });
 
   if (client_cert != nullptr && client_key != nullptr) {
@@ -7989,6 +8598,11 @@ inline void SSLClient::set_ca_cert_store(X509_STORE *ca_cert_store) {
   }
 }
 
+inline void SSLClient::load_ca_cert_store(const char *ca_cert,
+                                          std::size_t size) {
+  set_ca_cert_store(ClientImpl::create_ca_cert_store(ca_cert, size));
+}
+
 inline long SSLClient::get_openssl_verify_result() const {
   return verify_result_;
 }
@@ -8003,14 +8617,14 @@ inline bool SSLClient::create_and_connect_socket(Socket &socket, Error &error) {
 inline bool SSLClient::connect_with_proxy(Socket &socket, Response &res,
                                           bool &success, Error &error) {
   success = true;
-  Response res2;
+  Response proxy_res;
   if (!detail::process_client_socket(
           socket.sock, read_timeout_sec_, read_timeout_usec_,
           write_timeout_sec_, write_timeout_usec_, [&](Stream &strm) {
             Request req2;
             req2.method = "CONNECT";
             req2.path = host_and_port_;
-            return process_request(strm, req2, res2, false, error);
+            return process_request(strm, req2, proxy_res, false, error);
           })) {
     // Thread-safe to close everything because we are assuming there are no
     // requests in flight
@@ -8021,12 +8635,12 @@ inline bool SSLClient::connect_with_proxy(Socket &socket, Response &res,
     return false;
   }
 
-  if (res2.status == 407) {
+  if (proxy_res.status == StatusCode::ProxyAuthenticationRequired_407) {
     if (!proxy_digest_auth_username_.empty() &&
         !proxy_digest_auth_password_.empty()) {
       std::map<std::string, std::string> auth;
-      if (detail::parse_www_authenticate(res2, auth, true)) {
-        Response res3;
+      if (detail::parse_www_authenticate(proxy_res, auth, true)) {
+        proxy_res = Response();
         if (!detail::process_client_socket(
                 socket.sock, read_timeout_sec_, read_timeout_usec_,
                 write_timeout_sec_, write_timeout_usec_, [&](Stream &strm) {
@@ -8037,7 +8651,7 @@ inline bool SSLClient::connect_with_proxy(Socket &socket, Response &res,
                       req3, auth, 1, detail::random_string(10),
                       proxy_digest_auth_username_, proxy_digest_auth_password_,
                       true));
-                  return process_request(strm, req3, res3, false, error);
+                  return process_request(strm, req3, proxy_res, false, error);
                 })) {
           // Thread-safe to close everything because we are assuming there are
           // no requests in flight
@@ -8048,17 +8662,28 @@ inline bool SSLClient::connect_with_proxy(Socket &socket, Response &res,
           return false;
         }
       }
-    } else {
-      res = res2;
-      return false;
     }
   }
 
+  // If status code is not 200, proxy request is failed.
+  // Set error to ProxyConnection and return proxy response
+  // as the response of the request
+  if (proxy_res.status != StatusCode::OK_200) {
+    error = Error::ProxyConnection;
+    res = std::move(proxy_res);
+    // Thread-safe to close everything because we are assuming there are
+    // no requests in flight
+    shutdown_ssl(socket, true);
+    shutdown_socket(socket);
+    close_socket(socket);
+    return false;
+  }
+
   return true;
 }
 
 inline bool SSLClient::load_certs() {
-  bool ret = true;
+  auto ret = true;
 
   std::call_once(initialize_cert_, [&]() {
     std::lock_guard<std::mutex> guard(ctx_mutex_);
@@ -8134,7 +8759,11 @@ inline bool SSLClient::initialize_ssl(Socket &socket, Error &error) {
         return true;
       },
       [&](SSL *ssl2) {
-        SSL_set_tlsext_host_name(ssl2, host_.c_str());
+        // NOTE: Direct call instead of using the OpenSSL macro to suppress
+        // -Wold-style-cast warning
+        // SSL_set_tlsext_host_name(ssl2, host_.c_str());
+        SSL_ctrl(ssl2, SSL_CTRL_SET_TLSEXT_HOSTNAME, TLSEXT_NAMETYPE_host_name,
+                 static_cast<void *>(const_cast<char *>(host_.c_str())));
         return true;
       });
 
@@ -8208,8 +8837,8 @@ SSLClient::verify_host_with_subject_alt_name(X509 *server_cert) const {
 
   auto type = GEN_DNS;
 
-  struct in6_addr addr6;
-  struct in_addr addr;
+  struct in6_addr addr6 {};
+  struct in_addr addr {};
   size_t addr_len = 0;
 
 #ifndef __MINGW32__
@@ -8234,8 +8863,9 @@ SSLClient::verify_host_with_subject_alt_name(X509 *server_cert) const {
     for (decltype(count) i = 0; i < count && !dsn_matched; i++) {
       auto val = sk_GENERAL_NAME_value(alt_names, i);
       if (val->type == type) {
-        auto name = (const char *)ASN1_STRING_get0_data(val->d.ia5);
-        auto name_len = (size_t)ASN1_STRING_length(val->d.ia5);
+        auto name =
+            reinterpret_cast<const char *>(ASN1_STRING_get0_data(val->d.ia5));
+        auto name_len = static_cast<size_t>(ASN1_STRING_length(val->d.ia5));
 
         switch (type) {
         case GEN_DNS: dsn_matched = check_host_name(name, name_len); break;
@@ -8253,7 +8883,8 @@ SSLClient::verify_host_with_subject_alt_name(X509 *server_cert) const {
     if (dsn_matched || ip_matched) { ret = true; }
   }
 
-  GENERAL_NAMES_free((STACK_OF(GENERAL_NAME) *)alt_names);
+  GENERAL_NAMES_free(const_cast<STACK_OF(GENERAL_NAME) *>(
+      reinterpret_cast<const STACK_OF(GENERAL_NAME) *>(alt_names)));
   return ret;
 }
 
@@ -8282,7 +8913,7 @@ inline bool SSLClient::check_host_name(const char *pattern,
   std::vector<std::string> pattern_components;
   detail::split(&pattern[0], &pattern[pattern_len], '.',
                 [&](const char *b, const char *e) {
-                  pattern_components.emplace_back(std::string(b, e));
+                  pattern_components.emplace_back(b, e);
                 });
 
   if (host_components_.size() != pattern_components.size()) { return false; }
@@ -8361,7 +8992,7 @@ inline Client::Client(const std::string &host, int port,
     : cli_(detail::make_unique<ClientImpl>(host, port, client_cert_path,
                                            client_key_path)) {}
 
-inline Client::~Client() {}
+inline Client::~Client() = default;
 
 inline bool Client::is_valid() const {
   return cli_ != nullptr && cli_->is_valid();
@@ -8421,19 +9052,20 @@ inline Result Client::Get(const std::string &path, const Headers &headers,
 }
 inline Result Client::Get(const std::string &path, const Params &params,
                           const Headers &headers, Progress progress) {
-  return cli_->Get(path, params, headers, progress);
+  return cli_->Get(path, params, headers, std::move(progress));
 }
 inline Result Client::Get(const std::string &path, const Params &params,
                           const Headers &headers,
                           ContentReceiver content_receiver, Progress progress) {
-  return cli_->Get(path, params, headers, content_receiver, progress);
+  return cli_->Get(path, params, headers, std::move(content_receiver),
+                   std::move(progress));
 }
 inline Result Client::Get(const std::string &path, const Params &params,
                           const Headers &headers,
                           ResponseHandler response_handler,
                           ContentReceiver content_receiver, Progress progress) {
-  return cli_->Get(path, params, headers, response_handler, content_receiver,
-                   progress);
+  return cli_->Get(path, params, headers, std::move(response_handler),
+                   std::move(content_receiver), std::move(progress));
 }
 
 inline Result Client::Head(const std::string &path) { return cli_->Head(path); }
@@ -8665,12 +9297,16 @@ inline bool Client::send(Request &req, Response &res, Error &error) {
 
 inline Result Client::send(const Request &req) { return cli_->send(req); }
 
+inline void Client::stop() { cli_->stop(); }
+
+inline std::string Client::host() const { return cli_->host(); }
+
+inline int Client::port() const { return cli_->port(); }
+
 inline size_t Client::is_socket_open() const { return cli_->is_socket_open(); }
 
 inline socket_t Client::socket() const { return cli_->socket(); }
 
-inline void Client::stop() { cli_->stop(); }
-
 inline void
 Client::set_hostname_addr_map(std::map<std::string, std::string> addr_map) {
   cli_->set_hostname_addr_map(std::move(addr_map));
@@ -8680,6 +9316,11 @@ inline void Client::set_default_headers(Headers headers) {
   cli_->set_default_headers(std::move(headers));
 }
 
+inline void Client::set_header_writer(
+    std::function<ssize_t(Stream &, Headers &)> const &writer) {
+  cli_->set_header_writer(writer);
+}
+
 inline void Client::set_address_family(int family) {
   cli_->set_address_family(family);
 }
@@ -8754,7 +9395,9 @@ inline void Client::enable_server_certificate_verification(bool enabled) {
 }
 #endif
 
-inline void Client::set_logger(Logger logger) { cli_->set_logger(logger); }
+inline void Client::set_logger(Logger logger) {
+  cli_->set_logger(std::move(logger));
+}
 
 #ifdef CPPHTTPLIB_OPENSSL_SUPPORT
 inline void Client::set_ca_cert_path(const std::string &ca_cert_file_path,
@@ -8770,6 +9413,10 @@ inline void Client::set_ca_cert_store(X509_STORE *ca_cert_store) {
   }
 }
 
+inline void Client::load_ca_cert_store(const char *ca_cert, std::size_t size) {
+  set_ca_cert_store(cli_->create_ca_cert_store(ca_cert, size));
+}
+
 inline long Client::get_openssl_verify_result() const {
   if (is_ssl_) {
     return static_cast<SSLClient &>(*cli_).get_openssl_verify_result();