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autoproxy.c
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autoproxy.c
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/* redsocks2 - transparent TCP-to-proxy redirector
* Copyright (C) 2013-2017 Zhuofei Wang <[email protected]>
*
* This code is based on redsocks project developed by Leonid Evdokimov.
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy
* of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <errno.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <event2/bufferevent.h>
#include <event2/bufferevent_struct.h>
#include "utils.h"
#include "log.h"
#include "redsocks.h"
#include "parser.h"
#include "list.h"
#include "main.h"
#include "ipcache.h"
typedef enum autoproxy_state_t {
/* Introduce subsystem */
AUTOPROXY_NEW=10000,
AUTOPROXY_CONNECTED,
AUTOPROXY_CONFIRMED,
AUTOPROXY_SHUTDOWN, // Not used
} autoproxy_state;
typedef struct autoproxy_client_t {
autoproxy_state state;
size_t data_recv;
size_t data_sent;
struct event * recv_timer_event;
short quick_check; // flag indicating quick check initiated.
} autoproxy_client;
void redsocks_event_error(struct bufferevent *buffev, short what, void *_arg);
static int auto_retry_or_drop(redsocks_client * client);
static void direct_relay_clientreadcb(struct bufferevent *from, void *_client);
static void auto_event_error(struct bufferevent *buffev, short what, void *_arg);
#define QUICK_CONNECT_TIMEOUT_SECONDS 3
#define NO_CHECK_SECONDS 60
typedef struct autoproxy_config_t {
list_head list; // Make it a list to support multiple configurations
char * interface; // interface to be used for relay
uint16_t quick_connect_timeout;
uint16_t no_quick_check_seconds;
} autoproxy_config;
static autoproxy_config default_config = {
.quick_connect_timeout = QUICK_CONNECT_TIMEOUT_SECONDS,
.no_quick_check_seconds = NO_CHECK_SECONDS,
};
static list_head configs = LIST_HEAD_INIT(configs);
static parser_entry autoproxy_entries[] =
{
{ .key = "interface", .type = pt_pchar },
{ .key = "quick_connect_timeout", .type = pt_uint16 },
{ .key = "no_quick_check_seconds", .type = pt_uint16 },
{ }
};
static int autoproxy_onenter(parser_section *section)
{
autoproxy_config * config = malloc(sizeof(*config));
if (!config) {
parser_error(section->context, "Not enough memory");
return -1;
}
INIT_LIST_HEAD(&config->list);
/* initialize with default config */
memcpy(config, &default_config, sizeof(*config));
for (parser_entry *entry = §ion->entries[0]; entry->key; entry++)
entry->addr =
(strcmp(entry->key, "interface") == 0) ? (void*)&config->interface :
(strcmp(entry->key, "quick_connect_timeout") == 0) ? (void*)&config->quick_connect_timeout:
(strcmp(entry->key, "no_quick_check_seconds") == 0) ? (void*)&config->no_quick_check_seconds:
NULL;
section->data = config;
return 0;
}
static int autoproxy_onexit(parser_section *section)
{
/* FIXME: Rewrite in bullet-proof style. There are memory leaks if config
* file is not correct, so correct on-the-fly config reloading is
* currently impossible.
*/
const char *err = NULL;
autoproxy_config * config = section->data;
section->data = NULL;
for (parser_entry *entry = §ion->entries[0]; entry->key; entry++)
entry->addr = NULL;
/* Check and update values here */
if (!config->quick_connect_timeout)
err = "Timeout value for quick check can not be 0. Default: 3";
if (err)
parser_error(section->context, "%s", err);
else
// Add config to config list
list_add(&config->list, &configs);
return err ? -1 : 0;
}
static parser_section autoproxy_conf_section =
{
.name = "autoproxy",
.entries = autoproxy_entries,
.onenter = autoproxy_onenter,
.onexit = autoproxy_onexit
};
app_subsys autoproxy_app_subsys =
{
// .init = autoproxy_init,
// .fini = autoproxy_fini,
.conf_section = &autoproxy_conf_section,
};
static autoproxy_config * get_config(redsocks_client * client)
{
// TODO: By far, only the first configuration section takes effect.
// We need to find a proper way to let user specify which config section
// to associate with.
autoproxy_config * config = NULL;
if (!list_empty(&configs))
{
list_for_each_entry(config, &configs, list)
break;
return config;
}
else
{
return &default_config;
}
}
#define get_autoproxy_client(client) ((void*)(client + 1) + client->instance->relay_ss->payload_len)
static void auto_release_recv_timer(autoproxy_client * aclient)
{
// Cancel timer and release event object for timer
if (aclient->recv_timer_event)
{
event_del(aclient->recv_timer_event);
event_free(aclient->recv_timer_event);
aclient->recv_timer_event = NULL;
}
}
static void auto_client_init(redsocks_client *client)
{
autoproxy_client * aclient = get_autoproxy_client(client);
memset((void *) aclient, 0, sizeof(autoproxy_client));
aclient->state = AUTOPROXY_NEW;
}
static void auto_client_fini(redsocks_client *client)
{
autoproxy_client * aclient = get_autoproxy_client(client);
auto_release_recv_timer(aclient);
}
static void on_connection_confirmed(redsocks_client *client)
{
redsocks_log_error(client, LOG_DEBUG, "IP Confirmed");
cache_del_addr(&client->destaddr);
}
static void on_connection_blocked(redsocks_client *client)
{
redsocks_log_error(client, LOG_DEBUG, "IP Blocked");
}
static void auto_confirm_connection(redsocks_client * client)
{
autoproxy_client * aclient = get_autoproxy_client(client);
assert(aclient->state == AUTOPROXY_CONNECTED);
aclient->state = AUTOPROXY_CONFIRMED;
if (aclient->data_sent)
{
evbuffer_drain(bufferevent_get_input(client->client), aclient->data_sent);
aclient->data_sent = 0;
}
auto_release_recv_timer(aclient);
on_connection_confirmed(client);
}
static void auto_recv_timeout_cb(evutil_socket_t fd, short events, void * arg)
{
redsocks_client *client = arg;
autoproxy_client * aclient = get_autoproxy_client(client);
redsocks_log_error(client, LOG_DEBUG, "RECV Timeout, state: %d, data_sent: %zu", aclient->state, aclient->data_sent);
assert(events & EV_TIMEOUT);
redsocks_touch_client(client);
// Let's make connection confirmed
if (aclient->state == AUTOPROXY_CONNECTED)
auto_confirm_connection(client);
else
return;
// No ERROR/EOF/data received before timeout, continue sending data
if (!(client->relay_evshut & EV_WRITE))
{
if (bufferevent_write_buffer(client->relay, bufferevent_get_input(client->client)) == -1)
redsocks_log_errno(client, LOG_ERR, "bufferevent_write_buffer");
if (!(client->client_evshut & EV_READ) && bufferevent_enable(client->client, EV_READ) == -1)
redsocks_log_errno(client, LOG_ERR, "bufferevent_enable");
}
}
static void direct_relay_readcb_helper(redsocks_client *client, struct bufferevent *from, struct bufferevent *to)
{
if (evbuffer_get_length(bufferevent_get_output(to)) < get_write_hwm(to))
{
if (bufferevent_write_buffer(to, bufferevent_get_input(from)) == -1)
redsocks_log_errno(client, LOG_ERR, "bufferevent_write_buffer");
if (bufferevent_enable(from, EV_READ) == -1)
redsocks_log_errno(client, LOG_ERR, "bufferevent_enable");
}
else {
if (bufferevent_disable(from, EV_READ) == -1)
redsocks_log_errno(client, LOG_ERR, "bufferevent_disable");
}
}
// Caller should continue writing if this function returns 0.
// Otherwise, stop writing.
static int handle_write_to_relay(redsocks_client *client)
{
autoproxy_client * aclient = get_autoproxy_client(client);
struct bufferevent * from = client->client;
struct bufferevent * to = client->relay;
size_t input_size = evbuffer_get_length(bufferevent_get_input(from));
size_t output_size = evbuffer_get_length(bufferevent_get_output(to));
if (aclient->state == AUTOPROXY_CONNECTED )
{
redsocks_log_error(client, LOG_DEBUG, "sent: %zu, recv: %zu, in:%zu, out:%zu",
aclient->data_sent,
aclient->data_recv,
input_size,
output_size
);
/* Not send or receive data. */
if (!aclient->data_sent && !aclient->data_recv)
{
/* Ensure we have data to send */
if (input_size)
{
/* copy data from input to output of relay */
aclient->data_sent = copy_evbuffer (to, from, 0);
return 1;
}
}
/*
* Relay reaceived data before writing to relay.
*/
else if (!aclient->data_sent && aclient->data_recv)
{
// TODO:
// In case we receive data before sending any data,
// should we confirm connection immediately or after
// sending data?
//aclient->data_sent = copy_evbuffer(to, from, 0);
auto_confirm_connection(client);
}
/* aclient->state = AUTOPROXY_CONFIRMED; */
/* We have writen data to relay, but got nothing until we are requested to
* write to it again.
*/
else if (aclient->data_sent && !aclient->data_recv)
{
/* No response from relay and no CONNECTION RESET,
Send more data.
*/
/* Write more data util input buffer of relay is full */
if (input_size - aclient->data_sent > 0) /* we have more data waiting to be sent */
{
aclient->data_sent += copy_evbuffer(to, from, aclient->data_sent);
}
else if (output_size < aclient->data_sent /* data is sent out, more or less */
&& input_size == aclient->data_sent /* all data in read buffer is sent */
&& !aclient->recv_timer_event /* timer is not activated yet */
)
{
aclient->recv_timer_event = evtimer_new(bufferevent_get_base(to), auto_recv_timeout_cb, client);
if (aclient->recv_timer_event)
{
struct timeval tv;
tv.tv_sec = 0;
tv.tv_usec = 400000;
if (-1 == evtimer_add(aclient->recv_timer_event, &tv))
{
redsocks_log_error(client, LOG_DEBUG, "Failed to add timer!");
// In case we failed to add timer, it is abnormal.
// Let's confirm the connection directly so that normal service is not
// impacted.
auto_confirm_connection(client);
return 0;
}
}
}
return 1;
}
/* We sent data to and got data from relay. */
else if (aclient->data_sent && aclient->data_recv)
{
/* No CONNECTION RESET error occur after sending data, good. */
auto_confirm_connection(client);
}
}
return 0;
}
// Caller should continue writing if this function returns 0.
// Otherwise, stop writing.
static int handle_write_to_client(redsocks_client *client)
{
autoproxy_client * aclient = get_autoproxy_client(client);
struct bufferevent * from = client->relay;
size_t input_size = evbuffer_get_length(bufferevent_get_input(from));
if (aclient->state == AUTOPROXY_CONNECTED)
{
if (!aclient->data_recv)
{
aclient->data_recv = input_size;
if (input_size)
auto_confirm_connection(client);
}
}
return 0;
}
static void direct_relay_clientreadcb(struct bufferevent *from, void *_client)
{
redsocks_client *client = _client;
size_t input_size = evbuffer_get_length(bufferevent_get_input(from));
redsocks_log_error(client, LOG_DEBUG, "client in: %zu", input_size);
redsocks_touch_client(client);
if (handle_write_to_relay(client))
return;
direct_relay_readcb_helper(client, client->client, client->relay);
}
static void direct_relay_relayreadcb(struct bufferevent *from, void *_client)
{
redsocks_client *client = _client;
size_t input_size = evbuffer_get_length(bufferevent_get_input(from));
redsocks_log_error(client, LOG_DEBUG, "relay in: %zu", input_size);
redsocks_touch_client(client);
if (handle_write_to_client(client))
return;
direct_relay_readcb_helper(client, client->relay, client->client);
}
static void direct_relay_clientwritecb(struct bufferevent *to, void *_client)
{
redsocks_client *client = _client;
struct bufferevent * from = client->relay;
size_t output_size = evbuffer_get_length(bufferevent_get_output(to));
redsocks_touch_client(client);
if (process_shutdown_on_write_(client, from, to))
return;
if (handle_write_to_client(client))
return;
if (output_size < get_write_hwm(to))
{
if (bufferevent_write_buffer(to, bufferevent_get_input(from)) == -1)
redsocks_log_errno(client, LOG_ERR, "bufferevent_write_buffer");
if (!(client->relay_evshut & EV_READ) && bufferevent_enable(from, EV_READ) == -1)
redsocks_log_errno(client, LOG_ERR, "bufferevent_enable");
}
}
static int process_shutdown_on_write_2(redsocks_client *client, struct bufferevent *from, struct bufferevent *to)
{
autoproxy_client * aclient = get_autoproxy_client(client);
size_t input_size = evbuffer_get_length(bufferevent_get_input(from));
unsigned short from_evshut = from == client->client ? client->client_evshut : client->relay_evshut;
unsigned short to_evshut = to == client->client ? client->client_evshut : client->relay_evshut;
redsocks_log_error(client, LOG_DEBUG, "WCB %s, fs: %u, ts: %u, fin: %zu, fout: %zu, tin: %zu",
to == client->client?"client":"relay",
from_evshut,
to_evshut,
evbuffer_get_length(bufferevent_get_input(from)),
evbuffer_get_length(bufferevent_get_output(from)),
evbuffer_get_length(bufferevent_get_input(to)));
if ((from_evshut & EV_READ) && !(to_evshut & EV_WRITE))
{
if (input_size == 0
|| (input_size == aclient->data_sent && aclient->state == AUTOPROXY_CONNECTED))
{
redsocks_shutdown(client, to, SHUT_WR, 0);
return 1;
}
}
return 0;
}
static void direct_relay_relaywritecb(struct bufferevent *to, void *_client)
{
redsocks_client *client = _client;
autoproxy_client * aclient = get_autoproxy_client(client);
struct bufferevent * from = client->client;
size_t output_size = evbuffer_get_length(bufferevent_get_output(to));
redsocks_touch_client(client);
if (process_shutdown_on_write_2(client, from, to))
return;
if (handle_write_to_relay(client))
return;
if (aclient->state == AUTOPROXY_CONFIRMED)
{
if (output_size < get_write_hwm(to))
{
if (bufferevent_write_buffer(to, bufferevent_get_input(from)) == -1)
redsocks_log_errno(client, LOG_ERR, "bufferevent_write_buffer");
if (!(client->client_evshut & EV_READ) && bufferevent_enable(from, EV_READ) == -1)
redsocks_log_errno(client, LOG_ERR, "bufferevent_enable");
}
}
}
static void auto_drop_relay(redsocks_client *client)
{
int fd;
if (client->relay)
{
redsocks_log_error(client, LOG_DEBUG, "dropping relay only ");
fd = bufferevent_getfd(client->relay);
bufferevent_disable(client->relay, EV_READ|EV_WRITE);
bufferevent_free(client->relay);
redsocks_close(fd);
client->relay = NULL;
}
client->relay_evshut = 0;
client->relay_connected = 0;
}
static int auto_retry(redsocks_client * client, int updcache)
{
autoproxy_client * aclient = get_autoproxy_client(client);
int rc;
if (aclient->state == AUTOPROXY_CONNECTED)
bufferevent_disable(client->client, EV_READ| EV_WRITE);
/* drop relay and update state, then retry with specified relay */
if (updcache)
{
/* only add IP to cache when the IP is not in cache */
if (cache_get_addr_time(&client->destaddr) == NULL)
{
cache_add_addr(&client->destaddr);
redsocks_log_error(client, LOG_DEBUG, "ADD IP to cache: %s",
inet_ntoa(client->destaddr.sin_addr));
}
}
auto_release_recv_timer(aclient);
auto_drop_relay(client);
// restore callbacks for ordinary client.
bufferevent_setcb(client->client, NULL, NULL, redsocks_event_error, client);
// enable reading to handle EOF from client
if (!(client->client_evshut & EV_READ))
bufferevent_enable(client->client, EV_READ);
/* connect to relay */
if (client->instance->relay_ss->connect_relay)
{
rc = client->instance->relay_ss->connect_relay(client);
// In case the underline relay system does not connect relay,
// it maybe is waiting for client read event.
// Take 'http-relay' for example.
if (!rc && !client->relay && evbuffer_get_length(bufferevent_get_input(client->client)))
#if LIBEVENT_VERSION_NUMBER >= 0x02010100
bufferevent_trigger_event(client->client, EV_READ, 0);
#else
client->client->readcb(client->client, client);
#endif
}
else
rc = redsocks_connect_relay(client);
return rc;
}
/* return 1 for drop, 0 for retry. */
static int auto_retry_or_drop(redsocks_client * client)
{
autoproxy_client * aclient = get_autoproxy_client(client);
if (aclient->state == AUTOPROXY_NEW || aclient->state == AUTOPROXY_CONNECTED)
{
on_connection_blocked(client);
return auto_retry(client, 0);
}
/* drop */
return 1;
}
static void auto_relay_connected(struct bufferevent *buffev, void *_arg)
{
redsocks_client *client = _arg;
autoproxy_client * aclient = get_autoproxy_client(client);
assert(buffev == client->relay);
redsocks_touch_client(client);
if (!red_is_socket_connected_ok(buffev)) {
if (aclient->state == AUTOPROXY_NEW && !auto_retry_or_drop(client))
return;
redsocks_log_error(client, LOG_DEBUG, "failed to connect to destination");
redsocks_drop_client(client);
return;
}
/* update client state */
aclient->state = AUTOPROXY_CONNECTED;
client->relay_connected = 1;
/* We do not need to detect timeouts any more.
The two peers will handle it. */
bufferevent_set_timeouts(client->relay, NULL, NULL);
if (redsocks_start_relay(client))
// redsocks_start_relay() drops client on failure
return;
/* overwrite theread callback to my function */
bufferevent_setcb(client->client, direct_relay_clientreadcb,
direct_relay_clientwritecb,
auto_event_error,
client);
bufferevent_setcb(client->relay, direct_relay_relayreadcb,
direct_relay_relaywritecb,
auto_event_error,
client);
// Write any data received from client side to relay.
if (evbuffer_get_length(bufferevent_get_input(client->client)))
direct_relay_relaywritecb(client->relay, client);
return;
}
// Note: before relay is connected, READING EOF/ERROR reported from client
// is handled by redsocks default ERROR handler.
static void auto_event_error(struct bufferevent *buffev, short what, void *_arg)
{
redsocks_client *client = _arg;
autoproxy_client * aclient = get_autoproxy_client(client);
int saved_errno = errno;
assert(buffev == client->relay || buffev == client->client);
redsocks_touch_client(client);
if (!(what & BEV_EVENT_ERROR))
errno = red_socket_geterrno(buffev);
redsocks_log_errno(client, LOG_DEBUG, "%s, errno(%d), State: %d, what: " event_fmt_str,
buffev == client->client?"client":"relay",
errno, aclient->state, event_fmt(what));
if (buffev == client->relay)
{
/*
if (what & BEV_EVENT_CONNECTED)
{
auto_relay_connected(buffev, _arg);
return;
}
*/
if ( aclient->state == AUTOPROXY_NEW
&& what == (BEV_EVENT_WRITING | BEV_EVENT_TIMEOUT))
{
// Update access time for IP fails again.
if (aclient->quick_check)
cache_touch_addr(&client->destaddr);
on_connection_blocked(client);
/* In case timeout occurs while connecting relay, we try to connect
to target via configured proxy. It is possible that the connection to
target can be set up a bit longer than the timeout value we set.
However, it is still better to make connection via proxy. */
auto_retry(client, 1);
return;
}
if (aclient->state == AUTOPROXY_NEW && saved_errno == ECONNRESET)
if (!auto_retry_or_drop(client))
return;
if (aclient->state == AUTOPROXY_CONNECTED
&& what == (BEV_EVENT_READING|BEV_EVENT_ERROR)
/* No matter it is disconnected due to Connection Reset or any
other reason, we still have a chance to forward connection via
proxy. I prefer retry only if we got connection reset.
*/
&& saved_errno == ECONNRESET)
{
if (!auto_retry_or_drop(client))
return;
}
}
if (what == (BEV_EVENT_READING|BEV_EVENT_EOF))
{
// Timer cases:
// 1. READ EOF from relay (normal case, need to releae timer)
// 2. READ EOF from client (normal case, no need to release timer)
// 3. READ ERROR from client (abnormal, not recoverable)
// 4. READ ERROR from erlay (abnormal, not recoverable)
if (aclient->recv_timer_event && buffev == client->relay)
auto_confirm_connection(client);
redsocks_shutdown(client, buffev, SHUT_RD, 1);
// Ensure the other party could send remaining data and SHUT_WR also
if (buffev == client->client)
{
if (!(client->relay_evshut & EV_WRITE))
bufferevent_enable(client->relay, EV_WRITE);
}
else
{
if (!(client->client_evshut & EV_WRITE))
bufferevent_enable(client->client, EV_WRITE);
}
}
else
{
redsocks_drop_client(client);
}
}
static int auto_connect_relay(redsocks_client *client)
{
autoproxy_client * aclient = get_autoproxy_client(client);
autoproxy_config * config = get_config(client);
struct timeval tv = {client->instance->config.timeout, 0};
time_t * acc_time = NULL;
time_t now = redsocks_time(NULL);
if (aclient->state == AUTOPROXY_NEW)
{
acc_time = cache_get_addr_time(&client->destaddr);
if (acc_time)
{
redsocks_log_error(client, LOG_DEBUG, "Found dest IP in cache");
// No quick check when the time passed since IP is added to cache is
// less than NO_CHECK_SECONDS. Just let it go via proxy.
if (config->no_quick_check_seconds == 0
|| now - *acc_time < config->no_quick_check_seconds)
return auto_retry(client, 0);
/* update timeout value for quick detection.
* Sometimes, good sites are added into cache due to occasionally
* connection timeout. It is annoying. So, decision is made to
* always try to connect to destination first when the destination
* is found in cache.
* For most destinations, the connection could be set up correctly
* in short time. And, for most blocked sites, we get connection
* reset almost immediately when connection is set up or when HTTP
* request is sent.
*/
tv.tv_sec = config->quick_connect_timeout;
aclient->quick_check = 1;
}
/* connect to target directly without going through proxy */
client->relay = red_connect_relay(config->interface, &client->destaddr,
NULL, auto_relay_connected, auto_event_error, client,
&tv);
if (!client->relay) {
// Failed to connect to destination directly, try again via proxy.
return auto_retry(client, 0);
}
}
else
{
redsocks_log_errno(client, LOG_ERR, "invalid state: %d", aclient->state);
redsocks_drop_client(client);
return -1;
}
return 0;
}
relay_subsys autoproxy_subsys =
{
.name = "autoproxy",
.payload_len = sizeof(autoproxy_client),
.instance_payload_len = 0,
.readcb = direct_relay_relayreadcb,
.writecb = direct_relay_relaywritecb,
.init = auto_client_init,
.fini = auto_client_fini,
.connect_relay = auto_connect_relay,
};
/* vim:set tabstop=4 softtabstop=4 shiftwidth=4: */
/* vim:set foldmethod=marker foldlevel=32 foldmarker={,}: */