server: Add additional checks to hostName func

The hostName func is used to dynamically determine
the hostName value in various API endpoints. The previous
logic favored the Host value of request URL, but this value
is often not set (i.e. when not operating behind a proxy).
The default handling has been changed to return the
request Host value if the request URL Host is not set.

closes #1022

server/handle_map_style_test.go

@@ -14,22 +14,26 @@ import (
 
 func TestHandleMapStyle(t *testing.T) {
 	type tcase struct {
-		handler    http.Handler
-		uriPrefix  string
-		uri        string
-		uriPattern string
-		expected   style.Root
-	}
-
-	// config params this test relies on
-	server.HostName = &url.URL{
-		Host: serverHostName,
+		handler        http.Handler
+		uriPrefix      string
+		uri            string
+		uriPattern     string
+		serverHostName string
+		expected       style.Root
 	}
 
 	fn := func(tc tcase) func(t *testing.T) {
 		return func(t *testing.T) {
 			var err error
 
+			// config params this test relies on
+			server.HostName = nil
+			if tc.serverHostName != "" {
+				server.HostName = &url.URL{
+					Host: tc.serverHostName,
+				}
+			}
+
 			if tc.uriPrefix != "" {
 				server.URIPrefix = tc.uriPrefix
 			} else {
@@ -58,9 +62,10 @@ func TestHandleMapStyle(t *testing.T) {
 
 	tests := map[string]tcase{
 		"default": {
-			handler:    server.HandleMapStyle{},
-			uri:        path.Join("/maps", testMapName, "style.json"),
-			uriPattern: "/maps/:map_name/style.json",
+			handler:        server.HandleMapStyle{},
+			uri:            path.Join("/maps", testMapName, "style.json"),
+			uriPattern:     "/maps/:map_name/style.json",
+			serverHostName: serverHostName,
 			expected: style.Root{
 				Name:    testMapName,
 				Version: style.Version,
@@ -106,10 +111,11 @@ func TestHandleMapStyle(t *testing.T) {
 			},
 		},
 		"uri prefix set": {
-			handler:    server.HandleMapStyle{},
-			uriPrefix:  "/tegola",
-			uri:        path.Join("/tegola", "maps", testMapName, "style.json"),
-			uriPattern: "/tegola/maps/:map_name/style.json",
+			handler:        server.HandleMapStyle{},
+			uriPrefix:      "/tegola",
+			uri:            path.Join("/tegola", "maps", testMapName, "style.json"),
+			uriPattern:     "/tegola/maps/:map_name/style.json",
+			serverHostName: serverHostName,
 			expected: style.Root{
 				Name:    testMapName,
 				Version: style.Version,

server/server.go

@@ -143,18 +143,33 @@ func hostName(r *http.Request) *url.URL {
 		return HostName
 	}
 
-	return r.URL
+	// favor the r.URL.Host attribute in case tegola is behind a proxy
+	// https://stackoverflow.com/questions/42921567/what-is-the-difference-between-host-and-url-host-for-golang-http-request
+	if r.URL != nil && r.URL.Host != "" {
+		return r.URL
+	}
+
+	return &url.URL{
+		Host: r.Host,
+	}
 }
 
+const (
+	HeaderXForwardedProto = "X-Forwarded-Proto"
+)
+
 // various checks to determine if the request is http or https. the scheme is needed for the TileURLs
 // r.URL.Scheme can be empty if a relative request is issued from the client. (i.e. GET /foo.html)
 func scheme(r *http.Request) string {
 	if ProxyProtocol != "" {
 		return ProxyProtocol
 	}
-	if r.Header.Get("X-Forwarded-Proto") != "" {
-		return r.Header.Get("X-Forwarded-Proto")
-	} else if r.TLS != nil {
+
+	if r.Header.Get(HeaderXForwardedProto) != "" {
+		return r.Header.Get(HeaderXForwardedProto)
+	}
+
+	if r.TLS != nil {
 		return "https"
 	}
 

server/server_internal_test.go

@@ -83,6 +83,11 @@ func TestHostName(t *testing.T) {
 			url:      "http://localhost/capabilities",
 			expected: "localhost",
 		},
+		"no host on url": {
+			// With hostname & port unset in config, expect host:port matching URL
+			url:      "/capabilities",
+			expected: "",
+		},
 	}
 
 	for name, tc := range tests {