[feature] Support X-Forwarded-Host (#75)

proxy_headers.go

@@ -11,6 +11,7 @@ var (
 	xForwardedFor   = http.CanonicalHeaderKey("X-Forwarded-For")
 	xRealIP         = http.CanonicalHeaderKey("X-Real-IP")
 	xForwardedProto = http.CanonicalHeaderKey("X-Forwarded-Scheme")
+	xForwardedHost  = http.CanonicalHeaderKey("X-Forwarded-Host")
 )
 
 var (
@@ -49,7 +50,10 @@ func ProxyHeaders(h http.Handler) http.Handler {
 		if scheme := getScheme(r); scheme != "" {
 			r.URL.Scheme = scheme
 		}
-
+		// Set the host with the value passed by the proxy
+		if r.Header.Get(xForwardedHost) != "" {
+			r.Host = r.Header.Get(xForwardedHost)
+		}
 		// Call the next handler in the chain.
 		h.ServeHTTP(w, r)
 	}

proxy_headers_test.go

@@ -74,13 +74,17 @@ func TestProxyHeaders(t *testing.T) {
 
 	r.Header.Set(xForwardedFor, "8.8.8.8")
 	r.Header.Set(xForwardedProto, "https")
-
-	var addr string
-	var proto string
+	r.Header.Set(xForwardedHost, "google.com")
+	var (
+		addr  string
+		proto string
+		host  string
+	)
 	ProxyHeaders(http.HandlerFunc(
 		func(w http.ResponseWriter, r *http.Request) {
 			addr = r.RemoteAddr
 			proto = r.URL.Scheme
+			host = r.Host
 		})).ServeHTTP(rr, r)
 
 	if rr.Code != http.StatusOK {
@@ -96,5 +100,9 @@ func TestProxyHeaders(t *testing.T) {
 		t.Fatalf("wrong address: got %s want %s", proto,
 			r.Header.Get(xForwardedProto))
 	}
+	if host != r.Header.Get(xForwardedHost) {
+		t.Fatalf("wrong address: got %s want %s", host,
+			r.Header.Get(xForwardedHost))
+	}
 
 }