1 files changed, 26 insertions, 0 deletions
diff --git a/workhorse/internal/proxy/proxy.go b/workhorse/internal/proxy/proxy.go
index be161c833a9..06e2c65a6a8 100644
--- a/workhorse/internal/proxy/proxy.go
+++ b/workhorse/internal/proxy/proxy.go
@@ -19,6 +19,7 @@ type Proxy struct {
 	reverseProxy           *httputil.ReverseProxy
 	AllowResponseBuffering bool
 	customHeaders          map[string]string
+	forceTargetHostHeader  bool
 }
 
 func WithCustomHeaders(customHeaders map[string]string) func(*Proxy) {
@@ -27,6 +28,12 @@ func WithCustomHeaders(customHeaders map[string]string) func(*Proxy) {
 	}
 }
 
+func WithForcedTargetHostHeader() func(*Proxy) {
+	return func(proxy *Proxy) {
+		proxy.forceTargetHostHeader = true
+	}
+}
+
 func NewProxy(myURL *url.URL, version string, roundTripper http.RoundTripper, options ...func(*Proxy)) *Proxy {
 	p := Proxy{Version: version, AllowResponseBuffering: true, customHeaders: make(map[string]string)}
 
@@ -43,6 +50,25 @@ func NewProxy(myURL *url.URL, version string, roundTripper http.RoundTripper, op
 		option(&p)
 	}
 
+	if p.forceTargetHostHeader {
+		// because of https://github.com/golang/go/issues/28168, the
+		// upstream won't receive the expected Host header unless this
+		// is forced in the Director func here
+		previousDirector := p.reverseProxy.Director
+		p.reverseProxy.Director = func(request *http.Request) {
+			previousDirector(request)
+
+			// send original host along for the upstream
+			// to know it's being proxied under a different Host
+			// (for redirects and other stuff that depends on this)
+			request.Header.Set("X-Forwarded-Host", request.Host)
+			request.Header.Set("Forwarded", fmt.Sprintf("host=%s", request.Host))
+
+			// override the Host with the target
+			request.Host = request.URL.Host
+		}
+	}
+
 	return &p
 }