From fd0abe46dd7d057e9553d51a939227c6bafeefa1 Mon Sep 17 00:00:00 2001
From: Dmitri Rubinstein <dmitri.rubinstein@googlemail.com>
Date: Tue, 14 Aug 2018 13:39:48 +0200
Subject: [PATCH] Propagate Host header from gateway request to the function.

Host HTTP header was not propagated to the function because it is not
a part of http.Request.Header map.

Signed-off-by: Dmitri Rubinstein <dmitri.rubinstein@googlemail.com>
---
 gateway/handlers/forwarding_proxy.go      |  3 ++
 gateway/handlers/forwarding_proxy_test.go | 34 +++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/gateway/handlers/forwarding_proxy.go b/gateway/handlers/forwarding_proxy.go
index 757b2ce4..3ec96b90 100644
--- a/gateway/handlers/forwarding_proxy.go
+++ b/gateway/handlers/forwarding_proxy.go
@@ -53,6 +53,9 @@ func buildUpstreamRequest(r *http.Request, url string) *http.Request {
 	}
 
 	upstreamReq, _ := http.NewRequest(r.Method, url, nil)
+	if len(r.Host) > 0 {
+		upstreamReq.Host = r.Host
+	}
 	copyHeaders(upstreamReq.Header, &r.Header)
 
 	upstreamReq.Header["X-Forwarded-For"] = []string{r.RemoteAddr}
diff --git a/gateway/handlers/forwarding_proxy_test.go b/gateway/handlers/forwarding_proxy_test.go
index aaef9b96..4c314cfd 100644
--- a/gateway/handlers/forwarding_proxy_test.go
+++ b/gateway/handlers/forwarding_proxy_test.go
@@ -68,6 +68,40 @@ func Test_buildUpstreamRequest_NoBody_GetMethod_NoQuery(t *testing.T) {
 
 }
 
+func Test_buildUpstreamRequest_HasHostHeaderWhenSet(t *testing.T) {
+	srcBytes := []byte("hello world")
+
+	reader := bytes.NewReader(srcBytes)
+	request, err := http.NewRequest(http.MethodPost, "http://gateway/function?code=1", reader)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	upstream := buildUpstreamRequest(request, "/")
+
+	if request.Host != upstream.Host {
+		t.Errorf("Host - want: %s, got: %s", request.Host, upstream.Host)
+	}
+}
+
+func Test_buildUpstreamRequest_HostHeader_Empty_WhenNotSet(t *testing.T) {
+	srcBytes := []byte("hello world")
+
+	reader := bytes.NewReader(srcBytes)
+	request, err := http.NewRequest(http.MethodPost, "/function", reader)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	upstream := buildUpstreamRequest(request, "/")
+
+	if request.Host != upstream.Host {
+		t.Errorf("Host - want: %s, got: %s", request.Host, upstream.Host)
+	}
+}
+
 func Test_getServiceName(t *testing.T) {
 	scenarios := []struct {
 		name        string