From 2fa09e1cc662a02c938e750a21efd4ee652fb2ae Mon Sep 17 00:00:00 2001
From: Chung-Ting Huang <chungting@cloudflare.com>
Date: Wed, 19 Jun 2019 20:48:55 -0500
Subject: [PATCH] TUN-1976: Pass tunnel hostname through header

---
 h2mux/muxreader.go      |   6 +++
 h2mux/muxreader_test.go | 107 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 113 insertions(+)
 create mode 100644 h2mux/muxreader_test.go

diff --git a/h2mux/muxreader.go b/h2mux/muxreader.go
index 3bdc8216..d97fcd8c 100644
--- a/h2mux/muxreader.go
+++ b/h2mux/muxreader.go
@@ -11,6 +11,10 @@ import (
 	"golang.org/x/net/http2"
 )
 
+const (
+	CloudflaredProxyTunnelHostnameHeader = "cf-cloudflared-proxy-tunnel-hostname"
+)
+
 type MuxReader struct {
 	// f is used to read HTTP2 frames.
 	f *http2.Framer
@@ -235,6 +239,8 @@ func (r *MuxReader) receiveHeaderData(frame *http2.MetaHeadersFrame) error {
 			if r.dictionaries.write != nil {
 				continue
 			}
+		case CloudflaredProxyTunnelHostnameHeader:
+			stream.tunnelHostname = TunnelHostname(header.Value)
 		}
 		headers = append(headers, Header{Name: header.Name, Value: header.Value})
 	}
diff --git a/h2mux/muxreader_test.go b/h2mux/muxreader_test.go
new file mode 100644
index 00000000..dd3bf440
--- /dev/null
+++ b/h2mux/muxreader_test.go
@@ -0,0 +1,107 @@
+package h2mux
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+var (
+	methodHeader = Header{
+		Name:  ":method",
+		Value: "GET",
+	}
+	schemeHeader = Header{
+		Name:  ":scheme",
+		Value: "https",
+	}
+	pathHeader = Header{
+		Name:  ":path",
+		Value: "/api/tunnels",
+	}
+	tunnelHostnameHeader = Header{
+		Name:  CloudflaredProxyTunnelHostnameHeader,
+		Value: "tunnel.example.com",
+	}
+	respStatusHeader = Header{
+		Name:  ":status",
+		Value: "200",
+	}
+)
+
+type mockOriginStreamHandler struct {
+	stream *MuxedStream
+}
+
+func (mosh *mockOriginStreamHandler) ServeStream(stream *MuxedStream) error {
+	mosh.stream = stream
+	// Echo tunnel hostname in header
+	stream.WriteHeaders([]Header{respStatusHeader})
+	return nil
+}
+
+func getCloudflaredProxyTunnelHostnameHeader(stream *MuxedStream) string {
+	for _, header := range stream.Headers {
+		if header.Name == CloudflaredProxyTunnelHostnameHeader {
+			return header.Value
+		}
+	}
+	return ""
+}
+
+func assertOpenStreamSucceed(t *testing.T, stream *MuxedStream, err error) {
+	assert.NoError(t, err)
+	assert.Len(t, stream.Headers, 1)
+	assert.Equal(t, respStatusHeader, stream.Headers[0])
+}
+
+func TestMissingHeaders(t *testing.T) {
+	originHandler := &mockOriginStreamHandler{}
+	muxPair := NewDefaultMuxerPair(t, originHandler.ServeStream)
+	muxPair.Serve(t)
+
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+
+	reqHeaders := []Header{
+		{
+			Name:  "content-type",
+			Value: "application/json",
+		},
+	}
+
+	// Request doesn't contain CloudflaredProxyTunnelHostnameHeader
+	stream, err := muxPair.EdgeMux.OpenStream(ctx, reqHeaders, nil)
+	assertOpenStreamSucceed(t, stream, err)
+
+	assert.Empty(t, originHandler.stream.method)
+	assert.Empty(t, originHandler.stream.path)
+	assert.False(t, originHandler.stream.TunnelHostname().IsSet())
+}
+
+func TestReceiveHeaderData(t *testing.T) {
+	originHandler := &mockOriginStreamHandler{}
+	muxPair := NewDefaultMuxerPair(t, originHandler.ServeStream)
+	muxPair.Serve(t)
+
+	reqHeaders := []Header{
+		methodHeader,
+		schemeHeader,
+		pathHeader,
+		tunnelHostnameHeader,
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+
+	reqHeaders = append(reqHeaders, tunnelHostnameHeader)
+	stream, err := muxPair.EdgeMux.OpenStream(ctx, reqHeaders, nil)
+	assertOpenStreamSucceed(t, stream, err)
+
+	assert.Equal(t, methodHeader.Value, originHandler.stream.method)
+	assert.Equal(t, pathHeader.Value, originHandler.stream.path)
+	assert.True(t, originHandler.stream.TunnelHostname().IsSet())
+	assert.Equal(t, tunnelHostnameHeader.Value, originHandler.stream.TunnelHostname().String())
+}