From ceb576ea017d434c92d3413e8d5b5aae09c7c0b8 Mon Sep 17 00:00:00 2001
From: joshblakeley <jtblakeley@gmail.com>
Date: Thu, 8 Nov 2018 14:32:49 +0000
Subject: [PATCH] optionally dont strip target url trailing slash in reverse
 proxy

---
 apidef/api_definitions.go |  1 +
 reverse_proxy.go          |  9 ++++++---
 reverse_proxy_test.go     | 20 +++++++++++++++++---
 3 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/apidef/api_definitions.go b/apidef/api_definitions.go
index 4a54845ee61..a76d451edae 100644
--- a/apidef/api_definitions.go
+++ b/apidef/api_definitions.go
@@ -377,6 +377,7 @@ type APIDefinition struct {
 		PreserveHostHeader          bool                          `bson:"preserve_host_header" json:"preserve_host_header"`
 		ListenPath                  string                        `bson:"listen_path" json:"listen_path"`
 		TargetURL                   string                        `bson:"target_url" json:"target_url"`
+		DisableStripPrefix          bool                          `bson:"disable_strip_prefix" json:"disable_strip_prefix"`
 		StripListenPath             bool                          `bson:"strip_listen_path" json:"strip_listen_path"`
 		EnableLoadBalancing         bool                          `bson:"enable_load_balancing" json:"enable_load_balancing"`
 		Targets                     []string                      `bson:"target_list" json:"target_list"`
diff --git a/reverse_proxy.go b/reverse_proxy.go
index 5e5423e9ec4..e5d39259460 100644
--- a/reverse_proxy.go
+++ b/reverse_proxy.go
@@ -234,9 +234,9 @@ func TykNewSingleHostReverseProxy(target *url.URL, spec *APISpec) *ReverseProxy
 		if targetToUse == target {
 			req.URL.Scheme = targetToUse.Scheme
 			req.URL.Host = targetToUse.Host
-			req.URL.Path = singleJoiningSlash(targetToUse.Path, req.URL.Path)
+			req.URL.Path = singleJoiningSlash(targetToUse.Path, req.URL.Path, spec.Proxy.DisableStripPrefix)
 			if req.URL.RawPath != "" {
-				req.URL.RawPath = singleJoiningSlash(targetToUse.Path, req.URL.RawPath)
+				req.URL.RawPath = singleJoiningSlash(targetToUse.Path, req.URL.RawPath, spec.Proxy.DisableStripPrefix)
 			}
 		}
 		if !spec.Proxy.PreserveHostHeader {
@@ -317,7 +317,10 @@ func defaultTransport() *http.Transport {
 	}
 }
 
-func singleJoiningSlash(a, b string) string {
+func singleJoiningSlash(a, b string, disableStripPrefix bool) string {
+	if disableStripPrefix && len(b) == 0 {
+		return a
+	}
 	a = strings.TrimRight(a, "/")
 	b = strings.TrimLeft(b, "/")
 	if len(b) > 0 {
diff --git a/reverse_proxy_test.go b/reverse_proxy_test.go
index 92743a8ce13..266cdc86c82 100644
--- a/reverse_proxy_test.go
+++ b/reverse_proxy_test.go
@@ -109,7 +109,7 @@ func TestWrappedServeHTTP(t *testing.T) {
 }
 
 func TestSingleJoiningSlash(t *testing.T) {
-	tests := []struct {
+	testsFalse := []struct {
 		a, b, want string
 	}{
 		{"foo", "", "foo"},
@@ -119,9 +119,23 @@ func TestSingleJoiningSlash(t *testing.T) {
 		{"foo/", "/bar", "foo/bar"},
 		{"foo//", "//bar", "foo/bar"},
 	}
-	for _, tc := range tests {
+	for _, tc := range testsFalse {
+		t.Run(fmt.Sprintf("%s+%s", tc.a, tc.b), func(t *testing.T) {
+			got := singleJoiningSlash(tc.a, tc.b, false)
+			if got != tc.want {
+				t.Fatalf("want %s, got %s", tc.want, got)
+			}
+		})
+	}
+	testsTrue := []struct {
+		a, b, want string
+	}{
+		{"foo/", "", "foo/"},
+		{"foo", "", "foo"},
+	}
+	for _, tc := range testsTrue {
 		t.Run(fmt.Sprintf("%s+%s", tc.a, tc.b), func(t *testing.T) {
-			got := singleJoiningSlash(tc.a, tc.b)
+			got := singleJoiningSlash(tc.a, tc.b, true)
 			if got != tc.want {
 				t.Fatalf("want %s, got %s", tc.want, got)
 			}