From 2637a326fb86594da42d20e0f8af09a4a47c4dde Mon Sep 17 00:00:00 2001
From: Ben Schumacher <ben.schumacher@mattermost.com>
Date: Wed, 14 Jul 2021 15:07:31 +0200
Subject: [PATCH] [MM-36563] Only read body from inter-plugin request if there
 is one (#17798)

---
 app/plugin_api_test.go | 55 ++++++++++++++++++++++++++++++------------
 plugin/client_rpc.go   | 23 ++++++++++--------
 2 files changed, 52 insertions(+), 26 deletions(-)

diff --git a/app/plugin_api_test.go b/app/plugin_api_test.go
index 4a81a6c83a..a189958718 100644
--- a/app/plugin_api_test.go
+++ b/app/plugin_api_test.go
@@ -1414,23 +1414,27 @@ func TestInterpluginPluginHTTP(t *testing.T) {
 		}
 
 		func (p *MyPlugin) ServeHTTP(c *plugin.Context, w http.ResponseWriter, r *http.Request) {
-			if r.URL.Path != "/api/v2/test" {
-				return
-			}
+			switch r.URL.Path {
+			case "/api/v2/test":
+				if r.URL.Query().Get("abc") != "xyz" {
+					return
+				}
 
-			if r.URL.Query().Get("abc") != "xyz" {
-				return
-			}
+				if r.Header.Get("Mattermost-Plugin-ID") != "testplugininterclient" {
+					return
+				}
 
-			if r.Header.Get("Mattermost-Plugin-ID") != "testplugininterclient" {
-				return
+				buf := bytes.Buffer{}
+				buf.ReadFrom(r.Body)
+				resp := "we got:" + buf.String()
+				w.WriteHeader(598)
+				w.Write([]byte(resp))
+				if r.URL.Path != "/api/v2/test" {
+					return
+				}
+			case "/nobody":
+				w.WriteHeader(599)
 			}
-
-			buf := bytes.Buffer{}
-			buf.ReadFrom(r.Body)
-			resp := "we got:" + buf.String()
-			w.WriteHeader(598)
-			w.Write([]byte(resp))
 		}
 
 		func main() {
@@ -1474,7 +1478,26 @@ func TestInterpluginPluginHTTP(t *testing.T) {
 			if resp.StatusCode != 598 {
 				return nil, "wrong status " + string(respbody)
 			}
-			return nil, string(respbody)
+
+			if string(respbody) !=  "we got:This is the request" {
+				return nil, "wrong response " + string(respbody)
+			}
+
+			req, err = http.NewRequest("GET", "/testplugininterserver/nobody", nil)
+			if err != nil {
+				return nil, err.Error()
+			}
+
+			resp = p.API.PluginHTTP(req)
+			if resp == nil {
+				return nil, "Nil resp"
+			}
+
+			if resp.StatusCode != 599 {
+				return nil, "wrong status " + string(respbody)
+			}
+
+			return nil, "ok"
 		}
 
 		func main() {
@@ -1498,7 +1521,7 @@ func TestInterpluginPluginHTTP(t *testing.T) {
 	hooks, err := th.App.GetPluginsEnvironment().HooksForPlugin("testplugininterclient")
 	require.NoError(t, err)
 	_, ret := hooks.MessageWillBePosted(nil, nil)
-	assert.Equal(t, "we got:This is the request", ret)
+	assert.Equal(t, "ok", ret)
 }
 
 func TestApiMetrics(t *testing.T) {
diff --git a/plugin/client_rpc.go b/plugin/client_rpc.go
index 58c0841a8c..798a6c79f3 100644
--- a/plugin/client_rpc.go
+++ b/plugin/client_rpc.go
@@ -475,17 +475,20 @@ func (g *apiRPCClient) PluginHTTP(request *http.Request) *http.Response {
 		RequestURI: request.RequestURI,
 	}
 
-	requestBody, err := ioutil.ReadAll(request.Body)
-	if err != nil {
-		log.Printf("RPC call to PluginHTTP API failed: %s", err.Error())
-		return nil
-	}
-	request.Body.Close()
-	request.Body = nil
-
 	_args := &Z_PluginHTTPArgs{
-		Request:     forwardedRequest,
-		RequestBody: requestBody,
+		Request: forwardedRequest,
+	}
+
+	if request.Body != nil {
+		requestBody, err := ioutil.ReadAll(request.Body)
+		if err != nil {
+			log.Printf("RPC call to PluginHTTP API failed: %s", err.Error())
+			return nil
+		}
+		request.Body.Close()
+		request.Body = nil
+
+		_args.RequestBody = requestBody
 	}
 
 	_returns := &Z_PluginHTTPReturns{}