add plugin http handler (#7289)

10 files changed, 403 insertions, 30 deletions

diff --git a/plugin/hooks.go b/plugin/hooks.go
index 28a762a1a..336e56ccb 100644
--- a/plugin/hooks.go
+++ b/plugin/hooks.go
@@ -1,5 +1,9 @@
 package plugin
 
+import (
+	"net/http"
+)
+
 type Hooks interface {
 	// OnActivate is invoked when the plugin is activated.
 	OnActivate(API) error
@@ -7,4 +11,11 @@ type Hooks interface {
 	// OnDeactivate is invoked when the plugin is deactivated. This is the plugin's last chance to
 	// use the API, and the plugin will be terminated shortly after this invocation.
 	OnDeactivate() error
+
+	// ServeHTTP allows the plugin to implement the http.Handler interface. Requests destined for
+	// the /plugins/{id} path will be routed to the plugin.
+	//
+	// The Mattermost-User-Id header will be present if (and only if) the request is by an
+	// authenticated user.
+	ServeHTTP(http.ResponseWriter, *http.Request)
 }
diff --git a/plugin/plugintest/hooks.go b/plugin/plugintest/hooks.go
index 057c705c9..4cac515b4 100644
--- a/plugin/plugintest/hooks.go
+++ b/plugin/plugintest/hooks.go
@@ -1,6 +1,8 @@
 package plugintest
 
 import (
+	"net/http"
+
 	"github.com/stretchr/testify/mock"
 
 	"github.com/mattermost/platform/plugin"
@@ -19,3 +21,7 @@ func (m *Hooks) OnActivate(api plugin.API) error {
 func (m *Hooks) OnDeactivate() error {
 	return m.Called().Error(0)
 }
+
+func (m *Hooks) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	m.Called(w, r)
+}
diff --git a/plugin/rpcplugin/api.go b/plugin/rpcplugin/api.go
index a807d0837..84eb3baae 100644
--- a/plugin/rpcplugin/api.go
+++ b/plugin/rpcplugin/api.go
@@ -26,11 +26,6 @@ func (h *LocalAPI) LoadPluginConfiguration(args struct{}, reply *[]byte) error {
 	return nil
 }
 
-type RemoteAPI struct {
-	client *rpc.Client
-	muxer  *Muxer
-}
-
 func ServeAPI(api plugin.API, conn io.ReadWriteCloser, muxer *Muxer) {
 	server := rpc.NewServer()
 	server.Register(&LocalAPI{
@@ -40,6 +35,11 @@ func ServeAPI(api plugin.API, conn io.ReadWriteCloser, muxer *Muxer) {
 	server.ServeConn(conn)
 }
 
+type RemoteAPI struct {
+	client *rpc.Client
+	muxer  *Muxer
+}
+
 var _ plugin.API = (*RemoteAPI)(nil)
 
 func (h *RemoteAPI) LoadPluginConfiguration(dest interface{}) error {
diff --git a/plugin/rpcplugin/hooks.go b/plugin/rpcplugin/hooks.go
index 5b97742aa..995f4ae1a 100644
--- a/plugin/rpcplugin/hooks.go
+++ b/plugin/rpcplugin/hooks.go
@@ -1,7 +1,10 @@
 package rpcplugin
 
 import (
+	"bytes"
 	"io"
+	"io/ioutil"
+	"net/http"
 	"net/rpc"
 	"reflect"
 
@@ -83,6 +86,33 @@ func (h *LocalHooks) OnDeactivate(args, reply *struct{}) (err error) {
 	return
 }
 
+type ServeHTTPArgs struct {
+	ResponseWriterStream int64
+	Request              *http.Request
+	RequestBodyStream    int64
+}
+
+func (h *LocalHooks) ServeHTTP(args ServeHTTPArgs, reply *struct{}) error {
+	w := ConnectHTTPResponseWriter(h.muxer.Connect(args.ResponseWriterStream))
+	defer w.Close()
+
+	r := args.Request
+	if args.RequestBodyStream != 0 {
+		r.Body = ConnectIOReader(h.muxer.Connect(args.RequestBodyStream))
+	} else {
+		r.Body = ioutil.NopCloser(&bytes.Buffer{})
+	}
+	defer r.Body.Close()
+
+	if hook, ok := h.hooks.(http.Handler); ok {
+		hook.ServeHTTP(w, r)
+	} else {
+		http.NotFound(w, r)
+	}
+
+	return nil
+}
+
 func ServeHooks(hooks interface{}, conn io.ReadWriteCloser, muxer *Muxer) {
 	server := rpc.NewServer()
 	server.Register(&LocalHooks{
@@ -95,6 +125,7 @@ func ServeHooks(hooks interface{}, conn io.ReadWriteCloser, muxer *Muxer) {
 const (
 	remoteOnActivate = iota
 	remoteOnDeactivate
+	remoteServeHTTP
 	maxRemoteHookCount
 )
 
@@ -133,6 +164,45 @@ func (h *RemoteHooks) OnDeactivate() error {
 	return h.client.Call("LocalHooks.OnDeactivate", struct{}{}, nil)
 }
 
+func (h *RemoteHooks) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if !h.implemented[remoteServeHTTP] {
+		http.NotFound(w, r)
+		return
+	}
+
+	responseWriterStream, stream := h.muxer.Serve()
+	defer stream.Close()
+	go ServeHTTPResponseWriter(w, stream)
+
+	requestBodyStream := int64(0)
+	if r.Body != nil {
+		rid, rstream := h.muxer.Serve()
+		defer rstream.Close()
+		go ServeIOReader(r.Body, rstream)
+		requestBodyStream = rid
+	}
+
+	forwardedRequest := &http.Request{
+		Method:     r.Method,
+		URL:        r.URL,
+		Proto:      r.Proto,
+		ProtoMajor: r.ProtoMajor,
+		ProtoMinor: r.ProtoMinor,
+		Header:     r.Header,
+		Host:       r.Host,
+		RemoteAddr: r.RemoteAddr,
+		RequestURI: r.RequestURI,
+	}
+
+	if err := h.client.Call("LocalHooks.ServeHTTP", ServeHTTPArgs{
+		ResponseWriterStream: responseWriterStream,
+		Request:              forwardedRequest,
+		RequestBodyStream:    requestBodyStream,
+	}, nil); err != nil {
+		http.Error(w, "500 internal server error", http.StatusInternalServerError)
+	}
+}
+
 func (h *RemoteHooks) Close() error {
 	if h.apiCloser != nil {
 		h.apiCloser.Close()
@@ -157,6 +227,8 @@ func ConnectHooks(conn io.ReadWriteCloser, muxer *Muxer) (*RemoteHooks, error) {
 			remote.implemented[remoteOnActivate] = true
 		case "OnDeactivate":
 			remote.implemented[remoteOnDeactivate] = true
+		case "ServeHTTP":
+			remote.implemented[remoteServeHTTP] = true
 		}
 	}
 	return remote, nil
diff --git a/plugin/rpcplugin/hooks_test.go b/plugin/rpcplugin/hooks_test.go
index 6cd7ff547..eb684956b 100644
--- a/plugin/rpcplugin/hooks_test.go
+++ b/plugin/rpcplugin/hooks_test.go
@@ -2,6 +2,10 @@ package rpcplugin
 
 import (
 	"io"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -45,6 +49,31 @@ func TestHooks(t *testing.T) {
 
 		hooks.On("OnDeactivate").Return(nil)
 		assert.NoError(t, remote.OnDeactivate())
+
+		hooks.On("ServeHTTP", mock.AnythingOfType("*rpcplugin.RemoteHTTPResponseWriter"), mock.AnythingOfType("*http.Request")).Run(func(args mock.Arguments) {
+			w := args.Get(0).(http.ResponseWriter)
+			r := args.Get(1).(*http.Request)
+			assert.Equal(t, "/foo", r.URL.Path)
+			assert.Equal(t, "POST", r.Method)
+			body, err := ioutil.ReadAll(r.Body)
+			assert.NoError(t, err)
+			assert.Equal(t, "asdf", string(body))
+			assert.Equal(t, "header", r.Header.Get("Test-Header"))
+			w.Write([]byte("bar"))
+		})
+
+		w := httptest.NewRecorder()
+		r, err := http.NewRequest("POST", "/foo", strings.NewReader("asdf"))
+		r.Header.Set("Test-Header", "header")
+		assert.NoError(t, err)
+		remote.ServeHTTP(w, r)
+
+		resp := w.Result()
+		defer resp.Body.Close()
+		assert.Equal(t, http.StatusOK, resp.StatusCode)
+		body, err := ioutil.ReadAll(resp.Body)
+		assert.NoError(t, err)
+		assert.Equal(t, "bar", string(body))
 	}))
 }
 
@@ -73,9 +102,18 @@ func TestHooks_PartiallyImplemented(t *testing.T) {
 	}))
 }
 
-func BenchmarkOnDeactivate(b *testing.B) {
-	var hooks plugintest.Hooks
-	hooks.On("OnDeactivate").Return(nil)
+type benchmarkHooks struct{}
+
+func (*benchmarkHooks) OnDeactivate() error { return nil }
+
+func (*benchmarkHooks) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	ioutil.ReadAll(r.Body)
+	w.Header().Set("Foo-Header", "foo")
+	http.Error(w, "foo", http.StatusBadRequest)
+}
+
+func BenchmarkHooks_OnDeactivate(b *testing.B) {
+	var hooks benchmarkHooks
 
 	if err := testHooksRPC(&hooks, func(remote *RemoteHooks) {
 		b.ResetTimer()
@@ -88,7 +126,23 @@ func BenchmarkOnDeactivate(b *testing.B) {
 	}
 }
 
-func BenchmarkOnDeactivate_Unimplemented(b *testing.B) {
+func BenchmarkHooks_ServeHTTP(b *testing.B) {
+	var hooks benchmarkHooks
+
+	if err := testHooksRPC(&hooks, func(remote *RemoteHooks) {
+		b.ResetTimer()
+		for n := 0; n < b.N; n++ {
+			w := httptest.NewRecorder()
+			r, _ := http.NewRequest("POST", "/foo", strings.NewReader("12345678901234567890"))
+			remote.ServeHTTP(w, r)
+		}
+		b.StopTimer()
+	}); err != nil {
+		b.Fatal(err.Error())
+	}
+}
+
+func BenchmarkHooks_Unimplemented(b *testing.B) {
 	var hooks testHooks
 
 	if err := testHooksRPC(&hooks, func(remote *RemoteHooks) {
diff --git a/plugin/rpcplugin/http.go b/plugin/rpcplugin/http.go
new file mode 100644
index 000000000..cfcb7419d
--- /dev/null
+++ b/plugin/rpcplugin/http.go
@@ -0,0 +1,88 @@
+package rpcplugin
+
+import (
+	"io"
+	"net/http"
+	"net/rpc"
+)
+
+type LocalHTTPResponseWriter struct {
+	w http.ResponseWriter
+}
+
+func (w *LocalHTTPResponseWriter) Header(args struct{}, reply *http.Header) error {
+	*reply = w.w.Header()
+	return nil
+}
+
+func (w *LocalHTTPResponseWriter) Write(args []byte, reply *struct{}) error {
+	_, err := w.w.Write(args)
+	return err
+}
+
+func (w *LocalHTTPResponseWriter) WriteHeader(args int, reply *struct{}) error {
+	w.w.WriteHeader(args)
+	return nil
+}
+
+func (w *LocalHTTPResponseWriter) SyncHeader(args http.Header, reply *struct{}) error {
+	dest := w.w.Header()
+	for k := range dest {
+		if _, ok := args[k]; !ok {
+			delete(dest, k)
+		}
+	}
+	for k, v := range args {
+		dest[k] = v
+	}
+	return nil
+}
+
+func ServeHTTPResponseWriter(w http.ResponseWriter, conn io.ReadWriteCloser) {
+	server := rpc.NewServer()
+	server.Register(&LocalHTTPResponseWriter{
+		w: w,
+	})
+	server.ServeConn(conn)
+}
+
+type RemoteHTTPResponseWriter struct {
+	client *rpc.Client
+	header http.Header
+}
+
+var _ http.ResponseWriter = (*RemoteHTTPResponseWriter)(nil)
+
+func (w *RemoteHTTPResponseWriter) Header() http.Header {
+	if w.header == nil {
+		w.client.Call("LocalHTTPResponseWriter.Header", struct{}{}, &w.header)
+	}
+	return w.header
+}
+
+func (w *RemoteHTTPResponseWriter) Write(b []byte) (int, error) {
+	if err := w.client.Call("LocalHTTPResponseWriter.SyncHeader", w.header, nil); err != nil {
+		return 0, err
+	}
+	if err := w.client.Call("LocalHTTPResponseWriter.Write", b, nil); err != nil {
+		return 0, err
+	}
+	return len(b), nil
+}
+
+func (w *RemoteHTTPResponseWriter) WriteHeader(statusCode int) {
+	if err := w.client.Call("LocalHTTPResponseWriter.SyncHeader", w.header, nil); err != nil {
+		return
+	}
+	w.client.Call("LocalHTTPResponseWriter.WriteHeader", statusCode, nil)
+}
+
+func (h *RemoteHTTPResponseWriter) Close() error {
+	return h.client.Close()
+}
+
+func ConnectHTTPResponseWriter(conn io.ReadWriteCloser) *RemoteHTTPResponseWriter {
+	return &RemoteHTTPResponseWriter{
+		client: rpc.NewClient(conn),
+	}
+}
diff --git a/plugin/rpcplugin/http_test.go b/plugin/rpcplugin/http_test.go
new file mode 100644
index 000000000..afaaf7756
--- /dev/null
+++ b/plugin/rpcplugin/http_test.go
@@ -0,0 +1,61 @@
+package rpcplugin
+
+import (
+	"io"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func testHTTPResponseWriterRPC(w http.ResponseWriter, f func(w http.ResponseWriter)) {
+	r1, w1 := io.Pipe()
+	r2, w2 := io.Pipe()
+
+	c1 := NewMuxer(NewReadWriteCloser(r1, w2), false)
+	defer c1.Close()
+
+	c2 := NewMuxer(NewReadWriteCloser(r2, w1), true)
+	defer c2.Close()
+
+	id, server := c1.Serve()
+	go ServeHTTPResponseWriter(w, server)
+
+	remote := ConnectHTTPResponseWriter(c2.Connect(id))
+	defer remote.Close()
+
+	f(remote)
+}
+
+func TestHTTP(t *testing.T) {
+	w := httptest.NewRecorder()
+
+	testHTTPResponseWriterRPC(w, func(w http.ResponseWriter) {
+		headers := w.Header()
+		headers.Set("Test-Header-A", "a")
+		headers.Set("Test-Header-B", "b")
+		w.Header().Set("Test-Header-C", "c")
+		w.WriteHeader(http.StatusPaymentRequired)
+		n, err := w.Write([]byte("this is "))
+		assert.Equal(t, 8, n)
+		assert.NoError(t, err)
+		n, err = w.Write([]byte("a test"))
+		assert.Equal(t, 6, n)
+		assert.NoError(t, err)
+	})
+
+	r := w.Result()
+	defer r.Body.Close()
+
+	assert.Equal(t, http.StatusPaymentRequired, r.StatusCode)
+
+	body, err := ioutil.ReadAll(r.Body)
+	assert.NoError(t, err)
+	assert.EqualValues(t, "this is a test", body)
+
+	assert.Equal(t, "a", r.Header.Get("Test-Header-A"))
+	assert.Equal(t, "b", r.Header.Get("Test-Header-B"))
+	assert.Equal(t, "c", r.Header.Get("Test-Header-C"))
+}
diff --git a/plugin/rpcplugin/io.go b/plugin/rpcplugin/io.go
index f1b2f3c35..38229d868 100644
--- a/plugin/rpcplugin/io.go
+++ b/plugin/rpcplugin/io.go
@@ -1,7 +1,10 @@
 package rpcplugin
 
 import (
+	"bufio"
+	"encoding/binary"
 	"io"
+	"os"
 )
 
 type rwc struct {
@@ -9,15 +12,56 @@ type rwc struct {
 	io.WriteCloser
 }
 
-func (rwc *rwc) Close() error {
-	rerr := rwc.ReadCloser.Close()
+func (rwc *rwc) Close() (err error) {
+	if f, ok := rwc.ReadCloser.(*os.File); ok {
+		// https://groups.google.com/d/topic/golang-nuts/i4w58KJ5-J8/discussion
+		err = os.NewFile(f.Fd(), "").Close()
+	} else {
+		err = rwc.ReadCloser.Close()
+	}
 	werr := rwc.WriteCloser.Close()
-	if rerr != nil {
-		return rerr
+	if err == nil {
+		err = werr
 	}
-	return werr
+	return
 }
 
 func NewReadWriteCloser(r io.ReadCloser, w io.WriteCloser) io.ReadWriteCloser {
 	return &rwc{r, w}
 }
+
+type RemoteIOReader struct {
+	conn io.ReadWriteCloser
+}
+
+func (r *RemoteIOReader) Read(b []byte) (int, error) {
+	var buf [10]byte
+	n := binary.PutVarint(buf[:], int64(len(b)))
+	if _, err := r.conn.Write(buf[:n]); err != nil {
+		return 0, err
+	}
+	return r.conn.Read(b)
+}
+
+func (r *RemoteIOReader) Close() error {
+	return r.conn.Close()
+}
+
+func ConnectIOReader(conn io.ReadWriteCloser) io.ReadCloser {
+	return &RemoteIOReader{conn}
+}
+
+func ServeIOReader(r io.Reader, conn io.ReadWriteCloser) {
+	cr := bufio.NewReader(conn)
+	defer conn.Close()
+	buf := make([]byte, 32*1024)
+	for {
+		n, err := binary.ReadVarint(cr)
+		if err != nil {
+			break
+		}
+		if written, err := io.CopyBuffer(conn, io.LimitReader(r, n), buf); err != nil || written < n {
+			break
+		}
+	}
+}
diff --git a/plugin/rpcplugin/muxer.go b/plugin/rpcplugin/muxer.go
index a2bfbf8b6..393a122c4 100644
--- a/plugin/rpcplugin/muxer.go
+++ b/plugin/rpcplugin/muxer.go
@@ -114,20 +114,22 @@ func (m *Muxer) write(p []byte, sid int64) (int, error) {
 	if m.IsClosed() {
 		return 0, fmt.Errorf("muxer closed")
 	}
-	buf := make([]byte, 10)
-	n := binary.PutVarint(buf, sid)
+	var buf [10]byte
+	n := binary.PutVarint(buf[:], sid)
 	if _, err := m.conn.Write(buf[:n]); err != nil {
 		m.shutdown(err)
 		return 0, err
 	}
-	n = binary.PutVarint(buf, int64(len(p)))
+	n = binary.PutVarint(buf[:], int64(len(p)))
 	if _, err := m.conn.Write(buf[:n]); err != nil {
 		m.shutdown(err)
 		return 0, err
 	}
-	if _, err := m.conn.Write(p); err != nil {
-		m.shutdown(err)
-		return 0, err
+	if len(p) > 0 {
+		if _, err := m.conn.Write(p); err != nil {
+			m.shutdown(err)
+			return 0, err
+		}
 	}
 	return len(p), nil
 }
@@ -180,7 +182,11 @@ func (m *Muxer) loop() error {
 			}
 			continue
 		}
-		_, err = io.CopyN(&stream.readBuf, reader, len)
+		if len == 0 {
+			stream.remoteClosed = true
+		} else {
+			_, err = io.CopyN(&stream.readBuf, reader, len)
+		}
 		stream.mutex.Unlock()
 		if err != nil {
 			return err
@@ -207,13 +213,14 @@ func (m *Muxer) shutdown(err error) {
 }
 
 type muxerStream struct {
-	id       int64
-	muxer    *Muxer
-	readBuf  bytes.Buffer
-	mutex    *sync.Mutex
-	readWake *sync.Cond
-	isClosed bool
-	closeErr error
+	id           int64
+	muxer        *Muxer
+	readBuf      bytes.Buffer
+	mutex        *sync.Mutex
+	readWake     *sync.Cond
+	isClosed     bool
+	remoteClosed bool
+	closeErr     error
 }
 
 func (s *muxerStream) Read(p []byte) (int, error) {
@@ -225,8 +232,9 @@ func (s *muxerStream) Read(p []byte) (int, error) {
 		} else if s.isClosed {
 			return 0, io.EOF
 		} else if s.readBuf.Len() > 0 {
-			n, err := s.readBuf.Read(p)
-			return n, err
+			return s.readBuf.Read(p)
+		} else if s.remoteClosed {
+			return 0, io.EOF
 		}
 		s.readWake.Wait()
 	}
@@ -245,6 +253,7 @@ func (s *muxerStream) Close() error {
 	s.mutex.Lock()
 	defer s.mutex.Unlock()
 	if !s.isClosed {
+		s.muxer.write(nil, s.id)
 		s.isClosed = true
 		s.muxer.rm(s.id)
 	}
diff --git a/plugin/rpcplugin/muxer_test.go b/plugin/rpcplugin/muxer_test.go
index 7bb63d4f8..795a4fb1d 100644
--- a/plugin/rpcplugin/muxer_test.go
+++ b/plugin/rpcplugin/muxer_test.go
@@ -129,6 +129,34 @@ func TestMuxer_StreamCloseDuringRead(t *testing.T) {
 	assert.Equal(t, io.EOF, err)
 }
 
+// Closing a stream during a read should unblock and return io.EOF since this is the way for the
+// remote to gracefully close a connection.
+func TestMuxer_RemoteStreamCloseDuringRead(t *testing.T) {
+	r1, w1 := io.Pipe()
+	r2, w2 := io.Pipe()
+
+	alice := NewMuxer(NewReadWriteCloser(r1, w2), false)
+	defer func() { assert.NoError(t, alice.Close()) }()
+
+	bob := NewMuxer(NewReadWriteCloser(r2, w1), true)
+	defer func() { assert.NoError(t, bob.Close()) }()
+
+	id, as := alice.Serve()
+	bs := bob.Connect(id)
+
+	go func() {
+		as.Write([]byte("foo"))
+		as.Close()
+	}()
+	buf := make([]byte, 20)
+	n, err := bs.Read(buf)
+	assert.Equal(t, 3, n)
+	assert.Equal(t, "foo", string(buf[:n]))
+	n, err = bs.Read(buf)
+	assert.Equal(t, 0, n)
+	assert.Equal(t, io.EOF, err)
+}
+
 // Closing a muxer during a write should unblock, but return an error.
 func TestMuxer_CloseDuringWrite(t *testing.T) {
 	r1, w1 := io.Pipe()