Experimental: Add grpc-web HTTP client

clientconn.go

@@ -478,19 +478,9 @@ func DialContext(ctx context.Context, target string, opts ...DialOption) (conn *
 		}
 	}
 
-	if !cc.dopts.insecure {
-		if cc.dopts.copts.TransportCredentials == nil {
-			return nil, errNoTransportSecurity
-		}
-	} else {
-		if cc.dopts.copts.TransportCredentials != nil {
-			return nil, errCredentialsConflict
-		}
-		for _, cd := range cc.dopts.copts.PerRPCCredentials {
-			if cd.RequireTransportSecurity() {
-				return nil, errTransportCredentialsMissing
-			}
-		}
+	err = cc.validateClientOptions()
+	if err != nil {
+		return nil, err
 	}
 
 	cc.mkp = cc.dopts.copts.KeepaliveParams

dial.go

@@ -0,0 +1,39 @@
+// +build !js !wasm
+
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+func (cc *ClientConn) validateClientOptions() error {
+	if !cc.dopts.insecure {
+		if cc.dopts.copts.TransportCredentials == nil {
+			return errNoTransportSecurity
+		}
+	} else {
+		if cc.dopts.copts.TransportCredentials != nil {
+			return errCredentialsConflict
+		}
+		for _, cd := range cc.dopts.copts.PerRPCCredentials {
+			if cd.RequireTransportSecurity() {
+				return errTransportCredentialsMissing
+			}
+		}
+	}
+	return nil
+}

dial_js.go

@@ -0,0 +1,39 @@
+// +build js,wasm
+
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+	"errors"
+)
+
+var (
+	// errTransportSecurity indicates the client was attempting an RPC call
+	// from a WASM client with TransportCredentials configured.
+	errTransportSecurity = errors.New("cannot configure transport security for WASM clients")
+)
+
+func (cc *ClientConn) validateClientOptions() error {
+	if cc.dopts.copts.TransportCredentials != nil {
+		return errTransportSecurity
+	}
+
+	return nil
+}

newstream.go

@@ -0,0 +1,27 @@
+// +build !js !wasm
+
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import "golang.org/x/net/context"
+
+func (cc *ClientConn) newStream(ctx context.Context, desc *StreamDesc, method string, opts ...CallOption) (ClientStream, error) {
+	return cc.makeStream(ctx, desc, method, opts...)
+}

newstream_js.go

@@ -0,0 +1,34 @@
+// +build js,wasm
+
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+	"golang.org/x/net/context"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+func (cc *ClientConn) newStream(ctx context.Context, desc *StreamDesc, method string, opts ...CallOption) (ClientStream, error) {
+	if desc.ClientStreams {
+		return nil, status.Error(codes.Unimplemented, "client-side and bi-directional streaming is not yet supported by gRPC-web")
+	}
+	return cc.makeStream(ctx, desc, method, opts...)
+}

parse.go

@@ -0,0 +1,27 @@
+// +build !js !wasm
+
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import "google.golang.org/grpc/transport"
+
+func parseMsg(p *parser, s *transport.Stream, maxReceiveMessageSize int, pf payloadFormat, d []byte) ([]byte, error) {
+	return d, nil
+}

parse_js.go

@@ -0,0 +1,79 @@
+// +build js,wasm
+
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"io"
+	"net/http"
+	"strings"
+
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+	"google.golang.org/grpc/transport"
+)
+
+func parseMsg(p *parser, s *transport.Stream, maxReceiveMessageSize int, pf payloadFormat, d []byte) ([]byte, error) {
+	if pf == trailer || pf == compressedTrailer {
+		trailers, err := readTrailers(bytes.NewReader(d), len(d))
+		if err != nil {
+			return nil, status.Errorf(codes.Internal, "grpc: failed to parse returned trailers: %v", err)
+		}
+		// Holy layer violation :(
+		// This is necessary because the gRPC-Web trailers are part of the response body. See
+		// https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-WEB.md#protocol-differences-vs-grpc-over-http2
+		err = s.SetTrailers(trailers)
+		if err != nil {
+			return nil, status.Errorf(codes.Internal, "grpc: failed to set trailers on stream: %v", err)
+		}
+		// Sanity check that parser is done. This should return io.EOF
+		_, _, err = p.recvMsg(maxReceiveMessageSize)
+		if err == io.EOF {
+			return nil, err
+		}
+		return nil, status.Errorf(codes.Internal, "grpc: unexpected error reading last message from stream: %v", err)
+	}
+	return d, nil
+}
+
+// readTrailers consumes the rest of the reader and parses the
+// contents as "\r\n"-separated trailers, in accordance with
+// https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-WEB.md#protocol-differences-vs-grpc-over-http2
+func readTrailers(in io.Reader, bufSize int) (http.Header, error) {
+	s := bufio.NewScanner(in)
+	buf := make([]byte, bufSize)
+	s.Buffer(buf, len(buf))
+	// Uses http.Header instead of metadata.MD as .Add method
+	// normalizes trailer keys.
+	trailers := http.Header{}
+	for s.Scan() {
+		v := s.Text()
+		kv := strings.SplitN(v, ": ", 2)
+		if len(kv) != 2 {
+			return nil, errors.New("malformed trailer: " + v)
+		}
+		trailers.Add(kv[0], kv[1])
+	}
+
+	return trailers, s.Err()
+}

rpc_util.go

@@ -421,6 +421,10 @@ type payloadFormat uint8
 const (
 	compressionNone payloadFormat = 0 // no compression
 	compressionMade payloadFormat = 1 // compressed
+	// Defined for gRPC-Web
+	// https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-WEB.md#protocol-differences-vs-grpc-over-http2
+	trailer           payloadFormat = 1 << 7
+	compressedTrailer payloadFormat = (1 << 7) | 1
 )
 
 // parser reads complete gRPC messages from the underlying reader.
@@ -557,8 +561,8 @@ func outPayload(client bool, msg interface{}, data, payload []byte, t time.Time)
 
 func checkRecvPayload(pf payloadFormat, recvCompress string, haveCompressor bool) *status.Status {
 	switch pf {
-	case compressionNone:
-	case compressionMade:
+	case compressionNone, trailer:
+	case compressionMade, compressedTrailer:
 		if recvCompress == "" || recvCompress == encoding.Identity {
 			return status.New(codes.Internal, "grpc: compressed flag set with identity or empty encoding")
 		}
@@ -587,7 +591,7 @@ func recv(p *parser, c baseCodec, s *transport.Stream, dc Decompressor, m interf
 		return st.Err()
 	}
 
-	if pf == compressionMade {
+	if pf == compressionMade || pf == compressedTrailer {
 		// To match legacy behavior, if the decompressor is set by WithDecompressor or RPCDecompressor,
 		// use this decompressor as the default.
 		if dc != nil {
@@ -611,6 +615,10 @@ func recv(p *parser, c baseCodec, s *transport.Stream, dc Decompressor, m interf
 		// implementation.
 		return status.Errorf(codes.ResourceExhausted, "grpc: received message larger than max (%d vs. %d)", len(d), maxReceiveMessageSize)
 	}
+	d, err = parseMsg(p, s, maxReceiveMessageSize, pf, d)
+	if err != nil {
+		return err // already a status error (or io.EOF)
+	}
 	if err := c.Unmarshal(d, m); err != nil {
 		return status.Errorf(codes.Internal, "grpc: failed to unmarshal the received message %v", err)
 	}

stream.go

@@ -117,6 +117,10 @@ type ClientStream interface {
 // If none of the above happen, a goroutine and a context will be leaked, and grpc
 // will not call the optionally-configured stats handler with a stats.End message.
 func (cc *ClientConn) NewStream(ctx context.Context, desc *StreamDesc, method string, opts ...CallOption) (ClientStream, error) {
+	return cc.newStream(ctx, desc, method, opts...)
+}
+
+func (cc *ClientConn) makeStream(ctx context.Context, desc *StreamDesc, method string, opts ...CallOption) (ClientStream, error) {
 	// allow interceptor to see all applicable call options, which means those
 	// configured as defaults from dial option as well as per-call options
 	opts = combine(cc.dopts.callOptions, opts)