client: set grpc-accept-encoding to full list of registered compressors

encoding/encoding.go

@@ -28,6 +28,8 @@ package encoding
 import (
 	"io"
 	"strings"
+
+	"google.golang.org/grpc/internal/grpcutil"
 )
 
 // Identity specifies the optional encoding for uncompressed streams.
@@ -73,6 +75,7 @@ var registeredCompressor = make(map[string]Compressor)
 // registered with the same name, the one registered last will take effect.
 func RegisterCompressor(c Compressor) {
 	registeredCompressor[c.Name()] = c
+	grpcutil.RegisteredCompressorNames = append(grpcutil.RegisteredCompressorNames, c.Name())
 }
 
 // GetCompressor returns Compressor for the given compressor name.

internal/envconfig/envconfig.go

@@ -25,11 +25,15 @@ import (
 )
 
 const (
-	prefix          = "GRPC_GO_"
-	txtErrIgnoreStr = prefix + "IGNORE_TXT_ERRORS"
+	prefix                  = "GRPC_GO_"
+	txtErrIgnoreStr         = prefix + "IGNORE_TXT_ERRORS"
+	advertiseCompressorsStr = prefix + "ADVERTISE_COMPRESSORS"
 )
 
 var (
 	// TXTErrIgnore is set if TXT errors should be ignored ("GRPC_GO_IGNORE_TXT_ERRORS" is not "false").
 	TXTErrIgnore = !strings.EqualFold(os.Getenv(txtErrIgnoreStr), "false")
+	// AdvertiseCompressors is set if registered compressor should be advertised
+	// ("GRPC_GO_ADVERTISE_COMPRESSORS" is not "false").
+	AdvertiseCompressors = !strings.EqualFold(os.Getenv(advertiseCompressorsStr), "false")
 )

internal/grpcutil/compressor.go

@@ -0,0 +1,47 @@
+/*
+ *
+ * Copyright 2022 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 grpcutil
+
+import (
+	"strings"
+
+	"google.golang.org/grpc/internal/envconfig"
+)
+
+// RegisteredCompressorNames holds names of the registered compressors.
+var RegisteredCompressorNames []string
+
+// IsCompressorNameRegistered returns true when name is available in registry.
+func IsCompressorNameRegistered(name string) bool {
+	for _, compressor := range RegisteredCompressorNames {
+		if compressor == name {
+			return true
+		}
+	}
+	return false
+}
+
+// RegisteredCompressors returns a string of registered compressor names
+// separated by comma.
+func RegisteredCompressors() string {
+	if !envconfig.AdvertiseCompressors {
+		return ""
+	}
+	return strings.Join(RegisteredCompressorNames, ",")
+}

internal/grpcutil/compressor_test.go

@@ -0,0 +1,46 @@
+/*
+ *
+ * Copyright 2022 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 grpcutil
+
+import (
+	"testing"
+
+	"google.golang.org/grpc/internal/envconfig"
+)
+
+func TestRegisteredCompressors(t *testing.T) {
+	defer func(c []string) { RegisteredCompressorNames = c }(RegisteredCompressorNames)
+	defer func(v bool) { envconfig.AdvertiseCompressors = v }(envconfig.AdvertiseCompressors)
+	RegisteredCompressorNames = []string{"gzip", "snappy"}
+	tests := []struct {
+		desc    string
+		enabled bool
+		want    string
+	}{
+		{desc: "compressor_ad_disabled", enabled: false, want: ""},
+		{desc: "compressor_ad_enabled", enabled: true, want: "gzip,snappy"},
+	}
+	for _, tt := range tests {
+		envconfig.AdvertiseCompressors = tt.enabled
+		compressors := RegisteredCompressors()
+		if compressors != tt.want {
+			t.Fatalf("Unexpected compressors got:%s, want:%s", compressors, tt.want)
+		}
+	}
+}

internal/transport/http2_client.go

@@ -109,6 +109,7 @@ type http2Client struct {
 	streamsQuotaAvailable chan struct{}
 	waitingStreams        uint32
 	nextID                uint32
+	registeredCompressors string
 
 	// Do not access controlBuf with mu held.
 	mu            sync.Mutex // guard the following variables
@@ -299,6 +300,7 @@ func newHTTP2Client(connectCtx, ctx context.Context, addr resolver.Address, opts
 		ctxDone:               ctx.Done(), // Cache Done chan.
 		cancel:                cancel,
 		userAgent:             opts.UserAgent,
+		registeredCompressors: grpcutil.RegisteredCompressors(),
 		conn:                  conn,
 		remoteAddr:            conn.RemoteAddr(),
 		localAddr:             conn.LocalAddr(),
@@ -507,9 +509,22 @@ func (t *http2Client) createHeaderFields(ctx context.Context, callHdr *CallHdr)
 		headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-previous-rpc-attempts", Value: strconv.Itoa(callHdr.PreviousAttempts)})
 	}
 
+	registeredCompressors := t.registeredCompressors
 	if callHdr.SendCompress != "" {
 		headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-encoding", Value: callHdr.SendCompress})
-		headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-accept-encoding", Value: callHdr.SendCompress})
+		// Include the outgoing compressor name when compressor is not registered
+		// via encoding.RegisterCompressor. This is possible when client uses
+		// WithCompressor dial option.
+		if !grpcutil.IsCompressorNameRegistered(callHdr.SendCompress) {
+			if registeredCompressors != "" {
+				registeredCompressors += ","
+			}
+			registeredCompressors += callHdr.SendCompress
+		}
+	}
+
+	if registeredCompressors != "" {
+		headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-accept-encoding", Value: registeredCompressors})
 	}
 	if dl, ok := ctx.Deadline(); ok {
 		// Send out timeout regardless its value. The server can detect timeout context by itself.

test/end2end_test.go

@@ -3249,6 +3249,7 @@ func testMetadataUnaryRPC(t *testing.T, e env) {
 		delete(header, "date")    // the Date header is also optional
 		delete(header, "user-agent")
 		delete(header, "content-type")
+		delete(header, "grpc-accept-encoding")
 	}
 	if !reflect.DeepEqual(header, testMetadata) {
 		t.Fatalf("Received header metadata %v, want %v", header, testMetadata)
@@ -3288,6 +3289,7 @@ func testMetadataOrderUnaryRPC(t *testing.T, e env) {
 		delete(header, "date")    // the Date header is also optional
 		delete(header, "user-agent")
 		delete(header, "content-type")
+		delete(header, "grpc-accept-encoding")
 	}
 
 	if !reflect.DeepEqual(header, newMetadata) {
@@ -3400,6 +3402,8 @@ func testSetAndSendHeaderUnaryRPC(t *testing.T, e env) {
 	}
 	delete(header, "user-agent")
 	delete(header, "content-type")
+	delete(header, "grpc-accept-encoding")
+
 	expectedHeader := metadata.Join(testMetadata, testMetadata2)
 	if !reflect.DeepEqual(header, expectedHeader) {
 		t.Fatalf("Received header metadata %v, want %v", header, expectedHeader)
@@ -3444,6 +3448,7 @@ func testMultipleSetHeaderUnaryRPC(t *testing.T, e env) {
 	}
 	delete(header, "user-agent")
 	delete(header, "content-type")
+	delete(header, "grpc-accept-encoding")
 	expectedHeader := metadata.Join(testMetadata, testMetadata2)
 	if !reflect.DeepEqual(header, expectedHeader) {
 		t.Fatalf("Received header metadata %v, want %v", header, expectedHeader)
@@ -3487,6 +3492,7 @@ func testMultipleSetHeaderUnaryRPCError(t *testing.T, e env) {
 	}
 	delete(header, "user-agent")
 	delete(header, "content-type")
+	delete(header, "grpc-accept-encoding")
 	expectedHeader := metadata.Join(testMetadata, testMetadata2)
 	if !reflect.DeepEqual(header, expectedHeader) {
 		t.Fatalf("Received header metadata %v, want %v", header, expectedHeader)
@@ -3527,6 +3533,7 @@ func testSetAndSendHeaderStreamingRPC(t *testing.T, e env) {
 	}
 	delete(header, "user-agent")
 	delete(header, "content-type")
+	delete(header, "grpc-accept-encoding")
 	expectedHeader := metadata.Join(testMetadata, testMetadata2)
 	if !reflect.DeepEqual(header, expectedHeader) {
 		t.Fatalf("Received header metadata %v, want %v", header, expectedHeader)
@@ -3590,6 +3597,7 @@ func testMultipleSetHeaderStreamingRPC(t *testing.T, e env) {
 	}
 	delete(header, "user-agent")
 	delete(header, "content-type")
+	delete(header, "grpc-accept-encoding")
 	expectedHeader := metadata.Join(testMetadata, testMetadata2)
 	if !reflect.DeepEqual(header, expectedHeader) {
 		t.Fatalf("Received header metadata %v, want %v", header, expectedHeader)
@@ -3650,6 +3658,7 @@ func testMultipleSetHeaderStreamingRPCError(t *testing.T, e env) {
 	}
 	delete(header, "user-agent")
 	delete(header, "content-type")
+	delete(header, "grpc-accept-encoding")
 	expectedHeader := metadata.Join(testMetadata, testMetadata2)
 	if !reflect.DeepEqual(header, expectedHeader) {
 		t.Fatalf("Received header metadata %v, want %v", header, expectedHeader)
@@ -3981,6 +3990,7 @@ func testMetadataStreamingRPC(t *testing.T, e env) {
 		delete(headerMD, "trailer") // ignore if present
 		delete(headerMD, "user-agent")
 		delete(headerMD, "content-type")
+		delete(headerMD, "grpc-accept-encoding")
 		if err != nil || !reflect.DeepEqual(testMetadata, headerMD) {
 			t.Errorf("#1 %v.Header() = %v, %v, want %v, <nil>", stream, headerMD, err, testMetadata)
 		}
@@ -3989,6 +3999,7 @@ func testMetadataStreamingRPC(t *testing.T, e env) {
 		delete(headerMD, "trailer") // ignore if present
 		delete(headerMD, "user-agent")
 		delete(headerMD, "content-type")
+		delete(headerMD, "grpc-accept-encoding")
 		if err != nil || !reflect.DeepEqual(testMetadata, headerMD) {
 			t.Errorf("#2 %v.Header() = %v, %v, want %v, <nil>", stream, headerMD, err, testMetadata)
 		}
@@ -5431,6 +5442,72 @@ func (s) TestForceServerCodec(t *testing.T) {
 	}
 }
 
+// renameCompressor is a grpc.Compressor wrapper that allows customizing the
+// Type() of another compressor.
+type renameCompressor struct {
+	grpc.Compressor
+	name string
+}
+
+func (r *renameCompressor) Type() string { return r.name }
+
+// renameDecompressor is a grpc.Decompressor wrapper that allows customizing the
+// Type() of another Decompressor.
+type renameDecompressor struct {
+	grpc.Decompressor
+	name string
+}
+
+func (r *renameDecompressor) Type() string { return r.name }
+
+func (s) TestClientForwardsGrpcAcceptEncodingHeader(t *testing.T) {
+	wantGrpcAcceptEncodingCh := make(chan []string, 1)
+	defer close(wantGrpcAcceptEncodingCh)
+
+	compressor := renameCompressor{Compressor: grpc.NewGZIPCompressor(), name: "testgzip"}
+	decompressor := renameDecompressor{Decompressor: grpc.NewGZIPDecompressor(), name: "testgzip"}
+
+	ss := &stubserver.StubServer{
+		EmptyCallF: func(ctx context.Context, in *testpb.Empty) (*testpb.Empty, error) {
+			md, ok := metadata.FromIncomingContext(ctx)
+			if !ok {
+				return nil, status.Errorf(codes.Internal, "no metadata in context")
+			}
+			if got, want := md["grpc-accept-encoding"], <-wantGrpcAcceptEncodingCh; !reflect.DeepEqual(got, want) {
+				return nil, status.Errorf(codes.Internal, "got grpc-accept-encoding=%q; want [%q]", got, want)
+			}
+			return &testpb.Empty{}, nil
+		},
+	}
+	if err := ss.Start([]grpc.ServerOption{grpc.RPCDecompressor(&decompressor)}); err != nil {
+		t.Fatalf("Error starting endpoint server: %v", err)
+	}
+	defer ss.Stop()
+
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+
+	wantGrpcAcceptEncodingCh <- []string{"gzip"}
+	if _, err := ss.Client.EmptyCall(ctx, &testpb.Empty{}); err != nil {
+		t.Fatalf("ss.Client.EmptyCall(_, _) = _, %v; want _, nil", err)
+	}
+
+	wantGrpcAcceptEncodingCh <- []string{"gzip"}
+	if _, err := ss.Client.EmptyCall(ctx, &testpb.Empty{}, grpc.UseCompressor("gzip")); err != nil {
+		t.Fatalf("ss.Client.EmptyCall(_, _) = _, %v; want _, nil", err)
+	}
+
+	// Use compressor directly which is not registered via
+	// encoding.RegisterCompressor.
+	if err := ss.StartClient(grpc.WithCompressor(&compressor)); err != nil {
+		t.Fatalf("Error starting client: %v", err)
+	}
+	wantGrpcAcceptEncodingCh <- []string{"gzip,testgzip"}
+	if _, err := ss.Client.EmptyCall(ctx, &testpb.Empty{}); err != nil {
+		t.Fatalf("ss.Client.EmptyCall(_, _) = _, %v; want _, nil", err)
+	}
+}
+
 func (s) TestUnaryProxyDoesNotForwardMetadata(t *testing.T) {
 	const mdkey = "somedata"