From c84a5de06496bf8416cebf9d0058f481e37c165e Mon Sep 17 00:00:00 2001
From: Zach Reyes <39203661+zasweq@users.noreply.github.com>
Date: Wed, 15 Sep 2021 17:02:08 -0400
Subject: [PATCH] transport/server: add :method POST to incoming metadata
 (#4770)

* transport/server: add :method POST to incoming metadata
---
 binarylog/binarylog_end2end_test.go | 16 +++++++++++++
 internal/transport/http2_server.go  |  1 +
 test/end2end_test.go                | 37 +++++++++++++++++++++++++++++
 3 files changed, 54 insertions(+)

diff --git a/binarylog/binarylog_end2end_test.go b/binarylog/binarylog_end2end_test.go
index 61eeb68edae..7da91ad1a8d 100644
--- a/binarylog/binarylog_end2end_test.go
+++ b/binarylog/binarylog_end2end_test.go
@@ -850,11 +850,27 @@ func equalLogEntry(entries ...*pb.GrpcLogEntry) (equal bool) {
 			tmp := append(h.Metadata.Entry[:0], h.Metadata.Entry...)
 			h.Metadata.Entry = tmp
 			sort.Slice(h.Metadata.Entry, func(i, j int) bool { return h.Metadata.Entry[i].Key < h.Metadata.Entry[j].Key })
+			// Delete headers that have POST values here since we cannot control
+			// this.
+			for i, entry := range h.Metadata.Entry {
+				if entry.Key == ":method" {
+					h.Metadata.Entry = append(h.Metadata.Entry[:i], h.Metadata.Entry[i+1:]...)
+					break
+				}
+			}
 		}
 		if h := e.GetServerHeader(); h != nil {
 			tmp := append(h.Metadata.Entry[:0], h.Metadata.Entry...)
 			h.Metadata.Entry = tmp
 			sort.Slice(h.Metadata.Entry, func(i, j int) bool { return h.Metadata.Entry[i].Key < h.Metadata.Entry[j].Key })
+			// Delete headers that have POST values here since we cannot control
+			// this.
+			for i, entry := range h.Metadata.Entry {
+				if entry.Key == ":method" {
+					h.Metadata.Entry = append(h.Metadata.Entry[:i], h.Metadata.Entry[i+1:]...)
+					break
+				}
+			}
 		}
 		if h := e.GetTrailer(); h != nil {
 			sort.Slice(h.Metadata.Entry, func(i, j int) bool { return h.Metadata.Entry[i].Key < h.Metadata.Entry[j].Key })
diff --git a/internal/transport/http2_server.go b/internal/transport/http2_server.go
index cd0ebed9884..0ecfe09ceec 100644
--- a/internal/transport/http2_server.go
+++ b/internal/transport/http2_server.go
@@ -380,6 +380,7 @@ func (t *http2Server) operateHeaders(frame *http2.MetaHeadersFrame, handle func(
 			s.recvCompress = hf.Value
 		case ":method":
 			httpMethod = hf.Value
+			mdata[":method"] = append(mdata[":method"], hf.Value)
 		case ":path":
 			s.method = hf.Value
 		case "grpc-timeout":
diff --git a/test/end2end_test.go b/test/end2end_test.go
index bce752701da..4c7e2f1fc75 100644
--- a/test/end2end_test.go
+++ b/test/end2end_test.go
@@ -7847,3 +7847,40 @@ func (s) TestStreamingServerInterceptorGetsConnection(t *testing.T) {
 		t.Fatalf("ss.Client.StreamingInputCall(_) = _, %v, want _, %v", err, io.EOF)
 	}
 }
+
+func unaryInterceptorVerifyPost(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
+	md, ok := metadata.FromIncomingContext(ctx)
+	if !ok {
+		return nil, status.Error(codes.NotFound, "metadata was not in context")
+	}
+	method := md.Get(":method")
+	if len(method) != 1 {
+		return nil, status.Error(codes.InvalidArgument, ":method value had more than one value")
+	}
+	if method[0] != "POST" {
+		return nil, status.Error(codes.InvalidArgument, ":method value was not post")
+	}
+	return handler(ctx, req)
+}
+
+// TestUnaryInterceptorGetsPost verifies that the server transport adds a
+// :method POST header to metadata, and that that added Header is visibile at
+// the grpc layer.
+func (s) TestUnaryInterceptorGetsPost(t *testing.T) {
+	ss := &stubserver.StubServer{
+		EmptyCallF: func(ctx context.Context, in *testpb.Empty) (*testpb.Empty, error) {
+			return &testpb.Empty{}, nil
+		},
+	}
+	if err := ss.Start([]grpc.ServerOption{grpc.UnaryInterceptor(unaryInterceptorVerifyPost)}); err != nil {
+		t.Fatalf("Error starting endpoint server: %v", err)
+	}
+	defer ss.Stop()
+
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+
+	if _, err := ss.Client.EmptyCall(ctx, &testpb.Empty{}); status.Code(err) != codes.OK {
+		t.Fatalf("ss.Client.EmptyCall(_, _) = _, %v, want _, error code %s", err, codes.OK)
+	}
+}