Ignore plus and semicolon and anything following in Content-Type

transport/handler_server.go

@@ -55,6 +55,19 @@ import (
 	"google.golang.org/grpc/peer"
 )
 
+func isGrpcContentType(t string) bool {
+	e := "application/grpc"
+	if !strings.HasPrefix(t, e) {
+		return false
+	}
+	// Support variations on the content-type
+	// (e.g. "application/grpc+blah", "application/grpc;blah").
+	if len(t) > len(e) && t[len(e)] != '+' && t[len(e)] != ';' {
+		return false
+	}
+	return true
+}
+
 // NewServerHandlerTransport returns a ServerTransport handling gRPC
 // from inside an http.Handler. It requires that the http Server
 // supports HTTP/2.
@@ -65,7 +78,7 @@ func NewServerHandlerTransport(w http.ResponseWriter, r *http.Request) (ServerTr
 	if r.Method != "POST" {
 		return nil, errors.New("invalid gRPC request method")
 	}
-	if !strings.Contains(r.Header.Get("Content-Type"), "application/grpc") {
+	if !isGrpcContentType(r.Header.Get("Content-Type")) {
 		return nil, errors.New("invalid gRPC request content-type")
 	}
 	if _, ok := w.(http.Flusher); !ok {

transport/handler_server_test.go

@@ -387,3 +387,25 @@ func TestHandlerTransport_HandleStreams_Timeout(t *testing.T) {
 		t.Errorf("Header+Trailer Map mismatch.\n got: %#v\nwant: %#v", rw.HeaderMap, wantHeader)
 	}
 }
+
+func TestIsGrpcContentType(t *testing.T) {
+	tests := []struct {
+		h    string
+		want bool
+	}{
+		{"application/grpc", true},
+		{"application/grpc+", true},
+		{"application/grpc+blah", true},
+		{"application/grpc;", true},
+		{"application/grpc;blah", true},
+		{"application/grpcd", false},
+		{"application/grpd", false},
+		{"application/grp", false},
+	}
+	for _, tt := range tests {
+		got := isGrpcContentType(tt.h)
+		if got != tt.want {
+			t.Errorf("isGrpcContentType(%q) = %v; want %v", tt.h, got, tt.want)
+		}
+	}
+}