Pass permanent HTTP request headers (#252)

* Pass Permanent Request Headers

* Fix tests and update pr213

Author: tmc

README.md

@@ -206,7 +206,7 @@ To use the same port for custom HTTP handlers (e.g. serving `swagger.json`), gRP
 * Method parameters in query string
 * Enum fields in path parameter (including repeated enum fields).
 * Mapping streaming APIs to newline-delimited JSON streams
-* Mapping HTTP headers with `Grpc-Metadata-` prefix to gRPC metadata
+* Mapping HTTP headers with `Grpc-Metadata-` prefix to gRPC metadata (prefixed with `grpcgateway-`)
 * Optionally emitting API definition for [Swagger](http://swagger.io).
 * Setting [gRPC timeouts](http://www.grpc.io/docs/guides/wire.html) through inbound HTTP `Grpc-Timeout` header.
 
@@ -229,7 +229,8 @@ But patch is welcome.
 * HTTP request source IP is added as `X-Forwarded-For` gRPC request header
 * HTTP request host is added as `X-Forwarded-Host` gRPC request header
 * HTTP `Authorization` header is added as `authorization` gRPC request header 
-* Remaining HTTP header keys are prefixed with `Grpc-Metadata-` and added with their values to gRPC request header
+* Remaining Permanent HTTP header keys (as specified by the IANA [here](http://www.iana.org/assignments/message-headers/message-headers.xhtml) are prefixed with `grpcgateway-` and added with their values to gRPC request header
+* HTTP headers that start with 'Grpc-Metadata-' are mapped to gRPC metadata (prefixed with `grpcgateway-`)
 * While configurable, the default {un,}marshaling uses [jsonpb](https://godoc.org/github.com/golang/protobuf/jsonpb) with `OrigName: true`.
 
 # Contribution

examples/integration_test.go

@@ -128,10 +128,10 @@ func testEchoBody(t *testing.T) {
 	}
 
 	if got, want := resp.Header.Get("Grpc-Metadata-Foo"), "foo1"; got != want {
-		t.Errorf("Grpc-Header-Foo was %q, wanted %q", got, want)
+		t.Errorf("Grpc-Metadata-Foo was %q, wanted %q", got, want)
 	}
 	if got, want := resp.Header.Get("Grpc-Metadata-Bar"), "bar1"; got != want {
-		t.Errorf("Grpc-Header-Bar was %q, wanted %q", got, want)
+		t.Errorf("Grpc-Metadata-Bar was %q, wanted %q", got, want)
 	}
 
 	if got, want := resp.Trailer.Get("Grpc-Trailer-Foo"), "foo2"; got != want {
@@ -369,7 +369,7 @@ func testABEBulkCreate(t *testing.T) {
 	}
 
 	if got, want := resp.Header.Get("Grpc-Metadata-Count"), fmt.Sprintf("%d", count); got != want {
-		t.Errorf("Grpc-Header-Count was %q, wanted %q", got, want)
+		t.Errorf("Grpc-Metadata-Count was %q, wanted %q", got, want)
 	}
 
 	if got, want := resp.Trailer.Get("Grpc-Trailer-Foo"), "foo2"; got != want {
@@ -518,7 +518,7 @@ func testABEList(t *testing.T) {
 
 	value := resp.Header.Get("Grpc-Metadata-Count")
 	if value == "" {
-		t.Errorf("Grpc-Header-Count should not be empty")
+		t.Errorf("Grpc-Metadata-Count should not be empty")
 	}
 
 	count, err := strconv.Atoi(value)

runtime/context.go

@@ -15,12 +15,17 @@ import (
 	"google.golang.org/grpc/metadata"
 )
 
-// MetadataHeaderPrefix is prepended to HTTP headers in order to convert them to 
-// gRPC metadata for incoming requests processed by grpc-gateway
+// MetadataHeaderPrefix is the http prefix that represents custom metadata
+// parameters to or from a gRPC call.
 const MetadataHeaderPrefix = "Grpc-Metadata-"
+
+// MetadataPrefix is the prefix for grpc-gateway supplied custom metadata fields.
+const MetadataPrefix = "grpcgateway-"
+
 // MetadataTrailerPrefix is prepended to gRPC metadata as it is converted to
 // HTTP headers in a response handled by grpc-gateway
 const MetadataTrailerPrefix = "Grpc-Trailer-"
+
 const metadataGrpcTimeout = "Grpc-Timeout"
 
 const xForwardedFor = "X-Forwarded-For"
@@ -52,8 +57,12 @@ func AnnotateContext(ctx context.Context, req *http.Request) (context.Context, e
 
 	for key, vals := range req.Header {
 		for _, val := range vals {
-			if key == "Authorization" {
+			// For backwards-compatibility, pass through 'authorization' header with no prefix.
+			if strings.ToLower(key) == "authorization" {
 				pairs = append(pairs, "authorization", val)
+			}
+			if isPermanentHTTPHeader(key) {
+				pairs = append(pairs, strings.ToLower(fmt.Sprintf("%s%s", MetadataPrefix, key)), val)
 				continue
 			}
 			if strings.HasPrefix(key, MetadataHeaderPrefix) {
@@ -141,3 +150,38 @@ func timeoutUnitToDuration(u uint8) (d time.Duration, ok bool) {
 	}
 	return
 }
+
+// isPermanentHTTPHeader checks whether hdr belongs to the list of
+// permenant request headers maintained by IANA.
+// http://www.iana.org/assignments/message-headers/message-headers.xml
+func isPermanentHTTPHeader(hdr string) bool {
+	switch hdr {
+	case
+		"Accept",
+		"Accept-Charset",
+		"Accept-Language",
+		"Accept-Ranges",
+		"Authorization",
+		"Cache-Control",
+		"Content-Type",
+		"Cookie",
+		"Date",
+		"Expect",
+		"From",
+		"Host",
+		"If-Match",
+		"If-Modified-Since",
+		"If-None-Match",
+		"If-Schedule-Tag-Match",
+		"If-Unmodified-Since",
+		"Max-Forwards",
+		"Origin",
+		"Pragma",
+		"Referer",
+		"User-Agent",
+		"Via",
+		"Warning":
+		return true
+	}
+	return false
+}

runtime/context_test.go

@@ -51,14 +51,17 @@ func TestAnnotateContext_ForwardsGrpcMetadata(t *testing.T) {
 		return
 	}
 	md, ok := metadata.FromContext(annotated)
-	if got, want := len(md), emptyForwardMetaCount+3; !ok || got != want {
-		t.Errorf("Expected %d metadata items in context; got %d", got, want)
+	if got, want := len(md), emptyForwardMetaCount+4; !ok || got != want {
+		t.Errorf("metadata items in context = %d want %d: %v", got, want, md)
 	}
 	if got, want := md["foobar"], []string{"Value1"}; !reflect.DeepEqual(got, want) {
-		t.Errorf(`md["foobar"] = %q; want %q`, got, want)
+		t.Errorf(`md["grpcgateway-foobar"] = %q; want %q`, got, want)
 	}
 	if got, want := md["foo-baz"], []string{"Value2", "Value3"}; !reflect.DeepEqual(got, want) {
-		t.Errorf(`md["foo-baz"] = %q want %q`, got, want)
+		t.Errorf(`md["grpcgateway-foo-baz"] = %q want %q`, got, want)
+	}
+	if got, want := md["grpcgateway-authorization"], []string{"Token 1234567890"}; !reflect.DeepEqual(got, want) {
+		t.Errorf(`md["grpcgateway-authorization"] = %q want %q`, got, want)
 	}
 	if got, want := md["authorization"], []string{"Token 1234567890"}; !reflect.DeepEqual(got, want) {
 		t.Errorf(`md["authorization"] = %q want %q`, got, want)