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|
package runtime
import (
"fmt"
"io"
"net/http"
"net/textproto"
"github.com/golang/protobuf/proto"
"github.com/grpc-ecosystem/grpc-gateway/runtime/internal"
"golang.org/x/net/context"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/grpclog"
"google.golang.org/grpc/status"
)
// ForwardResponseStream forwards the stream from gRPC server to REST client.
func ForwardResponseStream(ctx context.Context, mux *ServeMux, marshaler Marshaler, w http.ResponseWriter, req *http.Request, recv func() (proto.Message, error), opts ...func(context.Context, http.ResponseWriter, proto.Message) error) {
f, ok := w.(http.Flusher)
if !ok {
grpclog.Printf("Flush not supported in %T", w)
http.Error(w, "unexpected type of web server", http.StatusInternalServerError)
return
}
md, ok := ServerMetadataFromContext(ctx)
if !ok {
grpclog.Printf("Failed to extract ServerMetadata from context")
http.Error(w, "unexpected error", http.StatusInternalServerError)
return
}
handleForwardResponseServerMetadata(w, mux, md)
w.Header().Set("Transfer-Encoding", "chunked")
w.Header().Set("Content-Type", marshaler.ContentType())
if err := handleForwardResponseOptions(ctx, w, nil, opts); err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
w.WriteHeader(http.StatusOK)
f.Flush()
for {
resp, err := recv()
if err == io.EOF {
return
}
if err != nil {
handleForwardResponseStreamError(marshaler, w, err)
return
}
if err := handleForwardResponseOptions(ctx, w, resp, opts); err != nil {
handleForwardResponseStreamError(marshaler, w, err)
return
}
buf, err := marshaler.Marshal(streamChunk(resp, nil))
if err != nil {
grpclog.Printf("Failed to marshal response chunk: %v", err)
return
}
if _, err = w.Write(buf); err != nil {
grpclog.Printf("Failed to send response chunk: %v", err)
return
}
f.Flush()
}
}
func handleForwardResponseServerMetadata(w http.ResponseWriter, mux *ServeMux, md ServerMetadata) {
for k, vs := range md.HeaderMD {
if h, ok := mux.outgoingHeaderMatcher(k); ok {
for _, v := range vs {
w.Header().Add(h, v)
}
}
}
}
func handleForwardResponseTrailerHeader(w http.ResponseWriter, md ServerMetadata) {
for k := range md.TrailerMD {
tKey := textproto.CanonicalMIMEHeaderKey(fmt.Sprintf("%s%s", MetadataTrailerPrefix, k))
w.Header().Add("Trailer", tKey)
}
}
func handleForwardResponseTrailer(w http.ResponseWriter, md ServerMetadata) {
for k, vs := range md.TrailerMD {
tKey := fmt.Sprintf("%s%s", MetadataTrailerPrefix, k)
for _, v := range vs {
w.Header().Add(tKey, v)
}
}
}
// ForwardResponseMessage forwards the message "resp" from gRPC server to REST client.
func ForwardResponseMessage(ctx context.Context, mux *ServeMux, marshaler Marshaler, w http.ResponseWriter, req *http.Request, resp proto.Message, opts ...func(context.Context, http.ResponseWriter, proto.Message) error) {
md, ok := ServerMetadataFromContext(ctx)
if !ok {
grpclog.Printf("Failed to extract ServerMetadata from context")
}
handleForwardResponseServerMetadata(w, mux, md)
handleForwardResponseTrailerHeader(w, md)
w.Header().Set("Content-Type", marshaler.ContentType())
if err := handleForwardResponseOptions(ctx, w, resp, opts); err != nil {
HTTPError(ctx, mux, marshaler, w, req, err)
return
}
buf, err := marshaler.Marshal(resp)
if err != nil {
grpclog.Printf("Marshal error: %v", err)
HTTPError(ctx, mux, marshaler, w, req, err)
return
}
if _, err = w.Write(buf); err != nil {
grpclog.Printf("Failed to write response: %v", err)
}
handleForwardResponseTrailer(w, md)
}
func handleForwardResponseOptions(ctx context.Context, w http.ResponseWriter, resp proto.Message, opts []func(context.Context, http.ResponseWriter, proto.Message) error) error {
if len(opts) == 0 {
return nil
}
for _, opt := range opts {
if err := opt(ctx, w, resp); err != nil {
grpclog.Printf("Error handling ForwardResponseOptions: %v", err)
return err
}
}
return nil
}
func handleForwardResponseStreamError(marshaler Marshaler, w http.ResponseWriter, err error) {
buf, merr := marshaler.Marshal(streamChunk(nil, err))
if merr != nil {
grpclog.Printf("Failed to marshal an error: %v", merr)
return
}
if _, werr := fmt.Fprintf(w, "%s\n", buf); werr != nil {
grpclog.Printf("Failed to notify error to client: %v", werr)
return
}
}
func streamChunk(result proto.Message, err error) map[string]proto.Message {
if err != nil {
grpcCode := codes.Unknown
if s, ok := status.FromError(err); ok {
grpcCode = s.Code()
}
httpCode := HTTPStatusFromCode(grpcCode)
return map[string]proto.Message{
"error": &internal.StreamError{
GrpcCode: int32(grpcCode),
HttpCode: int32(httpCode),
Message: err.Error(),
HttpStatus: http.StatusText(httpCode),
},
}
}
if result == nil {
return streamChunk(nil, fmt.Errorf("empty response"))
}
return map[string]proto.Message{"result": result}
}
|
