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