go.chromium.org/luci@v0.0.0-20240309015107-7cdc2e660f33/grpc/svcmux/svcmux.go (about)

     1  // Copyright 2016 The LUCI Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // Package svcmux contains utility functions used by code generated by
    16  // svcmux tool.
    17  // It is not designed to be used directly.
    18  package svcmux
    19  
    20  import (
    21  	"context"
    22  
    23  	"google.golang.org/grpc/codes"
    24  	"google.golang.org/grpc/metadata"
    25  	"google.golang.org/grpc/status"
    26  )
    27  
    28  // VersionMetadataKey is key in gRPC metadata that specifies requested
    29  // service version.
    30  const VersionMetadataKey = "X-Luci-Service-Version"
    31  
    32  // ServiceVersion extracts requested service version from metadata in ctx.
    33  func ServiceVersion(ctx context.Context, defaultVer string) string {
    34  	if md, ok := metadata.FromIncomingContext(ctx); ok {
    35  		values := md[VersionMetadataKey]
    36  		if len(values) != 0 {
    37  			return values[0]
    38  		}
    39  	}
    40  	return defaultVer
    41  }
    42  
    43  // NoImplementation creates an error for a service version that does not have an
    44  // implementation.
    45  func NoImplementation(version string) error {
    46  	return status.Errorf(codes.Unimplemented, "version %s not implemented", version)
    47  }