go.temporal.io/server@v1.23.0/common/headers/headers.go (about)

     1  // The MIT License
     2  //
     3  // Copyright (c) 2020 Temporal Technologies Inc.  All rights reserved.
     4  //
     5  // Copyright (c) 2020 Uber Technologies, Inc.
     6  //
     7  // Permission is hereby granted, free of charge, to any person obtaining a copy
     8  // of this software and associated documentation files (the "Software"), to deal
     9  // in the Software without restriction, including without limitation the rights
    10  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    11  // copies of the Software, and to permit persons to whom the Software is
    12  // furnished to do so, subject to the following conditions:
    13  //
    14  // The above copyright notice and this permission notice shall be included in
    15  // all copies or substantial portions of the Software.
    16  //
    17  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    18  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    19  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    20  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    21  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    22  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    23  // THE SOFTWARE.
    24  
    25  package headers
    26  
    27  import (
    28  	"context"
    29  
    30  	"google.golang.org/grpc/metadata"
    31  )
    32  
    33  const (
    34  	ClientNameHeaderName              = "client-name"
    35  	ClientVersionHeaderName           = "client-version"
    36  	SupportedServerVersionsHeaderName = "supported-server-versions"
    37  	SupportedFeaturesHeaderName       = "supported-features"
    38  	SupportedFeaturesHeaderDelim      = ","
    39  
    40  	callerNameHeaderName = "caller-name"
    41  	CallerTypeHeaderName = "caller-type"
    42  	callOriginHeaderName = "call-initiation"
    43  )
    44  
    45  var (
    46  	// propagateHeaders are the headers to propagate from the frontend to other services.
    47  	propagateHeaders = []string{
    48  		ClientNameHeaderName,
    49  		ClientVersionHeaderName,
    50  		SupportedServerVersionsHeaderName,
    51  		SupportedFeaturesHeaderName,
    52  		callerNameHeaderName,
    53  		CallerTypeHeaderName,
    54  		callOriginHeaderName,
    55  	}
    56  )
    57  
    58  // GetValues returns header values for passed header names.
    59  // It always returns slice of the same size as number of passed header names.
    60  func GetValues(ctx context.Context, headerNames ...string) []string {
    61  	headerValues := make([]string, len(headerNames))
    62  
    63  	if md, ok := metadata.FromIncomingContext(ctx); ok {
    64  		for i, headerName := range headerNames {
    65  			headerValues[i] = getSingleHeaderValue(md, headerName)
    66  		}
    67  	}
    68  
    69  	return headerValues
    70  }
    71  
    72  // Propagate propagates version headers from incoming context to outgoing context.
    73  // It copies all headers to outgoing context only if they are exist in incoming context
    74  // and doesn't exist in outgoing context already.
    75  func Propagate(ctx context.Context) context.Context {
    76  	if mdIncoming, ok := metadata.FromIncomingContext(ctx); ok {
    77  		var headersToAppend []string
    78  		mdOutgoing, mdOutgoingExist := metadata.FromOutgoingContext(ctx)
    79  		for _, headerName := range propagateHeaders {
    80  			if incomingValue := mdIncoming.Get(headerName); len(incomingValue) > 0 {
    81  				if mdOutgoingExist {
    82  					if outgoingValue := mdOutgoing.Get(headerName); len(outgoingValue) > 0 {
    83  						continue
    84  					}
    85  				}
    86  				headersToAppend = append(headersToAppend, headerName, incomingValue[0])
    87  			}
    88  		}
    89  		if headersToAppend != nil {
    90  			if mdOutgoingExist {
    91  				ctx = metadata.AppendToOutgoingContext(ctx, headersToAppend...)
    92  			} else {
    93  				ctx = metadata.NewOutgoingContext(ctx, metadata.Pairs(headersToAppend...))
    94  			}
    95  		}
    96  	}
    97  	return ctx
    98  }
    99  
   100  func getSingleHeaderValue(md metadata.MD, headerName string) string {
   101  	values := md.Get(headerName)
   102  	if len(values) == 0 {
   103  		return ""
   104  	}
   105  
   106  	return values[0]
   107  }