1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
|
/*
*
* Copyright 2014, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
// Package metadata define the structure of the metadata supported by gRPC library.
// Please refer to http://www.grpc.io/docs/guides/wire.html for more information about custom-metadata.
package metadata // import "google.golang.org/grpc/metadata"
import (
"encoding/base64"
"fmt"
"strings"
"golang.org/x/net/context"
)
const (
binHdrSuffix = "-bin"
)
// encodeKeyValue encodes key and value qualified for transmission via gRPC.
// Transmitting binary headers violates HTTP/2 spec.
// TODO(zhaoq): Maybe check if k is ASCII also.
func encodeKeyValue(k, v string) (string, string) {
k = strings.ToLower(k)
if strings.HasSuffix(k, binHdrSuffix) {
val := base64.StdEncoding.EncodeToString([]byte(v))
v = string(val)
}
return k, v
}
// DecodeKeyValue returns the original key and value corresponding to the
// encoded data in k, v.
// If k is a binary header and v contains comma, v is split on comma before decoded,
// and the decoded v will be joined with comma before returned.
func DecodeKeyValue(k, v string) (string, string, error) {
if !strings.HasSuffix(k, binHdrSuffix) {
return k, v, nil
}
vvs := strings.Split(v, ",")
for i, vv := range vvs {
val, err := base64.StdEncoding.DecodeString(vv)
if err != nil {
return "", "", err
}
vvs[i] = string(val)
}
return k, strings.Join(vvs, ","), nil
}
// MD is a mapping from metadata keys to values. Users should use the following
// two convenience functions New and Pairs to generate MD.
type MD map[string][]string
// New creates a MD from given key-value map.
// Keys are automatically converted to lowercase. And for keys having "-bin" as suffix, their values will be applied Base64 encoding.
func New(m map[string]string) MD {
md := MD{}
for k, v := range m {
key, val := encodeKeyValue(k, v)
md[key] = append(md[key], val)
}
return md
}
// Pairs returns an MD formed by the mapping of key, value ...
// Pairs panics if len(kv) is odd.
// Keys are automatically converted to lowercase. And for keys having "-bin" as suffix, their values will be appplied Base64 encoding.
func Pairs(kv ...string) MD {
if len(kv)%2 == 1 {
panic(fmt.Sprintf("metadata: Pairs got the odd number of input pairs for metadata: %d", len(kv)))
}
md := MD{}
var k string
for i, s := range kv {
if i%2 == 0 {
k = s
continue
}
key, val := encodeKeyValue(k, s)
md[key] = append(md[key], val)
}
return md
}
// Len returns the number of items in md.
func (md MD) Len() int {
return len(md)
}
// Copy returns a copy of md.
func (md MD) Copy() MD {
return Join(md)
}
// Join joins any number of MDs into a single MD.
// The order of values for each key is determined by the order in which
// the MDs containing those values are presented to Join.
func Join(mds ...MD) MD {
out := MD{}
for _, md := range mds {
for k, v := range md {
out[k] = append(out[k], v...)
}
}
return out
}
type mdIncomingKey struct{}
type mdOutgoingKey struct{}
// NewContext is a wrapper for NewOutgoingContext(ctx, md). Deprecated.
func NewContext(ctx context.Context, md MD) context.Context {
return NewOutgoingContext(ctx, md)
}
// NewIncomingContext creates a new context with incoming md attached.
func NewIncomingContext(ctx context.Context, md MD) context.Context {
return context.WithValue(ctx, mdIncomingKey{}, md)
}
// NewOutgoingContext creates a new context with outgoing md attached.
func NewOutgoingContext(ctx context.Context, md MD) context.Context {
return context.WithValue(ctx, mdOutgoingKey{}, md)
}
// FromContext is a wrapper for FromIncomingContext(ctx). Deprecated.
func FromContext(ctx context.Context) (md MD, ok bool) {
return FromIncomingContext(ctx)
}
// FromIncomingContext returns the incoming MD in ctx if it exists. The
// returned md should be immutable, writing to it may cause races.
// Modification should be made to the copies of the returned md.
func FromIncomingContext(ctx context.Context) (md MD, ok bool) {
md, ok = ctx.Value(mdIncomingKey{}).(MD)
return
}
// FromOutgoingContext returns the outgoing MD in ctx if it exists. The
// returned md should be immutable, writing to it may cause races.
// Modification should be made to the copies of the returned md.
func FromOutgoingContext(ctx context.Context) (md MD, ok bool) {
md, ok = ctx.Value(mdOutgoingKey{}).(MD)
return
}
|
