1/*
2 *
3 * Copyright 2020 gRPC authors.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18
19// Package metadata contains functions to set and get metadata from addresses.
20//
21// This package is experimental.
22package metadata
23
24import (
25 "fmt"
26 "strings"
27
28 "google.golang.org/grpc/metadata"
29 "google.golang.org/grpc/resolver"
30)
31
32type mdKeyType string
33
34const mdKey = mdKeyType("grpc.internal.address.metadata")
35
36type mdValue metadata.MD
37
38func (m mdValue) Equal(o any) bool {
39 om, ok := o.(mdValue)
40 if !ok {
41 return false
42 }
43 if len(m) != len(om) {
44 return false
45 }
46 for k, v := range m {
47 ov := om[k]
48 if len(ov) != len(v) {
49 return false
50 }
51 for i, ve := range v {
52 if ov[i] != ve {
53 return false
54 }
55 }
56 }
57 return true
58}
59
60// Get returns the metadata of addr.
61func Get(addr resolver.Address) metadata.MD {
62 attrs := addr.Attributes
63 if attrs == nil {
64 return nil
65 }
66 md, _ := attrs.Value(mdKey).(mdValue)
67 return metadata.MD(md)
68}
69
70// Set sets (overrides) the metadata in addr.
71//
72// When a SubConn is created with this address, the RPCs sent on it will all
73// have this metadata.
74func Set(addr resolver.Address, md metadata.MD) resolver.Address {
75 addr.Attributes = addr.Attributes.WithValue(mdKey, mdValue(md))
76 return addr
77}
78
79// Validate validates every pair in md with ValidatePair.
80func Validate(md metadata.MD) error {
81 for k, vals := range md {
82 if err := ValidatePair(k, vals...); err != nil {
83 return err
84 }
85 }
86 return nil
87}
88
89// hasNotPrintable return true if msg contains any characters which are not in %x20-%x7E
90func hasNotPrintable(msg string) bool {
91 // for i that saving a conversion if not using for range
92 for i := 0; i < len(msg); i++ {
93 if msg[i] < 0x20 || msg[i] > 0x7E {
94 return true
95 }
96 }
97 return false
98}
99
100// ValidatePair validate a key-value pair with the following rules (the pseudo-header will be skipped) :
101//
102// - key must contain one or more characters.
103// - the characters in the key must be contained in [0-9 a-z _ - .].
104// - if the key ends with a "-bin" suffix, no validation of the corresponding value is performed.
105// - the characters in the every value must be printable (in [%x20-%x7E]).
106func ValidatePair(key string, vals ...string) error {
107 // key should not be empty
108 if key == "" {
109 return fmt.Errorf("there is an empty key in the header")
110 }
111 // pseudo-header will be ignored
112 if key[0] == ':' {
113 return nil
114 }
115 // check key, for i that saving a conversion if not using for range
116 for i := 0; i < len(key); i++ {
117 r := key[i]
118 if !(r >= 'a' && r <= 'z') && !(r >= '0' && r <= '9') && r != '.' && r != '-' && r != '_' {
119 return fmt.Errorf("header key %q contains illegal characters not in [0-9a-z-_.]", key)
120 }
121 }
122 if strings.HasSuffix(key, "-bin") {
123 return nil
124 }
125 // check value
126 for _, val := range vals {
127 if hasNotPrintable(val) {
128 return fmt.Errorf("header key %q contains value with non-printable ASCII characters", key)
129 }
130 }
131 return nil
132}