120 lines
3.1 KiB
Go
120 lines
3.1 KiB
Go
// Copyright 2017 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package cryptobyte_test
|
|
|
|
import (
|
|
"encoding/asn1"
|
|
"fmt"
|
|
"golang.org/x/crypto/cryptobyte"
|
|
)
|
|
|
|
func ExampleString_lengthPrefixed() {
|
|
// This is an example of parsing length-prefixed data (as found in, for
|
|
// example, TLS). Imagine a 16-bit prefixed series of 8-bit prefixed
|
|
// strings.
|
|
|
|
input := cryptobyte.String([]byte{0, 12, 5, 'h', 'e', 'l', 'l', 'o', 5, 'w', 'o', 'r', 'l', 'd'})
|
|
var result []string
|
|
|
|
var values cryptobyte.String
|
|
if !input.ReadUint16LengthPrefixed(&values) ||
|
|
!input.Empty() {
|
|
panic("bad format")
|
|
}
|
|
|
|
for !values.Empty() {
|
|
var value cryptobyte.String
|
|
if !values.ReadUint8LengthPrefixed(&value) {
|
|
panic("bad format")
|
|
}
|
|
|
|
result = append(result, string(value))
|
|
}
|
|
|
|
// Output: []string{"hello", "world"}
|
|
fmt.Printf("%#v\n", result)
|
|
}
|
|
|
|
func ExampleString_asn1() {
|
|
// This is an example of parsing ASN.1 data that looks like:
|
|
// Foo ::= SEQUENCE {
|
|
// version [6] INTEGER DEFAULT 0
|
|
// data OCTET STRING
|
|
// }
|
|
|
|
input := cryptobyte.String([]byte{0x30, 12, 0xa6, 3, 2, 1, 2, 4, 5, 'h', 'e', 'l', 'l', 'o'})
|
|
|
|
var (
|
|
version int64
|
|
data, inner, versionBytes cryptobyte.String
|
|
haveVersion bool
|
|
)
|
|
if !input.ReadASN1(&inner, cryptobyte.Tag(asn1.TagSequence).Constructed()) ||
|
|
!input.Empty() ||
|
|
!inner.ReadOptionalASN1(&versionBytes, &haveVersion, cryptobyte.Tag(6).Constructed().ContextSpecific()) ||
|
|
(haveVersion && !versionBytes.ReadASN1Integer(&version)) ||
|
|
(haveVersion && !versionBytes.Empty()) ||
|
|
!inner.ReadASN1(&data, asn1.TagOctetString) ||
|
|
!inner.Empty() {
|
|
panic("bad format")
|
|
}
|
|
|
|
// Output: haveVersion: true, version: 2, data: hello
|
|
fmt.Printf("haveVersion: %t, version: %d, data: %s\n", haveVersion, version, string(data))
|
|
}
|
|
|
|
func ExampleBuilder_asn1() {
|
|
// This is an example of building ASN.1 data that looks like:
|
|
// Foo ::= SEQUENCE {
|
|
// version [6] INTEGER DEFAULT 0
|
|
// data OCTET STRING
|
|
// }
|
|
|
|
version := int64(2)
|
|
data := []byte("hello")
|
|
const defaultVersion = 0
|
|
|
|
var b cryptobyte.Builder
|
|
b.AddASN1(cryptobyte.Tag(asn1.TagSequence).Constructed(), func(b *cryptobyte.Builder) {
|
|
if version != defaultVersion {
|
|
b.AddASN1(cryptobyte.Tag(6).Constructed().ContextSpecific(), func(b *cryptobyte.Builder) {
|
|
b.AddASN1Int64(version)
|
|
})
|
|
}
|
|
b.AddASN1OctetString(data)
|
|
})
|
|
|
|
result, err := b.Bytes()
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
|
|
// Output: 300ca603020102040568656c6c6f
|
|
fmt.Printf("%x\n", result)
|
|
}
|
|
|
|
func ExampleBuilder_lengthPrefixed() {
|
|
// This is an example of building length-prefixed data (as found in,
|
|
// for example, TLS). Imagine a 16-bit prefixed series of 8-bit
|
|
// prefixed strings.
|
|
input := []string{"hello", "world"}
|
|
|
|
var b cryptobyte.Builder
|
|
b.AddUint16LengthPrefixed(func(b *cryptobyte.Builder) {
|
|
for _, value := range input {
|
|
b.AddUint8LengthPrefixed(func(b *cryptobyte.Builder) {
|
|
b.AddBytes([]byte(value))
|
|
})
|
|
}
|
|
})
|
|
|
|
result, err := b.Bytes()
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
|
|
// Output: 000c0568656c6c6f05776f726c64
|
|
fmt.Printf("%x\n", result)
|
|
}
|