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moby--moby/vendor/golang.org/x/crypto/cryptobyte/string.go
Sebastiaan van Stijn b606c8e440
vendor: update golang.org/x/crypto 69ecbb4d6d5dab05e49161c6e77ea40a030884e1
full diff: 88737f569e...69ecbb4d6d

Includes 69ecbb4d6d
(forward-port of 8b5121be2f),
which fixes CVE-2020-7919:

- Panic in crypto/x509 certificate parsing and golang.org/x/crypto/cryptobyte
  On 32-bit architectures, a malformed input to crypto/x509 or the ASN.1 parsing
  functions of golang.org/x/crypto/cryptobyte can lead to a panic.
  The malformed certificate can be delivered via a crypto/tls connection to a
  client, or to a server that accepts client certificates. net/http clients can
  be made to crash by an HTTPS server, while net/http servers that accept client
  certificates will recover the panic and are unaffected.
  Thanks to Project Wycheproof for providing the test cases that led to the
  discovery of this issue. The issue is CVE-2020-7919 and Go issue golang.org/issue/36837.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2020-01-29 18:36:06 +01:00

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// 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 contains types that help with parsing and constructing
// length-prefixed, binary messages, including ASN.1 DER. (The asn1 subpackage
// contains useful ASN.1 constants.)
//
// The String type is for parsing. It wraps a []byte slice and provides helper
// functions for consuming structures, value by value.
//
// The Builder type is for constructing messages. It providers helper functions
// for appending values and also for appending length-prefixed submessages
// without having to worry about calculating the length prefix ahead of time.
//
// See the documentation and examples for the Builder and String types to get
// started.
package cryptobyte // import "golang.org/x/crypto/cryptobyte"
// String represents a string of bytes. It provides methods for parsing
// fixed-length and length-prefixed values from it.
type String []byte
// read advances a String by n bytes and returns them. If less than n bytes
// remain, it returns nil.
func (s *String) read(n int) []byte {
if len(*s) < n || n < 0 {
return nil
}
v := (*s)[:n]
*s = (*s)[n:]
return v
}
// Skip advances the String by n byte and reports whether it was successful.
func (s *String) Skip(n int) bool {
return s.read(n) != nil
}
// ReadUint8 decodes an 8-bit value into out and advances over it.
// It reports whether the read was successful.
func (s *String) ReadUint8(out *uint8) bool {
v := s.read(1)
if v == nil {
return false
}
*out = uint8(v[0])
return true
}
// ReadUint16 decodes a big-endian, 16-bit value into out and advances over it.
// It reports whether the read was successful.
func (s *String) ReadUint16(out *uint16) bool {
v := s.read(2)
if v == nil {
return false
}
*out = uint16(v[0])<<8 | uint16(v[1])
return true
}
// ReadUint24 decodes a big-endian, 24-bit value into out and advances over it.
// It reports whether the read was successful.
func (s *String) ReadUint24(out *uint32) bool {
v := s.read(3)
if v == nil {
return false
}
*out = uint32(v[0])<<16 | uint32(v[1])<<8 | uint32(v[2])
return true
}
// ReadUint32 decodes a big-endian, 32-bit value into out and advances over it.
// It reports whether the read was successful.
func (s *String) ReadUint32(out *uint32) bool {
v := s.read(4)
if v == nil {
return false
}
*out = uint32(v[0])<<24 | uint32(v[1])<<16 | uint32(v[2])<<8 | uint32(v[3])
return true
}
func (s *String) readUnsigned(out *uint32, length int) bool {
v := s.read(length)
if v == nil {
return false
}
var result uint32
for i := 0; i < length; i++ {
result <<= 8
result |= uint32(v[i])
}
*out = result
return true
}
func (s *String) readLengthPrefixed(lenLen int, outChild *String) bool {
lenBytes := s.read(lenLen)
if lenBytes == nil {
return false
}
var length uint32
for _, b := range lenBytes {
length = length << 8
length = length | uint32(b)
}
v := s.read(int(length))
if v == nil {
return false
}
*outChild = v
return true
}
// ReadUint8LengthPrefixed reads the content of an 8-bit length-prefixed value
// into out and advances over it. It reports whether the read was successful.
func (s *String) ReadUint8LengthPrefixed(out *String) bool {
return s.readLengthPrefixed(1, out)
}
// ReadUint16LengthPrefixed reads the content of a big-endian, 16-bit
// length-prefixed value into out and advances over it. It reports whether the
// read was successful.
func (s *String) ReadUint16LengthPrefixed(out *String) bool {
return s.readLengthPrefixed(2, out)
}
// ReadUint24LengthPrefixed reads the content of a big-endian, 24-bit
// length-prefixed value into out and advances over it. It reports whether
// the read was successful.
func (s *String) ReadUint24LengthPrefixed(out *String) bool {
return s.readLengthPrefixed(3, out)
}
// ReadBytes reads n bytes into out and advances over them. It reports
// whether the read was successful.
func (s *String) ReadBytes(out *[]byte, n int) bool {
v := s.read(n)
if v == nil {
return false
}
*out = v
return true
}
// CopyBytes copies len(out) bytes into out and advances over them. It reports
// whether the copy operation was successful
func (s *String) CopyBytes(out []byte) bool {
n := len(out)
v := s.read(n)
if v == nil {
return false
}
return copy(out, v) == n
}
// Empty reports whether the string does not contain any bytes.
func (s String) Empty() bool {
return len(s) == 0
}