diff options
Diffstat (limited to 'src/vendor/golang.org/x/crypto/cryptobyte/string.go')
-rw-r--r-- | src/vendor/golang.org/x/crypto/cryptobyte/string.go | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/src/vendor/golang.org/x/crypto/cryptobyte/string.go b/src/vendor/golang.org/x/crypto/cryptobyte/string.go new file mode 100644 index 0000000..0531a3d --- /dev/null +++ b/src/vendor/golang.org/x/crypto/cryptobyte/string.go @@ -0,0 +1,172 @@ +// 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 +} + +// ReadUint64 decodes a big-endian, 64-bit value into out and advances over it. +// It reports whether the read was successful. +func (s *String) ReadUint64(out *uint64) bool { + v := s.read(8) + if v == nil { + return false + } + *out = uint64(v[0])<<56 | uint64(v[1])<<48 | uint64(v[2])<<40 | uint64(v[3])<<32 | uint64(v[4])<<24 | uint64(v[5])<<16 | uint64(v[6])<<8 | uint64(v[7]) + 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 +} |