diff --git a/src/pkg/crypto/openpgp/packet/packet.go b/src/pkg/crypto/openpgp/packet/packet.go new file mode 100644 index 00000000000..80e25e250f2 --- /dev/null +++ b/src/pkg/crypto/openpgp/packet/packet.go @@ -0,0 +1,395 @@ +// Copyright 2011 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. + +// This package implements parsing and serialisation of OpenPGP packets, as +// specified in RFC 4880. +package packet + +import ( + "crypto/aes" + "crypto/cast5" + "crypto/cipher" + "crypto/openpgp/error" + "io" + "os" +) + +// readFull is the same as io.ReadFull except that reading zero bytes returns +// ErrUnexpectedEOF rather than EOF. +func readFull(r io.Reader, buf []byte) (n int, err os.Error) { + n, err = io.ReadFull(r, buf) + if err == os.EOF { + err = io.ErrUnexpectedEOF + } + return +} + +// readLength reads an OpenPGP length from r. See RFC 4880, section 4.2.2. +func readLength(r io.Reader) (length int64, isPartial bool, err os.Error) { + var buf [4]byte + _, err = readFull(r, buf[:1]) + if err != nil { + return + } + switch { + case buf[0] < 192: + length = int64(buf[0]) + case buf[0] < 224: + length = int64(buf[0]-192) << 8 + _, err = readFull(r, buf[0:1]) + if err != nil { + return + } + length += int64(buf[0]) + 192 + case buf[0] < 255: + length = int64(1) << (buf[0] & 0x1f) + isPartial = true + default: + _, err = readFull(r, buf[0:4]) + if err != nil { + return + } + length = int64(buf[0])<<24 | + int64(buf[1])<<16 | + int64(buf[2])<<8 | + int64(buf[3]) + } + return +} + +// partialLengthReader wraps an io.Reader and handles OpenPGP partial lengths. +// The continuation lengths are parsed and removed from the stream and EOF is +// returned at the end of the packet. See RFC 4880, section 4.2.2.4. +type partialLengthReader struct { + r io.Reader + remaining int64 + isPartial bool +} + +func (r *partialLengthReader) Read(p []byte) (n int, err os.Error) { + for r.remaining == 0 { + if !r.isPartial { + return 0, os.EOF + } + r.remaining, r.isPartial, err = readLength(r.r) + if err != nil { + return 0, err + } + } + + toRead := int64(len(p)) + if toRead > r.remaining { + toRead = r.remaining + } + + n, err = r.r.Read(p[:int(toRead)]) + r.remaining -= int64(n) + if n < int(toRead) && err == os.EOF { + err = io.ErrUnexpectedEOF + } + return +} + +// A spanReader is an io.LimitReader, but it returns ErrUnexpectedEOF if the +// underlying Reader returns EOF before the limit has been reached. +type spanReader struct { + r io.Reader + n int64 +} + +func (l *spanReader) Read(p []byte) (n int, err os.Error) { + if l.n <= 0 { + return 0, os.EOF + } + if int64(len(p)) > l.n { + p = p[0:l.n] + } + n, err = l.r.Read(p) + l.n -= int64(n) + if l.n > 0 && err == os.EOF { + err = io.ErrUnexpectedEOF + } + return +} + +// readHeader parses a packet header and returns an io.Reader which will return +// the contents of the packet. See RFC 4880, section 4.2. +func readHeader(r io.Reader) (tag packetType, length int64, contents io.Reader, err os.Error) { + var buf [4]byte + _, err = io.ReadFull(r, buf[:1]) + if err != nil { + return + } + if buf[0]&0x80 == 0 { + err = error.StructuralError("tag byte does not have MSB set") + return + } + if buf[0]&0x40 == 0 { + // Old format packet + tag = packetType((buf[0] & 0x3f) >> 2) + lengthType := buf[0] & 3 + if lengthType == 3 { + length = -1 + contents = r + return + } + lengthBytes := 1 << lengthType + _, err = readFull(r, buf[0:lengthBytes]) + if err != nil { + return + } + for i := 0; i < lengthBytes; i++ { + length <<= 8 + length |= int64(buf[i]) + } + contents = &spanReader{r, length} + return + } + + // New format packet + tag = packetType(buf[0] & 0x3f) + length, isPartial, err := readLength(r) + if err != nil { + return + } + if isPartial { + contents = &partialLengthReader{ + remaining: length, + isPartial: true, + r: r, + } + length = -1 + } else { + contents = &spanReader{r, length} + } + return +} + +// serialiseHeader writes an OpenPGP packet header to w. See RFC 4880, section +// 4.2. +func serialiseHeader(w io.Writer, ptype packetType, length int) (err os.Error) { + var buf [5]byte + var n int + + buf[0] = 0x80 | 0x40 | byte(ptype) + if length < 192 { + buf[1] = byte(length) + n = 2 + } else if length < 8384 { + length -= 192 + buf[1] = byte(length >> 8) + buf[2] = byte(length) + n = 3 + } else { + buf[0] = 255 + buf[1] = byte(length >> 24) + buf[2] = byte(length >> 16) + buf[3] = byte(length >> 8) + buf[4] = byte(length) + n = 5 + } + + _, err = w.Write(buf[:n]) + return +} + +// Packet represents an OpenPGP packet. Users are expected to try casting +// instances of this interface to specific packet types. +type Packet interface { + parse(io.Reader) os.Error +} + +// consumeAll reads from the given Reader until error, returning the number of +// bytes read. +func consumeAll(r io.Reader) (n int64, err os.Error) { + var m int + var buf [1024]byte + + for { + m, err = r.Read(buf[:]) + n += int64(m) + if err == os.EOF { + err = nil + return + } + if err != nil { + return + } + } + + panic("unreachable") +} + +// packetType represents the numeric ids of the different OpenPGP packet types. See +// http://www.iana.org/assignments/pgp-parameters/pgp-parameters.xhtml#pgp-parameters-2 +type packetType uint8 + +const ( + packetTypeEncryptedKey packetType = 1 + packetTypeSignature packetType = 2 + packetTypeSymmetricKeyEncrypted packetType = 3 + packetTypeOnePassSignature packetType = 4 + packetTypePrivateKey packetType = 5 + packetTypePublicKey packetType = 6 + packetTypePrivateSubkey packetType = 7 + packetTypeCompressed packetType = 8 + packetTypeSymmetricallyEncrypted packetType = 9 + packetTypeLiteralData packetType = 11 + packetTypeUserId packetType = 13 + packetTypePublicSubkey packetType = 14 + packetTypeSymmetricallyEncryptedMDC packetType = 18 +) + +// Read reads a single OpenPGP packet from the given io.Reader. If there is an +// error parsing a packet, the whole packet is consumed from the input. +func Read(r io.Reader) (p Packet, err os.Error) { + tag, _, contents, err := readHeader(r) + if err != nil { + return + } + + switch tag { + case packetTypeEncryptedKey: + p = new(EncryptedKey) + case packetTypeSignature: + p = new(Signature) + case packetTypeSymmetricKeyEncrypted: + p = new(SymmetricKeyEncrypted) + case packetTypeOnePassSignature: + p = new(OnePassSignature) + case packetTypePrivateKey, packetTypePrivateSubkey: + pk := new(PrivateKey) + if tag == packetTypePrivateSubkey { + pk.IsSubKey = true + } + p = pk + case packetTypePublicKey, packetTypePublicSubkey: + pk := new(PublicKey) + if tag == packetTypePublicSubkey { + pk.IsSubKey = true + } + p = pk + case packetTypeCompressed: + p = new(Compressed) + case packetTypeSymmetricallyEncrypted: + p = new(SymmetricallyEncrypted) + case packetTypeLiteralData: + p = new(LiteralData) + case packetTypeUserId: + p = new(UserId) + case packetTypeSymmetricallyEncryptedMDC: + se := new(SymmetricallyEncrypted) + se.MDC = true + p = se + default: + err = error.UnknownPacketTypeError(tag) + } + if p != nil { + err = p.parse(contents) + } + if err != nil { + consumeAll(contents) + } + return +} + +// SignatureType represents the different semantic meanings of an OpenPGP +// signature. See RFC 4880, section 5.2.1. +type SignatureType uint8 + +const ( + SigTypeBinary SignatureType = 0 + SigTypeText SignatureType = 1 + SigTypeGenericCert = 0x10 + SigTypePersonaCert = 0x11 + SigTypeCasualCert = 0x12 + SigTypePositiveCert = 0x13 + SigTypeSubkeyBinding = 0x18 +) + +// PublicKeyAlgorithm represents the different public key system specified for +// OpenPGP. See +// http://www.iana.org/assignments/pgp-parameters/pgp-parameters.xhtml#pgp-parameters-12 +type PublicKeyAlgorithm uint8 + +const ( + PubKeyAlgoRSA PublicKeyAlgorithm = 1 + PubKeyAlgoRSAEncryptOnly PublicKeyAlgorithm = 2 + PubKeyAlgoRSASignOnly PublicKeyAlgorithm = 3 + PubKeyAlgoElgamal PublicKeyAlgorithm = 16 + PubKeyAlgoDSA PublicKeyAlgorithm = 17 +) + +// CipherFunction represents the different block ciphers specified for OpenPGP. See +// http://www.iana.org/assignments/pgp-parameters/pgp-parameters.xhtml#pgp-parameters-13 +type CipherFunction uint8 + +const ( + CipherCAST5 = 3 + CipherAES128 = 7 + CipherAES192 = 8 + CipherAES256 = 9 +) + +// keySize returns the key size, in bytes, of cipher. +func (cipher CipherFunction) keySize() int { + switch cipher { + case CipherCAST5: + return cast5.KeySize + case CipherAES128: + return 16 + case CipherAES192: + return 24 + case CipherAES256: + return 32 + } + return 0 +} + +// blockSize returns the block size, in bytes, of cipher. +func (cipher CipherFunction) blockSize() int { + switch cipher { + case CipherCAST5: + return 8 + case CipherAES128, CipherAES192, CipherAES256: + return 16 + } + return 0 +} + +// new returns a fresh instance of the given cipher. +func (cipher CipherFunction) new(key []byte) (block cipher.Block) { + switch cipher { + case CipherCAST5: + block, _ = cast5.NewCipher(key) + case CipherAES128, CipherAES192, CipherAES256: + block, _ = aes.NewCipher(key) + } + return +} + +// readMPI reads a big integer from r. The bit length returned is the bit +// length that was specified in r. This is preserved so that the integer can be +// reserialised exactly. +func readMPI(r io.Reader) (mpi []byte, bitLength uint16, err os.Error) { + var buf [2]byte + _, err = readFull(r, buf[0:]) + if err != nil { + return + } + bitLength = uint16(buf[0])<<8 | uint16(buf[1]) + numBytes := (int(bitLength) + 7) / 8 + mpi = make([]byte, numBytes) + _, err = readFull(r, mpi) + return +} + +// writeMPI serialises a big integer to r. +func writeMPI(w io.Writer, bitLength uint16, mpiBytes []byte) (err os.Error) { + _, err = w.Write([]byte{byte(bitLength >> 8), byte(bitLength)}) + if err == nil { + _, err = w.Write(mpiBytes) + } + return +} diff --git a/src/pkg/crypto/openpgp/packet/packet_test.go b/src/pkg/crypto/openpgp/packet/packet_test.go new file mode 100644 index 00000000000..050b7341fb8 --- /dev/null +++ b/src/pkg/crypto/openpgp/packet/packet_test.go @@ -0,0 +1,192 @@ +// Copyright 2011 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 packet + +import ( + "bytes" + "crypto/openpgp/error" + "encoding/hex" + "fmt" + "io" + "io/ioutil" + "os" + "testing" +) + +func TestReadFull(t *testing.T) { + var out [4]byte + + b := bytes.NewBufferString("foo") + n, err := readFull(b, out[:3]) + if n != 3 || err != nil { + t.Errorf("full read failed n:%d err:%s", n, err) + } + + b = bytes.NewBufferString("foo") + n, err = readFull(b, out[:4]) + if n != 3 || err != io.ErrUnexpectedEOF { + t.Errorf("partial read failed n:%d err:%s", n, err) + } + + b = bytes.NewBuffer(nil) + n, err = readFull(b, out[:3]) + if n != 0 || err != io.ErrUnexpectedEOF { + t.Errorf("empty read failed n:%d err:%s", n, err) + } +} + +func readerFromHex(s string) io.Reader { + data, err := hex.DecodeString(s) + if err != nil { + panic("readerFromHex: bad input") + } + return bytes.NewBuffer(data) +} + +var readLengthTests = []struct { + hexInput string + length int64 + isPartial bool + err os.Error +}{ + {"", 0, false, io.ErrUnexpectedEOF}, + {"1f", 31, false, nil}, + {"c0", 0, false, io.ErrUnexpectedEOF}, + {"c101", 256 + 1 + 192, false, nil}, + {"e0", 1, true, nil}, + {"e1", 2, true, nil}, + {"e2", 4, true, nil}, + {"ff", 0, false, io.ErrUnexpectedEOF}, + {"ff00", 0, false, io.ErrUnexpectedEOF}, + {"ff0000", 0, false, io.ErrUnexpectedEOF}, + {"ff000000", 0, false, io.ErrUnexpectedEOF}, + {"ff00000000", 0, false, nil}, + {"ff01020304", 16909060, false, nil}, +} + +func TestReadLength(t *testing.T) { + for i, test := range readLengthTests { + length, isPartial, err := readLength(readerFromHex(test.hexInput)) + if test.err != nil { + if err != test.err { + t.Errorf("%d: expected different error got:%s want:%s", i, err, test.err) + } + continue + } + if err != nil { + t.Errorf("%d: unexpected error: %s", i, err) + continue + } + if length != test.length || isPartial != test.isPartial { + t.Errorf("%d: bad result got:(%d,%t) want:(%d,%t)", i, length, isPartial, test.length, test.isPartial) + } + } +} + +var partialLengthReaderTests = []struct { + hexInput string + err os.Error + hexOutput string +}{ + {"e0", io.ErrUnexpectedEOF, ""}, + {"e001", io.ErrUnexpectedEOF, ""}, + {"e0010102", nil, "0102"}, + {"ff00000000", nil, ""}, + {"e10102e1030400", nil, "01020304"}, + {"e101", io.ErrUnexpectedEOF, ""}, +} + +func TestPartialLengthReader(t *testing.T) { + for i, test := range partialLengthReaderTests { + r := &partialLengthReader{readerFromHex(test.hexInput), 0, true} + out, err := ioutil.ReadAll(r) + if test.err != nil { + if err != test.err { + t.Errorf("%d: expected different error got:%s want:%s", i, err, test.err) + } + continue + } + if err != nil { + t.Errorf("%d: unexpected error: %s", i, err) + continue + } + + got := fmt.Sprintf("%x", out) + if got != test.hexOutput { + t.Errorf("%d: got:%s want:%s", test.hexOutput, got) + } + } +} + +var readHeaderTests = []struct { + hexInput string + structuralError bool + unexpectedEOF bool + tag int + length int64 + hexOutput string +}{ + {"", false, false, 0, 0, ""}, + {"7f", true, false, 0, 0, ""}, + + // Old format headers + {"80", false, true, 0, 0, ""}, + {"8001", false, true, 0, 1, ""}, + {"800102", false, false, 0, 1, "02"}, + {"81000102", false, false, 0, 1, "02"}, + {"820000000102", false, false, 0, 1, "02"}, + {"860000000102", false, false, 1, 1, "02"}, + {"83010203", false, false, 0, -1, "010203"}, + + // New format headers + {"c0", false, true, 0, 0, ""}, + {"c000", false, false, 0, 0, ""}, + {"c00102", false, false, 0, 1, "02"}, + {"c0020203", false, false, 0, 2, "0203"}, + {"c00202", false, true, 0, 2, ""}, + {"c3020203", false, false, 3, 2, "0203"}, +} + +func TestReadHeader(t *testing.T) { + for i, test := range readHeaderTests { + tag, length, contents, err := readHeader(readerFromHex(test.hexInput)) + if test.structuralError { + if _, ok := err.(error.StructuralError); ok { + continue + } + t.Errorf("%d: expected StructuralError, got:%s", i, err) + continue + } + if err != nil { + if len(test.hexInput) == 0 && err == os.EOF { + continue + } + if !test.unexpectedEOF || err != io.ErrUnexpectedEOF { + t.Errorf("%d: unexpected error from readHeader: %s", i, err) + } + continue + } + if int(tag) != test.tag || length != test.length { + t.Errorf("%d: got:(%d,%d) want:(%d,%d)", i, int(tag), length, test.tag, test.length) + continue + } + + body, err := ioutil.ReadAll(contents) + if err != nil { + if !test.unexpectedEOF || err != io.ErrUnexpectedEOF { + t.Errorf("%d: unexpected error from contents: %s", i, err) + } + continue + } + if test.unexpectedEOF { + t.Errorf("%d: expected ErrUnexpectedEOF from contents but got no error", i) + continue + } + got := fmt.Sprintf("%x", body) + if got != test.hexOutput { + t.Errorf("%d: got:%s want:%s", i, got, test.hexOutput) + } + } +}