| // Copyright 2010 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. |
| |
| // TLS low level connection and record layer |
| |
| package main |
| |
| import ( |
| "bytes" |
| "crypto/cipher" |
| "crypto/ecdsa" |
| "crypto/subtle" |
| "crypto/x509" |
| "encoding/binary" |
| "errors" |
| "fmt" |
| "io" |
| "net" |
| "sync" |
| "time" |
| ) |
| |
| // A Conn represents a secured connection. |
| // It implements the net.Conn interface. |
| type Conn struct { |
| // constant |
| conn net.Conn |
| isDTLS bool |
| isClient bool |
| |
| // constant after handshake; protected by handshakeMutex |
| handshakeMutex sync.Mutex // handshakeMutex < in.Mutex, out.Mutex, errMutex |
| handshakeErr error // error resulting from handshake |
| vers uint16 // TLS version |
| haveVers bool // version has been negotiated |
| config *Config // configuration passed to constructor |
| handshakeComplete bool |
| didResume bool // whether this connection was a session resumption |
| extendedMasterSecret bool // whether this session used an extended master secret |
| cipherSuite *cipherSuite |
| ocspResponse []byte // stapled OCSP response |
| peerCertificates []*x509.Certificate |
| // verifiedChains contains the certificate chains that we built, as |
| // opposed to the ones presented by the server. |
| verifiedChains [][]*x509.Certificate |
| // serverName contains the server name indicated by the client, if any. |
| serverName string |
| // firstFinished contains the first Finished hash sent during the |
| // handshake. This is the "tls-unique" channel binding value. |
| firstFinished [12]byte |
| |
| clientRandom, serverRandom [32]byte |
| masterSecret [48]byte |
| |
| clientProtocol string |
| clientProtocolFallback bool |
| usedALPN bool |
| |
| // verify_data values for the renegotiation extension. |
| clientVerify []byte |
| serverVerify []byte |
| |
| channelID *ecdsa.PublicKey |
| |
| srtpProtectionProfile uint16 |
| |
| clientVersion uint16 |
| |
| // input/output |
| in, out halfConn // in.Mutex < out.Mutex |
| rawInput *block // raw input, right off the wire |
| input *block // application record waiting to be read |
| hand bytes.Buffer // handshake record waiting to be read |
| |
| // DTLS state |
| sendHandshakeSeq uint16 |
| recvHandshakeSeq uint16 |
| handMsg []byte // pending assembled handshake message |
| handMsgLen int // handshake message length, not including the header |
| pendingFragments [][]byte // pending outgoing handshake fragments. |
| |
| tmp [16]byte |
| } |
| |
| func (c *Conn) init() { |
| c.in.isDTLS = c.isDTLS |
| c.out.isDTLS = c.isDTLS |
| c.in.config = c.config |
| c.out.config = c.config |
| |
| c.out.updateOutSeq() |
| } |
| |
| // Access to net.Conn methods. |
| // Cannot just embed net.Conn because that would |
| // export the struct field too. |
| |
| // LocalAddr returns the local network address. |
| func (c *Conn) LocalAddr() net.Addr { |
| return c.conn.LocalAddr() |
| } |
| |
| // RemoteAddr returns the remote network address. |
| func (c *Conn) RemoteAddr() net.Addr { |
| return c.conn.RemoteAddr() |
| } |
| |
| // SetDeadline sets the read and write deadlines associated with the connection. |
| // A zero value for t means Read and Write will not time out. |
| // After a Write has timed out, the TLS state is corrupt and all future writes will return the same error. |
| func (c *Conn) SetDeadline(t time.Time) error { |
| return c.conn.SetDeadline(t) |
| } |
| |
| // SetReadDeadline sets the read deadline on the underlying connection. |
| // A zero value for t means Read will not time out. |
| func (c *Conn) SetReadDeadline(t time.Time) error { |
| return c.conn.SetReadDeadline(t) |
| } |
| |
| // SetWriteDeadline sets the write deadline on the underlying conneciton. |
| // A zero value for t means Write will not time out. |
| // After a Write has timed out, the TLS state is corrupt and all future writes will return the same error. |
| func (c *Conn) SetWriteDeadline(t time.Time) error { |
| return c.conn.SetWriteDeadline(t) |
| } |
| |
| // A halfConn represents one direction of the record layer |
| // connection, either sending or receiving. |
| type halfConn struct { |
| sync.Mutex |
| |
| err error // first permanent error |
| version uint16 // protocol version |
| isDTLS bool |
| cipher interface{} // cipher algorithm |
| mac macFunction |
| seq [8]byte // 64-bit sequence number |
| outSeq [8]byte // Mapped sequence number |
| bfree *block // list of free blocks |
| |
| nextCipher interface{} // next encryption state |
| nextMac macFunction // next MAC algorithm |
| nextSeq [6]byte // next epoch's starting sequence number in DTLS |
| |
| // used to save allocating a new buffer for each MAC. |
| inDigestBuf, outDigestBuf []byte |
| |
| config *Config |
| } |
| |
| func (hc *halfConn) setErrorLocked(err error) error { |
| hc.err = err |
| return err |
| } |
| |
| func (hc *halfConn) error() error { |
| // This should be locked, but I've removed it for the renegotiation |
| // tests since we don't concurrently read and write the same tls.Conn |
| // in any case during testing. |
| err := hc.err |
| return err |
| } |
| |
| // prepareCipherSpec sets the encryption and MAC states |
| // that a subsequent changeCipherSpec will use. |
| func (hc *halfConn) prepareCipherSpec(version uint16, cipher interface{}, mac macFunction) { |
| hc.version = version |
| hc.nextCipher = cipher |
| hc.nextMac = mac |
| } |
| |
| // changeCipherSpec changes the encryption and MAC states |
| // to the ones previously passed to prepareCipherSpec. |
| func (hc *halfConn) changeCipherSpec(config *Config) error { |
| if hc.nextCipher == nil { |
| return alertInternalError |
| } |
| hc.cipher = hc.nextCipher |
| hc.mac = hc.nextMac |
| hc.nextCipher = nil |
| hc.nextMac = nil |
| hc.config = config |
| hc.incEpoch() |
| return nil |
| } |
| |
| // incSeq increments the sequence number. |
| func (hc *halfConn) incSeq(isOutgoing bool) { |
| limit := 0 |
| increment := uint64(1) |
| if hc.isDTLS { |
| // Increment up to the epoch in DTLS. |
| limit = 2 |
| } |
| for i := 7; i >= limit; i-- { |
| increment += uint64(hc.seq[i]) |
| hc.seq[i] = byte(increment) |
| increment >>= 8 |
| } |
| |
| // Not allowed to let sequence number wrap. |
| // Instead, must renegotiate before it does. |
| // Not likely enough to bother. |
| if increment != 0 { |
| panic("TLS: sequence number wraparound") |
| } |
| |
| hc.updateOutSeq() |
| } |
| |
| // incNextSeq increments the starting sequence number for the next epoch. |
| func (hc *halfConn) incNextSeq() { |
| for i := len(hc.nextSeq) - 1; i >= 0; i-- { |
| hc.nextSeq[i]++ |
| if hc.nextSeq[i] != 0 { |
| return |
| } |
| } |
| panic("TLS: sequence number wraparound") |
| } |
| |
| // incEpoch resets the sequence number. In DTLS, it also increments the epoch |
| // half of the sequence number. |
| func (hc *halfConn) incEpoch() { |
| if hc.isDTLS { |
| for i := 1; i >= 0; i-- { |
| hc.seq[i]++ |
| if hc.seq[i] != 0 { |
| break |
| } |
| if i == 0 { |
| panic("TLS: epoch number wraparound") |
| } |
| } |
| copy(hc.seq[2:], hc.nextSeq[:]) |
| for i := range hc.nextSeq { |
| hc.nextSeq[i] = 0 |
| } |
| } else { |
| for i := range hc.seq { |
| hc.seq[i] = 0 |
| } |
| } |
| |
| hc.updateOutSeq() |
| } |
| |
| func (hc *halfConn) updateOutSeq() { |
| if hc.config.Bugs.SequenceNumberMapping != nil { |
| seqU64 := binary.BigEndian.Uint64(hc.seq[:]) |
| seqU64 = hc.config.Bugs.SequenceNumberMapping(seqU64) |
| binary.BigEndian.PutUint64(hc.outSeq[:], seqU64) |
| |
| // The DTLS epoch cannot be changed. |
| copy(hc.outSeq[:2], hc.seq[:2]) |
| return |
| } |
| |
| copy(hc.outSeq[:], hc.seq[:]) |
| } |
| |
| func (hc *halfConn) recordHeaderLen() int { |
| if hc.isDTLS { |
| return dtlsRecordHeaderLen |
| } |
| return tlsRecordHeaderLen |
| } |
| |
| // removePadding returns an unpadded slice, in constant time, which is a prefix |
| // of the input. It also returns a byte which is equal to 255 if the padding |
| // was valid and 0 otherwise. See RFC 2246, section 6.2.3.2 |
| func removePadding(payload []byte) ([]byte, byte) { |
| if len(payload) < 1 { |
| return payload, 0 |
| } |
| |
| paddingLen := payload[len(payload)-1] |
| t := uint(len(payload)-1) - uint(paddingLen) |
| // if len(payload) >= (paddingLen - 1) then the MSB of t is zero |
| good := byte(int32(^t) >> 31) |
| |
| toCheck := 255 // the maximum possible padding length |
| // The length of the padded data is public, so we can use an if here |
| if toCheck+1 > len(payload) { |
| toCheck = len(payload) - 1 |
| } |
| |
| for i := 0; i < toCheck; i++ { |
| t := uint(paddingLen) - uint(i) |
| // if i <= paddingLen then the MSB of t is zero |
| mask := byte(int32(^t) >> 31) |
| b := payload[len(payload)-1-i] |
| good &^= mask&paddingLen ^ mask&b |
| } |
| |
| // We AND together the bits of good and replicate the result across |
| // all the bits. |
| good &= good << 4 |
| good &= good << 2 |
| good &= good << 1 |
| good = uint8(int8(good) >> 7) |
| |
| toRemove := good&paddingLen + 1 |
| return payload[:len(payload)-int(toRemove)], good |
| } |
| |
| // removePaddingSSL30 is a replacement for removePadding in the case that the |
| // protocol version is SSLv3. In this version, the contents of the padding |
| // are random and cannot be checked. |
| func removePaddingSSL30(payload []byte) ([]byte, byte) { |
| if len(payload) < 1 { |
| return payload, 0 |
| } |
| |
| paddingLen := int(payload[len(payload)-1]) + 1 |
| if paddingLen > len(payload) { |
| return payload, 0 |
| } |
| |
| return payload[:len(payload)-paddingLen], 255 |
| } |
| |
| func roundUp(a, b int) int { |
| return a + (b-a%b)%b |
| } |
| |
| // cbcMode is an interface for block ciphers using cipher block chaining. |
| type cbcMode interface { |
| cipher.BlockMode |
| SetIV([]byte) |
| } |
| |
| // decrypt checks and strips the mac and decrypts the data in b. Returns a |
| // success boolean, the number of bytes to skip from the start of the record in |
| // order to get the application payload, and an optional alert value. |
| func (hc *halfConn) decrypt(b *block) (ok bool, prefixLen int, alertValue alert) { |
| recordHeaderLen := hc.recordHeaderLen() |
| |
| // pull out payload |
| payload := b.data[recordHeaderLen:] |
| |
| macSize := 0 |
| if hc.mac != nil { |
| macSize = hc.mac.Size() |
| } |
| |
| paddingGood := byte(255) |
| explicitIVLen := 0 |
| |
| seq := hc.seq[:] |
| if hc.isDTLS { |
| // DTLS sequence numbers are explicit. |
| seq = b.data[3:11] |
| } |
| |
| // decrypt |
| if hc.cipher != nil { |
| switch c := hc.cipher.(type) { |
| case cipher.Stream: |
| c.XORKeyStream(payload, payload) |
| case *tlsAead: |
| nonce := seq |
| if c.explicitNonce { |
| explicitIVLen = 8 |
| if len(payload) < explicitIVLen { |
| return false, 0, alertBadRecordMAC |
| } |
| nonce = payload[:8] |
| payload = payload[8:] |
| } |
| |
| var additionalData [13]byte |
| copy(additionalData[:], seq) |
| copy(additionalData[8:], b.data[:3]) |
| n := len(payload) - c.Overhead() |
| additionalData[11] = byte(n >> 8) |
| additionalData[12] = byte(n) |
| var err error |
| payload, err = c.Open(payload[:0], nonce, payload, additionalData[:]) |
| if err != nil { |
| return false, 0, alertBadRecordMAC |
| } |
| b.resize(recordHeaderLen + explicitIVLen + len(payload)) |
| case cbcMode: |
| blockSize := c.BlockSize() |
| if hc.version >= VersionTLS11 || hc.isDTLS { |
| explicitIVLen = blockSize |
| } |
| |
| if len(payload)%blockSize != 0 || len(payload) < roundUp(explicitIVLen+macSize+1, blockSize) { |
| return false, 0, alertBadRecordMAC |
| } |
| |
| if explicitIVLen > 0 { |
| c.SetIV(payload[:explicitIVLen]) |
| payload = payload[explicitIVLen:] |
| } |
| c.CryptBlocks(payload, payload) |
| if hc.version == VersionSSL30 { |
| payload, paddingGood = removePaddingSSL30(payload) |
| } else { |
| payload, paddingGood = removePadding(payload) |
| } |
| b.resize(recordHeaderLen + explicitIVLen + len(payload)) |
| |
| // note that we still have a timing side-channel in the |
| // MAC check, below. An attacker can align the record |
| // so that a correct padding will cause one less hash |
| // block to be calculated. Then they can iteratively |
| // decrypt a record by breaking each byte. See |
| // "Password Interception in a SSL/TLS Channel", Brice |
| // Canvel et al. |
| // |
| // However, our behavior matches OpenSSL, so we leak |
| // only as much as they do. |
| default: |
| panic("unknown cipher type") |
| } |
| } |
| |
| // check, strip mac |
| if hc.mac != nil { |
| if len(payload) < macSize { |
| return false, 0, alertBadRecordMAC |
| } |
| |
| // strip mac off payload, b.data |
| n := len(payload) - macSize |
| b.data[recordHeaderLen-2] = byte(n >> 8) |
| b.data[recordHeaderLen-1] = byte(n) |
| b.resize(recordHeaderLen + explicitIVLen + n) |
| remoteMAC := payload[n:] |
| localMAC := hc.mac.MAC(hc.inDigestBuf, seq, b.data[:3], b.data[recordHeaderLen-2:recordHeaderLen], payload[:n]) |
| |
| if subtle.ConstantTimeCompare(localMAC, remoteMAC) != 1 || paddingGood != 255 { |
| return false, 0, alertBadRecordMAC |
| } |
| hc.inDigestBuf = localMAC |
| } |
| hc.incSeq(false) |
| |
| return true, recordHeaderLen + explicitIVLen, 0 |
| } |
| |
| // padToBlockSize calculates the needed padding block, if any, for a payload. |
| // On exit, prefix aliases payload and extends to the end of the last full |
| // block of payload. finalBlock is a fresh slice which contains the contents of |
| // any suffix of payload as well as the needed padding to make finalBlock a |
| // full block. |
| func padToBlockSize(payload []byte, blockSize int, config *Config) (prefix, finalBlock []byte) { |
| overrun := len(payload) % blockSize |
| prefix = payload[:len(payload)-overrun] |
| |
| paddingLen := blockSize - overrun |
| finalSize := blockSize |
| if config.Bugs.MaxPadding { |
| for paddingLen+blockSize <= 256 { |
| paddingLen += blockSize |
| } |
| finalSize = 256 |
| } |
| finalBlock = make([]byte, finalSize) |
| for i := range finalBlock { |
| finalBlock[i] = byte(paddingLen - 1) |
| } |
| if config.Bugs.PaddingFirstByteBad || config.Bugs.PaddingFirstByteBadIf255 && paddingLen == 256 { |
| finalBlock[overrun] ^= 0xff |
| } |
| copy(finalBlock, payload[len(payload)-overrun:]) |
| return |
| } |
| |
| // encrypt encrypts and macs the data in b. |
| func (hc *halfConn) encrypt(b *block, explicitIVLen int) (bool, alert) { |
| recordHeaderLen := hc.recordHeaderLen() |
| |
| // mac |
| if hc.mac != nil { |
| mac := hc.mac.MAC(hc.outDigestBuf, hc.outSeq[0:], b.data[:3], b.data[recordHeaderLen-2:recordHeaderLen], b.data[recordHeaderLen+explicitIVLen:]) |
| |
| n := len(b.data) |
| b.resize(n + len(mac)) |
| copy(b.data[n:], mac) |
| hc.outDigestBuf = mac |
| } |
| |
| payload := b.data[recordHeaderLen:] |
| |
| // encrypt |
| if hc.cipher != nil { |
| switch c := hc.cipher.(type) { |
| case cipher.Stream: |
| c.XORKeyStream(payload, payload) |
| case *tlsAead: |
| payloadLen := len(b.data) - recordHeaderLen - explicitIVLen |
| b.resize(len(b.data) + c.Overhead()) |
| nonce := hc.outSeq[:] |
| if c.explicitNonce { |
| nonce = b.data[recordHeaderLen : recordHeaderLen+explicitIVLen] |
| } |
| payload := b.data[recordHeaderLen+explicitIVLen:] |
| payload = payload[:payloadLen] |
| |
| var additionalData [13]byte |
| copy(additionalData[:], hc.outSeq[:]) |
| copy(additionalData[8:], b.data[:3]) |
| additionalData[11] = byte(payloadLen >> 8) |
| additionalData[12] = byte(payloadLen) |
| |
| c.Seal(payload[:0], nonce, payload, additionalData[:]) |
| case cbcMode: |
| blockSize := c.BlockSize() |
| if explicitIVLen > 0 { |
| c.SetIV(payload[:explicitIVLen]) |
| payload = payload[explicitIVLen:] |
| } |
| prefix, finalBlock := padToBlockSize(payload, blockSize, hc.config) |
| b.resize(recordHeaderLen + explicitIVLen + len(prefix) + len(finalBlock)) |
| c.CryptBlocks(b.data[recordHeaderLen+explicitIVLen:], prefix) |
| c.CryptBlocks(b.data[recordHeaderLen+explicitIVLen+len(prefix):], finalBlock) |
| default: |
| panic("unknown cipher type") |
| } |
| } |
| |
| // update length to include MAC and any block padding needed. |
| n := len(b.data) - recordHeaderLen |
| b.data[recordHeaderLen-2] = byte(n >> 8) |
| b.data[recordHeaderLen-1] = byte(n) |
| hc.incSeq(true) |
| |
| return true, 0 |
| } |
| |
| // A block is a simple data buffer. |
| type block struct { |
| data []byte |
| off int // index for Read |
| link *block |
| } |
| |
| // resize resizes block to be n bytes, growing if necessary. |
| func (b *block) resize(n int) { |
| if n > cap(b.data) { |
| b.reserve(n) |
| } |
| b.data = b.data[0:n] |
| } |
| |
| // reserve makes sure that block contains a capacity of at least n bytes. |
| func (b *block) reserve(n int) { |
| if cap(b.data) >= n { |
| return |
| } |
| m := cap(b.data) |
| if m == 0 { |
| m = 1024 |
| } |
| for m < n { |
| m *= 2 |
| } |
| data := make([]byte, len(b.data), m) |
| copy(data, b.data) |
| b.data = data |
| } |
| |
| // readFromUntil reads from r into b until b contains at least n bytes |
| // or else returns an error. |
| func (b *block) readFromUntil(r io.Reader, n int) error { |
| // quick case |
| if len(b.data) >= n { |
| return nil |
| } |
| |
| // read until have enough. |
| b.reserve(n) |
| for { |
| m, err := r.Read(b.data[len(b.data):cap(b.data)]) |
| b.data = b.data[0 : len(b.data)+m] |
| if len(b.data) >= n { |
| // TODO(bradfitz,agl): slightly suspicious |
| // that we're throwing away r.Read's err here. |
| break |
| } |
| if err != nil { |
| return err |
| } |
| } |
| return nil |
| } |
| |
| func (b *block) Read(p []byte) (n int, err error) { |
| n = copy(p, b.data[b.off:]) |
| b.off += n |
| return |
| } |
| |
| // newBlock allocates a new block, from hc's free list if possible. |
| func (hc *halfConn) newBlock() *block { |
| b := hc.bfree |
| if b == nil { |
| return new(block) |
| } |
| hc.bfree = b.link |
| b.link = nil |
| b.resize(0) |
| return b |
| } |
| |
| // freeBlock returns a block to hc's free list. |
| // The protocol is such that each side only has a block or two on |
| // its free list at a time, so there's no need to worry about |
| // trimming the list, etc. |
| func (hc *halfConn) freeBlock(b *block) { |
| b.link = hc.bfree |
| hc.bfree = b |
| } |
| |
| // splitBlock splits a block after the first n bytes, |
| // returning a block with those n bytes and a |
| // block with the remainder. the latter may be nil. |
| func (hc *halfConn) splitBlock(b *block, n int) (*block, *block) { |
| if len(b.data) <= n { |
| return b, nil |
| } |
| bb := hc.newBlock() |
| bb.resize(len(b.data) - n) |
| copy(bb.data, b.data[n:]) |
| b.data = b.data[0:n] |
| return b, bb |
| } |
| |
| func (c *Conn) doReadRecord(want recordType) (recordType, *block, error) { |
| if c.isDTLS { |
| return c.dtlsDoReadRecord(want) |
| } |
| |
| recordHeaderLen := tlsRecordHeaderLen |
| |
| if c.rawInput == nil { |
| c.rawInput = c.in.newBlock() |
| } |
| b := c.rawInput |
| |
| // Read header, payload. |
| if err := b.readFromUntil(c.conn, recordHeaderLen); err != nil { |
| // RFC suggests that EOF without an alertCloseNotify is |
| // an error, but popular web sites seem to do this, |
| // so we can't make it an error. |
| // if err == io.EOF { |
| // err = io.ErrUnexpectedEOF |
| // } |
| if e, ok := err.(net.Error); !ok || !e.Temporary() { |
| c.in.setErrorLocked(err) |
| } |
| return 0, nil, err |
| } |
| typ := recordType(b.data[0]) |
| |
| // No valid TLS record has a type of 0x80, however SSLv2 handshakes |
| // start with a uint16 length where the MSB is set and the first record |
| // is always < 256 bytes long. Therefore typ == 0x80 strongly suggests |
| // an SSLv2 client. |
| if want == recordTypeHandshake && typ == 0x80 { |
| c.sendAlert(alertProtocolVersion) |
| return 0, nil, c.in.setErrorLocked(errors.New("tls: unsupported SSLv2 handshake received")) |
| } |
| |
| vers := uint16(b.data[1])<<8 | uint16(b.data[2]) |
| n := int(b.data[3])<<8 | int(b.data[4]) |
| if c.haveVers { |
| if vers != c.vers { |
| c.sendAlert(alertProtocolVersion) |
| return 0, nil, c.in.setErrorLocked(fmt.Errorf("tls: received record with version %x when expecting version %x", vers, c.vers)) |
| } |
| } else { |
| if expect := c.config.Bugs.ExpectInitialRecordVersion; expect != 0 && vers != expect { |
| c.sendAlert(alertProtocolVersion) |
| return 0, nil, c.in.setErrorLocked(fmt.Errorf("tls: received record with version %x when expecting version %x", vers, expect)) |
| } |
| } |
| if n > maxCiphertext { |
| c.sendAlert(alertRecordOverflow) |
| return 0, nil, c.in.setErrorLocked(fmt.Errorf("tls: oversized record received with length %d", n)) |
| } |
| if !c.haveVers { |
| // First message, be extra suspicious: |
| // this might not be a TLS client. |
| // Bail out before reading a full 'body', if possible. |
| // The current max version is 3.1. |
| // If the version is >= 16.0, it's probably not real. |
| // Similarly, a clientHello message encodes in |
| // well under a kilobyte. If the length is >= 12 kB, |
| // it's probably not real. |
| if (typ != recordTypeAlert && typ != want) || vers >= 0x1000 || n >= 0x3000 { |
| c.sendAlert(alertUnexpectedMessage) |
| return 0, nil, c.in.setErrorLocked(fmt.Errorf("tls: first record does not look like a TLS handshake")) |
| } |
| } |
| if err := b.readFromUntil(c.conn, recordHeaderLen+n); err != nil { |
| if err == io.EOF { |
| err = io.ErrUnexpectedEOF |
| } |
| if e, ok := err.(net.Error); !ok || !e.Temporary() { |
| c.in.setErrorLocked(err) |
| } |
| return 0, nil, err |
| } |
| |
| // Process message. |
| b, c.rawInput = c.in.splitBlock(b, recordHeaderLen+n) |
| ok, off, err := c.in.decrypt(b) |
| if !ok { |
| c.in.setErrorLocked(c.sendAlert(err)) |
| } |
| b.off = off |
| return typ, b, nil |
| } |
| |
| // readRecord reads the next TLS record from the connection |
| // and updates the record layer state. |
| // c.in.Mutex <= L; c.input == nil. |
| func (c *Conn) readRecord(want recordType) error { |
| // Caller must be in sync with connection: |
| // handshake data if handshake not yet completed, |
| // else application data. |
| switch want { |
| default: |
| c.sendAlert(alertInternalError) |
| return c.in.setErrorLocked(errors.New("tls: unknown record type requested")) |
| case recordTypeHandshake, recordTypeChangeCipherSpec: |
| if c.handshakeComplete { |
| c.sendAlert(alertInternalError) |
| return c.in.setErrorLocked(errors.New("tls: handshake or ChangeCipherSpec requested after handshake complete")) |
| } |
| case recordTypeApplicationData: |
| if !c.handshakeComplete && !c.config.Bugs.ExpectFalseStart { |
| c.sendAlert(alertInternalError) |
| return c.in.setErrorLocked(errors.New("tls: application data record requested before handshake complete")) |
| } |
| } |
| |
| Again: |
| typ, b, err := c.doReadRecord(want) |
| if err != nil { |
| return err |
| } |
| data := b.data[b.off:] |
| if len(data) > maxPlaintext { |
| err := c.sendAlert(alertRecordOverflow) |
| c.in.freeBlock(b) |
| return c.in.setErrorLocked(err) |
| } |
| |
| switch typ { |
| default: |
| c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage)) |
| |
| case recordTypeAlert: |
| if len(data) != 2 { |
| c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage)) |
| break |
| } |
| if alert(data[1]) == alertCloseNotify { |
| c.in.setErrorLocked(io.EOF) |
| break |
| } |
| switch data[0] { |
| case alertLevelWarning: |
| // drop on the floor |
| c.in.freeBlock(b) |
| goto Again |
| case alertLevelError: |
| c.in.setErrorLocked(&net.OpError{Op: "remote error", Err: alert(data[1])}) |
| default: |
| c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage)) |
| } |
| |
| case recordTypeChangeCipherSpec: |
| if typ != want || len(data) != 1 || data[0] != 1 { |
| c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage)) |
| break |
| } |
| err := c.in.changeCipherSpec(c.config) |
| if err != nil { |
| c.in.setErrorLocked(c.sendAlert(err.(alert))) |
| } |
| |
| case recordTypeApplicationData: |
| if typ != want { |
| c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage)) |
| break |
| } |
| c.input = b |
| b = nil |
| |
| case recordTypeHandshake: |
| // TODO(rsc): Should at least pick off connection close. |
| if typ != want { |
| // A client might need to process a HelloRequest from |
| // the server, thus receiving a handshake message when |
| // application data is expected is ok. |
| if !c.isClient { |
| return c.in.setErrorLocked(c.sendAlert(alertNoRenegotiation)) |
| } |
| } |
| c.hand.Write(data) |
| } |
| |
| if b != nil { |
| c.in.freeBlock(b) |
| } |
| return c.in.err |
| } |
| |
| // sendAlert sends a TLS alert message. |
| // c.out.Mutex <= L. |
| func (c *Conn) sendAlertLocked(level byte, err alert) error { |
| c.tmp[0] = level |
| c.tmp[1] = byte(err) |
| if c.config.Bugs.FragmentAlert { |
| c.writeRecord(recordTypeAlert, c.tmp[0:1]) |
| c.writeRecord(recordTypeAlert, c.tmp[1:2]) |
| } else { |
| c.writeRecord(recordTypeAlert, c.tmp[0:2]) |
| } |
| // Error alerts are fatal to the connection. |
| if level == alertLevelError { |
| return c.out.setErrorLocked(&net.OpError{Op: "local error", Err: err}) |
| } |
| return nil |
| } |
| |
| // sendAlert sends a TLS alert message. |
| // L < c.out.Mutex. |
| func (c *Conn) sendAlert(err alert) error { |
| level := byte(alertLevelError) |
| if err == alertNoRenegotiation || err == alertCloseNotify { |
| level = alertLevelWarning |
| } |
| return c.SendAlert(level, err) |
| } |
| |
| func (c *Conn) SendAlert(level byte, err alert) error { |
| c.out.Lock() |
| defer c.out.Unlock() |
| return c.sendAlertLocked(level, err) |
| } |
| |
| // writeV2Record writes a record for a V2ClientHello. |
| func (c *Conn) writeV2Record(data []byte) (n int, err error) { |
| record := make([]byte, 2+len(data)) |
| record[0] = uint8(len(data)>>8) | 0x80 |
| record[1] = uint8(len(data)) |
| copy(record[2:], data) |
| return c.conn.Write(record) |
| } |
| |
| // writeRecord writes a TLS record with the given type and payload |
| // to the connection and updates the record layer state. |
| // c.out.Mutex <= L. |
| func (c *Conn) writeRecord(typ recordType, data []byte) (n int, err error) { |
| if c.isDTLS { |
| return c.dtlsWriteRecord(typ, data) |
| } |
| |
| recordHeaderLen := tlsRecordHeaderLen |
| b := c.out.newBlock() |
| first := true |
| isClientHello := typ == recordTypeHandshake && len(data) > 0 && data[0] == typeClientHello |
| for len(data) > 0 || first { |
| m := len(data) |
| if m > maxPlaintext { |
| m = maxPlaintext |
| } |
| if typ == recordTypeHandshake && c.config.Bugs.MaxHandshakeRecordLength > 0 && m > c.config.Bugs.MaxHandshakeRecordLength { |
| m = c.config.Bugs.MaxHandshakeRecordLength |
| // By default, do not fragment the client_version or |
| // server_version, which are located in the first 6 |
| // bytes. |
| if first && isClientHello && !c.config.Bugs.FragmentClientVersion && m < 6 { |
| m = 6 |
| } |
| } |
| explicitIVLen := 0 |
| explicitIVIsSeq := false |
| first = false |
| |
| var cbc cbcMode |
| if c.out.version >= VersionTLS11 { |
| var ok bool |
| if cbc, ok = c.out.cipher.(cbcMode); ok { |
| explicitIVLen = cbc.BlockSize() |
| } |
| } |
| if explicitIVLen == 0 { |
| if aead, ok := c.out.cipher.(*tlsAead); ok && aead.explicitNonce { |
| explicitIVLen = 8 |
| // The AES-GCM construction in TLS has an |
| // explicit nonce so that the nonce can be |
| // random. However, the nonce is only 8 bytes |
| // which is too small for a secure, random |
| // nonce. Therefore we use the sequence number |
| // as the nonce. |
| explicitIVIsSeq = true |
| } |
| } |
| b.resize(recordHeaderLen + explicitIVLen + m) |
| b.data[0] = byte(typ) |
| vers := c.vers |
| if vers == 0 { |
| // Some TLS servers fail if the record version is |
| // greater than TLS 1.0 for the initial ClientHello. |
| vers = VersionTLS10 |
| } |
| b.data[1] = byte(vers >> 8) |
| b.data[2] = byte(vers) |
| b.data[3] = byte(m >> 8) |
| b.data[4] = byte(m) |
| if explicitIVLen > 0 { |
| explicitIV := b.data[recordHeaderLen : recordHeaderLen+explicitIVLen] |
| if explicitIVIsSeq { |
| copy(explicitIV, c.out.seq[:]) |
| } else { |
| if _, err = io.ReadFull(c.config.rand(), explicitIV); err != nil { |
| break |
| } |
| } |
| } |
| copy(b.data[recordHeaderLen+explicitIVLen:], data) |
| c.out.encrypt(b, explicitIVLen) |
| _, err = c.conn.Write(b.data) |
| if err != nil { |
| break |
| } |
| n += m |
| data = data[m:] |
| } |
| c.out.freeBlock(b) |
| |
| if typ == recordTypeChangeCipherSpec { |
| err = c.out.changeCipherSpec(c.config) |
| if err != nil { |
| // Cannot call sendAlert directly, |
| // because we already hold c.out.Mutex. |
| c.tmp[0] = alertLevelError |
| c.tmp[1] = byte(err.(alert)) |
| c.writeRecord(recordTypeAlert, c.tmp[0:2]) |
| return n, c.out.setErrorLocked(&net.OpError{Op: "local error", Err: err}) |
| } |
| } |
| return |
| } |
| |
| func (c *Conn) doReadHandshake() ([]byte, error) { |
| if c.isDTLS { |
| return c.dtlsDoReadHandshake() |
| } |
| |
| for c.hand.Len() < 4 { |
| if err := c.in.err; err != nil { |
| return nil, err |
| } |
| if err := c.readRecord(recordTypeHandshake); err != nil { |
| return nil, err |
| } |
| } |
| |
| data := c.hand.Bytes() |
| n := int(data[1])<<16 | int(data[2])<<8 | int(data[3]) |
| if n > maxHandshake { |
| return nil, c.in.setErrorLocked(c.sendAlert(alertInternalError)) |
| } |
| for c.hand.Len() < 4+n { |
| if err := c.in.err; err != nil { |
| return nil, err |
| } |
| if err := c.readRecord(recordTypeHandshake); err != nil { |
| return nil, err |
| } |
| } |
| return c.hand.Next(4 + n), nil |
| } |
| |
| // readHandshake reads the next handshake message from |
| // the record layer. |
| // c.in.Mutex < L; c.out.Mutex < L. |
| func (c *Conn) readHandshake() (interface{}, error) { |
| data, err := c.doReadHandshake() |
| if err != nil { |
| return nil, err |
| } |
| |
| var m handshakeMessage |
| switch data[0] { |
| case typeHelloRequest: |
| m = new(helloRequestMsg) |
| case typeClientHello: |
| m = &clientHelloMsg{ |
| isDTLS: c.isDTLS, |
| } |
| case typeServerHello: |
| m = &serverHelloMsg{ |
| isDTLS: c.isDTLS, |
| } |
| case typeNewSessionTicket: |
| m = new(newSessionTicketMsg) |
| case typeCertificate: |
| m = new(certificateMsg) |
| case typeCertificateRequest: |
| m = &certificateRequestMsg{ |
| hasSignatureAndHash: c.vers >= VersionTLS12, |
| } |
| case typeCertificateStatus: |
| m = new(certificateStatusMsg) |
| case typeServerKeyExchange: |
| m = new(serverKeyExchangeMsg) |
| case typeServerHelloDone: |
| m = new(serverHelloDoneMsg) |
| case typeClientKeyExchange: |
| m = new(clientKeyExchangeMsg) |
| case typeCertificateVerify: |
| m = &certificateVerifyMsg{ |
| hasSignatureAndHash: c.vers >= VersionTLS12, |
| } |
| case typeNextProtocol: |
| m = new(nextProtoMsg) |
| case typeFinished: |
| m = new(finishedMsg) |
| case typeHelloVerifyRequest: |
| m = new(helloVerifyRequestMsg) |
| case typeEncryptedExtensions: |
| m = new(encryptedExtensionsMsg) |
| default: |
| return nil, c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage)) |
| } |
| |
| // The handshake message unmarshallers |
| // expect to be able to keep references to data, |
| // so pass in a fresh copy that won't be overwritten. |
| data = append([]byte(nil), data...) |
| |
| if !m.unmarshal(data) { |
| return nil, c.in.setErrorLocked(c.sendAlert(alertUnexpectedMessage)) |
| } |
| return m, nil |
| } |
| |
| // skipPacket processes all the DTLS records in packet. It updates |
| // sequence number expectations but otherwise ignores them. |
| func (c *Conn) skipPacket(packet []byte) error { |
| for len(packet) > 0 { |
| // Dropped packets are completely ignored save to update |
| // expected sequence numbers for this and the next epoch. (We |
| // don't assert on the contents of the packets both for |
| // simplicity and because a previous test with one shorter |
| // timeout schedule would have done so.) |
| epoch := packet[3:5] |
| seq := packet[5:11] |
| length := uint16(packet[11])<<8 | uint16(packet[12]) |
| if bytes.Equal(c.in.seq[:2], epoch) { |
| if !bytes.Equal(c.in.seq[2:], seq) { |
| return errors.New("tls: sequence mismatch") |
| } |
| c.in.incSeq(false) |
| } else { |
| if !bytes.Equal(c.in.nextSeq[:], seq) { |
| return errors.New("tls: sequence mismatch") |
| } |
| c.in.incNextSeq() |
| } |
| packet = packet[13+length:] |
| } |
| return nil |
| } |
| |
| // simulatePacketLoss simulates the loss of a handshake leg from the |
| // peer based on the schedule in c.config.Bugs. If resendFunc is |
| // non-nil, it is called after each simulated timeout to retransmit |
| // handshake messages from the local end. This is used in cases where |
| // the peer retransmits on a stale Finished rather than a timeout. |
| func (c *Conn) simulatePacketLoss(resendFunc func()) error { |
| if len(c.config.Bugs.TimeoutSchedule) == 0 { |
| return nil |
| } |
| if !c.isDTLS { |
| return errors.New("tls: TimeoutSchedule may only be set in DTLS") |
| } |
| if c.config.Bugs.PacketAdaptor == nil { |
| return errors.New("tls: TimeoutSchedule set without PacketAdapter") |
| } |
| for _, timeout := range c.config.Bugs.TimeoutSchedule { |
| // Simulate a timeout. |
| packets, err := c.config.Bugs.PacketAdaptor.SendReadTimeout(timeout) |
| if err != nil { |
| return err |
| } |
| for _, packet := range packets { |
| if err := c.skipPacket(packet); err != nil { |
| return err |
| } |
| } |
| if resendFunc != nil { |
| resendFunc() |
| } |
| } |
| return nil |
| } |
| |
| // Write writes data to the connection. |
| func (c *Conn) Write(b []byte) (int, error) { |
| if err := c.Handshake(); err != nil { |
| return 0, err |
| } |
| |
| c.out.Lock() |
| defer c.out.Unlock() |
| |
| if err := c.out.err; err != nil { |
| return 0, err |
| } |
| |
| if !c.handshakeComplete { |
| return 0, alertInternalError |
| } |
| |
| if c.config.Bugs.SendSpuriousAlert != 0 { |
| c.sendAlertLocked(alertLevelError, c.config.Bugs.SendSpuriousAlert) |
| } |
| |
| // SSL 3.0 and TLS 1.0 are susceptible to a chosen-plaintext |
| // attack when using block mode ciphers due to predictable IVs. |
| // This can be prevented by splitting each Application Data |
| // record into two records, effectively randomizing the IV. |
| // |
| // http://www.openssl.org/~bodo/tls-cbc.txt |
| // https://bugzilla.mozilla.org/show_bug.cgi?id=665814 |
| // http://www.imperialviolet.org/2012/01/15/beastfollowup.html |
| |
| var m int |
| if len(b) > 1 && c.vers <= VersionTLS10 && !c.isDTLS { |
| if _, ok := c.out.cipher.(cipher.BlockMode); ok { |
| n, err := c.writeRecord(recordTypeApplicationData, b[:1]) |
| if err != nil { |
| return n, c.out.setErrorLocked(err) |
| } |
| m, b = 1, b[1:] |
| } |
| } |
| |
| n, err := c.writeRecord(recordTypeApplicationData, b) |
| return n + m, c.out.setErrorLocked(err) |
| } |
| |
| func (c *Conn) handleRenegotiation() error { |
| c.handshakeComplete = false |
| if !c.isClient { |
| panic("renegotiation should only happen for a client") |
| } |
| |
| msg, err := c.readHandshake() |
| if err != nil { |
| return err |
| } |
| _, ok := msg.(*helloRequestMsg) |
| if !ok { |
| c.sendAlert(alertUnexpectedMessage) |
| return alertUnexpectedMessage |
| } |
| |
| return c.Handshake() |
| } |
| |
| func (c *Conn) Renegotiate() error { |
| if !c.isClient { |
| helloReq := new(helloRequestMsg) |
| c.writeRecord(recordTypeHandshake, helloReq.marshal()) |
| } |
| |
| c.handshakeComplete = false |
| return c.Handshake() |
| } |
| |
| // Read can be made to time out and return a net.Error with Timeout() == true |
| // after a fixed time limit; see SetDeadline and SetReadDeadline. |
| func (c *Conn) Read(b []byte) (n int, err error) { |
| if err = c.Handshake(); err != nil { |
| return |
| } |
| |
| c.in.Lock() |
| defer c.in.Unlock() |
| |
| // Some OpenSSL servers send empty records in order to randomize the |
| // CBC IV. So this loop ignores a limited number of empty records. |
| const maxConsecutiveEmptyRecords = 100 |
| for emptyRecordCount := 0; emptyRecordCount <= maxConsecutiveEmptyRecords; emptyRecordCount++ { |
| for c.input == nil && c.in.err == nil { |
| if err := c.readRecord(recordTypeApplicationData); err != nil { |
| // Soft error, like EAGAIN |
| return 0, err |
| } |
| if c.hand.Len() > 0 { |
| // We received handshake bytes, indicating the |
| // start of a renegotiation. |
| if err := c.handleRenegotiation(); err != nil { |
| return 0, err |
| } |
| continue |
| } |
| } |
| if err := c.in.err; err != nil { |
| return 0, err |
| } |
| |
| n, err = c.input.Read(b) |
| if c.input.off >= len(c.input.data) || c.isDTLS { |
| c.in.freeBlock(c.input) |
| c.input = nil |
| } |
| |
| // If a close-notify alert is waiting, read it so that |
| // we can return (n, EOF) instead of (n, nil), to signal |
| // to the HTTP response reading goroutine that the |
| // connection is now closed. This eliminates a race |
| // where the HTTP response reading goroutine would |
| // otherwise not observe the EOF until its next read, |
| // by which time a client goroutine might have already |
| // tried to reuse the HTTP connection for a new |
| // request. |
| // See https://codereview.appspot.com/76400046 |
| // and http://golang.org/issue/3514 |
| if ri := c.rawInput; ri != nil && |
| n != 0 && err == nil && |
| c.input == nil && len(ri.data) > 0 && recordType(ri.data[0]) == recordTypeAlert { |
| if recErr := c.readRecord(recordTypeApplicationData); recErr != nil { |
| err = recErr // will be io.EOF on closeNotify |
| } |
| } |
| |
| if n != 0 || err != nil { |
| return n, err |
| } |
| } |
| |
| return 0, io.ErrNoProgress |
| } |
| |
| // Close closes the connection. |
| func (c *Conn) Close() error { |
| var alertErr error |
| |
| c.handshakeMutex.Lock() |
| defer c.handshakeMutex.Unlock() |
| if c.handshakeComplete { |
| alertErr = c.sendAlert(alertCloseNotify) |
| } |
| |
| if err := c.conn.Close(); err != nil { |
| return err |
| } |
| return alertErr |
| } |
| |
| // Handshake runs the client or server handshake |
| // protocol if it has not yet been run. |
| // Most uses of this package need not call Handshake |
| // explicitly: the first Read or Write will call it automatically. |
| func (c *Conn) Handshake() error { |
| c.handshakeMutex.Lock() |
| defer c.handshakeMutex.Unlock() |
| if err := c.handshakeErr; err != nil { |
| return err |
| } |
| if c.handshakeComplete { |
| return nil |
| } |
| |
| if c.isDTLS && c.config.Bugs.SendSplitAlert { |
| c.conn.Write([]byte{ |
| byte(recordTypeAlert), // type |
| 0xfe, 0xff, // version |
| 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, // sequence |
| 0x0, 0x2, // length |
| }) |
| c.conn.Write([]byte{alertLevelError, byte(alertInternalError)}) |
| } |
| if c.isClient { |
| c.handshakeErr = c.clientHandshake() |
| } else { |
| c.handshakeErr = c.serverHandshake() |
| } |
| if c.handshakeErr == nil && c.config.Bugs.SendInvalidRecordType { |
| c.writeRecord(recordType(42), []byte("invalid record")) |
| } |
| return c.handshakeErr |
| } |
| |
| // ConnectionState returns basic TLS details about the connection. |
| func (c *Conn) ConnectionState() ConnectionState { |
| c.handshakeMutex.Lock() |
| defer c.handshakeMutex.Unlock() |
| |
| var state ConnectionState |
| state.HandshakeComplete = c.handshakeComplete |
| if c.handshakeComplete { |
| state.Version = c.vers |
| state.NegotiatedProtocol = c.clientProtocol |
| state.DidResume = c.didResume |
| state.NegotiatedProtocolIsMutual = !c.clientProtocolFallback |
| state.NegotiatedProtocolFromALPN = c.usedALPN |
| state.CipherSuite = c.cipherSuite.id |
| state.PeerCertificates = c.peerCertificates |
| state.VerifiedChains = c.verifiedChains |
| state.ServerName = c.serverName |
| state.ChannelID = c.channelID |
| state.SRTPProtectionProfile = c.srtpProtectionProfile |
| state.TLSUnique = c.firstFinished[:] |
| } |
| |
| return state |
| } |
| |
| // OCSPResponse returns the stapled OCSP response from the TLS server, if |
| // any. (Only valid for client connections.) |
| func (c *Conn) OCSPResponse() []byte { |
| c.handshakeMutex.Lock() |
| defer c.handshakeMutex.Unlock() |
| |
| return c.ocspResponse |
| } |
| |
| // VerifyHostname checks that the peer certificate chain is valid for |
| // connecting to host. If so, it returns nil; if not, it returns an error |
| // describing the problem. |
| func (c *Conn) VerifyHostname(host string) error { |
| c.handshakeMutex.Lock() |
| defer c.handshakeMutex.Unlock() |
| if !c.isClient { |
| return errors.New("tls: VerifyHostname called on TLS server connection") |
| } |
| if !c.handshakeComplete { |
| return errors.New("tls: handshake has not yet been performed") |
| } |
| return c.peerCertificates[0].VerifyHostname(host) |
| } |
| |
| // ExportKeyingMaterial exports keying material from the current connection |
| // state, as per RFC 5705. |
| func (c *Conn) ExportKeyingMaterial(length int, label, context []byte, useContext bool) ([]byte, error) { |
| c.handshakeMutex.Lock() |
| defer c.handshakeMutex.Unlock() |
| if !c.handshakeComplete { |
| return nil, errors.New("tls: handshake has not yet been performed") |
| } |
| |
| seedLen := len(c.clientRandom) + len(c.serverRandom) |
| if useContext { |
| seedLen += 2 + len(context) |
| } |
| seed := make([]byte, 0, seedLen) |
| seed = append(seed, c.clientRandom[:]...) |
| seed = append(seed, c.serverRandom[:]...) |
| if useContext { |
| seed = append(seed, byte(len(context)>>8), byte(len(context))) |
| seed = append(seed, context...) |
| } |
| result := make([]byte, length) |
| prfForVersion(c.vers, c.cipherSuite)(result, c.masterSecret[:], label, seed) |
| return result, nil |
| } |