diff options
author | Dimitri Sokolyuk <demon@dim13.org> | 2018-02-13 01:17:35 +0100 |
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committer | Dimitri Sokolyuk <demon@dim13.org> | 2018-02-13 01:17:35 +0100 |
commit | c32d9bf24c3b670c3a56ea55aeefb6232f3d4ec8 (patch) | |
tree | f9891ff5b851d40c2f48c8e73e36e32197bfcc89 /vendor/golang.org/x/crypto/ssh/handshake.go | |
parent | 886201867ac7383535c08d81dbabc6c9c77fe855 (diff) |
switch to subcommands
Diffstat (limited to 'vendor/golang.org/x/crypto/ssh/handshake.go')
-rw-r--r-- | vendor/golang.org/x/crypto/ssh/handshake.go | 640 |
1 files changed, 0 insertions, 640 deletions
diff --git a/vendor/golang.org/x/crypto/ssh/handshake.go b/vendor/golang.org/x/crypto/ssh/handshake.go deleted file mode 100644 index 932ce83..0000000 --- a/vendor/golang.org/x/crypto/ssh/handshake.go +++ /dev/null @@ -1,640 +0,0 @@ -// Copyright 2013 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 ssh - -import ( - "crypto/rand" - "errors" - "fmt" - "io" - "log" - "net" - "sync" -) - -// debugHandshake, if set, prints messages sent and received. Key -// exchange messages are printed as if DH were used, so the debug -// messages are wrong when using ECDH. -const debugHandshake = false - -// chanSize sets the amount of buffering SSH connections. This is -// primarily for testing: setting chanSize=0 uncovers deadlocks more -// quickly. -const chanSize = 16 - -// keyingTransport is a packet based transport that supports key -// changes. It need not be thread-safe. It should pass through -// msgNewKeys in both directions. -type keyingTransport interface { - packetConn - - // prepareKeyChange sets up a key change. The key change for a - // direction will be effected if a msgNewKeys message is sent - // or received. - prepareKeyChange(*algorithms, *kexResult) error -} - -// handshakeTransport implements rekeying on top of a keyingTransport -// and offers a thread-safe writePacket() interface. -type handshakeTransport struct { - conn keyingTransport - config *Config - - serverVersion []byte - clientVersion []byte - - // hostKeys is non-empty if we are the server. In that case, - // it contains all host keys that can be used to sign the - // connection. - hostKeys []Signer - - // hostKeyAlgorithms is non-empty if we are the client. In that case, - // we accept these key types from the server as host key. - hostKeyAlgorithms []string - - // On read error, incoming is closed, and readError is set. - incoming chan []byte - readError error - - mu sync.Mutex - writeError error - sentInitPacket []byte - sentInitMsg *kexInitMsg - pendingPackets [][]byte // Used when a key exchange is in progress. - - // If the read loop wants to schedule a kex, it pings this - // channel, and the write loop will send out a kex - // message. - requestKex chan struct{} - - // If the other side requests or confirms a kex, its kexInit - // packet is sent here for the write loop to find it. - startKex chan *pendingKex - - // data for host key checking - hostKeyCallback HostKeyCallback - dialAddress string - remoteAddr net.Addr - - // Algorithms agreed in the last key exchange. - algorithms *algorithms - - readPacketsLeft uint32 - readBytesLeft int64 - - writePacketsLeft uint32 - writeBytesLeft int64 - - // The session ID or nil if first kex did not complete yet. - sessionID []byte -} - -type pendingKex struct { - otherInit []byte - done chan error -} - -func newHandshakeTransport(conn keyingTransport, config *Config, clientVersion, serverVersion []byte) *handshakeTransport { - t := &handshakeTransport{ - conn: conn, - serverVersion: serverVersion, - clientVersion: clientVersion, - incoming: make(chan []byte, chanSize), - requestKex: make(chan struct{}, 1), - startKex: make(chan *pendingKex, 1), - - config: config, - } - t.resetReadThresholds() - t.resetWriteThresholds() - - // We always start with a mandatory key exchange. - t.requestKex <- struct{}{} - return t -} - -func newClientTransport(conn keyingTransport, clientVersion, serverVersion []byte, config *ClientConfig, dialAddr string, addr net.Addr) *handshakeTransport { - t := newHandshakeTransport(conn, &config.Config, clientVersion, serverVersion) - t.dialAddress = dialAddr - t.remoteAddr = addr - t.hostKeyCallback = config.HostKeyCallback - if config.HostKeyAlgorithms != nil { - t.hostKeyAlgorithms = config.HostKeyAlgorithms - } else { - t.hostKeyAlgorithms = supportedHostKeyAlgos - } - go t.readLoop() - go t.kexLoop() - return t -} - -func newServerTransport(conn keyingTransport, clientVersion, serverVersion []byte, config *ServerConfig) *handshakeTransport { - t := newHandshakeTransport(conn, &config.Config, clientVersion, serverVersion) - t.hostKeys = config.hostKeys - go t.readLoop() - go t.kexLoop() - return t -} - -func (t *handshakeTransport) getSessionID() []byte { - return t.sessionID -} - -// waitSession waits for the session to be established. This should be -// the first thing to call after instantiating handshakeTransport. -func (t *handshakeTransport) waitSession() error { - p, err := t.readPacket() - if err != nil { - return err - } - if p[0] != msgNewKeys { - return fmt.Errorf("ssh: first packet should be msgNewKeys") - } - - return nil -} - -func (t *handshakeTransport) id() string { - if len(t.hostKeys) > 0 { - return "server" - } - return "client" -} - -func (t *handshakeTransport) printPacket(p []byte, write bool) { - action := "got" - if write { - action = "sent" - } - - if p[0] == msgChannelData || p[0] == msgChannelExtendedData { - log.Printf("%s %s data (packet %d bytes)", t.id(), action, len(p)) - } else { - msg, err := decode(p) - log.Printf("%s %s %T %v (%v)", t.id(), action, msg, msg, err) - } -} - -func (t *handshakeTransport) readPacket() ([]byte, error) { - p, ok := <-t.incoming - if !ok { - return nil, t.readError - } - return p, nil -} - -func (t *handshakeTransport) readLoop() { - first := true - for { - p, err := t.readOnePacket(first) - first = false - if err != nil { - t.readError = err - close(t.incoming) - break - } - if p[0] == msgIgnore || p[0] == msgDebug { - continue - } - t.incoming <- p - } - - // Stop writers too. - t.recordWriteError(t.readError) - - // Unblock the writer should it wait for this. - close(t.startKex) - - // Don't close t.requestKex; it's also written to from writePacket. -} - -func (t *handshakeTransport) pushPacket(p []byte) error { - if debugHandshake { - t.printPacket(p, true) - } - return t.conn.writePacket(p) -} - -func (t *handshakeTransport) getWriteError() error { - t.mu.Lock() - defer t.mu.Unlock() - return t.writeError -} - -func (t *handshakeTransport) recordWriteError(err error) { - t.mu.Lock() - defer t.mu.Unlock() - if t.writeError == nil && err != nil { - t.writeError = err - } -} - -func (t *handshakeTransport) requestKeyExchange() { - select { - case t.requestKex <- struct{}{}: - default: - // something already requested a kex, so do nothing. - } -} - -func (t *handshakeTransport) resetWriteThresholds() { - t.writePacketsLeft = packetRekeyThreshold - if t.config.RekeyThreshold > 0 { - t.writeBytesLeft = int64(t.config.RekeyThreshold) - } else if t.algorithms != nil { - t.writeBytesLeft = t.algorithms.w.rekeyBytes() - } else { - t.writeBytesLeft = 1 << 30 - } -} - -func (t *handshakeTransport) kexLoop() { - -write: - for t.getWriteError() == nil { - var request *pendingKex - var sent bool - - for request == nil || !sent { - var ok bool - select { - case request, ok = <-t.startKex: - if !ok { - break write - } - case <-t.requestKex: - break - } - - if !sent { - if err := t.sendKexInit(); err != nil { - t.recordWriteError(err) - break - } - sent = true - } - } - - if err := t.getWriteError(); err != nil { - if request != nil { - request.done <- err - } - break - } - - // We're not servicing t.requestKex, but that is OK: - // we never block on sending to t.requestKex. - - // We're not servicing t.startKex, but the remote end - // has just sent us a kexInitMsg, so it can't send - // another key change request, until we close the done - // channel on the pendingKex request. - - err := t.enterKeyExchange(request.otherInit) - - t.mu.Lock() - t.writeError = err - t.sentInitPacket = nil - t.sentInitMsg = nil - - t.resetWriteThresholds() - - // we have completed the key exchange. Since the - // reader is still blocked, it is safe to clear out - // the requestKex channel. This avoids the situation - // where: 1) we consumed our own request for the - // initial kex, and 2) the kex from the remote side - // caused another send on the requestKex channel, - clear: - for { - select { - case <-t.requestKex: - // - default: - break clear - } - } - - request.done <- t.writeError - - // kex finished. Push packets that we received while - // the kex was in progress. Don't look at t.startKex - // and don't increment writtenSinceKex: if we trigger - // another kex while we are still busy with the last - // one, things will become very confusing. - for _, p := range t.pendingPackets { - t.writeError = t.pushPacket(p) - if t.writeError != nil { - break - } - } - t.pendingPackets = t.pendingPackets[:0] - t.mu.Unlock() - } - - // drain startKex channel. We don't service t.requestKex - // because nobody does blocking sends there. - go func() { - for init := range t.startKex { - init.done <- t.writeError - } - }() - - // Unblock reader. - t.conn.Close() -} - -// The protocol uses uint32 for packet counters, so we can't let them -// reach 1<<32. We will actually read and write more packets than -// this, though: the other side may send more packets, and after we -// hit this limit on writing we will send a few more packets for the -// key exchange itself. -const packetRekeyThreshold = (1 << 31) - -func (t *handshakeTransport) resetReadThresholds() { - t.readPacketsLeft = packetRekeyThreshold - if t.config.RekeyThreshold > 0 { - t.readBytesLeft = int64(t.config.RekeyThreshold) - } else if t.algorithms != nil { - t.readBytesLeft = t.algorithms.r.rekeyBytes() - } else { - t.readBytesLeft = 1 << 30 - } -} - -func (t *handshakeTransport) readOnePacket(first bool) ([]byte, error) { - p, err := t.conn.readPacket() - if err != nil { - return nil, err - } - - if t.readPacketsLeft > 0 { - t.readPacketsLeft-- - } else { - t.requestKeyExchange() - } - - if t.readBytesLeft > 0 { - t.readBytesLeft -= int64(len(p)) - } else { - t.requestKeyExchange() - } - - if debugHandshake { - t.printPacket(p, false) - } - - if first && p[0] != msgKexInit { - return nil, fmt.Errorf("ssh: first packet should be msgKexInit") - } - - if p[0] != msgKexInit { - return p, nil - } - - firstKex := t.sessionID == nil - - kex := pendingKex{ - done: make(chan error, 1), - otherInit: p, - } - t.startKex <- &kex - err = <-kex.done - - if debugHandshake { - log.Printf("%s exited key exchange (first %v), err %v", t.id(), firstKex, err) - } - - if err != nil { - return nil, err - } - - t.resetReadThresholds() - - // By default, a key exchange is hidden from higher layers by - // translating it into msgIgnore. - successPacket := []byte{msgIgnore} - if firstKex { - // sendKexInit() for the first kex waits for - // msgNewKeys so the authentication process is - // guaranteed to happen over an encrypted transport. - successPacket = []byte{msgNewKeys} - } - - return successPacket, nil -} - -// sendKexInit sends a key change message. -func (t *handshakeTransport) sendKexInit() error { - t.mu.Lock() - defer t.mu.Unlock() - if t.sentInitMsg != nil { - // kexInits may be sent either in response to the other side, - // or because our side wants to initiate a key change, so we - // may have already sent a kexInit. In that case, don't send a - // second kexInit. - return nil - } - - msg := &kexInitMsg{ - KexAlgos: t.config.KeyExchanges, - CiphersClientServer: t.config.Ciphers, - CiphersServerClient: t.config.Ciphers, - MACsClientServer: t.config.MACs, - MACsServerClient: t.config.MACs, - CompressionClientServer: supportedCompressions, - CompressionServerClient: supportedCompressions, - } - io.ReadFull(rand.Reader, msg.Cookie[:]) - - if len(t.hostKeys) > 0 { - for _, k := range t.hostKeys { - msg.ServerHostKeyAlgos = append( - msg.ServerHostKeyAlgos, k.PublicKey().Type()) - } - } else { - msg.ServerHostKeyAlgos = t.hostKeyAlgorithms - } - packet := Marshal(msg) - - // writePacket destroys the contents, so save a copy. - packetCopy := make([]byte, len(packet)) - copy(packetCopy, packet) - - if err := t.pushPacket(packetCopy); err != nil { - return err - } - - t.sentInitMsg = msg - t.sentInitPacket = packet - - return nil -} - -func (t *handshakeTransport) writePacket(p []byte) error { - switch p[0] { - case msgKexInit: - return errors.New("ssh: only handshakeTransport can send kexInit") - case msgNewKeys: - return errors.New("ssh: only handshakeTransport can send newKeys") - } - - t.mu.Lock() - defer t.mu.Unlock() - if t.writeError != nil { - return t.writeError - } - - if t.sentInitMsg != nil { - // Copy the packet so the writer can reuse the buffer. - cp := make([]byte, len(p)) - copy(cp, p) - t.pendingPackets = append(t.pendingPackets, cp) - return nil - } - - if t.writeBytesLeft > 0 { - t.writeBytesLeft -= int64(len(p)) - } else { - t.requestKeyExchange() - } - - if t.writePacketsLeft > 0 { - t.writePacketsLeft-- - } else { - t.requestKeyExchange() - } - - if err := t.pushPacket(p); err != nil { - t.writeError = err - } - - return nil -} - -func (t *handshakeTransport) Close() error { - return t.conn.Close() -} - -func (t *handshakeTransport) enterKeyExchange(otherInitPacket []byte) error { - if debugHandshake { - log.Printf("%s entered key exchange", t.id()) - } - - otherInit := &kexInitMsg{} - if err := Unmarshal(otherInitPacket, otherInit); err != nil { - return err - } - - magics := handshakeMagics{ - clientVersion: t.clientVersion, - serverVersion: t.serverVersion, - clientKexInit: otherInitPacket, - serverKexInit: t.sentInitPacket, - } - - clientInit := otherInit - serverInit := t.sentInitMsg - if len(t.hostKeys) == 0 { - clientInit, serverInit = serverInit, clientInit - - magics.clientKexInit = t.sentInitPacket - magics.serverKexInit = otherInitPacket - } - - var err error - t.algorithms, err = findAgreedAlgorithms(clientInit, serverInit) - if err != nil { - return err - } - - // We don't send FirstKexFollows, but we handle receiving it. - // - // RFC 4253 section 7 defines the kex and the agreement method for - // first_kex_packet_follows. It states that the guessed packet - // should be ignored if the "kex algorithm and/or the host - // key algorithm is guessed wrong (server and client have - // different preferred algorithm), or if any of the other - // algorithms cannot be agreed upon". The other algorithms have - // already been checked above so the kex algorithm and host key - // algorithm are checked here. - if otherInit.FirstKexFollows && (clientInit.KexAlgos[0] != serverInit.KexAlgos[0] || clientInit.ServerHostKeyAlgos[0] != serverInit.ServerHostKeyAlgos[0]) { - // other side sent a kex message for the wrong algorithm, - // which we have to ignore. - if _, err := t.conn.readPacket(); err != nil { - return err - } - } - - kex, ok := kexAlgoMap[t.algorithms.kex] - if !ok { - return fmt.Errorf("ssh: unexpected key exchange algorithm %v", t.algorithms.kex) - } - - var result *kexResult - if len(t.hostKeys) > 0 { - result, err = t.server(kex, t.algorithms, &magics) - } else { - result, err = t.client(kex, t.algorithms, &magics) - } - - if err != nil { - return err - } - - if t.sessionID == nil { - t.sessionID = result.H - } - result.SessionID = t.sessionID - - if err := t.conn.prepareKeyChange(t.algorithms, result); err != nil { - return err - } - if err = t.conn.writePacket([]byte{msgNewKeys}); err != nil { - return err - } - if packet, err := t.conn.readPacket(); err != nil { - return err - } else if packet[0] != msgNewKeys { - return unexpectedMessageError(msgNewKeys, packet[0]) - } - - return nil -} - -func (t *handshakeTransport) server(kex kexAlgorithm, algs *algorithms, magics *handshakeMagics) (*kexResult, error) { - var hostKey Signer - for _, k := range t.hostKeys { - if algs.hostKey == k.PublicKey().Type() { - hostKey = k - } - } - - r, err := kex.Server(t.conn, t.config.Rand, magics, hostKey) - return r, err -} - -func (t *handshakeTransport) client(kex kexAlgorithm, algs *algorithms, magics *handshakeMagics) (*kexResult, error) { - result, err := kex.Client(t.conn, t.config.Rand, magics) - if err != nil { - return nil, err - } - - hostKey, err := ParsePublicKey(result.HostKey) - if err != nil { - return nil, err - } - - if err := verifyHostKeySignature(hostKey, result); err != nil { - return nil, err - } - - err = t.hostKeyCallback(t.dialAddress, t.remoteAddr, hostKey) - if err != nil { - return nil, err - } - - return result, nil -} |