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client.js
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// TODO: emit error when connection severed early (e.g. before handshake)
// TODO: add '.connected' or similar property to allow immediate connection
// status checking
'use strict';
const {
createHash,
getHashes,
randomFillSync,
} = require('crypto');
const { Socket } = require('net');
const { lookup: dnsLookup } = require('dns');
const EventEmitter = require('events');
const HASHES = getHashes();
const {
COMPAT,
CHANNEL_EXTENDED_DATATYPE: { STDERR },
CHANNEL_OPEN_FAILURE,
DEFAULT_CIPHER,
DEFAULT_COMPRESSION,
DEFAULT_KEX,
DEFAULT_MAC,
DEFAULT_SERVER_HOST_KEY,
DISCONNECT_REASON,
DISCONNECT_REASON_BY_VALUE,
EDDSA_SUPPORTED,
SUPPORTED_CIPHER,
SUPPORTED_COMPRESSION,
SUPPORTED_KEX,
SUPPORTED_MAC,
SUPPORTED_SERVER_HOST_KEY,
} = require('./protocol/constants.js');
const Protocol = require('./protocol/Protocol.js');
const { parseKey } = require('./protocol/keyParser.js');
const { SFTP } = require('./protocol/SFTP.js');
const { makeError, readUInt32BE } = require('./protocol/utils.js');
const agentQuery = require('./agent.js');
const {
Channel,
MAX_WINDOW,
PACKET_SIZE,
windowAdjust,
WINDOW_THRESHOLD,
} = require('./Channel.js');
const {
ChannelManager,
generateAlgorithmList,
isWritable,
onChannelOpenFailure,
onCHANNEL_CLOSE,
} = require('./utils.js');
const RE_OPENSSH = /^OpenSSH_(?:(?![0-4])\d)|(?:\d{2,})/;
const noop = (err) => {};
class Client extends EventEmitter {
constructor() {
super();
this.config = {
host: undefined,
port: undefined,
localAddress: undefined,
localPort: undefined,
forceIPv4: undefined,
forceIPv6: undefined,
keepaliveCountMax: undefined,
keepaliveInterval: undefined,
readyTimeout: undefined,
ident: undefined,
username: undefined,
password: undefined,
privateKey: undefined,
tryKeyboard: undefined,
agent: undefined,
allowAgentFwd: undefined,
authHandler: undefined,
hostHashAlgo: undefined,
hostHashCb: undefined,
strictVendor: undefined,
debug: undefined
};
this._readyTimeout = undefined;
this._chanMgr = undefined;
this._callbacks = undefined;
this._forwarding = undefined;
this._forwardingUnix = undefined;
this._acceptX11 = undefined;
this._agentFwdEnabled = undefined;
this._remoteVer = undefined;
this._protocol = undefined;
this._sock = undefined;
this._resetKA = undefined;
}
connect(cfg) {
if (this._sock && isWritable(this._sock)) {
this.once('close', () => {
this.connect(cfg);
});
this.end();
return this;
}
this.config.host = cfg.hostname || cfg.host || 'localhost';
this.config.port = cfg.port || 22;
this.config.localAddress = (typeof cfg.localAddress === 'string'
? cfg.localAddress
: undefined);
this.config.localPort = (typeof cfg.localPort === 'string'
|| typeof cfg.localPort === 'number'
? cfg.localPort
: undefined);
this.config.forceIPv4 = cfg.forceIPv4 || false;
this.config.forceIPv6 = cfg.forceIPv6 || false;
this.config.keepaliveCountMax = (typeof cfg.keepaliveCountMax === 'number'
&& cfg.keepaliveCountMax >= 0
? cfg.keepaliveCountMax
: 3);
this.config.keepaliveInterval = (typeof cfg.keepaliveInterval === 'number'
&& cfg.keepaliveInterval > 0
? cfg.keepaliveInterval
: 0);
this.config.readyTimeout = (typeof cfg.readyTimeout === 'number'
&& cfg.readyTimeout >= 0
? cfg.readyTimeout
: 20000);
this.config.ident = (typeof cfg.ident === 'string'
|| Buffer.isBuffer(cfg.ident)
? cfg.ident
: undefined);
const algorithms = {
kex: undefined,
serverHostKey: undefined,
cs: {
cipher: undefined,
mac: undefined,
compress: undefined,
lang: [],
},
sc: undefined,
};
let allOfferDefaults = true;
if (typeof cfg.algorithms === 'object' && cfg.algorithms !== null) {
algorithms.kex = generateAlgorithmList(cfg.algorithms.kex,
DEFAULT_KEX,
SUPPORTED_KEX);
if (algorithms.kex !== DEFAULT_KEX)
allOfferDefaults = false;
algorithms.serverHostKey =
generateAlgorithmList(cfg.algorithms.serverHostKey,
DEFAULT_SERVER_HOST_KEY,
SUPPORTED_SERVER_HOST_KEY);
if (algorithms.serverHostKey !== DEFAULT_SERVER_HOST_KEY)
allOfferDefaults = false;
algorithms.cs.cipher = generateAlgorithmList(cfg.algorithms.cipher,
DEFAULT_CIPHER,
SUPPORTED_CIPHER);
if (algorithms.cs.cipher !== DEFAULT_CIPHER)
allOfferDefaults = false;
algorithms.cs.mac = generateAlgorithmList(cfg.algorithms.hmac,
DEFAULT_MAC,
SUPPORTED_MAC);
if (algorithms.cs.mac !== DEFAULT_MAC)
allOfferDefaults = false;
algorithms.cs.compress = generateAlgorithmList(cfg.algorithms.compress,
DEFAULT_COMPRESSION,
SUPPORTED_COMPRESSION);
if (algorithms.cs.compress !== DEFAULT_COMPRESSION)
allOfferDefaults = false;
if (!allOfferDefaults)
algorithms.sc = algorithms.cs;
}
if (typeof cfg.username === 'string')
this.config.username = cfg.username;
else if (typeof cfg.user === 'string')
this.config.username = cfg.user;
else
throw new Error('Invalid username');
this.config.password = (typeof cfg.password === 'string'
? cfg.password
: undefined);
this.config.privateKey = (typeof cfg.privateKey === 'string'
|| Buffer.isBuffer(cfg.privateKey)
? cfg.privateKey
: undefined);
this.config.localHostname = (typeof cfg.localHostname === 'string'
&& cfg.localHostname.length
? cfg.localHostname
: undefined);
this.config.localUsername = (typeof cfg.localUsername === 'string'
&& cfg.localUsername.length
? cfg.localUsername
: undefined);
this.config.tryKeyboard = (cfg.tryKeyboard === true);
this.config.agent = (typeof cfg.agent === 'string' && cfg.agent.length
? cfg.agent
: undefined);
this.config.allowAgentFwd = (cfg.agentForward === true
&& this.config.agent !== undefined);
let authHandler = this.config.authHandler = (
typeof cfg.authHandler === 'function' ? cfg.authHandler : undefined
);
this.config.strictVendor = (typeof cfg.strictVendor === 'boolean'
? cfg.strictVendor
: true);
const debug = this.config.debug = (typeof cfg.debug === 'function'
? cfg.debug
: undefined);
if (cfg.agentForward === true && !this.config.allowAgentFwd) {
throw new Error(
'You must set a valid agent path to allow agent forwarding'
);
}
let callbacks = this._callbacks = [];
this._chanMgr = new ChannelManager(this);
this._forwarding = {};
this._forwardingUnix = {};
this._acceptX11 = 0;
this._agentFwdEnabled = false;
this._remoteVer = undefined;
let privateKey;
if (this.config.privateKey) {
privateKey = parseKey(this.config.privateKey, cfg.passphrase);
if (privateKey instanceof Error)
throw new Error(`Cannot parse privateKey: ${privateKey.message}`);
if (Array.isArray(privateKey)) {
// OpenSSH's newer format only stores 1 key for now
privateKey = privateKey[0];
}
if (privateKey.getPrivatePEM() === null) {
throw new Error(
'privateKey value does not contain a (valid) private key'
);
}
}
let hostVerifier;
if (typeof cfg.hostVerifier === 'function') {
const hashCb = cfg.hostVerifier;
let hasher;
if (HASHES.indexOf(cfg.hostHash) !== -1) {
// Default to old behavior of hashing on user's behalf
hasher = createHash(cfg.hostHash);
}
hostVerifier = (key, verify) => {
if (hasher) {
hasher.update(key);
key = hasher.digest('hex');
}
const ret = hashCb(key, verify);
if (ret !== undefined)
verify(ret);
};
}
const sock = this._sock = (cfg.sock || new Socket());
let ready = false;
let sawHeader = false;
if (this._protocol)
this._protocol.cleanup();
const DEBUG_HANDLER = (!debug ? undefined : (p, display, msg) => {
debug(`Debug output from server: ${JSON.stringify(msg)}`);
});
const proto = this._protocol = new Protocol({
ident: this.config.ident,
offer: (allOfferDefaults ? undefined : algorithms),
onWrite: (data) => {
if (isWritable(sock))
sock.write(data);
},
onError: (err) => {
if (err.level === 'handshake')
clearTimeout(this._readyTimeout);
if (!proto._destruct)
sock.removeAllListeners('data');
this.emit('error', err);
try {
sock.end();
} catch {}
},
onHeader: (header) => {
sawHeader = true;
this._remoteVer = header.versions.software;
if (header.greeting)
this.emit('greeting', header.greeting);
},
onHandshakeComplete: (negotiated) => {
this.emit('handshake', negotiated);
if (!ready) {
ready = true;
proto.service('ssh-userauth');
}
},
debug,
hostVerifier,
messageHandlers: {
DEBUG: DEBUG_HANDLER,
DISCONNECT: (p, reason, desc) => {
if (reason !== DISCONNECT_REASON.BY_APPLICATION) {
if (!desc) {
desc = DISCONNECT_REASON_BY_VALUE[reason];
if (desc === undefined)
desc = `Unexpected disconnection reason: ${reason}`;
}
const err = new Error(desc);
err.code = reason;
this.emit('error', err);
}
sock.end();
},
SERVICE_ACCEPT: (p, name) => {
if (name === 'ssh-userauth')
tryNextAuth();
},
USERAUTH_BANNER: (p, msg) => {
this.emit('banner', msg);
},
USERAUTH_SUCCESS: (p) => {
// Start keepalive mechanism
resetKA();
clearTimeout(this._readyTimeout);
this.emit('ready');
},
USERAUTH_FAILURE: (p, authMethods, partialSuccess) => {
if (curAuth === 'agent') {
debug && debug(`Client: Agent key #${agentKeyPos + 1} failed`);
return tryNextAgentKey();
}
debug && debug(`Client: ${curAuth} auth failed`);
curPartial = partialSuccess;
curAuthsLeft = authMethods;
tryNextAuth();
},
USERAUTH_PASSWD_CHANGEREQ: (p, prompt) => {
if (curAuth === 'password') {
this.emit('change password', prompt, (newPassword) => {
proto.authPassword(
this.config.username,
this.config.password,
newPassword
);
});
}
},
USERAUTH_PK_OK: (p) => {
if (curAuth === 'agent') {
const agentKey = agentKeys[agentKeyPos];
const keyLen = readUInt32BE(agentKey, 0);
const pubKeyFullType = agentKey.utf8Slice(4, 4 + keyLen);
const pubKeyType = pubKeyFullType.slice(4);
// Check that we support the key type first
// TODO: move key type checking logic to protocol implementation
switch (pubKeyFullType) {
case 'ssh-rsa':
case 'ssh-dss':
case 'ecdsa-sha2-nistp256':
case 'ecdsa-sha2-nistp384':
case 'ecdsa-sha2-nistp521':
break;
case 'ssh-ed25519':
if (EDDSA_SUPPORTED)
break;
// FALLTHROUGH
default:
debug && debug(
`Agent: Skipping unsupported key type: ${pubKeyFullType}`
);
return tryNextAgentKey();
}
proto.authPK(this.config.username, agentKey, (buf, cb) => {
agentQuery(this.config.agent,
agentKey,
pubKeyType,
buf,
(err, signed) => {
if (err) {
err.level = 'agent';
this.emit('error', err);
} else {
const sigFullTypeLen = readUInt32BE(signed, 0);
if (4 + sigFullTypeLen + 4 < signed.length) {
const sigFullType = signed.utf8Slice(4, 4 + sigFullTypeLen);
if (sigFullType !== pubKeyFullType) {
err = new Error('Agent key/signature type mismatch');
err.level = 'agent';
this.emit('error', err);
} else {
// Skip algoLen + algo + sigLen
return cb(signed.slice(4 + sigFullTypeLen + 4));
}
}
}
tryNextAgentKey();
});
});
} else if (curAuth === 'publickey') {
proto.authPK(this.config.username, privateKey, (buf, cb) => {
const signature = privateKey.sign(buf);
if (signature instanceof Error) {
signature.message =
`Error signing data with privateKey: ${signature.message}`;
signature.level = 'client-authentication';
this.emit('error', signature);
return tryNextAuth();
}
cb(signature);
});
}
},
USERAUTH_INFO_REQUEST: (p, name, instructions, prompts) => {
const nprompts = (Array.isArray(prompts) ? prompts.length : 0);
if (nprompts === 0) {
debug && debug('Client: Sending automatic USERAUTH_INFO_RESPONSE');
proto.authInfoRes();
return;
}
// We sent a keyboard-interactive user authentication request and now
// the server is sending us the prompts we need to present to the user
this.emit('keyboard-interactive',
name,
instructions,
'',
prompts,
(answers) => {
proto.authInfoRes(answers);
}
);
},
REQUEST_SUCCESS: (p, data) => {
if (callbacks.length)
callbacks.shift()(false, data);
},
REQUEST_FAILURE: (p) => {
if (callbacks.length)
callbacks.shift()(true);
},
GLOBAL_REQUEST: (name, wantReply, data) => {
// Auto-reject all global requests, this can be especially useful if
// the server is sending us dummy keepalive global requests
if (wantReply)
proto.requestFailure();
},
CHANNEL_OPEN: (p, info) => {
// Handle incoming requests from server, typically a forwarded TCP or
// X11 connection
onCHANNEL_OPEN(this, info);
},
CHANNEL_OPEN_CONFIRMATION: (p, info) => {
const channel = this._chanMgr.get(info.recipient);
if (typeof channel !== 'function')
return;
const isSFTP = (channel.type === 'sftp');
const type = (isSFTP ? 'session' : channel.type);
const chanInfo = {
type,
incoming: {
id: info.recipient,
window: MAX_WINDOW,
packetSize: PACKET_SIZE,
state: 'open'
},
outgoing: {
id: info.sender,
window: info.window,
packetSize: info.packetSize,
state: 'open'
}
};
const instance = (
isSFTP
? new SFTP(this, chanInfo, { debug })
: new Channel(this, chanInfo)
);
this._chanMgr.update(info.recipient, instance);
channel(undefined, instance);
},
CHANNEL_OPEN_FAILURE: (p, recipient, reason, description) => {
const channel = this._chanMgr.get(recipient);
if (typeof channel !== 'function')
return;
const info = { reason, description };
onChannelOpenFailure(this, recipient, info, channel);
},
CHANNEL_DATA: (p, recipient, data) => {
const channel = this._chanMgr.get(recipient);
if (typeof channel !== 'object' || channel === null)
return;
// The remote party should not be sending us data if there is no
// window space available ...
// TODO: raise error on data with not enough window?
if (channel.incoming.window === 0)
return;
channel.incoming.window -= data.length;
if (channel.push(data) === false) {
channel._waitChanDrain = true;
return;
}
if (channel.incoming.window <= WINDOW_THRESHOLD)
windowAdjust(channel);
},
CHANNEL_EXTENDED_DATA: (p, recipient, data, type) => {
if (type !== STDERR)
return;
const channel = this._chanMgr.get(recipient);
if (typeof channel !== 'object' || channel === null)
return;
// The remote party should not be sending us data if there is no
// window space available ...
// TODO: raise error on data with not enough window?
if (channel.incoming.window === 0)
return;
channel.incoming.window -= data.length;
if (!channel.stderr.push(data)) {
channel._waitChanDrain = true;
return;
}
if (channel.incoming.window <= WINDOW_THRESHOLD)
windowAdjust(channel);
},
CHANNEL_WINDOW_ADJUST: (p, recipient, amount) => {
const channel = this._chanMgr.get(recipient);
if (typeof channel !== 'object' || channel === null)
return;
// The other side is allowing us to send `amount` more bytes of data
channel.outgoing.window += amount;
if (channel._waitWindow) {
channel._waitWindow = false;
if (channel._chunk) {
channel._write(channel._chunk, null, channel._chunkcb);
} else if (channel._chunkcb) {
channel._chunkcb();
} else if (channel._chunkErr) {
channel.stderr._write(channel._chunkErr,
null,
channel._chunkcbErr);
} else if (channel._chunkcbErr) {
channel._chunkcbErr();
}
}
},
CHANNEL_SUCCESS: (p, recipient) => {
const channel = this._chanMgr.get(recipient);
if (typeof channel !== 'object' || channel === null)
return;
this._resetKA();
if (channel._callbacks.length)
channel._callbacks.shift()(false);
},
CHANNEL_FAILURE: (p, recipient) => {
const channel = this._chanMgr.get(recipient);
if (typeof channel !== 'object' || channel === null)
return;
this._resetKA();
if (channel._callbacks.length)
channel._callbacks.shift()(true);
},
CHANNEL_REQUEST: (p, recipient, type, wantReply, data) => {
const channel = this._chanMgr.get(recipient);
if (typeof channel !== 'object' || channel === null)
return;
const exit = channel._exit;
if (exit.code !== undefined)
return;
switch (type) {
case 'exit-status':
channel.emit('exit', exit.code = data);
return;
case 'exit-signal':
channel.emit('exit',
exit.code = null,
exit.signal = `SIG${data.signal}`,
exit.dump = data.coreDumped,
exit.desc = data.errorMessage);
return;
}
// Keepalive request? OpenSSH will send one as a channel request if
// there is a channel open
if (wantReply)
p.channelFailure(channel.outgoing.id);
},
CHANNEL_EOF: (p, recipient) => {
const channel = this._chanMgr.get(recipient);
if (typeof channel !== 'object' || channel === null)
return;
if (channel.incoming.state !== 'open')
return;
channel.incoming.state = 'eof';
if (channel.readable)
channel.push(null);
if (channel.stderr.readable)
channel.stderr.push(null);
},
CHANNEL_CLOSE: (p, recipient) => {
onCHANNEL_CLOSE(this, recipient, this._chanMgr.get(recipient));
},
},
});
sock.on('data', (data) => {
// TODO: wrap in try-catch and emit caught error(s)
try {
proto.parse(data, 0, data.length);
} catch (ex) {
this.emit('error', ex);
try {
if (isWritable(sock))
sock.end();
} catch {}
}
});
// Drain stderr if we are connection hopping using an exec stream
if (sock.stderr && typeof sock.stderr.resume === 'function')
sock.stderr.resume();
// TODO: check keepalive implementation
// Keepalive-related
const kainterval = this.config.keepaliveInterval;
const kacountmax = this.config.keepaliveCountMax;
let kacount = 0;
let katimer;
const sendKA = () => {
if (++kacount > kacountmax) {
clearInterval(katimer);
if (sock.readable) {
const err = new Error('Keepalive timeout');
err.level = 'client-timeout';
this.emit('error', err);
sock.destroy();
}
return;
}
if (isWritable(sock)) {
// Append dummy callback to keep correct callback order
callbacks.push(resetKA);
proto.ping();
} else {
clearInterval(katimer);
}
};
function resetKA() {
if (kainterval > 0) {
kacount = 0;
clearInterval(katimer);
if (isWritable(sock))
katimer = setInterval(sendKA, kainterval);
}
}
this._resetKA = resetKA;
const onDone = (() => {
let called = false;
return () => {
if (called)
return;
called = true;
if (!sawHeader) {
const err =
makeError('Connection lost before handshake', 'protocol', true);
this.emit('error', err);
}
};
})();
sock.on('connect', () => {
debug && debug('Socket connected');
this.emit('connect');
}).on('timeout', () => {
this.emit('timeout');
}).on('error', (err) => {
debug && debug(`Socket error: ${err.message}`);
clearTimeout(this._readyTimeout);
err.level = 'client-socket';
this.emit('error', err);
}).on('end', () => {
debug && debug('Socket ended');
onDone();
proto.cleanup();
clearTimeout(this._readyTimeout);
clearInterval(katimer);
this.emit('end');
}).on('close', () => {
debug && debug('Socket closed');
onDone();
proto.cleanup();
clearTimeout(this._readyTimeout);
clearInterval(katimer);
this.emit('close');
// Notify outstanding channel requests of disconnection ...
const callbacks_ = callbacks;
callbacks = this._callbacks = [];
const err = new Error('No response from server');
for (let i = 0; i < callbacks_.length; ++i)
callbacks_[i](err);
// Simulate error for any channels waiting to be opened
this._chanMgr.cleanup(err);
});
// Begin authentication handling ===========================================
let curAuth;
let curPartial = null;
let curAuthsLeft = null;
let agentKeys;
let agentKeyPos = 0;
const authsAllowed = ['none'];
if (this.config.password !== undefined)
authsAllowed.push('password');
if (privateKey !== undefined)
authsAllowed.push('publickey');
if (this.config.agent !== undefined)
authsAllowed.push('agent');
if (this.config.tryKeyboard)
authsAllowed.push('keyboard-interactive');
if (privateKey !== undefined
&& this.config.localHostname !== undefined
&& this.config.localUsername !== undefined) {
authsAllowed.push('hostbased');
}
if (authHandler === undefined) {
let authPos = 0;
authHandler = (authsLeft, partial, cb) => {
if (authPos === authsAllowed.length)
return false;
return authsAllowed[authPos++];
};
}
let hasSentAuth = false;
const doNextAuth = (authName) => {
hasSentAuth = true;
if (authName === false) {
const err = new Error('All configured authentication methods failed');
err.level = 'client-authentication';
this.emit('error', err);
this.end();
return;
}
if (authsAllowed.indexOf(authName) === -1)
throw new Error(`Authentication method not allowed: ${authName}`);
curAuth = authName;
switch (curAuth) {
case 'password':
proto.authPassword(this.config.username, this.config.password);
break;
case 'publickey':
proto.authPK(this.config.username, privateKey);
break;
case 'hostbased':
function hostbasedCb(buf, cb) {
const signature = privateKey.sign(buf);
if (signature instanceof Error) {
signature.message =
`Error while signing with privateKey: ${signature.message}`;
signature.level = 'client-authentication';
this.emit('error', signature);
return tryNextAuth();
}
cb(signature);
}
proto.authHostbased(this.config.username,
privateKey,
this.config.localHostname,
this.config.localUsername,
hostbasedCb);
break;
case 'agent':
agentQuery(this.config.agent, (err, keys) => {
if (err) {
err.level = 'agent';
this.emit('error', err);
agentKeys = undefined;
return tryNextAuth();
} else if (keys.length === 0) {
debug && debug('Agent: No keys stored in agent');
agentKeys = undefined;
return tryNextAuth();
}
agentKeys = keys;
agentKeyPos = 0;
proto.authPK(this.config.username, keys[0]);
});
break;
case 'keyboard-interactive':
proto.authKeyboard(this.config.username);
break;
case 'none':
proto.authNone(this.config.username);
break;
}
};
function tryNextAuth() {
hasSentAuth = false;
const auth = authHandler(curAuthsLeft, curPartial, doNextAuth);
if (hasSentAuth || auth === undefined)
return;
doNextAuth(auth);
}
const tryNextAgentKey = () => {
if (curAuth === 'agent') {
if (agentKeyPos >= agentKeys.length)
return;
if (++agentKeyPos >= agentKeys.length) {
debug && debug('Agent: No more keys left to try');
debug && debug('Client: agent auth failed');
agentKeys = undefined;
tryNextAuth();
} else {
debug && debug(`Agent: Trying key #${agentKeyPos + 1}`);
proto.authPK(this.config.username, agentKeys[agentKeyPos]);
}
}
};
const startTimeout = () => {
if (this.config.readyTimeout > 0) {
this._readyTimeout = setTimeout(() => {
const err = new Error('Timed out while waiting for handshake');
err.level = 'client-timeout';
this.emit('error', err);
sock.destroy();
}, this.config.readyTimeout);
}
};
if (!cfg.sock) {
let host = this.config.host;
const forceIPv4 = this.config.forceIPv4;
const forceIPv6 = this.config.forceIPv6;
debug && debug(`Client: Trying ${host} on port ${this.config.port} ...`);
const doConnect = () => {
startTimeout();
sock.connect({
host,
port: this.config.port,
localAddress: this.config.localAddress,
localPort: this.config.localPort
});
sock.setNoDelay(true);
sock.setMaxListeners(0);
sock.setTimeout(typeof cfg.timeout === 'number' ? cfg.timeout : 0);
};
if ((!forceIPv4 && !forceIPv6) || (forceIPv4 && forceIPv6)) {
doConnect();
} else {
dnsLookup(host, (forceIPv4 ? 4 : 6), (err, address, family) => {
if (err) {
const type = (forceIPv4 ? 'IPv4' : 'IPv6');
const error = new Error(
`Error while looking up ${type} address for '${host}': ${err}`
);
clearTimeout(this._readyTimeout);
error.level = 'client-dns';
this.emit('error', error);
this.emit('close');
return;
}
host = address;
doConnect();
});
}
} else {
// Custom socket passed in
startTimeout();
}
return this;
}
end() {
if (this._sock && isWritable(this._sock)) {
this._protocol.disconnect(DISCONNECT_REASON.BY_APPLICATION);
this._sock.end();
}
return this;
}
destroy() {
this._sock && isWritable(this._sock) && this._sock.destroy();
return this;
}
exec(cmd, opts, cb) {
if (!this._sock || !isWritable(this._sock))
throw new Error('Not connected');
if (typeof opts === 'function') {
cb = opts;
opts = {};
}
const extraOpts = { allowHalfOpen: (opts.allowHalfOpen !== false) };
openChannel(this, 'session', extraOpts, (err, chan) => {
if (err) {
cb(err);
return;
}
const todo = [];
function reqCb(err) {
if (err) {
chan.close();
cb(err);
return;
}
if (todo.length)
todo.shift()();
}
if (this.config.allowAgentFwd === true
|| (opts
&& opts.agentForward === true
&& this.config.agent !== undefined)) {
todo.push(() => reqAgentFwd(chan, reqCb));
}
if (typeof opts === 'object' && opts !== null) {
if (typeof opts.env === 'object' && opts.env !== null)
reqEnv(chan, opts.env);
if ((typeof opts.pty === 'object' && opts.pty !== null)
|| opts.pty === true) {
todo.push(() => reqPty(chan, opts.pty, reqCb));
}
if ((typeof opts.x11 === 'object' && opts.x11 !== null)
|| opts.x11 === 'number'
|| opts.x11 === true) {
todo.push(() => reqX11(chan, opts.x11, reqCb));
}
}
todo.push(() => reqExec(chan, cmd, opts, cb));
todo.shift()();
});
return this;
}
shell(wndopts, opts, cb) {
if (!this._sock || !isWritable(this._sock))
throw new Error('Not connected');
if (typeof wndopts === 'function') {
cb = wndopts;