: Net::SSH::Transport::Session [Net::SSH: a pure-Ruby implementation of the SSH2 client protocol.]

The transport layer represents the lowest level of the SSH protocol, and implements basic message exchanging and protocol initialization. It will never be instantiated directly (unless you really know what you’re about), but will instead be created for you automatically when you create a new SSH session via Net::SSH.start.

Methods

public class

new

public instance

close
closed?
configure_client
configure_server
enqueue_message
hint
host_as_string
next_message
peer
poll_message
push
rekey!
rekey_as_needed
send_message
service_request
shutdown!
wait

Included modules

Constants

DEFAULT_PORT = 22 The standard port for the SSH protocol.

Attributes

algorithms	[R]	The Algorithms instance used to perform key exchanges.
host	[R]	The host to connect to, as given to the constructor.
host_key_verifier	[R]	The host-key verifier object used to verify host keys, to ensure that the connection is not being spoofed.
options	[R]	The hash of options that were given to the object at initialization.
port	[R]	The port number to connect to, as given in the options to the constructor. If no port number was given, this will default to DEFAULT_PORT.
server_version	[R]	The ServerVersion instance that encapsulates the negotiated protocol version.
socket	[R]	The underlying socket object being used to communicate with the remote host.

Public class methods

new (host, options={})

Instantiates a new transport layer abstraction. This will block until the initial key exchange completes, leaving you with a ready-to-use transport session.

    # File lib/net/ssh/transport/session.rb, line 56
56:     def initialize(host, options={})
57:       self.logger = options[:logger]
58: 
59:       @host = host
60:       @port = options[:port] || DEFAULT_PORT
61:       @options = options
62: 
63:       debug { "establishing connection to #{@host}:#{@port}" }
64:       factory = options[:proxy] || TCPSocket
65:       @socket = timeout(options[:timeout] || 0) { factory.open(@host, @port) }
66:       @socket.extend(PacketStream)
67:       @socket.logger = @logger
68: 
69:       debug { "connection established" }
70: 
71:       @queue = []
72: 
73:       @host_key_verifier = select_host_key_verifier(options[:paranoid])
74: 
75:       @server_version = ServerVersion.new(socket, logger)
76: 
77:       @algorithms = Algorithms.new(self, options)
78:       wait { algorithms.initialized? }
79:     end

Public instance methods

close ()

Cleans up (see PacketStream#cleanup) and closes the underlying socket.

     # File lib/net/ssh/transport/session.rb, line 102
102:     def close
103:       socket.cleanup
104:       socket.close
105:     end

closed? ()

Returns true if the underlying socket has been closed.

    # File lib/net/ssh/transport/session.rb, line 97
97:     def closed?
98:       socket.closed?
99:     end

configure_client (options={})

Configure’s the packet stream’s client state with the given set of options. This is typically used to define the cipher, compression, and hmac algorithms to use when sending packets to the server.

     # File lib/net/ssh/transport/session.rb, line 229
229:     def configure_client(options={})
230:       socket.client.set(options)
231:     end

configure_server (options={})

Configure’s the packet stream’s server state with the given set of options. This is typically used to define the cipher, compression, and hmac algorithms to use when reading packets from the server.

     # File lib/net/ssh/transport/session.rb, line 236
236:     def configure_server(options={})
237:       socket.server.set(options)
238:     end

enqueue_message (message)

Enqueues the given message, such that it will be sent at the earliest opportunity. This does not block, but returns immediately.

     # File lib/net/ssh/transport/session.rb, line 222
222:     def enqueue_message(message)
223:       socket.enqueue_packet(message)
224:     end

hint (which, value=true)

Sets a new hint for the packet stream, which the packet stream may use to change its behavior. (See PacketStream#hints).

     # File lib/net/ssh/transport/session.rb, line 242
242:     def hint(which, value=true)
243:       socket.hints[which] = value
244:     end

host_as_string ()

Returns the host (and possibly IP address) in a format compatible with SSH known-host files.

    # File lib/net/ssh/transport/session.rb, line 83
83:     def host_as_string
84:       @host_as_string ||= begin
85:         string = "#{host}"
86:         string = "[#{string}]:#{port}" if port != DEFAULT_PORT
87:         if socket.peer_ip != host
88:           string2 = socket.peer_ip
89:           string2 = "[#{string2}]:#{port}" if port != DEFAULT_PORT
90:           string << "," << string2
91:         end
92:         string
93:       end
94:     end

next_message ()

Blocks until a new packet is available to be read, and returns that packet. See poll_message.

     # File lib/net/ssh/transport/session.rb, line 148
148:     def next_message
149:       poll_message(:block)
150:     end

peer ()

Returns a hash of information about the peer (remote) side of the socket, including :ip, :port, :host, and :canonized (see host_as_string).

     # File lib/net/ssh/transport/session.rb, line 142
142:     def peer
143:       @peer ||= { :ip => socket.peer_ip, :port => @port.to_i, :host => @host, :canonized => host_as_string }
144:     end

poll_message (mode=:nonblock, consume_queue=true)

Tries to read the next packet from the socket. If mode is :nonblock (the default), this will not block and will return nil if there are no packets waiting to be read. Otherwise, this will block until a packet is available. Note that some packet types (DISCONNECT, IGNORE, UNIMPLEMENTED, DEBUG, and KEXINIT) are handled silently by this method, and will never be returned.

If a key-exchange is in process and a disallowed packet type is received, it will be enqueued and otherwise ignored. When a key-exchange is not in process, and consume_queue is true, packets will be first read from the queue before the socket is queried.

     # File lib/net/ssh/transport/session.rb, line 163
163:     def poll_message(mode=:nonblock, consume_queue=true)
164:       loop do
165:         if consume_queue && @queue.any? && algorithms.allow?(@queue.first)
166:           return @queue.shift
167:         end
168: 
169:         packet = socket.next_packet(mode)
170:         return nil if packet.nil?
171: 
172:         case packet.type
173:         when DISCONNECT
174:           raise Net::SSH::Disconnect, "disconnected: #{packet[:description]} (#{packet[:reason_code]})"
175: 
176:         when IGNORE
177:           debug { "IGNORE packet recieved: #{packet[:data].inspect}" }
178: 
179:         when UNIMPLEMENTED
180:           lwarn { "UNIMPLEMENTED: #{packet[:number]}" }
181: 
182:         when DEBUG
183:           send(packet[:always_display] ? :fatal : :debug) { packet[:message] }
184: 
185:         when KEXINIT
186:           algorithms.accept_kexinit(packet)
187: 
188:         else
189:           return packet if algorithms.allow?(packet)
190:           push(packet)
191:         end
192:       end
193:     end

push (packet)

Adds the given packet to the packet queue. If the queue is non-empty, poll_message will return packets from the queue in the order they were received.

     # File lib/net/ssh/transport/session.rb, line 210
210:     def push(packet)
211:       @queue.push(packet)
212:     end

rekey! ()

Requests a rekey operation, and blocks until the operation completes. If a rekey is already pending, this returns immediately, having no effect.

     # File lib/net/ssh/transport/session.rb, line 125
125:     def rekey!
126:       if !algorithms.pending?
127:         algorithms.rekey!
128:         wait { algorithms.initialized? }
129:       end
130:     end

rekey_as_needed ()

Returns immediately if a rekey is already in process. Otherwise, if a rekey is needed (as indicated by the socket, see PacketStream#if_needs_rekey?) one is performed, causing this method to block until it completes.

     # File lib/net/ssh/transport/session.rb, line 135
135:     def rekey_as_needed
136:       return if algorithms.pending?
137:       socket.if_needs_rekey? { rekey! }
138:     end

send_message (message)

Sends the given message via the packet stream, blocking until the entire message has been sent.

     # File lib/net/ssh/transport/session.rb, line 216
216:     def send_message(message)
217:       socket.send_packet(message)
218:     end

service_request (service)

Returns a new service_request packet for the given service name, ready for sending to the server.

     # File lib/net/ssh/transport/session.rb, line 118
118:     def service_request(service)
119:       Net::SSH::Buffer.from(:byte, SERVICE_REQUEST, :string, service)
120:     end

shutdown! ()

Performs a “hard” shutdown of the connection. In general, this should never be done, but it might be necessary (in a rescue clause, for instance, when the connection needs to close but you don’t know the status of the underlying protocol’s state).

     # File lib/net/ssh/transport/session.rb, line 111
111:     def shutdown!
112:       error { "forcing connection closed" }
113:       socket.close
114:     end

wait () {|| ...}

Waits (blocks) until the given block returns true. If no block is given, this just waits long enough to see if there are any pending packets. Any packets read are enqueued (see push).

     # File lib/net/ssh/transport/session.rb, line 198
198:     def wait
199:       loop do
200:         break if block_given? && yield
201:         message = poll_message(:nonblock, false)
202:         push(message) if message
203:         break if !block_given?
204:       end
205:     end