class Net::SSH::Transport::Session
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.
Constants
- DEFAULT_PORT
The standard port for the SSH protocol.
Attributes
The Algorithms instance used to perform key exchanges.
The host to connect to, as given to the constructor.
The host-key verifier object used to verify host keys, to ensure that the connection is not being spoofed.
The hash of options that were given to the object at initialization.
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.
The ServerVersion instance that encapsulates the negotiated protocol version.
The underlying socket object being used to communicate with the remote host.
Public Class Methods
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 57 def initialize(host, options={}) self.logger = options[:logger] @host = host @port = options[:port] || DEFAULT_PORT @bind_address = options[:bind_address] || nil @options = options debug { "establishing connection to #{@host}:#{@port}" } factory = options[:proxy] || TCPSocket @socket = timeout(options[:timeout] || 0) { case when options[:proxy] then factory.open(@host, @port, options) when @bind_address.nil? then factory.open(@host, @port) else factory.open(@host, @port, @bind_address) end } @socket.extend(PacketStream) @socket.logger = @logger debug { "connection established" } @queue = [] @host_key_verifier = select_host_key_verifier(options[:paranoid]) @server_version = timeout(options[:timeout] || 0) { ServerVersion.new(socket, logger) } @algorithms = Algorithms.new(self, options) wait { algorithms.initialized? } end
Public Instance Methods
Cleans up (see Net::SSH::Transport::PacketStream#cleanup) and closes the underlying socket.
# File lib/net/ssh/transport/session.rb, line 116 def close socket.cleanup socket.close end
Returns true if the underlying socket has been closed.
# File lib/net/ssh/transport/session.rb, line 111 def closed? socket.closed? end
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 243 def configure_client(options={}) socket.client.set(options) end
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 250 def configure_server(options={}) socket.server.set(options) end
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 236 def enqueue_message(message) socket.enqueue_packet(message) end
Sets a new hint for the packet stream, which the packet stream may use to change its behavior. (See Net::SSH::Transport::PacketStream#hints).
# File lib/net/ssh/transport/session.rb, line 256 def hint(which, value=true) socket.hints[which] = value end
Returns the host (and possibly IP address) in a format compatible with SSH known-host files.
# File lib/net/ssh/transport/session.rb, line 92 def host_as_string @host_as_string ||= begin string = "#{host}" string = "[#{string}]:#{port}" if port != DEFAULT_PORT peer_ip = socket.peer_ip if peer_ip != Net::SSH::Transport::PacketStream::PROXY_COMMAND_HOST_IP && peer_ip != host string2 = peer_ip string2 = "[#{string2}]:#{port}" if port != DEFAULT_PORT string << "," << string2 end string end end
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 162 def next_message poll_message(:block) end
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 156 def peer @peer ||= { :ip => socket.peer_ip, :port => @port.to_i, :host => @host, :canonized => host_as_string } end
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 177 def poll_message(mode=:nonblock, consume_queue=true) loop do if consume_queue && @queue.any? && algorithms.allow?(@queue.first) return @queue.shift end packet = socket.next_packet(mode) return nil if packet.nil? case packet.type when DISCONNECT raise Net::SSH::Disconnect, "disconnected: #{packet[:description]} (#{packet[:reason_code]})" when IGNORE debug { "IGNORE packet recieved: #{packet[:data].inspect}" } when UNIMPLEMENTED lwarn { "UNIMPLEMENTED: #{packet[:number]}" } when DEBUG send(packet[:always_display] ? :fatal : :debug) { packet[:message] } when KEXINIT algorithms.accept_kexinit(packet) else return packet if algorithms.allow?(packet) push(packet) end end end
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 224 def push(packet) @queue.push(packet) end
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 139 def rekey! if !algorithms.pending? algorithms.rekey! wait { algorithms.initialized? } end end
Returns immediately if a rekey is already in process. Otherwise, if a rekey is needed (as indicated by the socket, see Net::SSH::Transport::PacketStream#if_needs_rekey?) one is performed, causing this method to block until it completes.
# File lib/net/ssh/transport/session.rb, line 149 def rekey_as_needed return if algorithms.pending? socket.if_needs_rekey? { rekey! } end
Sends the given message via the packet stream, blocking until the entire message has been sent.
# File lib/net/ssh/transport/session.rb, line 230 def send_message(message) socket.send_packet(message) end
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 132 def service_request(service) Net::SSH::Buffer.from(:byte, SERVICE_REQUEST, :string, service) end
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 125 def shutdown! error { "forcing connection closed" } socket.close end
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 212 def wait loop do break if block_given? && yield message = poll_message(:nonblock, false) push(message) if message break if !block_given? end end
Private Instance Methods
Instantiates a new host-key verification class, based on the value of the parameter. When true or nil, the default Lenient verifier is returned. If it is false, the Null verifier is returned, and if it is :very, the Strict verifier is returned. If it is :secure, the even more strict Secure verifier is returned. If the argument happens to respond to :verify, it is returned directly. Otherwise, an exception is raised.
# File lib/net/ssh/transport/session.rb, line 274 def select_host_key_verifier(paranoid) case paranoid when true, nil then Net::SSH::Verifiers::Lenient.new when false then Net::SSH::Verifiers::Null.new when :very then Net::SSH::Verifiers::Strict.new when :secure then Net::SSH::Verifiers::Secure.new else if paranoid.respond_to?(:verify) paranoid else raise ArgumentError, "argument to :paranoid is not valid: #{paranoid.inspect}" end end end