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require 'net/ssh/errors'
require 'net/ssh/loggable'
require 'net/ssh/version'
module Net
module SSH
module Transport
# Negotiates the SSH protocol version and trades information about server
# and client. This is never used directly--it is always called by the
# transport layer as part of the initialization process of the transport
# layer.
#
# Note that this class also encapsulates the negotiated version, and acts as
# the authoritative reference for any queries regarding the version in effect.
class ServerVersion
include Loggable
# The SSH version string as reported by Net::SSH
PROTO_VERSION = "SSH-2.0-Ruby/Net::SSH_#{Net::SSH::Version::CURRENT} #{RUBY_PLATFORM}"
# Any header text sent by the server prior to sending the version.
attr_reader :header
# The version string reported by the server.
attr_reader :version
# Instantiates a new ServerVersion and immediately (and synchronously)
# negotiates the SSH protocol in effect, using the given socket.
def initialize(socket, logger, timeout = nil)
@header = String.new
@version = nil
@logger = logger
negotiate!(socket, timeout)
end
private
# Negotiates the SSH protocol to use, via the given socket. If the server
# reports an incompatible SSH version (e.g., SSH1), this will raise an
# exception.
def negotiate!(socket, timeout)
info { "negotiating protocol version" }
debug { "local is `#{PROTO_VERSION}'" }
socket.write "#{PROTO_VERSION}\r\n"
socket.flush
raise Net::SSH::ConnectionTimeout, "timeout during server version negotiating" if timeout && !IO.select([socket], nil, nil, timeout)
loop do
@version = String.new
loop do
begin
b = socket.readpartial(1)
raise Net::SSH::Disconnect, "connection closed by remote host" if b.nil?
rescue EOFError
raise Net::SSH::Disconnect, "connection closed by remote host"
end
@version << b
break if b == "\n"
end
break if @version.match(/^SSH-/)
@header << @version
end
@version.chomp!
debug { "remote is `#{@version}'" }
raise Net::SSH::Exception, "incompatible SSH version `#{@version}'" unless @version.match(/^SSH-(1\.99|2\.0)-/)
raise Net::SSH::ConnectionTimeout, "timeout during client version negotiating" if timeout && !IO.select(nil, [socket], nil, timeout)
end
end
end
end
end
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