134 lines
4.5 KiB
Ruby
134 lines
4.5 KiB
Ruby
require 'net/ssh/loggable'
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require 'net/ssh/transport/constants'
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require 'net/ssh/authentication/constants'
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require 'net/ssh/authentication/key_manager'
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require 'net/ssh/authentication/methods/publickey'
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require 'net/ssh/authentication/methods/hostbased'
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require 'net/ssh/authentication/methods/password'
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require 'net/ssh/authentication/methods/keyboard_interactive'
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module Net; module SSH; module Authentication
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# Represents an authentication session. It manages the authentication of
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# a user over an established connection (the "transport" object, see
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# Net::SSH::Transport::Session).
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#
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# The use of an authentication session to manage user authentication is
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# internal to Net::SSH (specifically Net::SSH.start). Consumers of the
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# Net::SSH library will never need to access this class directly.
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class Session
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include Transport::Constants, Constants, Loggable
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# transport layer abstraction
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attr_reader :transport
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# the list of authentication methods to try
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attr_reader :auth_methods
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# the list of authentication methods that are allowed
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attr_reader :allowed_auth_methods
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# a hash of options, given at construction time
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attr_reader :options
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# Instantiates a new Authentication::Session object over the given
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# transport layer abstraction.
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def initialize(transport, options={})
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self.logger = transport.logger
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@transport = transport
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@auth_methods = options[:auth_methods] || %w(publickey hostbased password keyboard-interactive)
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@options = options
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@allowed_auth_methods = @auth_methods
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end
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# Attempts to authenticate the given user, in preparation for the next
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# service request. Returns true if an authentication method succeeds in
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# authenticating the user, and false otherwise.
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def authenticate(next_service, username, password=nil)
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debug { "beginning authentication of `#{username}'" }
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transport.send_message(transport.service_request("ssh-userauth"))
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message = expect_message(SERVICE_ACCEPT)
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key_manager = KeyManager.new(logger, options)
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keys.each { |key| key_manager.add(key) } unless keys.empty?
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key_data.each { |key2| key_manager.add_key_data(key2) } unless key_data.empty?
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attempted = []
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@auth_methods.each do |name|
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next unless @allowed_auth_methods.include?(name)
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attempted << name
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debug { "trying #{name}" }
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method = Methods.const_get(name.split(/\W+/).map { |p| p.capitalize }.join).new(self, :key_manager => key_manager)
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return true if method.authenticate(next_service, username, password)
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end
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error { "all authorization methods failed (tried #{attempted.join(', ')})" }
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return false
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ensure
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key_manager.finish if key_manager
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end
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# Blocks until a packet is received. It silently handles USERAUTH_BANNER
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# packets, and will raise an error if any packet is received that is not
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# valid during user authentication.
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def next_message
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loop do
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packet = transport.next_message
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case packet.type
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when USERAUTH_BANNER
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info { packet[:message] }
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# TODO add a hook for people to retrieve the banner when it is sent
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when USERAUTH_FAILURE
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@allowed_auth_methods = packet[:authentications].split(/,/)
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debug { "allowed methods: #{packet[:authentications]}" }
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return packet
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when USERAUTH_METHOD_RANGE, SERVICE_ACCEPT
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return packet
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when USERAUTH_SUCCESS
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transport.hint :authenticated
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return packet
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else
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raise Net::SSH::Exception, "unexpected message #{packet.type} (#{packet})"
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end
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end
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end
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# Blocks until a packet is received, and returns it if it is of the given
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# type. If it is not, an exception is raised.
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def expect_message(type)
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message = next_message
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unless message.type == type
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raise Net::SSH::Exception, "expected #{type}, got #{message.type} (#{message})"
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end
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message
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end
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private
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# Returns an array of paths to the key files that should be used when
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# attempting any key-based authentication mechanism.
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def keys
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Array(
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options[:keys] ||
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%w(~/.ssh/id_dsa ~/.ssh/id_rsa ~/.ssh2/id_dsa ~/.ssh2/id_rsa)
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)
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end
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# Returns an array of the key data that should be used when
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# attempting any key-based authentication mechanism.
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def key_data
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Array(options[:key_data])
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end
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end
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end; end; end |