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|
#--
#
# Author:: Francis Cianfrocca (gmail: blackhedd)
# Homepage:: http://rubyeventmachine.com
# Date:: 15 November 2006
#
# See EventMachine and EventMachine::Connection for documentation and
# usage examples.
#
#----------------------------------------------------------------------------
#
# Copyright (C) 2006-07 by Francis Cianfrocca. All Rights Reserved.
# Gmail: blackhedd
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of either: 1) the GNU General Public License
# as published by the Free Software Foundation; either version 2 of the
# License, or (at your option) any later version; or 2) Ruby's License.
#
# See the file COPYING for complete licensing information.
#
#---------------------------------------------------------------------------
#
#
#
module EventMachine
module Protocols
# Implements SASL authd.
# This is a very, very simple protocol that mimics the one used
# by saslauthd and pwcheck, two outboard daemons included in the
# standard SASL library distro.
# The only thing this is really suitable for is SASL PLAIN
# (user+password) authentication, but the SASL libs that are
# linked into standard servers (like imapd and sendmail) implement
# the other ones.
#
# SASL-auth is intended for reasonably fast operation inside a
# single machine, so it has no transport-security (although there
# have been multi-machine extensions incorporating transport-layer
# encryption).
#
# The standard saslauthd module generally runs privileged and does
# its work by referring to the system-account files.
#
# This feature was added to EventMachine to enable the development
# of custom authentication/authorization engines for standard servers.
#
# To use SASLauth, include it in a class that subclasses EM::Connection,
# and reimplement the validate method.
#
# The typical way to incorporate this module into an authentication
# daemon would be to set it as the handler for a UNIX-domain socket.
# The code might look like this:
#
# EM.start_unix_domain_server( "/var/run/saslauthd/mux", MyHandler )
# File.chmod( 0777, "/var/run/saslauthd/mux")
#
# The chmod is probably needed to ensure that unprivileged clients can
# access the UNIX-domain socket.
#
# It's also a very good idea to drop superuser privileges (if any), after
# the UNIX-domain socket has been opened.
#--
# Implementation details: assume the client can send us pipelined requests,
# and that the client will close the connection.
#
# The client sends us four values, each encoded as a two-byte length field in
# network order followed by the specified number of octets.
# The fields specify the username, password, service name (such as imap),
# and the "realm" name. We send back the barest minimum reply, a single
# field also encoded as a two-octet length in network order, followed by
# either "NO" or "OK" - simplicity itself.
#
# We enforce a maximum field size just as a sanity check.
# We do NOT automatically time out the connection.
#
# The code we use to parse out the values is ugly and probably slow.
# Improvements welcome.
#
module SASLauth
MaxFieldSize = 128*1024
def post_init
super
@sasl_data = ""
@sasl_values = []
end
def receive_data data
@sasl_data << data
while @sasl_data.length >= 2
len = (@sasl_data[0,2].unpack("n")).first
raise "SASL Max Field Length exceeded" if len > MaxFieldSize
if @sasl_data.length >= (len + 2)
@sasl_values << @sasl_data[2,len]
@sasl_data.slice!(0...(2+len))
if @sasl_values.length == 4
send_data( validate(*@sasl_values) ? "\0\002OK" : "\0\002NO" )
@sasl_values.clear
end
else
break
end
end
end
def validate username, psw, sysname, realm
p username
p psw
p sysname
p realm
true
end
end
# Implements the SASL authd client protocol.
# This is a very, very simple protocol that mimics the one used
# by saslauthd and pwcheck, two outboard daemons included in the
# standard SASL library distro.
# The only thing this is really suitable for is SASL PLAIN
# (user+password) authentication, but the SASL libs that are
# linked into standard servers (like imapd and sendmail) implement
# the other ones.
#
# You can use this module directly as a handler for EM Connections,
# or include it in a module or handler class of your own.
#
# First connect to a SASL server (it's probably a TCP server, or more
# likely a Unix-domain socket). Then call the #validate? method,
# passing at least a username and a password. #validate? returns
# a Deferrable which will either succeed or fail, depending
# on the status of the authentication operation.
#
module SASLauthclient
MaxFieldSize = 128*1024
def validate? username, psw, sysname=nil, realm=nil
str = [username, psw, sysname, realm].map {|m|
[(m || "").length, (m || "")]
}.flatten.pack( "nA*" * 4 )
send_data str
d = EM::DefaultDeferrable.new
@queries.unshift d
d
end
def post_init
@sasl_data = ""
@queries = []
end
def receive_data data
@sasl_data << data
while @sasl_data.length > 2
len = (@sasl_data[0,2].unpack("n")).first
raise "SASL Max Field Length exceeded" if len > MaxFieldSize
if @sasl_data.length >= (len + 2)
val = @sasl_data[2,len]
@sasl_data.slice!(0...(2+len))
q = @queries.pop
(val == "NO") ? q.fail : q.succeed
else
break
end
end
end
end
end
end
|
