Using TLS/SSL with Net::SMTP

A

appleman

So I'm trying to add onto the existing Net::SMTP library so I can send
email to a secure SMTP server (specifically gmail). I looked through
the CVS repository and I noticed that at some point in time, there was
an attempt to integrate this functionality into the release. I
extracted the logic and I'm attempting to leverage it and this how far
I've gotten....

Here's my simple ruby program to test the SMTPS module (email and
password have been changed for the example so aren't valid, but in the
tests they were):

====================================
require 'smtps'

msg = [ "Subject: Test\n", "\n", "Now is the time\n" ]

Net::SMTP.enable_tls OpenSSL::SSL::VERIFY_PEER, nil
puts Net::SMTP.use_tls?
Net::SMTP.start('smtp.gmail.com', 587, 'johndoe.com',
'(e-mail address removed)', 'password', :plain) do |smtp|
smtp.send_message(msg, '(e-mail address removed)',
'(e-mail address removed)')
end
====================================

And now the SMTPS code:

====================================

# = net/smtps.rb
#
#--
# Copyright (C) 1999-2004 Yukihiro Matsumoto
# Copyright (C) 1999-2004 Minero Aoki
#
# written and maintained by Minero Aoki <[email protected]>
#
# This program is free software. You can re-distribute and/or
# modify this program under the same terms as Ruby itself.
#
# NOTE: You can find Japanese version of this document at:
# http://www.ruby-lang.org/ja/man/index.cgi?cmd=view;name=net/smtp.rb
#
# $Id: smtp.rb,v 1.73 2004/04/21 09:40:48 aamine Exp $
#++
#
# == What is This Library?
#
# This library provides functionality to send internet
# mail via SMTP, the Simple Mail Transfer Protocol. For details of
# SMTP itself, see [RFC2821] (http://www.ietf.org/rfc/rfc2821.txt).
#
# == What is This Library NOT?
#
# This library does NOT provide functions to compose internet mails.
# You must create them by yourself. If you want better mail support,
# try RubyMail or TMail. You can get both libraries from RAA.
# (http://www.ruby-lang.org/en/raa.html)
#
# FYI: the official documentation on internet mail is: [RFC2822]
(http://www.ietf.org/rfc/rfc2822.txt).
#
# == Examples
#
# === Sending Messages
#
# You must open a connection to an SMTP server before sending messages.
# The first argument is the address of your SMTP server, and the second

# argument is the port number. Using SMTP.start with a block is the
simplest
# way to do this. This way, the SMTP connection is closed automatically

# after the block is executed.
#
# require 'net/smtp'
# Net::SMTP.start('your.smtp.server', 25) {|smtp|
# # use the SMTP object smtp only in this block
# }
#
# Replace 'your.smtp.server' with your SMTP server. Normally
# your system manager or internet provider supplies a server
# for you.
#
# Then you can send messages.
#
# msgstr = <<END_OF_MESSAGE
# From: Your Name <[email protected]>
# To: Destination Address <[email protected]>
# Subject: test message
# Date: Sat, 23 Jun 2001 16:26:43 +0900
# Message-Id: <[email protected]>
#
# This is a test message.
# END_OF_MESSAGE
#
# require 'net/smtp'
# Net::SMTP.start('your.smtp.server', 25) {|smtp|
# smtp.send_message msgstr,
# '(e-mail address removed)',
# '(e-mail address removed)'
# }
#
# === Closing the Session
#
# You MUST close the SMTP session after sending messages, by calling
# the #finish method:
#
# # using SMTP#finish
# smtp = Net::SMTP.start('your.smtp.server', 25)
# smtp.send_message msgstr, 'from@address', 'to@address'
# smtp.finish
#
# You can also use the block form of SMTP.start/SMTP#start. This
closes
# the SMTP session automatically:
#
# # using block form of SMTP.start
# Net::SMTP.start('your.smtp.server', 25) {|smtp|
# smtp.send_message msgstr, 'from@address', 'to@address'
# }
#
# I strongly recommend this scheme. This form is simpler and more
robust.
#
# === HELO domain
#
# In almost all situations, you must provide a third argument
# to SMTP.start/SMTP#start. This is the domain name which you are on
# (the host to send mail from). It is called the "HELO domain".
# The SMTP server will judge whether it should send or reject
# the SMTP session by inspecting the HELO domain.
#
# Net::SMTP.start('your.smtp.server', 25,
# 'mail.from.domain') {|smtp| ... }
#
# === SMTP Authentication
#
# The Net::SMTP class supports three authentication schemes;
# PLAIN, LOGIN and CRAM MD5. (SMTP Authentication: [RFC2554])
# To use SMTP authentication, pass extra arguments to
# SMTP.start/SMTP#start. Use in conjunction with STARTTLS to
# prevent authentication information passing in the clear.
#
# # PLAIN
# Net::SMTP.start('your.smtp.server', 25, 'mail.from,domain',
# 'Your Account', 'Your Password', :plain)
# # LOGIN
# Net::SMTP.start('your.smtp.server', 25, 'mail.from,domain',
# 'Your Account', 'Your Password', :login)
#
# # CRAM MD5
# Net::SMTP.start('your.smtp.server', 25, 'mail.from,domain',
# 'Your Account', 'Your Password', :cram_md5)
#
# === STARTTLS support
#
# The Net::SMTP class supports STARTTLS.
#
# # Per Instance STARTTLS
# smtp = Net::SMTP.new('smtp.example.com',25)
# smtp.enable_tls(verify, certs) if $use_tls #(1)
# smtp.start('your host','username','password') { |s|
# s.send_message msgstr,
# '(e-mail address removed)',
# '(e-mail address removed)'
# }
# smtp.finish
#
# 1. +verify+ tells the openssl library how to verify the server
# certificate. Defaults to OpenSSL::SSL::VERIFY_PEER
# +certs+ is a file or directory holding CA certs to use to verify
the
# server cert; Defaults to nil.
#
#
# # USE STARTTLS for all subsequent instances
# Net::SMTP.enable_tls
# # We will now use starttls for all connections.
# Net::SMTP.start('your.smtp.server', 25, 'mail.from,domain',
# 'Your Account', 'Your Password', :plain) {|smtp|
# smtp.send_message msgstr,
# '(e-mail address removed)',
# '(e-mail address removed)'
# }
#

require 'net/protocol'
require 'digest/md5'
require 'timeout'
begin
require "openssl"
rescue LoadError
end

module Net # :nodoc:

# Module mixed in to all SMTP error classes
module SMTPError
# This *class* is module for some reason.
# In ruby 1.9.x, this module becomes a class.
end

# Represents an SMTP authentication error.
class SMTPAuthenticationError < ProtoAuthError
include SMTPError
end

# Represents SMTP error code 420 or 450, a temporary error.
class SMTPServerBusy < ProtoServerError
include SMTPError
end

# Represents an SMTP command syntax error (error code 500)
class SMTPSyntaxError < ProtoSyntaxError
include SMTPError
end

# Represents a fatal SMTP error (error code 5xx, except for 500)
class SMTPFatalError < ProtoFatalError
include SMTPError
end

# Unexpected reply code returned from server.
class SMTPUnknownError < ProtoUnknownError
include SMTPError
end

#
# Class providing SMTP client functionality.
#
# See documentation for the file smtp.rb for examples of usage.
#
class SMTP

Revision = %q$Revision: 1.73 $.split[1]

# The default SMTP port, port 25.
def SMTP.default_port
25
end

@use_tls = false
@verify = nil
@Certs = nil

# Enable SSL for all new instances.
# +verify+ is the type of verification to do on the Server Cert;
Defaults
# to OpenSSL::SSL::VERIFY_PEER.
# +certs+ is a file or directory holding CA certs to use to verify
the
# server cert; Defaults to nil.
def SMTP.enable_tls(verify = OpenSSL::SSL::VERIFY_PEER, certs =
nil)
@use_tls = true
@verify = verify
@Certs = certs
end

# Disable SSL for all new instances.
def SMTP.disable_tls
@use_tls = nil
@verify = nil
@Certs = nil
end

def SMTP.use_tls?
@use_tls
end

def SMTP.verify
@verify
end

def SMTP.certs
@Certs
end

# Creates a new Net::SMTP object. +address+ is the hostname
# or ip address of your SMTP server. +port+ is the port to
# connect to; it defaults to port 25.
# This method does not open the TCP connection.
def initialize(address, port = nil)
@address = address
@port = (port || SMTP.default_port)
@esmtp = true
@socket = nil
@started = false
@open_timeout = 30
@read_timeout = 60
@error_occured = false
@debug_output = nil
@use_tls = SMTP.use_tls?
@Certs = SMTP.certs
@verify = SMTP.verify
end

# Provide human-readable stringification of class state.
def inspect
"#<#{self.class} #{@address}:#{@port} started=#{@started}>"
end

# +true+ if the SMTP object uses ESMTP (which it does by default).
def esmtp?
@esmtp
end

# Set whether to use ESMTP or not. This should be done before
# calling #start. Note that if #start is called in ESMTP mode,
# and the connection fails due to a ProtocolError, the SMTP
# object will automatically switch to plain SMTP mode and
# retry (but not vice versa).
def esmtp=(bool)
@esmtp = bool
end

alias esmtp esmtp?

# does this instance use SSL?
def use_tls?
@use_tls
end

# Enables STARTTLS for this instance.
# +verify+ is the type of verification to do on the Server Cert;
Defaults
# to OpenSSL::SSL::VERIFY_PEER.
# +certs+ is a file or directory holding CA certs to use to verify
the
# server cert; Defaults to nil.
def enable_tls(verify = OpenSSL::SSL::VERIFY_PEER, certs = nil)
@use_tls = true
@verify = verify
@Certs = certs
end

def disable_tls
@use_tls = false
@verify = nil
@Certs = nil
end

# The address of the SMTP server to connect to.
attr_reader :address

# The port number of the SMTP server to connect to.
attr_reader :port

# Seconds to wait while attempting to open a connection.
# If the connection cannot be opened within this time, a
# TimeoutError is raised.
attr_accessor :eek:pen_timeout

# Seconds to wait while reading one block (by one read(2) call).
# If the read(2) call does not complete within this time, a
# TimeoutError is raised.
attr_reader :read_timeout

# Set the number of seconds to wait until timing-out a read(2)
# call.
def read_timeout=(sec)
@socket.read_timeout = sec if @socket
@read_timeout = sec
end

# WARNING: This method causes serious security holes.
# Use this method for only debugging.
#
# Set an output stream for debug logging.
# You must call this before #start.
#
# # example
# smtp = Net::SMTP.new(addr, port)
# smtp.set_debug_output $stderr
# smtp.start {
# ....
# }
def set_debug_output(arg)
@debug_output = arg
end

#
# SMTP session control
#

# Creates a new Net::SMTP object and connects to the server.
#
# This method is equivalent to:
#
#
Net::SMTP.new(address,port).start(helo_domain,account,password,authtype)
#
# # example
# Net::SMTP.start('your.smtp.server') {
# smtp.send_message msgstr, '(e-mail address removed)',
['(e-mail address removed)']
# }
#
# If called with a block, the newly-opened Net::SMTP object is
yielded
# to the block, and automatically closed when the block finishes.
If called
# without a block, the newly-opened Net::SMTP object is returned to
# the caller, and it is the caller's responsibility to close it
when
# finished.
#
# +address+ is the hostname or ip address of your smtp server.
# +port+ is the port to connect to; it defaults to port 25.
# +helo+ is the _HELO_ _domain_ provided by the client to the
# server (see overview comments); it defaults to
'localhost.localdomain'.
# The remaining arguments are used for SMTP authentication, if
required
# or desired. +user+ is the account name; +secret+ is your
password
# or other authentication token; and +authtype+ is the
authentication
# type, one of :plain, :login, or :cram_md5. See the discussion of
# SMTP Authentication in the overview notes.
#
# This method may raise:
#
# * Net::SMTPAuthenticationError
# * Net::SMTPServerBusy
# * Net::SMTPSyntaxError
# * Net::SMTPFatalError
# * Net::SMTPUnknownError
# * IOError
# * TimeoutError
def SMTP.start(address, port = nil, helo = 'localhost.localdomain',
user = nil, secret = nil, authtype = nil,
&block) # :yield: smtp
new(address, port).start(helo, user, secret, authtype, &block)
end

# +true+ if the SMTP session has been started.
def started?
@started
end

# Opens a TCP connection and starts the SMTP session.
#
# +helo+ is the _HELO_ _domain_ that you'll dispatch mails from;
see
# the discussion in the overview notes.
#
# When this methods is called with a block, the newly-started SMTP
# object is yielded to the block, and automatically closed after
# the block call finishes. Otherwise, it is the caller's
# responsibility to close the session when finished.
#
# If both of +user+ and +secret+ are given, SMTP authentication
# will be attempted using the AUTH command. +authtype+ specifies
# the type of authentication to attempt; it must be one of
# :login, :plain, and :cram_md5. See the notes on SMTP
Authentication
# in the overview.
#
# If session has already been started, an IOError will be raised.
#
# This method may raise:
#
# * Net::SMTPAuthenticationError
# * Net::SMTPServerBusy
# * Net::SMTPSyntaxError
# * Net::SMTPFatalError
# * Net::SMTPUnknownError
# * IOError
# * TimeoutError
def start(helo = 'localhost.localdomain',
user = nil, secret = nil, authtype = nil) #:yield: smtp
if block_given?
begin
do_start(helo, user, secret, authtype)
return yield(self)
ensure
do_finish
end
else
do_start(helo, user, secret, authtype)
return self
end
end

def do_start(helodomain, user, secret, authtype)
raise IOError, 'SMTP session already started' if @started
check_auth_args user, secret, authtype if user or secret
s = timeout(@open_timeout) { TCPSocket.open(@address, @port) }
@socket = InternetMessageIO.new(s)

logging "SMTP session opened: #{@address}:#{@port}"
@socket.read_timeout = @read_timeout
@socket.debug_output = @debug_output
check_response(critical { recv_response() })
do_helo(helodomain)

if @use_tls
raise 'openssl library not installed' unless defined?(OpenSSL)
context = OpenSSL::SSL::SSLContext.new
context.verify_mode = @verify
if @Certs
if File.file?(@Certs)
context.ca_file = @Certs
elsif File.directory?(@Certs)
context.ca_path = @Certs
else
raise ArgumentError, "certs given but is not file or
directory: #{@certs}"
end
end
s = OpenSSL::SSL::SSLSocket.new(s, context)
s.sync_close = true
starttls
begin
s.connect
rescue OpenSSL::SSL::SSLError => bang
print "Error: " + bang
end

logging 'TLS started'
@socket = InternetMessageIO.new(s)
@socket.read_timeout = @read_timeout
@socket.debug_output = @debug_output
# helo response may be different after STARTTLS
do_helo(helodomain)
end

authenticate user, secret, authtype if user
@started = true
ensure
unless @started
# authentication failed, cancel connection.
s.close if s and not s.closed?
@socket = nil
end
end
private :do_start

# method to send helo or ehlo based on defaults and to
# retry with helo if server doesn't like ehlo.
#
def do_helo(helodomain)
begin
if @esmtp
ehlo helodomain
else
helo helodomain
end
rescue ProtocolError
if @esmtp
@esmtp = false
@error_occured = false
retry
end
raise
end
end

# Finishes the SMTP session and closes TCP connection.
# Raises IOError if not started.
def finish
raise IOError, 'not yet started' unless started?
do_finish
end

def do_finish
quit if @socket and not @socket.closed? and not @error_occured
ensure
@started = false
@error_occured = false
@socket.close if @socket and not @socket.closed?
@socket = nil
end
private :do_finish

#
# message send
#

public

# Sends +msgstr+ as a message. Single CR ("\r") and LF ("\n")
found
# in the +msgstr+, are converted into the CR LF pair. You cannot
send a
# binary message with this method. +msgstr+ should include both
# the message headers and body.
#
# +from_addr+ is a String representing the source mail address.
# +to_addr+ is a String or Strings or Array of Strings,
representing
# the destination mail address or addresses.
#
# # example
# Net::SMTP.start('smtp.example.com') {|smtp|
# smtp.send_message msgstr,
# '(e-mail address removed)',
# ['(e-mail address removed)', '(e-mail address removed)']
# }
#
# This method may raise:
#
# * Net::SMTPServerBusy
# * Net::SMTPSyntaxError
# * Net::SMTPFatalError
# * Net::SMTPUnknownError
# * IOError
# * TimeoutError
def send_message(msgstr, from_addr, *to_addrs)
send0(from_addr, to_addrs.flatten) {
@socket.write_message msgstr
}
end

alias send_mail send_message
alias sendmail send_message # obsolete

# Opens a message writer stream and gives it to the block.
# The stream is valid only in the block, and has these methods:
#
# puts(str = ''):: outputs STR and CR LF.
# print(str):: outputs STR.
# printf(fmt, *args):: outputs sprintf(fmt,*args).
# write(str):: outputs STR and returns the length of written
bytes.
# <<(str):: outputs STR and returns self.
#
# If a single CR ("\r") or LF ("\n") is found in the message,
# it is converted to the CR LF pair. You cannot send a binary
# message with this method.
#
# +from_addr+ is a String representing the source mail address.
# +to_addr+ is a String or Strings or Array of Strings,
representing
# the destination mail address or addresses.
#
# # example
# Net::SMTP.start('smtp.example.com', 25) {|smtp|
# smtp.open_message_stream('(e-mail address removed)',
['(e-mail address removed)']) {|f|
# f.puts 'From: (e-mail address removed)'
# f.puts 'To: (e-mail address removed)'
# f.puts 'Subject: test message'
# f.puts
# f.puts 'This is a test message.'
# }
# }
#
# This method may raise:
#
# * Net::SMTPServerBusy
# * Net::SMTPSyntaxError
# * Net::SMTPFatalError
# * Net::SMTPUnknownError
# * IOError
# * TimeoutError
def open_message_stream(from_addr, *to_addrs, &block) #:yield:
stream
send0(from_addr, to_addrs.flatten) {
@socket.write_message_by_block(&block)
}
end

alias ready open_message_stream # obsolete

private

def send0(from_addr, to_addrs)
raise IOError, 'closed session' unless @socket
raise ArgumentError, 'mail destination not given' if
to_addrs.empty?
if $SAFE > 0
raise SecurityError, 'tainted from_addr' if from_addr.tainted?
to_addrs.each do |to|
raise SecurityError, 'tainted to_addr' if to.tainted?
end
end

mailfrom from_addr
to_addrs.each do |to|
rcptto to
end
res = critical {
check_response(get_response('DATA'), true)
yield
recv_response()
}
check_response(res)
end

#
# auth
#

private

def check_auth_args(user, secret, authtype)
raise ArgumentError, 'both user and secret are required'\
unless user and secret
auth_method = "auth_#{authtype || 'cram_md5'}"
raise ArgumentError, "wrong auth type #{authtype}"\
unless respond_to?(auth_method, true)
end

def authenticate(user, secret, authtype)
__send__("auth_#{authtype || 'cram_md5'}", user, secret)
end

def auth_plain(user, secret)
res = critical { get_response('AUTH PLAIN %s',

base64_encode("\0#{user}\0#{secret}")) }
raise SMTPAuthenticationError, res unless /\A2../ === res
end

def auth_login(user, secret)
res = critical {
check_response(get_response('AUTH LOGIN'), true)
check_response(get_response(base64_encode(user)), true)
get_response(base64_encode(secret))
}
raise SMTPAuthenticationError, res unless /\A2../ === res
end

def auth_cram_md5(user, secret)
# CRAM-MD5: [RFC2195]
res = nil
critical {
res = check_response(get_response('AUTH CRAM-MD5'), true)
challenge = res.split(/ /)[1].unpack('m')[0]
secret = Digest::MD5.digest(secret) if secret.size > 64

isecret = secret + "\0" * (64 - secret.size)
osecret = isecret.dup
0.upto(63) do |i|
isecret ^= 0x36
osecret ^= 0x5c
end
tmp = Digest::MD5.digest(isecret + challenge)
tmp = Digest::MD5.hexdigest(osecret + tmp)

res = get_response(base64_encode(user + ' ' + tmp))
}
raise SMTPAuthenticationError, res unless /\A2../ === res
end

def base64_encode(str)
# expects "str" may not become too long
[str].pack('m').gsub(/\s+/, '')
end

#
# SMTP command dispatcher
#

private

def helo(domain)
getok('HELO %s', domain)
end

def ehlo(domain)
getok('EHLO %s', domain)
end

def mailfrom(fromaddr)
getok('MAIL FROM:<%s>', fromaddr)
end

def rcptto(to)
getok('RCPT TO:<%s>', to)
end

def quit
getok('QUIT')
end

def starttls
getok('STARTTLS')
end
#
# row level library
#

private

def getok(fmt, *args)
res = critical {
@socket.writeline sprintf(fmt, *args)
recv_response()
}
return check_response(res)
end

def get_response(fmt, *args)
@socket.writeline sprintf(fmt, *args)
recv_response()
end

def recv_response
res = ''
while true
line = @socket.readline
res << line << "\n"
break unless line[3] == ?- # "210-PIPELINING"
end
res
end

def check_response(res, allow_continue = false)
return res if /\A2/ === res
return res if allow_continue and /\A3/ === res
err = case res
when /\A4/ then SMTPServerBusy
when /\A50/ then SMTPSyntaxError
when /\A55/ then SMTPFatalError
else SMTPUnknownError
end
raise err, res
end

def critical(&block)
return '200 dummy reply code' if @error_occured
begin
return yield()
rescue Exception
@error_occured = true
raise
end
end

def logging(msg)
@debug_output << msg + "\n" if @debug_output
end

end # class SMTP

SMTPSession = SMTP

end # module Net
===============================================

Here's the output, when I run it....

===============================================
true
Error: c:/ruby/lib/ruby/site_ruby/1.8/openssl/buffering.rb:178:in
`syswrite': SSL_write: (OpenSSL::SSL::SSLError)
from c:/ruby/lib/ruby/site_ruby/1.8/openssl/buffering.rb:178:in
`do_write'
from c:/ruby/lib/ruby/site_ruby/1.8/openssl/buffering.rb:192:in
`write'
from c:/ruby/lib/ruby/1.8/net/protocol.rb:175:in `write0'
from c:/ruby/lib/ruby/1.8/net/protocol.rb:157:in `writeline'
from c:/ruby/lib/ruby/1.8/net/protocol.rb:166:in `writing'
from c:/ruby/lib/ruby/1.8/net/protocol.rb:156:in `writeline'
from ./smtps.rb:730:in `getok'
from ./smtps.rb:766:in `critical'
from ./smtps.rb:729:in `getok'
from ./smtps.rb:704:in `ehlo'
from ./smtps.rb:494:in `do_helo'
from ./smtps.rb:474:in `do_start'
from ./smtps.rb:424:in `start'
from ./smtps.rb:385:in `start'
from bitsmtp.rb:8
Exit code: 1

==================================================

Any ruby pro's able to debug what's wrong with protocol.rb that is
causing it to fail? Thanks in advance....
 

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