| Subject: | libnet: Net::SMTP->auth() forces SASL methods (including broken DIGEST-MD5) |
| Date: | Tue, 01 Jun 2010 09:47:41 +1200 |
| To: | bug-libnet [...] rt.cpan.org |
| From: | Ewen McNeill <cpan [...] ewen.mcneill.gen.nz> |
Net::SMTP (in libnet) provides a auth() method which will do SMTP AUTH
against the mail server prior to attempting to send mail. This
auto-detects the SMTP AUTH methods available and (AFAICT) always uses
the first one that is reported, even if the caller knows that method
will not work (in my case DIGEST-MD5 appears not to work; see below).
The auth() method provides an option to receive an Authen::SASL object
as the "username" parameter, rather than username/password in plain
text, which has been preconfigured with the necessary authentication
parameters.
Howver Net::SMTP in libnet 1.22 and 1.22_01 explicitly overrides the
specified mechanisms in the provided Authen::SASL object, which means
that it will use the first reported SMTP AUTH mechanism (even if the
caller knows that it won't work).
A simple patch would change Net::SMTP::auth() so that it uses the
specified SMTP AUTH mechanism(s), and conveniently falls back to the
auto-detected approach if none is specified:
-=- cut here -=-
ewen@bethel:~$ diff -u /tmp/Net-SMTP.pm
/opt/local/lib/perl5/5.8.9/Net/SMTP.pm
--- /tmp/Net-SMTP.pm 2010-06-01 09:23:57.000000000 +1200
+++ /opt/local/lib/perl5/5.8.9/Net/SMTP.pm 2010-06-01 09:22:23.000000000
+1200
@@ -124,7 +124,10 @@
if (ref($username) and UNIVERSAL::isa($username, 'Authen::SASL')) {
$sasl = $username;
- $sasl->mechanism($mechanisms);
+ my $requested_mechanisms = $sasl->mechanism();
+ if (! defined($requested_mechanisms) || $requested_mechanisms eq '') {
+ $sasl->mechanism($mechanisms);
+ }
}
else {
die "auth(username, password)" if not length $username;
-=- cut here -=-
(viz rather than explicitly forcing the methods set them only if the
provided object doesn't have any set).
Ewen
DIGEST-MD5 auth failing against (at least) Sendmail 8.14:
Given a trivial test script against test.smtp.org
(http://test.smtp.org/), using MIME::Lite which then calls Net::SMTP
when in "smtp" mode:
-=- cut here -=-
#! /usr/bin/env perl
use MIME::Lite;
use Authen::SASL;
my $auth = Authen::SASL->new(# mechanism => 'CRAM-MD5 LOGIN PLAIN',
callback => { user => 'user17',
pass => 'pass17',
authname => 'user17' });
MIME::Lite->send('smtp', 'test.smtp.org',
AuthUser => $auth, AuthPass => 'pass16');
my $msg = MIME::Lite->new(
From => 'user@example.com',
To => 'bit-bucket@test.smtp.org',
Subject => 'Test relayed message',
Type => 'multipart/mixed',
Datestamp => 0, # Let mailserver
create Date:
) || die "Unable to create new message: $!\n"; # Else need
Mail::Date::Format
$msg->attach(
Type => 'TEXT',
Data => 'Test message from MIME::Lite',
);
print $msg->as_string;
$msg->send();
-=- cut here -=-
the message will fail to be delivered with:
SMTP mail() command failed:
because the remote Sendmail server closes the connection after doing
DIGEST-MD5 and receiving the MAIL FROM: line (even though it reports
that the SMTP AUTH was successful).
TCP session looks like:
-=- cut here -=-
220 test.smtp.org ESMTP Sendmail 8.14.4.Alpha1 ready at Mon, 31 May 2010
13:59:01 -0700 (PDT); see http://test.smtp.org/
EHLO localhost.localdomain
250-test.smtp.org Hello 203-167-144-68.cable.telstraclear.net
[203.167.144.68], pleased to meet you
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-EXPN
250-VERB
250-8BITMIME
250-SIZE
250-DSN
250-ETRN
250-AUTH DIGEST-MD5 CRAM-MD5 PLAIN LOGIN ANONYMOUS
250-STARTTLS
250-DELIVERBY
250 HELP
AUTH DIGEST-MD5
334
bm9uY2U9Ik5KYWh6dUVaNDkwcEpFYzhDUWlpc0pYQlVvdjFMYUVDd0VpVjJlYk0vOFU9IixyZWFsbT0idGVzdC5zbXRwLm9yZyIscW9wPSJhdXRoLGF1dGgtaW50LGF1dGgtY29uZiIsY2lwaGVyPSJyYzQtNDAscmM0LTU2LHJjNCxkZXMsM2RlcyIsbWF4YnVmPTgxOTIsY2hhcnNldD11dGYtOCxhbGdvcml0aG09bWQ1LXNlc3M=
YXV0aHppZD0idXNlcjE2IixjaGFyc2V0PXV0Zi04LGNub25jZT0iYzE3MDgxNDE4YmQ0MzE1YjZkMzMxYTUzMDY1YmNlN2UiLGRpZ2VzdC11cmk9InNtdHAvdGVzdC5zbXRwLm9yZyIsbmM9MDAwMDAwMDEsbm9uY2U9Ik5KYWh6dUVaNDkwcEpFYzhDUWlpc0pYQlVvdjFMYUVDd0VpVjJlYk0vOFU9Iixxb3A9YXV0aC1pbnQscmVhbG09InRlc3Quc210cC5vcmciLHJlc3BvbnNlPWU2ZjJjZDFlNTM4MzQxOTA4OTI3YTAxZDg3ZmIwOTFmLHVzZXJuYW1lPSJ1c2VyMTYi
334 cnNwYXV0aD04YTU5NTFmNWRhM2U1NzgxNDA4YTg3MmNlYjZiODc4NQ==
235 2.0.0 OK Authenticated
MAIL FROM:<test@example.com>
-=- cut here -=-
Logs from mail server look like:
-=- cut here -=-
May 31 14:22:55 zim testmail[1613]: AUTH=server,
relay=203-167-144-68.cable.telstraclear.net [203.167.144.68],
authid=user17, mech=DIGEST-MD5, bits=1
May 31 14:22:55 zim testmail[1613]: encoded packet size too big
(1296124236 > 8192)
May 31 14:22:55 zim testmail[1613]: AUTH: sasl_decode error=-1
May 31 14:22:55 zim testmail[1613]: o4VLMsgN001613:
203-167-144-68.cable.telstraclear.net [203.167.144.68] did not issue
MAIL/EXPN/VRFY/ETRN during connection to testv4
-=- cut here -=-
This also fails to another Sendmail SMTP Server used by a client, which
is where I first encountered the problem.
SMTP AUTH Digest-MD5 does work to both servers using, eg, msmtp
(http://msmtp.sourceforge.net/) so the servers do appear to have working
DIGEST-MD5 support.