git-send-email and "mailhost" misbehavior

Mike Frysinger· Nov 15, 2010, 20:24 UTC · lore

i have sendemail in my ~/.gitconfig setup like so:
[sendemail]
    smtpserver = localhost:1111

and i have a ssh tunnel running there to forward my e-mail to another machine's localhost:25

however, when i attempt to send e-mail from some systems, the `git send-email` process pauses for like 2 minutes without doing anything. after hassling my e-mail admin about greylisting (which is disabled for localhost), i looked at git-send-email a bit closer.

running it through a heavy strace shows the source of the pause: connect(6, {sa_family=AF_INET, sin_port=htons(25), sin_addr=inet_addr("208.68.139.38")}, 16) then there's a timeout after 120 seconds trying to connect to this guy

so wtf is "208.68.139.38" !? well, my shitty ISP (comcast) is doing DNS hijacking for unresolved DNS names. so git-send-email tried to look up some host and it got back "208.68.139.38". while comcast is wrong here, why is git-send-email looking up anything at all considering my sendemail.smtpserver is configured to localhost ?

it seems that buried in the bowels of git-send-email and totally
undocumented is this nugget:
/usr/libexec/git-core/git-send-email:
...
sub maildomain_mta {
    my $maildomain;

    if (eval { require Net::SMTP; 1 }) {
        for my $host (qw(mailhost localhost)) {
            my $smtp = Net::SMTP->new($host);
...

so git-send-email is so kind as to attempt port 25 connections to "mailhost:25" and "localhost:25" while attempting to locate its FQDN !? this doesnt sound right at all. DNS lookups do not require actual TCP/IP connection attempts.

stubbing out "mailhost" to 127.0.0.1 in /etc/hosts fixes my troubles. -mike

Junio C Hamano· Nov 16, 2010, 19:06 UTC · re: Mike Frysinger · lore

Re: git-send-email and "mailhost" misbehavior

Mike Frysinger <vapier@gentoo.org> writes:

Show 42 quoted lines

> i have sendemail in my ~/.gitconfig setup like so:
> [sendemail]
>     smtpserver = localhost:1111
>
> and i have a ssh tunnel running there to forward my e-mail to another
> machine's localhost:25
>
> however, when i attempt to send e-mail from some systems, the `git
> send-email` process pauses for like 2 minutes without doing anything.
> after hassling my e-mail admin about greylisting (which is disabled
> for localhost), i looked at git-send-email a bit closer.
>
> running it through a heavy strace shows the source of the pause:
> connect(6, {sa_family=AF_INET, sin_port=htons(25),
> sin_addr=inet_addr("208.68.139.38")}, 16)
> then there's a timeout after 120 seconds trying to connect to this guy
>
> so wtf is "208.68.139.38" !?  well, my shitty ISP (comcast) is doing
> DNS hijacking for unresolved DNS names.  so git-send-email tried to
> look up some host and it got back "208.68.139.38".  while comcast is
> wrong here, why is git-send-email looking up anything at all
> considering my sendemail.smtpserver is configured to localhost ?
>
> it seems that buried in the bowels of git-send-email and totally
> undocumented is this nugget:
> /usr/libexec/git-core/git-send-email:
> ...
> sub maildomain_mta {
>     my $maildomain;
>
>     if (eval { require Net::SMTP; 1 }) {
>         for my $host (qw(mailhost localhost)) {
>             my $smtp = Net::SMTP->new($host);
> ...
>
> so git-send-email is so kind as to attempt port 25 connections to
> "mailhost:25" and "localhost:25" while attempting to locate its FQDN
> !?  this doesnt sound right at all.  DNS lookups do not require actual
> TCP/IP connection attempts.
>
> stubbing out "mailhost" to 127.0.0.1 in /etc/hosts fixes my troubles.
> -mike

Redirecting to Jari Aalto for 134550f (git-send-email.perl - try to give real name of the calling host to HELO/EHLO, 2010-03-14)