#!/usr/bin/perl -T #---------------------------------------------------------------------- # Pull mails from an IMAP mailbox and deliver them to a SMTP session # Copyright © 2016 Guilhem Moulin # # This program is free software: you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation, either version 3 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program. If not, see . #---------------------------------------------------------------------- use strict; use warnings; our $VERSION = '0.3'; my $NAME = 'pullimap'; use Errno 'EINTR'; use Fcntl qw/O_CREAT O_RDWR O_DSYNC F_SETLK F_WRLCK SEEK_SET F_GETFD F_SETFD FD_CLOEXEC/; use Getopt::Long qw/:config posix_default no_ignore_case gnu_getopt auto_version/; use List::Util 'first'; use Socket qw/PF_INET PF_INET6 SOCK_STREAM/; use Net::IMAP::InterIMAP qw/read_config compact_set/; # Clean up PATH $ENV{PATH} = join ':', qw{/usr/bin /bin}; delete @ENV{qw/IFS CDPATH ENV BASH_ENV/}; my %CONFIG; sub usage(;$) { my $rv = shift // 0; if ($rv) { print STDERR "Usage: $NAME [OPTIONS] SECTION\n" ."Try '$NAME --help' or consult the manpage for more information.\n"; } else { print STDERR "Usage: $NAME [OPTIONS] SECTION\n" ."Consult the manpage for more information.\n"; } exit $rv; } usage(1) unless GetOptions(\%CONFIG, qw/config=s quiet|q debug help|h idle:i no-delivery/); usage(0) if $CONFIG{help}; usage(1) unless $#ARGV == 0 and $ARGV[0] ne '_'; ####################################################################### # Read and validate configuration # my $CONF = read_config( delete $CONFIG{config} // $NAME, , [$ARGV[0]] , statefile => qr/\A(\P{Control}+)\z/ , mailbox => qr/\A([\x01-\x7F]+)\z/ , 'deliver-method' => qr/\A([ls]mtp:\[.*\]:\d+)\z/ , 'deliver-ehlo' => qr/\A(\P{Control}+)\z/ , 'deliver-rcpt' => qr/\A(\P{Control}+)\z/ , 'purge-after' => qr/\A(\d*)\z/ )->{$ARGV[0]}; my ($MAILBOX, $STATE); do { $MAILBOX = $CONF->{mailbox} // 'INBOX'; my $statefile = $CONF->{statefile} // $ARGV[0]; die "Missing option statefile" unless defined $statefile; $statefile = $statefile =~ /\A(\p{Print}+)\z/ ? $1 : die "Insecure $statefile"; unless ($statefile =~ /\A\//) { my $dir = ($ENV{XDG_DATA_HOME} // "$ENV{HOME}/.local/share") .'/'. $NAME; $dir = $dir =~ /\A(\/\p{Print}+)\z/ ? $1 : die "Insecure $dir"; $statefile = $dir .'/'. $statefile; unless (-d $dir) { mkdir $dir, 0700 or die "Can't mkdir $dir: $!\n"; } } sysopen($STATE, $statefile, O_CREAT|O_RDWR|O_DSYNC, 0600) or die "Can't open $statefile: $!"; # XXX we need to pack the struct flock manually: not portable! my $struct_flock = pack('s!s!l!l!i!', F_WRLCK, SEEK_SET, 0, 0, 0); fcntl($STATE, F_SETLK, $struct_flock) or die "Can't lock $statefile: $!"; my $flags = fcntl($STATE, F_GETFD, 0) or die "fcntl F_GETFD: $!"; fcntl($STATE, F_SETFD, $flags | FD_CLOEXEC) or die "fcntl F_SETFD: $!"; }; ####################################################################### # Read a UID (32-bits integer) from the statefile, or undef if we're at # the end of the statefile sub readUID() { my $n = sysread($STATE, my $buf, 4) // die "Can't sysread: $!"; return if $n == 0; # EOF # file length is a multiple of 4 bytes, and we always read 4 bytes at a time die "Corrupted state file!" if $n != 4; unpack('N', $buf); } # Write a UID (32-bits integer) to the statefile sub writeUID($) { my $uid = pack('N', shift); my $offset = 0; for ( my $offset = 0 ; $offset < 4 ; $offset += syswrite($STATE, $uid, 4-$offset, $offset) // die "Can't syswrite: $!" ) {} # no need to sync (or flush) since $STATE is opened with O_DSYNC } ####################################################################### # SMTP/LMTP part # my ($SMTP, $SMTP_PIPELINING); sub sendmail($$) { my ($from, $rfc822) = @_; unless (defined $SMTP) { # TODO we need to be able to reconnect when the server closes # the connection due to a timeout (RFC 5321 section 4.5.3.2) my ($fam, $addr) = (PF_INET, $CONF->{'deliver-method'} // 'smtp:[127.0.0.1]:25'); $addr =~ s/^([ls]mtp):// or die; my $ehlo = $1 eq 'lmtp' ? 'LHLO' : $1 eq 'smtp' ? 'EHLO' : die; $ehlo .= ' '. ($CONF->{'deliver-ehlo'} // 'localhost.localdomain'); my $port = $addr =~ s/:(\d+)$// ? $1 : die; $addr =~ s/^\[(.*)\]$/$1/ or die; $fam = PF_INET6 if $addr =~ /:/; $addr = Socket::inet_pton($fam, $addr) // die "Invalid address $addr\n"; my $sockaddr = $fam == PF_INET ? Socket::pack_sockaddr_in($port, $addr) : $fam == PF_INET6 ? Socket::pack_sockaddr_in6($port, $addr) : die; my $proto = getprotobyname("tcp") // die; socket($SMTP, $fam, SOCK_STREAM, $proto) or die "socket: $!"; until (connect($SMTP, $sockaddr)) { next if $! == EINTR; # try again if connect(2) was interrupted by a signal die "connect: $!"; } binmode($SMTP) // die "binmode: $!"; smtp_resp('220'); my @r = smtp_send($ehlo => '250'); $SMTP_PIPELINING = grep {$_ eq 'PIPELINING'} @r; # SMTP pipelining (RFC 2920) } my $rcpt = $CONF->{'deliver-rcpt'} // getpwuid($>) // die; # return codes are from RFC 5321 section 4.3.2 smtp_send( "MAIL FROM:<$from>" => '250' , "RCPT TO:<$rcpt>" => '250' , "DATA" => '354' ); print STDERR "C: [...]\n" if $CONFIG{debug}; if ($$rfc822 eq '') { # RFC 5321 section 4.1.1.4: if there was no mail data, the first # "\r\n" ends the DATA command itself $SMTP->printflush("\r\n.\r\n") or die; } else { my $offset = 0; my $length = length($$rfc822); while ((my $end = index($$rfc822, "\r\n", $offset) + 2) != 1) { my $line = substr($$rfc822, $offset, $end-$offset); # RFC 5321 section 4.5.2: the character sequence "\r\n.\r\n" # ends the mail text and cannot be sent by the user $SMTP->print($line eq ".\r\n" ? "..\r\n" : $line) or die; $offset = $end; } if ($offset < $length) { # the last line did not end with "\r\n"; add it in order to # have the receiving SMTP server recognize the "end of data" # condition. See RFC 5321 section 4.1.1.4 my $line = substr($$rfc822, $offset); $SMTP->print(($line eq "." ? ".." : $line), "\r\n") or die; } $SMTP->printflush(".\r\n") or die; } smtp_resp('250'); } sub smtp_resp($) { my $code = shift; my @resp; while(1) { local $_ = $SMTP->getline() // die; s/\r\n\z// or die "Invalid SMTP reply: $_"; print STDERR "S: $_\n" if $CONFIG{debug}; s/\A\Q$code\E([ -])// or die "SMTP error: Expected $code, got: $_\n"; push @resp, $_; return @resp if $1 eq ' '; } } sub smtp_send(@) { my (@cmd, @code, @r); while (@_) { push @cmd, shift // die; push @code, shift // die; } if ($SMTP_PIPELINING) { # SMTP pipelining (RFC 2920) print STDERR (map {"C: $_\n"} @cmd) if $CONFIG{debug}; $SMTP->printflush(map {"$_\r\n"} @cmd) or die; @r = smtp_resp($_) foreach @code; } else { foreach (@cmd) { print STDERR "C: $_\n" if $CONFIG{debug}; $SMTP->printflush("$_\r\n") or die; @r = smtp_resp(shift(@code)); } } return @r; } ####################################################################### # Initialize the cache from the statefile, then pull new messages from # the remote mailbox # my $IMAP = do { my %config = (%$CONF, %CONFIG{qw/quiet debug/}, name => $ARGV[0]); $config{keepalive} = 1 if defined $CONFIG{idle}; $config{'logger-fd'} = \*STDERR if $CONFIG{debug}; Net::IMAP::InterIMAP::->new( %config ); }; # Remove messages with UID < UIDNEXT and INTERNALDATE at most # $CONF->{'purge-after'} days ago. my $LAST_PURGED; sub purge() { my $days = $CONF->{'purge-after'} // return; my ($uidnext) = $IMAP->get_cache('UIDNEXT'); return unless $days ne '' and 1<$uidnext; my $set = "1:".($uidnext-1); unless ($days == 0) { my $now = time; return if defined $LAST_PURGED and $now - $LAST_PURGED < 43200; # purge every 12h $LAST_PURGED = $now; my @now = gmtime($now - $days*86400); my @m = qw/Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec/; # RFC 3501's date-month my $date = sprintf("%02d-%s-%04d", $now[3], $m[$now[4]], $now[5]+1900); my @uid = $IMAP->search("UID $set BEFORE $date"); $set = @uid ? compact_set(@uid) : undef; $IMAP->log("Removing ".($#uid+1)." UID(s) $set") if defined $set and !$CONFIG{quiet}; } if (defined $set) { $IMAP->silent_store($set, '+', '\Deleted'); $IMAP->expunge($set); } # pull messages that have been received in the meantime pull() if $IMAP->has_new_mails($MAILBOX); } # Use BODY.PEEK[] so if something gets wrong, unpulled messages # won't be marked as \Seen in the mailbox my $ATTRS = "ENVELOPE INTERNALDATE"; $ATTRS .= " BODY.PEEK[]" unless $CONFIG{'no-delivery'}; sub pull_callback($$) { my ($uids, $mail) = @_; return unless exists $mail->{RFC822} or $CONFIG{'no-delivery'}; # not for us my $uid = $mail->{UID}; my $from = first { defined $_ and @$_ } @{$mail->{ENVELOPE}}[2,3,4]; $from = (defined $from and @$from) ? $from->[0]->[2].'@'.$from->[0]->[3] : ''; $IMAP->log("UID $uid from <$from> ($mail->{INTERNALDATE})") unless $CONFIG{quiet}; sendmail($from, $mail->{RFC822}) unless $CONFIG{'no-delivery'}; push @$uids, $uid; writeUID($uid); } # Pull new messages from IMAP and deliver them to SMTP, then update the # statefile sub pull(;$) { my $ignore = shift // []; my @uid; my $callback = sub($) { pull_callback(\@uid, shift) }; do { # invariant: we're at pos 8 + 4*(1+$#ignore + 1+$#uids) in the statefile $IMAP->pull_new_messages($ATTRS, $callback, @$ignore); # now that everything has been deliverd, mark @ignore and @uid as \Seen $IMAP->silent_store(compact_set(@$ignore, @uid), '+', '\Seen') if @$ignore or @uid; } # repeat if we got a message in the meantime while ($IMAP->has_new_mails($MAILBOX)); # terminate the SMTP transmission channel gracefully, cf RFC 5321 section 4.5.3.2 smtp_send('QUIT' => '221') if defined $SMTP; undef $SMTP; # update the statefile my $p = sysseek($STATE, 4, SEEK_SET) // die "Can't seek: $!"; die "Couldn't seek to 4" unless $p == 4; # safety check my ($uidnext) = $IMAP->get_cache('UIDNEXT'); writeUID($uidnext); truncate($STATE, 8) // die "Can't truncate"; } do { my $uidvalidity = readUID(); my $uidnext = readUID(); my $ignore = []; $IMAP->set_cache($MAILBOX, UIDVALIDITY => $uidvalidity, UIDNEXT => $uidnext); $IMAP->select($MAILBOX); unless (defined $uidvalidity) { ($uidvalidity) = $IMAP->get_cache('UIDVALIDITY'); # we were at pos 0 before the write, at pos 4 afterwards writeUID($uidvalidity); die if defined $uidnext; # sanity check } if (!defined $uidnext) { # we were at pos 4 before the write, at pos 8 afterwards writeUID(1); } else { # put the remaining UIDs in the @ignore list: these messages # have already been delivered, but the process exited before the # statefile was updated while (defined (my $uid = readUID())) { push @$ignore, $uid; } } pull($ignore); purge(); }; unless (defined $CONFIG{idle}) { $IMAP->logout(); exit 0; } $CONFIG{idle} = 1740 if defined $CONFIG{idle} and $CONFIG{idle} == 0; # 29 mins while(1) { pull() if $IMAP->idle($CONFIG{idle}, \&Net::IMAP::InterIMAP::has_new_mails); purge(); }