Running two different POP3 servers with my script: pop3switch

Bruno Negrão Tue, 05 Oct 2004 12:17:12 -0700

Hi guys,

I'm migrating a Qmail + Vpopmail mail server to a Qmail-ldap installation.

Before I completely migrate all the domains to qmail-ldap, the two different qmailservers will coexist in the same machine.

In order to deal with the POP3 users, i wrote the perl script bellow and I'd like you to comment it.

See you,
bruno negr�o.

#!/usr/bin/perl -w # # /bin/pop3switch - switches the authorization/popup of POP3 users between two # different qmail-pop3d servers running in the same machine # # SYNOPSIS # /bin/pop3switch --server1-exec "COMMANDLINE1" --server1-user "USERNAME1" \ # --server1-domainslistfile "PATH_TO_FILE" \ # --server2-exec "COMMANDLINE2" --server2-user "USERNAME2" # # DESCRIPTION # This program is designed to help in the situation when a given host # has two different Qmail servers running, we gonna call them "server1" # and "server2". For example, server1 could be a qmail-ldap # server, and server2 could be an installation of Qmail + Vpopmail. # pop3switch provides a means for authenticating and getting messages # of the POP3 users from both servers. # Also, it will execute COMMANDLINEX under the UserID and GroupID of # the user specified by the --serverX-user option. # # HOW DOES IT DISTINGUISH WHICH SERVER OWNS EACH ACCOUNT # When the mail server receives a pop3 client connecting on port 110, tcpserver # will be listening on this port, then it will invoke qmail-popup which, in turn, # will interact with the client and catch the user/password information. # qmail-popup will call pop3switch and pass this information to it. # Finally, to discover if this POP3 user pertains to server1 or server2, # pop3switch will check if the user's domain is listed in the file set # with the --server1-domainslistfile option. # If the user's domain is not listed in this file, pop2switch assume this # user pertains to server2. # When it decides which server to use, pop3switch gonna exec the program specified # by --serverX-exec option. # # HOW TO USE IT # Call this program from the /service/qmail-pop3d/run file, in substitution of # the authorization program you're using there. Bellow, see an example of # "tcpserver" calling pop3switch to switch between a Qmail-ldap pop3d and # a Qmail + Vpopmail pop3d: # # tcpserver -u 0 -g 0 0 110 \ # /var/qmail/bin/qmail-popup $DOMAINNAME \ # /bin/pop3switch \ # --server1-exec "/var/qmldap/bin/auth_pop /var/qmldap/bin/qmail-pop3d Maildir" \ # --server1-user "qmldapv" \ # --server1-domainslistfile "/var/qmldap/control/ldapdomains" \ # --server2-exec "/var/vpopmail/bin/vchkpw /var/qmail/bin/qmail-pop3d Maildir" \ # --server2-user "vpopmail" # # ERROR MESSAGES # This program prints its error messages to a file called /tmp/pop3switch_error. It can't # just print them to standard out since it will be connected to the network when this program # is executed. # # KNOWN LIMITATIONS # - pop3switch expects to receive an email in the format: "[EMAIL PROTECTED]". It won't # work with e-mails in different formats. # - To increase performance, pop3switch won't check the validity of the arguments # it receives. Check them yourself carefully. # # SECURITY LIMITATIONS # - pop3switch must be run as root. # - When it passes the username/password to the pop3 server executable, this information # can be seen with the "ps -ef" command. # # DEPENDENCIES # DJ Bernstein's Daemontools package is required for the use of 'setuidgid' executable # # AUTHOR # Bruno Negr�o - vpopmail at engepel.com.br # # LAST MODIFIED # 10/05/2004 ########################################################################################## use strict;

# subroutine prototypes sub my_die($); # prints the error message in /tmp/pop3switch_error file and dies.

# setuidgid's path
my $SETUIDGID = "/usr/local/bin/setuidgid";

# check for its existence my_die "$0: ERROR: cannot find $SETUIDGID. If you don't have daemontools installed in your" . " system, install it. If it's installed in a path different than '/usr/local/bin'," . " then edit the pop3switch's '\$SETUIDGID' variable to reflect the right path.\n" if (! -x $SETUIDGID);

# getting the arguments
my %ARG = @ARGV;

# Option Variables
my $SERVER1_EXEC = $ARG{"--server1-exec"};
my $SERVER2_EXEC = $ARG{"--server2-exec"};
my $SERVER1_USER = $ARG{"--server1-user"};
my $SERVER2_USER = $ARG{"--server2-user"};
my $SERVER1_DOMAINSLISTFILE = $ARG{"--server1-domainslistfile"};

# check for the passed arguments validity
if ( (my $error = checkAllArguments()) ) {
   my_die "$error";
}

# 1 - We read the user/password input from qmail-popup in the # descriptor 3 and store it in a variable my $qmail_popup_input; # input read from qmail-popup open(FH, "<&=3") or my_die "$0: ERROR: I couldn't open descriptor 3 for reading.\n"; binmode (FH); $qmail_popup_input = <FH>; close FH;

# 2 - Now we parse this input, breaking it in user, password and
# timestamp (these fields are separated by NUL characters)
my ($user, $pwd, $time) = ( split(/\x00/, $qmail_popup_input) );

# 3 - Now we extract the domain name from the username
my $domain = (split(/\@/, $user))[1];

# 4 - Check if this domain is in server1's database. If it is, # sets the variable $IS_DOMAIN_IN_SERVER1 to 1. For doing this, we gonna # search for this domain in the $SERVER1_DOMAINSLISTFILE my $IS_DOMAIN_IN_SERVER1 = 0; # says if $domain is in the LDAP database open (LDF, "<$SERVER1_DOMAINSLISTFILE") or my_die "$0: ERROR: I couldn't open the file ". "$SERVER1_DOMAINSLISTFILE for reading.\n"; while (<LDF>) { chomp; # no newline s/#.*//; # no comments s/^\s+//; # no leading white s/\s+$//; # no trailing white next unless length; if ( /^$domain$/ ) { $IS_DOMAIN_IN_SERVER1 = 1; last; } }

# 5 - Escaping the <, >, and \0 caracters: $time =~ s/([<>])/\\$1/g; # escaping $time # escaping qmail-popup input to feed shell: my $qmail_popup_input_escaped = $user . '\\\\000' . $pwd . '\\\\000' . $time . '\\\\000';

# 6 - Choose the apropriate command line to execute
my $CMD_LINE = "$SETUIDGID ";
$CMD_LINE .= ($IS_DOMAIN_IN_SERVER1 ?
   "$SERVER1_USER $SERVER1_EXEC"   :
   "$SERVER2_USER $SERVER2_EXEC");

# 7 - exec the AUTH program, taking care to maintain the descriptors 0 and 1 # connected to the network and to read the user/pwd info from descriptor 3 exec (qq(exec 4<&0; echo -ne $qmail_popup_input_escaped | $CMD_LINE 3<&0 0<&4 4<&-));

sub my_die($) {
   my $msg = shift;
   my $error_file = "/tmp/pop3switch_error";
   open (ERROR, "> $error_file");
   print ERROR $msg;
   die "\n";
}

sub checkAllArguments { sub error { my $opt = shift; return "$0: ERROR: The option $opt is not correctly set up.\n"; } unless ( $SERVER1_EXEC ) { return error("--server1-exec"); } unless ( $SERVER2_EXEC ) { return error("--server2-exec"); } unless ( $SERVER1_USER ) { return error("--server1-user"); } unless ( $SERVER2_USER ) { return error("--server2-user"); } unless ( $SERVER1_DOMAINSLISTFILE ) { return error("--server1-domainslistfile"); } return ""; }

Running two different POP3 servers with my script: pop3switch

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