An SMTP Simulator in Perl

smtpsim.pl
Copy and paste the code from the text area below to smtpsim.pl

# Jim Lawless

# jimbo@radiks.net

# http://www.radiks.net/~jimbo

use Socket;

$port = 25;

$sockaddr = 'S n a4 x8';

$authcount=0;

($name, $aliases, $proto) = getprotobyname('tcp');

print "Port = $port\n";

$thisaddr = gethostbyname('localhost');

$this = pack($sockaddr, AF_INET, $port, $thisaddr);

if (socket(S, AF_INET, SOCK_STREAM, $proto)) {

print "socket ok\n";

}

bind(S,$this) || die "bind: $!";

listen(S,5) || die "connect: $!";

select(S); $| = 1; select(stdout);

for(;;) {

print "Listening for connection....\n";

($addr = accept(NS,S)) || die $!;

#select(NS); $| = 1; select(stdout);

send(NS,"200 okey-dokey\r\n",0);

print "accept ok\n";

($af,$port,$inetaddr) = unpack($sockaddr,$addr);

@inetaddr = unpack('C4',$inetaddr);

print "$af $port @inetaddr\n";

$ctr=0;

while ($t=<NS>) {

$ctr++;

if( substr($t,0,4) eq "QUIT") {

last;

}

print $t;

print FIL $t;

if( substr($t,0,1) eq '.') {

send(NS,"200 okey-dokey\r\n",0);

next;

}

$x=substr($t,0,4);

if( ($x eq "HELO") || ($x eq "RCPT") || ($x eq "MAIL") ||

($x eq "RSET") || ($x eq "DATA") || ($x eq "QUIT")) {

send(NS,"200 "  . $t .  " okey-dokey\r\n",0);

}

close(NS);

}

I use the above code to tinker with my command-line e-mail client MailSend.

I use this script and variations of it to simulate various SMTP conditions to ensure that MailSend can appropriately handle various kinds of exceptions.

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