Re: I've thought better of Linux

Ulrich Hobelmann <u.hobelmann@xxxxxx> writes:
> After all, what huge amounts of work does a mail server do? Not THAT
> much, accepting SMTPs, putting it into files for local users, having
> an outgoing queue that gets delivered if the remote server is
> responsive, then some firewall-like filtering options, like what mail
> to reject. Where's the immense inherent complexity of the application
> domain? Where would it be in a web server, or in an FTP?

Who needs anything else than telnet remote.host 25 to send email?

And to receive:

#!/bin/bash
#*****************************************************************************
#FILE: smtpd.sh
#LANGUAGE: sh
#SYSTEM: POSIX
#USER-INTERFACE: NONE
#DESCRIPTION
#
# A very SIMPLE mail transfer agent.
#
# Put in inetd.conf:
# smtp stream tcp nowait mail /usr/local/bin/smtpd.sh smtpd.sh
#
#AUTHORS
# <PJB> Pascal Bourguignon <pjb@xxxxxxxxxxxxxxxxx>
#MODIFICATIONS
# 2003-09-04 <PJB> Created.
#BUGS
#LEGAL
# GPL
#
# Copyright Pascal Bourguignon 2003 - 2003
#
# 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
# 2 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, write to the Free
# Software Foundation, Inc., 59 Temple Place, Suite 330,
# Boston, MA 02111-1307 USA
#*****************************************************************************

mailboxes=/tmp/var/spool/mail
mkdir -p "$mailboxes" >/dev/null 2>&1 || true
echo "220 `hostname` SMTP SIMPLE mail transport agent Version 1.0"

done=0
while [ $done -eq 0 ] ; do
read command arguments
command="$(echo "$command" | tr -d '\015')"
arguments="$(echo "$arguments" | tr -d '\015')"
case "$command" in
[hH][eE][lL][oO]) echo "250 Hi $arguments" ; done=1 ;;
*) echo "503 Bad command" ;;
esac
done

s_idle=0 ; s_from=1 ; s_rcpt=2
state=$s_idle
while true ; do
read command arguments
command="$(echo "$command" | tr -d '\015')"
arguments="$(echo "$arguments" | tr -d '\015')"
case "$command" in
[Mm][Aa][Ii][Ll])
if [ 0 -eq $(( $state & $s_from )) ] ; then
from=$(echo "$arguments" | sed -e 's/^ *[Ff][Rr][Oo][Mm] *: *//')
state=$(( $state | $s_from ))
echo "250 OK"
else
echo "503 Bad sequence of commands."
fi
;;
[Rr][Cc][Pp][Tt])
if [ $s_from -eq $(( $state & ( $s_from | $s_rcpt ) )) ] ; then
to=$(echo "$arguments" | sed -e 's/^ *[Tt][Oo] *: *//')
state=$(( $state | $s_rcpt ))
echo "250 OK"
else
echo "503 Bad sequence of commands."
fi
;;
[Dd][Aa][Tt][Aa])
if [ $(( $s_from | $s_rcpt )) -eq $(( $state & ( $s_from | $s_rcpt ) )) ] ; then
file="${mailboxes}/$(echo "$to" | sed -e 's/^ *< *//' -e 's/ *> *$/\1/' -e 's/@.*//')"
echo "From $from `date '+%a %b %d %H:%M:%S %Y'`" >> "$file"
echo "354 Enter mail, end with <CR><LF>.<CR><LF>"
data=1
while [ $data -eq 1 ] ; do
read line
line="$(echo "$line" | tr -d '\015')"
if [ "$line" = "." ] ; then
data=0
state=$s_idle
echo "" >> "$file"
echo "250 OK"
else
echo "$line" >> "$file"
fi
done
else
echo "503 Bad sequence of commands."
fi
;;
[Nn][Oo][Oo][Pp]) echo "250 OK" ;;
[Rr][Ss][Ee][Tt]) state=$s_idle ; echo "250 OK" ;;
[Vv][Rr][Ff][Yy]) echo "252 Cannot VRFY." ;;
[Qq][Uu][Ii][Tt]) echo "221 Bye" ; exit 0 ;;
*) echo "502 Command not implemented." ;;
esac
done
#### smtpd.sh -- 2003-09-04 19:20:50 -- pascal ####

--
__Pascal Bourguignon__ http://www.informatimago.com/
Kitty like plastic.
Confuses for litter box.
Don't leave tarp around.
.

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