#!/bin/sh
#
# This script is called when dhcp connects to the network.
#		 
# Here is where we'll start sendmail if needed, and will
# run the queue in either case.
#
# Written By Richard Nelson <cowboy@debian.org>
#
# NOTE: The following lines (without the #) must be in /etc/mail/sendmail.mc:
# include(`/etc/mail/dialup.m4')dnl
# include(`/etc/mail/provider.m4')dnl
#
# NOTE: The dhcp DNS name is used as the peer name in /etc/mail/peers.
#
# Exit by default, check for validity before commenting out the next line:
exit 0;

provider_m4='/etc/mail/provider.m4';
#provider_m4='provider.m4';
dialup_m4='/etc/mail/dialup.m4';
#dialup_m4='dialup.m4';

update_sendmail() {
	# Build a new sendmail.cf from sendmail.mc, including our address.
	m4 /etc/mail/sendmail.mc \
		> /etc/mail/sendmail.cf.pnew;
	chmod 0644 /etc/mail/sendmail.cf.pnew;
	chown mail:mail /etc/mail/sendmail.cf.pnew;
	mv -f /etc/mail/sendmail.cf.pnew /etc/mail/sendmail.cf;

	# Purge any latent host status that might cause us to *NOT* send mail
	AM='-Am';
	if [ ! -f /usr/share/sendmail/cf/feature/msp.m4 ]; then
		AM='';
		fi;
	sendmail $AM -bH -O Timeout.hoststatus=1s;

	# Start/reload sendmail as needed
	/etc/init.d/sendmail reload;            # may be up, or down

	# Process the sendmail queue 
	# (background so as to not defer other ip-up work)
	runq &
	};

update_provider() {
	# Add smarthost information (if any)...
	# But not if provider.m4 is a link !
	local domain;
	domain="$1";
	if [ -f /etc/mail/peers/$domain -a ! -L $provider_m4 ]; then
		cat <<-EOT > $provider_m4;
			LOCAL_CONFIG
			#------------------------------------------------------------
			#
			# Dynamic provider updates from $0 
			#
			# NOTE: the following line *MUST* be in /etc/mail/sendmail.mc
			dnl include(\`/etc/mail/provider.m4')dnl
			#
			# Provider information from /etc/mail/peers/$domain
			EOT
		cat /etc/mail/peers/$domain >> $provider_m4;
		cat <<-EOT >> $provider_m4;
			#------------------------------------------------------------
			EOT
		fi;
	};

find_host() {
	# Determine our fqdn from our ISP
	local addr;
	addr="$1";
	maxloop=20; 
	cntr=0;
	host='';
	until (test ! -z "$host"); do
		cntr=$(($cntr+1));      
		rev=$(host $addr);
		host=$(echo "$rev" | grep '^Name:' | awk '{print $2}');
		if [ -z "$host" ]; then
			host=${rev##*domain name pointer };
			host=${host%.};
			fi;
		test=$(echo $host | cut -d ' ' -f 1);
		if [ "$host" != "**" ]; then 
			break;
		elif (($cntr > $maxloop)); then
			host='';
			break;
			fi;
		done;
	echo "addr=$addr,       name=$host";
	};

update_host() {
	local host ip;
	ip="$1";
	find_host "$ip";
	if [ ! -z "$host" ]; then
		cat <<-EOT > $dialup_m4;
			LOCAL_CONFIG
			#------------------------------------------------------------
			#
			# Dynamic host/ip updates from $0
			#
			# NOTE: the following line *MUST* be in /etc/mail/sendmail.mc
			dnl include(\`/etc/mail/dialup.m4')dnl
			#
			# Chose one of the following two options:
			#  * Add our true hostname as a Virtual Host (we'll accept
			#    mail for it, but keep our local name for SMTP AUTH, etc)
			C{VirtHost}$host
			#
			#  * Define our true hostname (from our ISP) - becomes \$j
			dnl define(\`confDOMAIN_NAME', \`$host')dnl
			#
			# Make sure we accept mail as this name (for bounces, etc)
			Cw$host
			Cw$ip
			# Add our hostname to class G for genericstable support
			CG$host
			#------------------------------------------------------------
			EOT
		fi;
	};

# No need to continue if we're called with an unsupported option
if [ "$reason" != BOUND ] && [ "$reason" != RENEW ] \
   && [ "$reason" != REBIND ] && [ "$reason" != REBOOT ] \
   && [ "$reason" != EXPIRE ] && [ "$reason" != FAIL ]
   then
	return;
	fi;

# Flag to denote changed have been made;
changed=0;

# If the domain name has changed, update the provider information
if [ "$new_domain_name" != "$old_domain_name" ]; then
	changed=1;
	update_provider "$new_domain_name";
	fi;

# If the ip address has changed, update the host information
if [ "$new_ip_address" != "$oldnew_ip_address" ]; then
	changed=1;
	update_host "$new_ip_address";
	fi;

# If anything has been changed, update sendmail.cf and reload
if [ $changed -eq 1 ]; then
	update_sendmail;
	fi;

exit 0;