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#!/bin/sh
#------------------------------------------------------------------------
#
# $Sendmail: dynamic,v 8.17.1.9 2024-06-16 21:07:57 cowboy Exp $
#
# Shell functions to handle dynamic network updates.
# Supports ppp, dhcp, ifup/down, etc.
#
# Copyright (c) 2004-2010 Richard Nelson.  All Rights Reserved.
#
# This script is called from the following places:
#   /etc/ppp/ip-down.d/sendmail                 #\
#   /etc/ppp/ip-up.d/sendmail                   # | These are deprecated
#   /etc/dhcp3/dhclient-exit-hooks.d/sendmail   #/
#   /etc/network/if-down.d/sendmail             #standard
#   /etc/network/if-post-down.d/sendmail        #standard
#   /etc/network/if-up.d/sendmail               #standard
#   /etc/resolvconf/update-libc.d/sendmail      #More or less useless :(
#
# The other half of the logic is in /etc/mail/sendmail.conf
#
# DAEMON_NETMODE="Dynamic";  Keyword  SMTP network mode
#   static:  Do not monitor any network interfaces for changes
#   dynamic: Monitor one or more interfaces for changes
#
# DAEMON_NETIF="eth0";  string SMTP interface(s)
#   This parameter defines the network interface(s) that the daemon
#   will monitor for status changes (via ppp, dhcp, ifup/down hooks).
#
# NOTES:
#   1) Only list more than one interfaces if they only used for fallback,
#      otherwise the daemon will wind up ping-ponging between interfaces.
#   2) Do not use 'lo' unless your daemon only listens on the localhost.
#
# LOG_CMDS="No"; Binary command logging flag
#   Will cause syslog entries for many of the sendmail related commands
#   like runq, mailq, etc - you'll also see cron jobs (if enabled).
#
# HANDS_OFF="No"; Binary  Do *NOT* touch the configuration
#   Set this *ONLY* if you are going to be fully responsible for the entire
#   setup of sendmail - the directories, permissions, databases, etc.  With
#   this variable set to "Yes", nothing will be done for you during
#   updates.
#
#   In other words, "The blood be upon your hands" if you set this...
#   My ability to help with problems will be greatly reduced !
#
#   "Well, a pet peeve of mine is people who directly edit the
#   .cf file instead of using the m4 configuration files.
#   Don't do it! [laughs] I treat the .cf file as a binary
#   file - you should too."
#       --  Eric Allman 1999/10/18
#
#------------------------------------------------------------------------
#

# The files we may alter
provider_m4='/etc/mail/m4/provider.m4';
dialup_m4='/etc/mail/m4/dialup.m4';

# Default values
SM_ignore=0;              # Ignore any changes
SM_changed=0;             # Something has changed, dunno what
SM_delay=0;               # Expect another call soon, do work then
SM_interface='';          # The interface that changed
SM_state='';              # How the interface changed
SM_provider='';           # ISP/domain name/IPPARM/etc
SM_ip='';                 # IP for the interface
SM_host='';               # Reverse FQDN of IP
SM_debug=1;               # Of minimal value

# Path to other sendmail helpers
if [ -x ./update_sendmail ]; then
	sm_path='.';
elif [ -x $(/usr/bin/dirname $0)/update_sendmail ]; then
	sm_path=$(/usr/bin/dirname $0);
else
	sm_path=/usr/share/sendmail;
	fi;

# Bring in sendmail.conf for the network definitions
if [ ! -f /etc/mail/sendmail.conf ]; then
	if [ -x $sm_path/update_conf ]; then
		$sm_path/update_conf;
		fi;
	fi;
DAEMON_NETMODE='Static';
DAEMON_NETIF='';
HANDS_OFF='No';
LOG_CMDS='Yes';
if [ -f /etc/mail/sendmail.conf ]; then
	. /etc/mail/sendmail.conf;
	fi;

# Record information on an interface and its status
update_interface() {
	SM_interface="$1";
	SM_reason="$2";

	# Translate DHCP style actions to a simple up/down
	case "$SM_reason" in
		DOWN|EXPIRE|FAIL|RELEASE|STOP)  # and TIMEOUT too ???
			SM_state='down';
			;;
		UP|BOUND|RENEW|REBIND|REBOOT|TIMEOUT) # why TIMEOUT here ???
			SM_state='up';
			if [ "$SM_reason" = "BOUND" ]; then
				SM_changed=1;
				fi;
			;;
		*)
			SM_state='unknown';
			;;
		esac;

	# Mark what we're doing...
	local msg;
	msg="$SM_interface $SM_state $SM_provider $SM_ip $SM_host";
	if [ "$LOG_CMDS" != 'No' ]; then
		/usr/bin/logger -i -p mail.debug -- "$0 (dynamic) update_interface: $msg";
		fi;

	# Do absolutely nothing if they say so...
	if [ "$HANDS_OFF" != 'No' -o "$DAEMON_NETMODE" = 'Static' ]; then
		SM_ignore=1;
		fi;
	if [ -z "$SM_interface" ]; then
		SM_ignore=1;
		fi;

	# Check to see if we care about this interface
	if [ $SM_ignore -eq 0 ]; then
		SM_ignore=1;
		for if in $DAEMON_NETIF; do
			if [ "$if" = "$SM_interface" ]; then
				SM_ignore=0;
				break;
				fi;
			done;
		fi;

	if [ $SM_ignore -ne 0 ]; then
		return;
		fi;
	};

# Record information about the upstream provider
update_provider() {
	SM_provider="$1";

	# Mark what we're doing...
	local msg;
	msg="$SM_interface $SM_state $SM_provider $SM_ip $SM_host";
	if [ "$LOG_CMDS" != 'No' ]; then
		/usr/bin/logger -i -p mail.debug -- "$0 (dynamic) update_provider: $msg";
		fi;

	# Do absolutely nothing if they say so...
	if [ "$HANDS_OFF" != 'No' -o "$DAEMON_NETMODE" = 'Static' ]; then
		SM_ignore=1;
		fi;
	if [ $SM_ignore -ne 0 ]; then
		return;
		fi;
	# Add smarthost information (if any)...
	# But not if provider.m4 is a link !
	if [ -z "$SM_provider" ]; then
		return;
		fi;
	if [ ! -e "/etc/mail/peers/$SM_provider" ]; then
		SM_provider='default';
		fi;
	if [ -e "/etc/mail/peers/$SM_provider" ] \
	&& [ ! -L "$provider_m4" ]; then
		SM_changed=1;
		cat <<-EOT > "$provider_m4";
			LOCAL_CONFIG
			#------------------------------------------------------------
			#
			# Dynamic provider updates from $0:
			#   Device=$SM_interface
			#   State=$SM_state
			#   Provider=$SM_provider
			#
			# NOTE: The following line *MUST* be in /etc/mail/sendmail.mc
			#dnl    include(\`/etc/mail/provider.m4')dnl
			#
			# You may also need to include this file in submit.mc !
			#
			# Provider information from /etc/mail/peers/$SM_provider
			EOT
		cat "/etc/mail/peers/$SM_provider" >> "$provider_m4";
		cat <<-EOT >> "$provider_m4";
			#------------------------------------------------------------
			EOT
		fi;
	};

# Record information on an ip/host
update_host() {
	SM_ip="$1";

	# Mark what we're doing...
	local msg;
	msg="$SM_interface $SM_state $SM_provider $SM_ip $SM_host";
	if [ "$LOG_CMDS" != 'No' ]; then
		/usr/bin/logger -i -p mail.debug -- "$0 (dynamic) update_host: $msg";
		fi;

	# Do absolutely nothing if they say so...
	if [ "$HANDS_OFF" != 'No' -o "$DAEMON_NETMODE" = 'Static' ]; then
		SM_ignore=1;
		fi;
	if [ $SM_ignore -ne 0 ]; then
		return;
		fi;
	if [ -z "$SM_ip" ]; then
		return;
		fi;
	find_host;
	if [ $SM_ignore -ne 0 ]; then
		return;
		fi;
	# Add ip related information (if any)...
	# But not if dialup.m4 is a link !
	if [ ! -L "$dialup_m4" ]; then
		SM_changed=1;
		cat <<-EOT > "$dialup_m4";
			LOCAL_CONFIG
			#------------------------------------------------------------
			#
			# Dynamic host/ip updates from $0:
			#   Device=$SM_interface
			#   State=$SM_state
			#   Provider=$SM_provider
			#   IP=$SM_ip
			#   Host=$SM_host
			#
			# NOTE: The following line *MUST* be in /etc/mail/sendmail.mc
			#dnl    include(\`/etc/mail/dialup.m4')dnl
			#
			# This should *NOT* be included in submit.mc !
			#
			# Make sure we accept mail as this ip (for bounces, etc)
			Cw$SM_ip
			EOT
		if [ -z "$SM_host" ]; then
			cat <<-EOT >> "$dialup_m4";
				#
				# Rats... FQDN lookup failed, your kit is incomplete :(
				EOT
		else
			cat <<-EOT >> "$dialup_m4";
				#
				# Define our true hostname (from our ISP) - becomes \$j
				define(\`confDOMAIN_NAME', \`$SM_host')dnl
				#
				# Make sure we accept mail as this name (for bounces, etc)
				Cw$SM_host
				#
				# Add our hostname to class G for genericstable support
				CG$SM_host
				#------------------------------------------------------------
				EOT
			fi;
		fi;
	};

# DNS support changed, we may (or may not) have a new name
# but in any case, we may have stale host info in the queue
update_resolv() {

	# Mark what we're doing...
	local msg;
	msg="$SM_interface $SM_state $SM_provider $SM_ip $SM_host";
	if [ "$LOG_CMDS" != 'No' ]; then
		/usr/bin/logger -i -p mail.debug -- "$0 (dynamic) update_resolv: $msg";
		fi;

	# Do absolutely nothing if they say so...
	if [ "$HANDS_OFF" != 'No' -o "$DAEMON_NETMODE" = 'Static' ]; then
		SM_ignore=1;
		fi;
	if [ $SM_ignore -ne 0 ]; then
		return;
		fi;

	# Ideally, we should re-check our IP if we didn't find the
	# FQDN previously - but we need a state file to do that :(
	#
	# Hell, we don't even know what IF is, and if it is up or down :(

	#SM_interface='?';  #\
	#SM_state='up';     # \
	#SM_provider='?';   #  |  Need to get these from somewhere !
	#SM_ip='?';         # /
	#SM_host='?';       #/
	#find_host;

	# Purge any latent host status that might cause us to *NOT* send mail
	if [ -x /etc/init.d/sendmail ]; then
		if [ "$SM_state" = 'up' ]; then
			/etc/init.d/sendmail purgestat now;
			fi;
		fi;

	# resolvconf is called as a DHCP pre-exit, so we'll defer any changes
	SM_changed=0;
	}

# Attempt to locate our FQDN
find_host() {
	# Determine our fqdn from our ISP
	maxloop=30;
	cntr=0;
	SM_host='';
	until (test ! -z "$SM_host"); do
		cntr=`expr $cntr + 1`;
		if [ $cntr -gt $maxloop ]; then
			SM_host='';
			break;
			fi;
		rev=$(host $SM_ip);
		SM_host=$(echo "$rev" | grep '^Name:' | awk '{print $2}');
		if [ -z "$SM_host" ]; then
			test=$(echo "$rev" | egrep -e 'not found:');
			if [ -n "$test" ]; then
				continue;
			else
				SM_host=${rev##*domain name pointer };
				SM_host=${SM_host%.};
				fi;
			fi;
		test=$(echo $SM_host | cut -d ' ' -f 1);
		# continue scanning if we get this:
		# ;; connection timed out; no servers could be reached
		if [ "$test" = ";;" ]; then
			SM_host='';
		elif [ "$test" != "**" ]; then
			break;
			fi;
		sleep 1s;
		done;

	# See if we actually found a host !
	if [ -z "$SM_host" ]; then
		# Drats, no host name :(
		# We have a few choices - none pretty
		#  1) Do not start sendmail
		#  2) Use the info we have (ip) - but
		#     then we may not accept mail we should,
		#     accept mail we should not,
		#     and our ougoing name may be wrong
		#  3) Use the last known hostname
		#     If it is not correct, we have the same
		#     exposurs as option 2 !
		#
		# For the nonce, I choose option 2
		:
		fi;

	if [ $SM_debug -ne 0 ]; then
		echo "addr=$SM_ip,		 name=$SM_host";
		fi;
	};

# If our state has changed in any way, update sendmail
update_sendmail() {
	SM_caller="$1";
	SM_opts="$2";

	# Mark what we're doing...
	local msg;
	msg="$SM_interface $SM_state $SM_provider $SM_ip $SM_host";
	if [ "$LOG_CMDS" != 'No' ]; then
		/usr/bin/logger -i -p mail.debug -- "$0 (dynamic) update_sendmail: $msg";
		fi;

	# Do absolutely nothing if they say so...
	if [ "$HANDS_OFF" != 'No' -o "$DAEMON_NETMODE" = 'Static' ]; then
		SM_ignore=1;
		fi;
	if [ $SM_ignore -ne 0 ]; then
		return;
		fi;

	# Check for a delayed restart (for DHCP/PPP)
	case "$SM_opts" in
		[Dd]*)
			if [ "$SM_state" = 'up' ]; then
				SM_delay=1;
				fi;
			;;
		esac;

	if [ "$SM_state" = 'down' ]; then
		SM_changed=1;
		cat <<-EOT > "$dialup_m4";
			LOCAL_CONFIG
			#------------------------------------------------------------
			# Dynamic host/ip updates from $0:
			#   Device=$SM_interface
			#   State=$SM_state
			#   Provider=$SM_provider
			#   IP=$SM_ip
			#   Host=$SM_host
			#
			# NOTE: The following line *MUST* be in /etc/mail/sendmail.mc
			#dnl    include(\`/etc/mail/dialup.m4')dnl
			# This should *NOT* be included in submit.mc !
			#
			# sendmail is to only queue messages until connected again
			define(\`confDELIVERY_MODE', \`deferred')dnl
			#
			# Allow the queue to age without carping every four hours
			define(\`confTO_QUEUEWARN',\`1d')dnl
			#
			# Don't keep host status while the network is down
			define(\`confHOST_STATUS_DIRECTORY')dnl
			#------------------------------------------------------------
			EOT
		fi;

	if  [ $SM_changed -eq 1 ]; then
		# Build a new sendmail.cf from sendmail.mc, including our address.
		/usr/bin/make -f /etc/mail/Makefile sendmail.cf;
		/usr/bin/make -f /etc/mail/Makefile;

		# Purge any latent host status that might cause us to *NOT* send mail
		# Reload sendmail, IFF already running
		if [ -x /etc/init.d/sendmail ]; then
			if [ "$SM_state" = 'up' ]; then
				/etc/init.d/sendmail purgestat now;
				fi;
			/etc/init.d/sendmail reload-if-running &  # up, or down
			fi;
		fi;

	# Process the sendmail queue
	# (background so as to not defer other ip-up work)
	# This can be fatal on IF ping-pongs :(
	# runq &
	};