Reply to IRC PING with PONG in bash script - bash

Question

So far I have a basic IRC Bot which I hope to be able to successfully PRIVMSG myself with but on the server I am testing on it requires a PONG response to PING.
I have absolutely no idea how to get around this. How do I reply to the PING?
My current code:
#!/bin/bash
function ircpreamble {
echo "NICK ${1}"
}
function privmsg {
TARGET=$1
sed -re "s/^(.*)\$/PRIVMSG ${TARGET} :\1/"
}
function delay {
while read LINE; do
sleep 2
echo $LINE
done
}
function messages {
msg=`cat pmmsg.txt`
echo $msg
}
function disconnect {
echo "QUIT goodbye :)"
}
(
nick=`cat randnick.txt`
pms=`cat pmnickname.txt`
ircpreamble "$nick";
messages | privmsg "$pms";
disconnect;
) | delay | nc irc.seersirc.net 6667

Answer 1

You first need to "catch" the server responses. This can be done like:
$ nc irc.seersirc.net 6667 |while read res;do echo "==>$res";done
==>:irc.seersirc.net NOTICE AUTH :*** Looking up your hostname...
==>:irc.seersirc.net NOTICE AUTH :*** Couldn't resolve your hostname; using your IP address instead
Since now you catch the response in a variable, you can filter out these responses and send the appropriate commands back to the server.
The problem is that when running netcat/telnet from a script a simple echo "PONG" is not sending the messages back to server but echo prints the messages locally in your terminal.
To send messages to the server you need either to pipe those messages to netcat in the beginning (the technique you already use) or to use some kind of expect script or to use a file to feed the netcat.
Regarding the PONG response, note that in order pong to be accepted by the server it must include the message sent by the server along with it's ping request.
Your server sends something like PING :D7AA1D1D (different every time) and thus the correct pong response is PONG :D7AA1D1D
As a result you can not just include a pong response in the first messages send in the beginning to netcat, since you don't know what is the ID that your server will sent to you along with the ping request.
This is a working draft script using a file to continuously feed the netcat:
rm .ircbot
touch .ircbot
prmnick="gv"
tail -f .ircbot |nc irc.seersirc.net 6667 |while read res
do
echo "==>$res"
if [[ "$res" == *"Couldn't resolve your hostname; using your IP address instead"* ]];then
sleep 2
echo "NICK gvgv" >>.ircbot
tail -n1 .ircbot #used just to display the last line of the helper file in my screen.
elif [[ "$res" == *"PING"* ]]; then
sleep 2
echo "$res" |sed 's/PING/PONG/' >>.ircbot
tail -n1 .ircbot
sleep 2
echo "USER gvgv 8 * :gvgv " >>.ircbot
tail -n1 .ircbot
sleep 2
echo "PRIVMSG $prmnick : hello from bot" >>.ircbot
tail -n1 .ircbot
fi
done
Tip: By opening a second terminal , you can manually "control" above bot by sending more commands to the .ircbot file (i.e $ echo "JOIN #channel" >>.ircbot) which will be also fed to netcat.
By the way, some web search about bash irc bots will return some useful results.
This is one easy bash script to use as an irc bot: https://github.com/Newbrict/bash-irc-bot/blob/master/bot.sh
Also , i found this useful IRC Over Telnet guide: http://archive.oreilly.com/pub/h/1963
Finally , this is an alternative using the /dev/tcp directly : https://gist.github.com/Wollw/3330337