Question

I have a python IRC bot that I’m starting to work on to practice my python. However, for some servers, it won’t join a channel, though it logs on successfully. I also want it to react to user commands like !test, but I’m not sure how to do it. On the servers it works, it pings back successfully.

from socket import socket, AF_INET, SOCK_STREAM
network = raw_input("Server: ")
port = 6667
chan = raw_input("Channel: ")
nick = raw_input("Nick: ")
irc=socket(AF_INET,SOCK_STREAM)
irc.connect((network, port))
a=irc.recv (4096)
print a
irc.send('NICK ' + nick + '\r\n')
irc.send('USER john_bot john_bot bla :john_bot\r\n')
irc.send('JOIN :' + chan + '\r\n')
irc.send('PRIVMSG ' + chan + ' :Hello.\r\n')

def ircSend(msg):
     print(msg)
     irc.send(msg)

while True:
    data = irc.recv(4096)
    print data
    if data.find('PING') != -1:
       ircSend('PONG ' + data.split()[1] + '\r\n')

Answer 1

On some servers you have to respond to a PING with a PONG before you can actually do anything.

ircSend('NICK ' + nick + '\r\n')
ircSend('USER john_bot john_bot bla :john_bot\r\n')

data = ircRecv() # explained later
if data.find('PING') != -1:
    ircSend('PONG ' + data.split()[1] + '\r\n')

ircSend('JOIN :' + chan + '\r\n')
ircSend('PRIVMSG ' + chan + ' :Hello.\r\n')

You don’t really need this

a=irc.recv (4096)
print a

Sometimes the IRC server sends multiple lines at once (like MOTD or NAMES for example). This will handle it well as long as the total number of bytes does not exceed 4096 (some lines would split to two lines)

data = irc.recv(4096)
for line in data.split('\r\n'):
    # process the line

If it is a problem that a line would cut in half (it can rarely be, like if a PING happens to be there), we can receive one line at time and leave the rest characters to socket’s buffer. However this may be a little less efficient (I haven’t tested it, so maybe it doesn’t matter at all)

def ircRecv():
    line = ''
    while 1: # same as while True:
        character = irc.recv(1)
        if character == '\n':
            break # exit the loop
        elif character != '\r':
            line += character
    print line
    return line

From page 8 of the IRC RFC:

<message>  ::= [':' <prefix> <SPACE> ] <command> <params> <crlf>
<prefix>   ::= <servername> | <nick> [ '!' <user> ] [ '@' <host> ]
<command>  ::= <letter> { <letter> } | <number> <number> <number>
<SPACE>    ::= ' ' { ' ' }
<params>   ::= <SPACE> [ ':' <trailing> | <middle> <params> ]
<middle>   ::= <Any *non-empty* sequence of octets not including SPACE
           or NUL or CR or LF, the first of which may not be ':'>
<trailing> ::= <Any, possibly *empty*, sequence of octets not including
             NUL or CR or LF>
<crlf>     ::= CR LF

This means that you can always get of message’s sender easily and for sure like this:

# put this inside the main loop
# this will throw an IndexError when the connection is closed,
# an empty line does not contain any spaces
line = ircRecv()
if line.split()[0].find('!') != -1:
    # the first character must be a colon because <command> can't include
    # an exclamation mark
    someOneElsesNick = line[1:line.find('!')]
    command = line.split()[1]

Answer when someone greets!

    if command == 'PRIVMSG':
        destination = line.split()[2] # channel or bot's nick
        # <trailing>, in this case, the message
        message = line[line[1:].find(':')+2 : ] # everything after the 2nd colon

        # we add one since we don't want include the <trailing> colon in
        # the message and an other one because line[1:].find() is one smaller 
        # number than line.find() would be

        # if we receive a private message, we have to respond to the sender,
        # not to ourself
        if destination == nick:
            destination = someOneElsesNick

        if message.startswith('hi!'):
            ircSend('PRIVMSG ' + destination + ' :Hi, '
            + someOneElsesNick + '!\r\n')

For more info, check out the IRC RFC: http://www.ietf.org/rfc/rfc1459.txt (especially sections 2.3.1 and 4). If you don’t want to deal with the IRC protocol, use Twisted 🙂 http://twistedmatrix.com/trac/