#identd.py

#!/usr/bin/python
#####
# author: kay ~ irc.nullnetwork.net
# version: 1.0
# date: 17/10/2005
# description: this is a basic identd, run it as super user and get
#              going, no configuration required!
#
# notes: 
# errors HIDDEN-USER isn't implemented
#
# this was implemented (or the parts that were) based on rfc1413
#####
import socket, sys, re, pwd
EOL = "\r\n";
OPSYS = "UNIX";


def gettcpuid(localp, remotep, localh, remoteh):
	lph = "%X" % localp
	rph = "%X" % remotep
	for i in range(4-len(lph)):
		lph = "0" + lph
	for i in range(4-len(rph)):
		rph = "0" + rph
	
	fp = open("/proc/net/tcp", "r")
	d = fp.read()
	lines = re.split("[\r\n]", d)
	for line in lines:
		r = re.findall("([^ ]+)", line)
		if r:
			remoteaddr = r[2]
			localaddr = r[1]
			uid = r[7]
			rs = remoteaddr.split(":")
			ls = localaddr.split(":")
			if len(ls) > 1 and len(rs) > 1:
				print "comparing ", rs, rph, "and", ls, lph
				if rph == rs[1] and lph == ls[1]:
					print "remote =", remoteaddr, "local =", localaddr, "uid =", uid
					return uid
	return -1



if (len(sys.argv) > 1):
	USERNAME = sys.argv[1];
	
if (len(sys.argv) > 2):
	OPSYS = sys.argv[2];


listener = socket.socket(socket.AF_INET, socket.SOCK_STREAM);

listener.bind((socket.gethostname(), 113));
listener.listen(5);
while 1:
	print "=[listening on " + socket.gethostname() + ":113]=";
	(clientsocket, address) = listener.accept();
	print "=[accepted connection from " + address[0] + ":" + str(address[1]) + "]=";
	
	last2chrs = ['',''];
	data = "";
	
	while 1:
		buf = clientsocket.recv(1);
		last2chrs[0] = last2chrs[1];
		last2chrs[1] = buf;
		if last2chrs[0] == '\r' and last2chrs[1] == '\n':
			break;
		data = data + buf;
		
	print "<<" + data;
	p = re.compile( '\s');
	data = p.sub('', data);
	ports = re.split(",",data);
	localp = int(ports[0]);
	remotep = int(ports[1]);
	portpair = str(localp) + "," + str(remotep);
	
	uid = gettcpuid(localp, remotep, socket.gethostname(), address[0])


	if (localp > 0 and localp < 65535) and (remotep > 0 and remotep < 65535):
		if uid >= 0:
			ud = pwd.getpwuid(int(uid))
			if len(ud) >= 1:
				username = ud[0]
				outdata = portpair + ":USERID:" + OPSYS + ":" + username;
			else:
				outdata = portpair + ":ERROR:UNKNOWN-ERROR";
				
		else:
			outdata = portpair + ":ERROR:NO-USER"
	else:
		outdata = portpair + ":ERROR:INVALID-PORT";
	
	clientsocket.send(outdata + EOL);
	print ">>" + outdata;
	print "=[request fullfilled]=";
	clientsocket.close()
	
print "=[closing]=";
listener.close();