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################################################################################
#
# Stand-alone VoIP honeypot client (preparation for Dionaea integration)
# Copyright (c) 2010 Tobias Wulff (twu200 at gmail)
#
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation; either version 2 of the License, or (at your option) any later
# version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc., 51 Franklin
# Street, Fifth Floor, Boston, MA 02110-1301, USA.
#
################################################################################
import sys
import string
# SIP headers have short forms
shortHeaders = {"call-id": "i",
"contact": "m",
"content-encoding": "e",
"content-length": "l",
"content-type": "c",
"from": "f",
"subject": "s",
"to": "t",
"via": "v",
"cseq": "cseq",
"accept": "accept",
"user-agent": "user-agent",
"max-forwards": "max-forwards",
"www-authentication": "www-authentication",
"authorization": "authorization",
"allow": "allow",
"recv-info": "recv-info",
"supported": "supported"
}
longHeaders = {}
for k, v in shortHeaders.items():
longHeaders[v] = k
del k, v
class SipParsingError(Exception):
"""Exception class for errors occuring during SIP message parsing"""
def parseSipMessage(msg):
"""Parses a SIP message (string), returns a tupel (type, firstLine, header,
body)"""
# Sanitize input: remove superfluous leading and trailing newlines and
# spaces
msg = msg.strip("\n\r\t ")
# Split request/status line plus headers and body: we don't care about the
# body in the SIP parser
parts = msg.split("\n\r\n", 1)
if len(parts) < 1:
raise SipParsingError("Message too short")
msg = parts[0]
# Python way of doing a ? b : c
body = len(parts) == 2 and parts[1] or parts[len(parts)-1]
# Normalize line feed and carriage return to \n
msg = msg.replace("\n\r", "\n")
# Split lines into a list, each item containing one line
lines = msg.split('\n')
# Get message type (first word, smallest possible one is "ACK" or "BYE")
sep = lines[0].find(' ')
if sep < 3:
raise SipParsingError("Malformed request or status line")
msgType = lines[0][:sep]
firstLine = lines[0][sep+1:]
# Done with first line: delete from list of lines
del lines[0]
# Parse header
headers = {}
for i in range(len(lines)):
# Take first line and remove from list of lines
line = lines.pop(0)
# Strip each line of leading and trailing whitespaces
line = line.strip("\n\r\t ")
# Break on empty line (end of headers)
if len(line.strip(' ')) == 0:
break
# Parse header lines
sep = line.find(':')
if sep < 1:
raise SipParsingError("Malformed header line (no ':')")
# Get header identifier (word before the ':')
identifier = line[:sep]
identifier = identifier.lower()
# Check for valid header
if identifier not in shortHeaders.keys() and \
identifier not in longHeaders.keys():
raise SipParsingError("Unknown header type: {}".format(identifier))
# Get long header identifier if necessary
if identifier in longHeaders.keys():
identifier = longHeaders[identifier]
# Get header value (line after ':')
value = line[sep+1:].strip(' ')
# The Via header can occur multiple times
if identifier == "via":
if identifier not in headers:
headers["via"] = [value]
else:
headers["via"].append(value)
# Assign any other header value directly to the header key
else:
headers[identifier] = value
# Return message type, header dictionary, and body string
return (msgType, firstLine, headers, body)
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