I'm beginner in Python and I would like to build simple port sniffer. For this purpose I'm using code from this site, as example: Simple packege snffer using python And I would like to unpack bites from socket to exctract http header, using function struct.unpack()
What format of string should I use in unpack HTTP header, (e.g '!BBH', "!BBHHHBBH4s4s",'!HHLLBBHHH')
the HTTP header is not fixed-length, so you'll need to parse it other way, for example:
import logging
log = logging.getLogger(__name__)
def parse_http(data):
lines = data.split(b'\r\n')
if len(lines) < 1:
log.error('Invalid http header: %s', lines)
return
request = lines[0]
header = {}
rest = []
in_header = True
for line in lines[1:]:
if line == b'':
in_header = False
continue
if in_header:
try:
key, val = line.split(b': ')
except ValueError:
log.error('Invalid header line: %s', line)
continue
header[key] = val
else:
rest.append(line)
return request, header, b'\r\n'.join(rest)
In order to detect a HTTP packet, you could check if the payload starts with POST, GET, HTTP ... etc
