219 lines
6.9 KiB
Python
219 lines
6.9 KiB
Python
""" robotparser.py
|
|
|
|
Copyright (C) 2000 Bastian Kleineidam
|
|
|
|
You can choose between two licenses when using this package:
|
|
1) GNU GPLv2
|
|
2) PYTHON 2.0 OPEN SOURCE LICENSE
|
|
|
|
The robots.txt Exclusion Protocol is implemented as specified in
|
|
http://info.webcrawler.com/mak/projects/robots/norobots-rfc.html
|
|
"""
|
|
import re,urlparse,urllib
|
|
|
|
__all__ = ["RobotFileParser"]
|
|
|
|
debug = 0
|
|
|
|
def _debug(msg):
|
|
if debug: print msg
|
|
|
|
|
|
class RobotFileParser:
|
|
def __init__(self, url=''):
|
|
self.entries = []
|
|
self.disallow_all = 0
|
|
self.allow_all = 0
|
|
self.set_url(url)
|
|
self.last_checked = 0
|
|
|
|
def mtime(self):
|
|
return self.last_checked
|
|
|
|
def modified(self):
|
|
import time
|
|
self.last_checked = time.time()
|
|
|
|
def set_url(self, url):
|
|
self.url = url
|
|
self.host, self.path = urlparse.urlparse(url)[1:3]
|
|
|
|
def read(self):
|
|
import httplib
|
|
tries = 0
|
|
while tries<5:
|
|
connection = httplib.HTTP(self.host)
|
|
connection.putrequest("GET", self.path)
|
|
connection.putheader("Host", self.host)
|
|
connection.endheaders()
|
|
status, text, mime = connection.getreply()
|
|
if status in [301,302] and mime:
|
|
tries = tries + 1
|
|
newurl = mime.get("Location", mime.get("Uri", ""))
|
|
newurl = urlparse.urljoin(self.url, newurl)
|
|
self.set_url(newurl)
|
|
else:
|
|
break
|
|
if status==401 or status==403:
|
|
self.disallow_all = 1
|
|
elif status>=400:
|
|
self.allow_all = 1
|
|
else:
|
|
# status < 400
|
|
self.parse(connection.getfile().readlines())
|
|
|
|
def parse(self, lines):
|
|
"""parse the input lines from a robot.txt file.
|
|
We allow that a user-agent: line is not preceded by
|
|
one or more blank lines."""
|
|
state = 0
|
|
linenumber = 0
|
|
entry = Entry()
|
|
|
|
for line in lines:
|
|
line = line.strip()
|
|
linenumber = linenumber + 1
|
|
if not line:
|
|
if state==1:
|
|
_debug("line %d: warning: you should insert"
|
|
" allow: or disallow: directives below any"
|
|
" user-agent: line" % linenumber)
|
|
entry = Entry()
|
|
state = 0
|
|
elif state==2:
|
|
self.entries.append(entry)
|
|
entry = Entry()
|
|
state = 0
|
|
# remove optional comment and strip line
|
|
i = line.find('#')
|
|
if i>=0:
|
|
line = line[:i]
|
|
line = line.strip()
|
|
if not line:
|
|
continue
|
|
line = line.split(':', 1)
|
|
if len(line) == 2:
|
|
line[0] = line[0].strip().lower()
|
|
line[1] = line[1].strip()
|
|
if line[0] == "user-agent":
|
|
if state==2:
|
|
_debug("line %d: warning: you should insert a blank"
|
|
" line before any user-agent"
|
|
" directive" % linenumber)
|
|
self.entries.append(entry)
|
|
entry = Entry()
|
|
entry.useragents.append(line[1])
|
|
state = 1
|
|
elif line[0] == "disallow":
|
|
if state==0:
|
|
_debug("line %d: error: you must insert a user-agent:"
|
|
" directive before this line" % linenumber)
|
|
else:
|
|
entry.rulelines.append(RuleLine(line[1], 0))
|
|
state = 2
|
|
elif line[0] == "allow":
|
|
if state==0:
|
|
_debug("line %d: error: you must insert a user-agent:"
|
|
" directive before this line" % linenumber)
|
|
else:
|
|
entry.rulelines.append(RuleLine(line[1], 1))
|
|
else:
|
|
_debug("line %d: warning: unknown key %s" % (linenumber,
|
|
line[0]))
|
|
else:
|
|
_debug("line %d: error: malformed line %s"%(linenumber, line))
|
|
if state==2:
|
|
self.entries.append(entry)
|
|
_debug("Parsed rules:\n%s" % str(self))
|
|
|
|
|
|
def can_fetch(self, useragent, url):
|
|
"""using the parsed robots.txt decide if useragent can fetch url"""
|
|
_debug("Checking robot.txt allowance for\n%s\n%s" % (useragent, url))
|
|
if self.disallow_all:
|
|
return 0
|
|
if self.allow_all:
|
|
return 1
|
|
# search for given user agent matches
|
|
# the first match counts
|
|
useragent = useragent.lower()
|
|
url = urllib.quote(urlparse.urlparse(url)[2])
|
|
for entry in self.entries:
|
|
if entry.applies_to(useragent):
|
|
return entry.allowance(url)
|
|
# agent not found ==> access granted
|
|
return 1
|
|
|
|
|
|
def __str__(self):
|
|
ret = ""
|
|
for entry in self.entries:
|
|
ret = ret + str(entry) + "\n"
|
|
return ret
|
|
|
|
|
|
class RuleLine:
|
|
"""A rule line is a single "Allow:" (allowance==1) or "Disallow:"
|
|
(allowance==0) followed by a path."""
|
|
def __init__(self, path, allowance):
|
|
self.path = urllib.quote(path)
|
|
self.allowance = allowance
|
|
|
|
def applies_to(self, filename):
|
|
return self.path=="*" or re.match(self.path, filename)
|
|
|
|
def __str__(self):
|
|
return (self.allowance and "Allow" or "Disallow")+": "+self.path
|
|
|
|
|
|
class Entry:
|
|
"""An entry has one or more user-agents and zero or more rulelines"""
|
|
def __init__(self):
|
|
self.useragents = []
|
|
self.rulelines = []
|
|
|
|
def __str__(self):
|
|
ret = ""
|
|
for agent in self.useragents:
|
|
ret = ret + "User-agent: "+agent+"\n"
|
|
for line in self.rulelines:
|
|
ret = ret + str(line) + "\n"
|
|
return ret
|
|
|
|
def applies_to(self, useragent):
|
|
"check if this entry applies to the specified agent"
|
|
for agent in self.useragents:
|
|
if agent=="*":
|
|
return 1
|
|
if re.match(agent, useragent):
|
|
return 1
|
|
return 0
|
|
|
|
def allowance(self, filename):
|
|
"""Preconditions:
|
|
- our agent applies to this entry
|
|
- filename is URL decoded"""
|
|
for line in self.rulelines:
|
|
if line.applies_to(filename):
|
|
return line.allowance
|
|
return 1
|
|
|
|
|
|
def _test():
|
|
global debug
|
|
import sys
|
|
rp = RobotFileParser()
|
|
debug = 1
|
|
if len(sys.argv) <= 1:
|
|
rp.set_url('http://www.musi-cal.com/robots.txt')
|
|
rp.read()
|
|
else:
|
|
rp.parse(open(sys.argv[1]).readlines())
|
|
print rp.can_fetch('*', 'http://www.musi-cal.com/')
|
|
print rp.can_fetch('Musi-Cal-Robot/1.0',
|
|
'http://www.musi-cal.com/cgi-bin/event-search'
|
|
'?city=San+Francisco')
|
|
|
|
if __name__ == '__main__':
|
|
_test()
|