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""" 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,string,urlparse,urllib
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 = string.strip(line)
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 = string.find(line, '#')
if i>=0:
line = line[:i]
line = string.strip(line)
if not line:
continue
line = string.split(line, ':', 1)
if len(line) == 2:
line[0] = string.lower(string.strip(line[0]))
line[1] = string.strip(line[1])
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 = string.lower(useragent)
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()
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