mirror of
https://github.com/python/cpython.git
synced 2025-11-03 23:21:29 +00:00
294 lines
9.9 KiB
Python
294 lines
9.9 KiB
Python
""" robotparser.py
|
|
|
|
Copyright (C) 2000 Bastian Kleineidam
|
|
|
|
You can choose between two licenses when using this package:
|
|
1) GNU GPLv2
|
|
2) PSF license for Python 2.2
|
|
|
|
The robots.txt Exclusion Protocol is implemented as specified in
|
|
http://info.webcrawler.com/mak/projects/robots/norobots-rfc.html
|
|
"""
|
|
import urlparse,urllib
|
|
|
|
__all__ = ["RobotFileParser"]
|
|
|
|
debug = 0
|
|
|
|
def _debug(msg):
|
|
if debug: print msg
|
|
|
|
|
|
class RobotFileParser:
|
|
""" This class provides a set of methods to read, parse and answer
|
|
questions about a single robots.txt file.
|
|
|
|
"""
|
|
|
|
def __init__(self, url=''):
|
|
self.entries = []
|
|
self.default_entry = None
|
|
self.disallow_all = False
|
|
self.allow_all = False
|
|
self.set_url(url)
|
|
self.last_checked = 0
|
|
|
|
def mtime(self):
|
|
"""Returns the time the robots.txt file was last fetched.
|
|
|
|
This is useful for long-running web spiders that need to
|
|
check for new robots.txt files periodically.
|
|
|
|
"""
|
|
return self.last_checked
|
|
|
|
def modified(self):
|
|
"""Sets the time the robots.txt file was last fetched to the
|
|
current time.
|
|
|
|
"""
|
|
import time
|
|
self.last_checked = time.time()
|
|
|
|
def set_url(self, url):
|
|
"""Sets the URL referring to a robots.txt file."""
|
|
self.url = url
|
|
self.host, self.path = urlparse.urlparse(url)[1:3]
|
|
|
|
def read(self):
|
|
"""Reads the robots.txt URL and feeds it to the parser."""
|
|
opener = URLopener()
|
|
f = opener.open(self.url)
|
|
lines = []
|
|
line = f.readline()
|
|
while line:
|
|
lines.append(line.strip())
|
|
line = f.readline()
|
|
self.errcode = opener.errcode
|
|
if self.errcode in (401, 403):
|
|
self.disallow_all = True
|
|
_debug("disallow all")
|
|
elif self.errcode >= 400:
|
|
self.allow_all = True
|
|
_debug("allow all")
|
|
elif self.errcode == 200 and lines:
|
|
_debug("parse lines")
|
|
self.parse(lines)
|
|
|
|
def _add_entry(self, entry):
|
|
if "*" in entry.useragents:
|
|
# the default entry is considered last
|
|
self.default_entry = entry
|
|
else:
|
|
self.entries.append(entry)
|
|
|
|
def parse(self, lines):
|
|
"""parse the input lines from a robots.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:
|
|
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._add_entry(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] = urllib.unquote(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._add_entry(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], False))
|
|
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], True))
|
|
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 robots.txt allowance for:\n user agent: %s\n url: %s" %
|
|
(useragent, url))
|
|
if self.disallow_all:
|
|
return False
|
|
if self.allow_all:
|
|
return True
|
|
# search for given user agent matches
|
|
# the first match counts
|
|
url = urllib.quote(urlparse.urlparse(urllib.unquote(url))[2]) or "/"
|
|
for entry in self.entries:
|
|
if entry.applies_to(useragent):
|
|
return entry.allowance(url)
|
|
# try the default entry last
|
|
if self.default_entry:
|
|
return self.default_entry.allowance(url)
|
|
# agent not found ==> access granted
|
|
return True
|
|
|
|
|
|
def __str__(self):
|
|
return ''.join([str(entry) + "\n" for entry in self.entries])
|
|
|
|
|
|
class RuleLine:
|
|
"""A rule line is a single "Allow:" (allowance==True) or "Disallow:"
|
|
(allowance==False) followed by a path."""
|
|
def __init__(self, path, allowance):
|
|
if path == '' and not allowance:
|
|
# an empty value means allow all
|
|
allowance = True
|
|
self.path = urllib.quote(path)
|
|
self.allowance = allowance
|
|
|
|
def applies_to(self, filename):
|
|
return self.path=="*" or filename.startswith(self.path)
|
|
|
|
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.extend(["User-agent: ", agent, "\n"])
|
|
for line in self.rulelines:
|
|
ret.extend([str(line), "\n"])
|
|
return ''.join(ret)
|
|
|
|
def applies_to(self, useragent):
|
|
"""check if this entry applies to the specified agent"""
|
|
# split the name token and make it lower case
|
|
useragent = useragent.split("/")[0].lower()
|
|
for agent in self.useragents:
|
|
if agent=='*':
|
|
# we have the catch-all agent
|
|
return True
|
|
agent = agent.lower()
|
|
if agent in useragent:
|
|
return True
|
|
return False
|
|
|
|
def allowance(self, filename):
|
|
"""Preconditions:
|
|
- our agent applies to this entry
|
|
- filename is URL decoded"""
|
|
for line in self.rulelines:
|
|
_debug((filename, str(line), line.allowance))
|
|
if line.applies_to(filename):
|
|
return line.allowance
|
|
return True
|
|
|
|
class URLopener(urllib.FancyURLopener):
|
|
def __init__(self, *args):
|
|
urllib.FancyURLopener.__init__(self, *args)
|
|
self.errcode = 200
|
|
|
|
def prompt_user_passwd(self, host, realm):
|
|
## If robots.txt file is accessible only with a password,
|
|
## we act as if the file wasn't there.
|
|
return None, None
|
|
|
|
def http_error_default(self, url, fp, errcode, errmsg, headers):
|
|
self.errcode = errcode
|
|
return urllib.FancyURLopener.http_error_default(self, url, fp, errcode,
|
|
errmsg, headers)
|
|
|
|
def _check(a,b):
|
|
if not b:
|
|
ac = "access denied"
|
|
else:
|
|
ac = "access allowed"
|
|
if a!=b:
|
|
print "failed"
|
|
else:
|
|
print "ok (%s)" % ac
|
|
print
|
|
|
|
def _test():
|
|
global debug
|
|
rp = RobotFileParser()
|
|
debug = 1
|
|
|
|
# robots.txt that exists, gotten to by redirection
|
|
rp.set_url('http://www.musi-cal.com/robots.txt')
|
|
rp.read()
|
|
|
|
# test for re.escape
|
|
_check(rp.can_fetch('*', 'http://www.musi-cal.com/'), 1)
|
|
# this should match the first rule, which is a disallow
|
|
_check(rp.can_fetch('', 'http://www.musi-cal.com/'), 0)
|
|
# various cherry pickers
|
|
_check(rp.can_fetch('CherryPickerSE',
|
|
'http://www.musi-cal.com/cgi-bin/event-search'
|
|
'?city=San+Francisco'), 0)
|
|
_check(rp.can_fetch('CherryPickerSE/1.0',
|
|
'http://www.musi-cal.com/cgi-bin/event-search'
|
|
'?city=San+Francisco'), 0)
|
|
_check(rp.can_fetch('CherryPickerSE/1.5',
|
|
'http://www.musi-cal.com/cgi-bin/event-search'
|
|
'?city=San+Francisco'), 0)
|
|
# case sensitivity
|
|
_check(rp.can_fetch('ExtractorPro', 'http://www.musi-cal.com/blubba'), 0)
|
|
_check(rp.can_fetch('extractorpro', 'http://www.musi-cal.com/blubba'), 0)
|
|
# substring test
|
|
_check(rp.can_fetch('toolpak/1.1', 'http://www.musi-cal.com/blubba'), 0)
|
|
# tests for catch-all * agent
|
|
_check(rp.can_fetch('spam', 'http://www.musi-cal.com/search'), 0)
|
|
_check(rp.can_fetch('spam', 'http://www.musi-cal.com/Musician/me'), 1)
|
|
_check(rp.can_fetch('spam', 'http://www.musi-cal.com/'), 1)
|
|
_check(rp.can_fetch('spam', 'http://www.musi-cal.com/'), 1)
|
|
|
|
# robots.txt that does not exist
|
|
rp.set_url('http://www.lycos.com/robots.txt')
|
|
rp.read()
|
|
_check(rp.can_fetch('Mozilla', 'http://www.lycos.com/search'), 1)
|
|
|
|
if __name__ == '__main__':
|
|
_test()
|