Mass Deface = 400: self.allow_all = True elif self.errcode == 200 and lines: self.parse(lines) def _add_entry(self, entry): if "*" in entry.useragents: # the default entry is considered last if self.default_entry is None: # the first default entry wins 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.""" # states: # 0: start state # 1: saw user-agent line # 2: saw an allow or disallow line state = 0 linenumber = 0 entry = Entry() for line in lines: linenumber += 1 if not line: if state == 1: 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: self._add_entry(entry) entry = Entry() entry.useragents.append(line[1]) state = 1 elif line[0] == "disallow": if state != 0: entry.rulelines.append(RuleLine(line[1], False)) state = 2 elif line[0] == "allow": if state != 0: entry.rulelines.append(RuleLine(line[1], True)) state = 2 if state == 2: self._add_entry(entry) def can_fetch(self, useragent, url): """using the parsed robots.txt decide if useragent can fetch url""" if self.disallow_all: return False if self.allow_all: return True # search for given user agent matches # the first match counts parsed_url = urlparse.urlparse(urllib.unquote(url)) url = urlparse.urlunparse(('', '', parsed_url.path, parsed_url.params, parsed_url.query, parsed_url.fragment)) url = urllib.quote(url) if not url: url = "/" 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: 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)