"""Integration with Python standard library module urllib2. Also includes a redirection bugfix, support for parsing HTML HEAD blocks for the META HTTP-EQUIV tag contents, and following Refresh header redirects. Copyright 2002-2003 John J Lee This code is free software; you can redistribute it and/or modify it under the terms of the BSD License (see the file COPYING included with the distribution). """ import copy, time import ClientCookie from _ClientCookie import CookieJar, request_host from _Util import isstringlike from _Debug import _debug try: True except NameError: True = 1 False = 0 CHUNK = 1024 # size of chunks fed to HTML HEAD parser, in bytes try: from urllib2 import AbstractHTTPHandler except ImportError: pass else: import urlparse, urllib2, urllib, httplib, htmllib, formatter, string from urllib2 import URLError, HTTPError import types, string, socket from cStringIO import StringIO from _Util import seek_wrapper try: import threading _threading = threading; del threading except ImportError: import dummy_threading _threading = dummy_threading; del dummy_threading # This fixes a bug in urllib2 as of Python 2.1.3 and 2.2.2 # (http://www.python.org/sf/549151) # 2.2.3 is broken here (my fault!), 2.3 is fixed. class HTTPRedirectHandler(urllib2.BaseHandler): # maximum number of redirections before assuming we're in a loop max_redirections = 10 # Implementation notes: # To avoid the server sending us into an infinite loop, the request # object needs to track what URLs we have already seen. Do this by # adding a handler-specific attribute to the Request object. The value # of the dict is used to count the number of times the same url has # been visited. This is needed because this isn't necessarily a loop: # there is more than one way to redirect (Refresh, 302, 303, 307). # Another handler-specific Request attribute, original_url, is used to # remember the URL of the original request so that it is possible to # decide whether or not RFC 2965 cookies should be turned on during # redirect. # Always unhandled redirection codes: # 300 Multiple Choices: should not handle this here. # 304 Not Modified: no need to handle here: only of interest to caches # that do conditional GETs # 305 Use Proxy: probably not worth dealing with here # 306 Unused: what was this for in the previous versions of protocol?? def redirect_request(self, newurl, req, fp, code, msg, headers): """Return a Request or None in response to a redirect. This is called by the http_error_30x methods when a redirection response is received. If a redirection should take place, return a new Request to allow http_error_30x to perform the redirect; otherwise, return None to indicate that an HTTPError should be raised. """ if code in (301, 302, 303) or (code == 307 and not req.has_data()): # Strictly (according to RFC 2616), 301 or 302 in response to # a POST MUST NOT cause a redirection without confirmation # from the user (of urllib2, in this case). In practice, # essentially all clients do redirect in this case, so we do # the same. return Request(newurl, headers=req.headers) else: raise HTTPError(req.get_full_url(), code, msg, headers, fp) def http_error_302(self, req, fp, code, msg, headers): if headers.has_key('location'): newurl = headers['location'] elif headers.has_key('uri'): newurl = headers['uri'] else: return newurl = urlparse.urljoin(req.get_full_url(), newurl) # XXX Probably want to forget about the state of the current # request, although that might interact poorly with other # handlers that also use handler-specific request attributes new = self.redirect_request(newurl, req, fp, code, msg, headers) if new is None: return # remember where we started from if hasattr(req, "original_url"): new.original_url = req.original_url else: new.original_url = req.get_full_url() # loop detection # .error_302_dict[(url, code)] is number of times url # previously visited as a result of a redirection with this # code (error_30x_dict would be a better name). new.origin_req_host = req.origin_req_host if not hasattr(req, 'error_302_dict'): new.error_302_dict = req.error_302_dict = {(newurl, code): 1} else: ed = new.error_302_dict = req.error_302_dict nr_visits = ed.get((newurl, code), 0) # Refreshes generate fake 302s, so we can hit the same URL as # a result of the same redirection code twice without # necessarily being in a loop! So, allow two visits to each # URL as a result of each redirection code. if len(ed) < self.max_redirections and nr_visits < 2: ed[(newurl, code)] = nr_visits + 1 else: raise HTTPError(req.get_full_url(), code, self.inf_msg + msg, headers, fp) if ClientCookie.REDIRECT_DEBUG: _debug("redirecting to %s", newurl) # Don't close the fp until we are sure that we won't use it # with HTTPError. fp.read() fp.close() return self.parent.open(new) http_error_301 = http_error_303 = http_error_307 = http_error_302 inf_msg = "The HTTP server returned a redirect error that would " \ "lead to an infinite loop.\n" \ "The last 30x error message was:\n" class Request(urllib2.Request): def __init__(self, url, data=None, headers={}): urllib2.Request.__init__(self, url, data, headers) self.unredirected_hdrs = {} def add_unredirected_header(self, key, val): # these headers do not persist from one request to the next in a chain # of requests self.unredirected_hdrs[string.capitalize(key)] = val def has_key(self, header_name): if (self.headers.has_key(header_name) or self.unredirected_hdrs.has_key(header_name)): return True return False def get(self, header_name, failobj=None): if self.headers.has_key(header_name): return self.headers[header_name] if self.unredirected_headers.has_key(header_name): return self.unredirected_headers[header_name] return failobj class BaseProcessor: processor_order = 500 def add_parent(self, parent): self.parent = parent def close(self): self.parent = None def __lt__(self, other): if not hasattr(other, "processor_order"): return True return self.processor_order < other.processor_order class HTTPRequestUpgradeProcessor(BaseProcessor): # upgrade Request to class with support for headers that don't get # redirected processor_order = 0 # before anything else def http_request(self, request): if not hasattr(request, "add_unredirected_header"): request = Request(request._Request__original, request.data, request.headers) return request https_request = http_request class HTTPEquivProcessor(BaseProcessor): """Append META HTTP-EQUIV headers to regular HTTP headers.""" def http_response(self, request, response): if not hasattr(response, "seek"): response = seek_wrapper(response) # grab HTTP-EQUIV headers and add them to the true HTTP headers headers = response.info() for hdr, val in parse_head(response): headers[hdr] = val response.seek(0) return response https_response = http_response # XXX ATM this only takes notice of http responses -- probably # should be independent of protocol scheme (http, ftp, etc.) class SeekableProcessor(BaseProcessor): """Make responses seekable.""" def http_response(self, request, response): if not hasattr(response, "seek"): return seek_wrapper(response) return response https_response = http_response # XXX if this gets added to urllib2, unverifiable would end up as an # attribute on Request. class HTTPCookieProcessor(BaseProcessor): """Handle HTTP cookies.""" def __init__(self, cookies=None): if cookies is None: cookies = CookieJar() self.cookies = cookies def _unverifiable(self, request): if hasattr(request, "error_302_dict") and request.error_302_dict: redirect = True else: redirect = False if (redirect or (hasattr(request, "unverifiable") and request.unverifiable)): unverifiable = True else: unverifiable = False return unverifiable def http_request(self, request): unverifiable = self._unverifiable(request) if not unverifiable: # Stuff request-host of this origin transaction into Request # object, because we need to know it to know whether cookies # should be in operation during derived requests (redirects, # specifically -- including refreshes). request.origin_req_host = request_host(request) self.cookies.add_cookie_header(request, unverifiable) return request def http_response(self, request, response): unverifiable = self._unverifiable(request) self.cookies.extract_cookies(response, request, unverifiable) return response https_request = http_request https_response = http_response class HTTPRefererProcessor(BaseProcessor): """Add Referer header to requests. This only makes sense if you use each RefererProcessor for a single chain of requests only (so, for example, if you use a single HTTPRefererProcessor to fetch a series of URLs extracted from a single page, this will break). """ def __init__(self): self.referer = None def http_request(self, request): if ((self.referer is not None) and not request.has_key("Referer")): request.add_unredirected_header("Referer", self.referer) return request def http_response(self, request, response): self.referer = response.geturl() return response https_request = http_request https_response = http_response class HTTPStandardHeadersProcessor(BaseProcessor): def http_request(self, request): host = request.get_host() if not host: raise URLError('no host given') if request.has_data(): # POST data = request.get_data() if not request.has_key('Content-type'): request.add_unredirected_header( 'Content-type', 'application/x-www-form-urlencoded') if not request.has_key('Content-length'): request.add_unredirected_header( 'Content-length', '%d' % len(data)) scheme, sel = urllib.splittype(request.get_selector()) sel_host, sel_path = urllib.splithost(sel) if not request.has_key('Host'): request.add_unredirected_header('Host', sel_host or host) for name, value in self.parent.addheaders: name = string.capitalize(name) if not request.has_key(name): request.add_unredirected_header(name, value) return request https_request = http_request class HTTPResponseDebugProcessor(BaseProcessor): processor_order = 900 # before redirections, after everything else def http_response(self, request, response): if not hasattr(response, "seek"): response = seek_wrapper(response) _debug(response.read()) _debug("*****************************************************") response.seek(0) return response https_response = http_response class HTTPRefreshProcessor(BaseProcessor): """Perform HTTP Refresh redirections. Note that if a non-200 HTTP code has occurred (for example, a 30x redirect), this processor will do nothing. By default, only zero-time Refresh headers are redirected. Use the max_time constructor argument to allow Refresh with longer pauses. Use the honor_time argument to control whether the requested pause is honoured (with a time.sleep()) or skipped in favour of immediate redirection. """ processor_order = 1000 def __init__(self, max_time=0, honor_time=True): self.max_time = max_time self.honor_time = honor_time def http_response(self, request, response): code, msg, hdrs = response.code, response.msg, response.info() if code == 200 and hdrs.has_key("refresh"): refresh = hdrs["refresh"] i = string.find(refresh, ";") if i != -1: pause, newurl_spec = refresh[:i], refresh[i+1:] i = string.find(newurl_spec, "=") if i != -1: pause = int(pause) if pause <= self.max_time: if pause != 0 and self.honor_time: time.sleep(pause) newurl = newurl_spec[i+1:] # fake a 302 response hdrs["location"] = newurl response = self.parent.error( 'http', request, response, 302, msg, hdrs) return response https_response = http_response class HTTPErrorProcessor(BaseProcessor): """Process non-200 HTTP error responses. This just passes the job on to the Handler._error_ methods, via the OpenerDirector.error method. """ processor_order = 1000 def http_response(self, request, response): code, msg, hdrs = response.code, response.msg, response.info() if code != 200: response = self.parent.error( 'http', request, response, code, msg, hdrs) return response https_response = http_response class OpenerDirector(urllib2.OpenerDirector): # XXX might be useful to have remove_processor, too (say you want to # set a new RefererProcessor, but keep the old CookieProcessor -- # could always just create everything anew, though (using old # CookieJar object to create CookieProcessor) def __init__(self): urllib2.OpenerDirector.__init__(self) #self.processors = [] self.process_response = {} self.process_request = {} def add_handler(self, handler): # XXX # tidy me # the same handler could be added twice without detection added = 0 for meth in dir(handler.__class__): if meth[-5:] == '_open': protocol = meth[:-5] if self.handle_open.has_key(protocol): self.handle_open[protocol].append(handler) self.handle_open[protocol].sort() else: self.handle_open[protocol] = [handler] added = 1 continue i = string.find(meth, '_') j = string.find(meth[i+1:], '_') + i + 1 if j != -1 and meth[i+1:j] == 'error': proto = meth[:i] kind = meth[j+1:] try: kind = int(kind) except ValueError: pass dict = self.handle_error.get(proto, {}) if dict.has_key(kind): dict[kind].append(handler) dict[kind].sort() else: dict[kind] = [handler] self.handle_error[proto] = dict added = 1 continue if meth[-9:] == "_response": protocol = meth[:-9] if self.process_response.has_key(protocol): self.process_response[protocol].append(handler) self.process_response[protocol].sort() else: self.process_response[protocol] = [handler] added = True continue elif meth[-8:] == "_request": protocol = meth[:-8] if self.process_request.has_key(protocol): self.process_request[protocol].append(handler) self.process_request[protocol].sort() else: self.process_request[protocol] = [handler] added = True continue if added: self.handlers.append(handler) self.handlers.sort() handler.add_parent(self) ## def add_processor(self, processor): ## added = False ## for meth in dir(processor): ## if meth[-9:] == "_response": ## protocol = meth[:-9] ## if self.process_response.has_key(protocol): ## self.process_response[protocol].append(processor) ## self.process_response[protocol].sort() ## else: ## self.process_response[protocol] = [processor] ## added = True ## continue ## elif meth[-8:] == "_request": ## protocol = meth[:-8] ## if self.process_request.has_key(protocol): ## self.process_request[protocol].append(processor) ## self.process_request[protocol].sort() ## else: ## self.process_request[protocol] = [processor] ## added = True ## continue ## if added: ## self.processors.append(processor) ## # XXX base class sorts .handlers, but I have no idea why ## #self.processors.sort() ## processor.add_parent(self) def _request(self, url_or_req, data): if isstringlike(url_or_req): req = Request(url_or_req, data) else: # already a urllib2.Request instance req = url_or_req if data is not None: req.add_data(data) return req def open(self, fullurl, data=None): req = self._request(fullurl, data) type = req.get_type() # pre-process request # XXX should we allow a Processor to change the type (URL # scheme) of the request? meth_name = type+"_request" for processor in self.process_request.get(type, []): meth = getattr(processor, meth_name) req = meth(req) response = urllib2.OpenerDirector.open(self, req, data) # post-process response meth_name = type+"_response" for processor in self.process_response.get(type, []): meth = getattr(processor, meth_name) response = meth(req, response) return response ## def close(self): ## urllib2.OpenerDirector.close(self) ## for processor in self.processors: ## processor.close() ## self.processors = [] # Note the absence of redirect and header-adding code here # (AbstractHTTPHandler), and the lack of other clutter that would be # here without Processors. class AbstractHTTPHandler(urllib2.BaseHandler): def do_open(self, http_class, req): host = req.get_host() if not host: raise URLError('no host given') h = http_class(host) # will parse host:port if ClientCookie.HTTP_DEBUG: h.set_debuglevel(1) if req.has_data(): h.putrequest('POST', req.get_selector()) else: h.putrequest('GET', req.get_selector()) for k, v in req.headers.items(): h.putheader(k, v) for k, v in req.unredirected_hdrs.items(): h.putheader(k, v) # httplib will attempt to connect() here. be prepared # to convert a socket error to a URLError. try: h.endheaders() except socket.error, err: raise URLError(err) if req.has_data(): h.send(req.get_data()) code, msg, hdrs = h.getreply() fp = h.getfile() response = urllib.addinfourl(fp, hdrs, req.get_full_url()) response.code = code response.msg = msg return response # XXX would self.reset() work, instead of raising this exception? class EndOfHeadError(Exception): pass class HeadParser(htmllib.HTMLParser): # only these elements are allowed in or before HEAD of document head_elems = ("html", "head", "title", "base", "script", "style", "meta", "link", "object") def __init__(self): htmllib.HTMLParser.__init__(self, formatter.NullFormatter()) self.http_equiv = [] def start_meta(self, attrs): http_equiv = content = None for key, value in attrs: if key == "http-equiv": http_equiv = value elif key == "content": content = value if http_equiv is not None: self.http_equiv.append((http_equiv, content)) def handle_starttag(self, tag, method, attrs): if tag in self.head_elems: method(attrs) else: raise EndOfHeadError() def handle_endtag(self, tag, method): if tag in self.head_elems: method() else: raise EndOfHeadError() def end_head(self): raise EndOfHeadError() def parse_head(file): """Return a list of key, value pairs.""" hp = HeadParser() while 1: data = file.read(CHUNK) try: hp.feed(data) except EndOfHeadError: break if len(data) != CHUNK: # this should only happen if there is no HTML body, or if # CHUNK is big break return hp.http_equiv class HTTPHandler(AbstractHTTPHandler): def http_open(self, req): return self.do_open(httplib.HTTP, req) if hasattr(httplib, 'HTTPS'): class HTTPSHandler(AbstractHTTPHandler): def https_open(self, req): return self.do_open(httplib.HTTPS, req) def build_opener(*handlers): """Create an opener object from a list of handlers and processors. The opener will use several default handlers and processors, including support for HTTP and FTP. If there is a ProxyHandler, it must be at the front of the list of handlers. (Yuck. This is fixed in 2.3.) If any of the handlers passed as arguments are subclasses of the default handlers, the default handlers will not be used. """ opener = OpenerDirector() default_classes = [ # handlers urllib2.ProxyHandler, urllib2.UnknownHandler, HTTPHandler, # from this module (derived from new AbstractHTTPHandler) urllib2.HTTPDefaultErrorHandler, HTTPRedirectHandler, # from this module (bugfixed) urllib2.FTPHandler, urllib2.FileHandler, # processors HTTPRequestUpgradeProcessor, #HTTPEquivProcessor, #SeekableProcessor, HTTPCookieProcessor, #HTTPRefererProcessor, HTTPStandardHeadersProcessor, #HTTPRefreshProcessor, HTTPErrorProcessor ] if hasattr(httplib, 'HTTPS'): default_classes.append(HTTPSHandler) skip = [] for klass in default_classes: for check in handlers: if type(check) == types.ClassType: if issubclass(check, klass): skip.append(klass) elif type(check) == types.InstanceType: if isinstance(check, klass): skip.append(klass) for klass in skip: default_classes.remove(klass) to_add = [] for klass in default_classes: to_add.append(klass()) for h in handlers: if type(h) == types.ClassType: h = h() to_add.append(h) for instance in to_add: opener.add_handler(instance) ## # yuck ## if hasattr(instance, "processor_order"): ## opener.add_processor(instance) ## else: ## opener.add_handler(instance) return opener _opener = None urlopen_lock = _threading.Lock() def urlopen(url, data=None): global _opener if _opener is None: urlopen_lock.acquire() try: if _opener is None: _opener = build_opener() finally: urlopen_lock.release() return _opener.open(url, data) def install_opener(opener): global _opener _opener = opener