mirror of
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411 lines
11 KiB
Python
Executable File
411 lines
11 KiB
Python
Executable File
# Open an arbitrary URL
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#
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# See the following document for a tentative description of URLs:
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# Uniform Resource Locators Tim Berners-Lee
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# INTERNET DRAFT CERN
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# IETF URL Working Group 14 July 1993
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# draft-ietf-uri-url-01.txt
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#
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# The object returned by URLopener().open(file) will differ per
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# protocol. All you know is that is has methods read(), readline(),
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# readlines(), fileno(), close() and info(). The read*(), fileno()
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# and close() methods work like those of open files.
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# The info() method returns an rfc822.Message object which can be
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# used to query various info about the object, if available.
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# (rfc822.Message objects are queried with the getheader() method.)
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import socket
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import regex
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# This really consists of two pieces:
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# (1) a class which handles opening of all sorts of URLs
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# (plus assorted utilities etc.)
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# (2) a set of functions for parsing URLs
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# XXX Should these be separated out into different modules?
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# Shortcut for basic usage
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_urlopener = None
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def urlopen(url):
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global _urlopener
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if not _urlopener:
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_urlopener = URLopener()
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return _urlopener.open(url)
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def urlretrieve(url):
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global _urlopener
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if not _urlopener:
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_urlopener = URLopener()
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return _urlopener.retrieve(url)
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def urlcleanup():
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if _urlopener:
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_urlopener.cleanup()
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# Class to open URLs.
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# This is a class rather than just a subroutine because we may need
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# more than one set of global protocol-specific options.
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ftpcache = {}
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class URLopener:
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# Constructor
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def __init__(self):
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self.addheaders = []
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self.tempcache = {}
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self.ftpcache = ftpcache
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# Undocumented feature: you can use a different
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# ftp cache by assigning to the .ftpcache member;
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# in case you want logically independent URL openers
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def __del__(self):
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self.close()
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def close(self):
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self.cleanup()
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def cleanup(self):
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import os
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for url in self.tempcache.keys():
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try:
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os.unlink(self.tempcache[url][0])
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except os.error:
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pass
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del self.tempcache[url]
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# Add a header to be used by the HTTP interface only
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# e.g. u.addheader('Accept', 'sound/basic')
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def addheader(self, *args):
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self.addheaders.append(args)
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# External interface
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# Use URLopener().open(file) instead of open(file, 'r')
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def open(self, url):
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type, url = splittype(unwrap(url))
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if not type: type = 'file'
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name = 'open_' + type
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if '-' in name:
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import regsub
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name = regsub.gsub('-', '_', name)
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if not hasattr(self, name):
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raise IOError, ('url error', 'unknown url type', type)
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try:
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return getattr(self, name)(url)
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except socket.error, msg:
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raise IOError, ('socket error', msg)
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# External interface
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# retrieve(url) returns (filename, None) for a local object
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# or (tempfilename, headers) for a remote object
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def retrieve(self, url):
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if self.tempcache.has_key(url):
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return self.tempcache[url]
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url1 = unwrap(url)
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if self.tempcache.has_key(url1):
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self.tempcache[url] = self.tempcache[url1]
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return self.tempcache[url1]
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type, url1 = splittype(url1)
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if not type or type == 'file':
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try:
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fp = self.open_local_file(url1)
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del fp
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return splithost(url1)[1], None
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except IOError, msg:
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pass
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fp = self.open(url)
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headers = fp.info()
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import tempfile
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tfn = tempfile.mktemp()
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self.tempcache[url] = result = tfn, headers
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tfp = open(tfn, 'w')
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bs = 1024*8
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block = fp.read(bs)
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while block:
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tfp.write(block)
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block = fp.read(bs)
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del fp
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del tfp
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return result
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# Each method named open_<type> knows how to open that type of URL
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# Use HTTP protocol
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def open_http(self, url):
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import httplib
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host, selector = splithost(url)
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h = httplib.HTTP(host)
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h.putrequest('GET', selector)
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for args in self.addheaders: apply(h.putheader, args)
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errcode, errmsg, headers = h.getreply()
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if errcode == 200: return addinfo(h.getfile(), headers)
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else: raise IOError, ('http error', errcode, errmsg, headers)
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# Use Gopher protocol
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def open_gopher(self, url):
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import gopherlib
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host, selector = splithost(url)
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type, selector = splitgophertype(selector)
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selector, query = splitquery(selector)
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if query: fp = gopherlib.send_query(selector, query, host)
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else: fp = gopherlib.send_selector(selector, host)
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return addinfo(fp, noheaders())
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# Use local file or FTP depending on form of URL
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def open_file(self, url):
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try:
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return self.open_local_file(url)
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except IOError:
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return self.open_ftp(url)
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# Use local file
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def open_local_file(self, url):
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host, file = splithost(url)
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if not host: return addinfo(open(file, 'r'), noheaders())
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host, port = splitport(host)
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if not port and socket.gethostbyname(host) in (
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localhost(), thishost()):
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return addinfo(open(file, 'r'), noheaders())
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raise IOError, ('local file error', 'not on local host')
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# Use FTP protocol
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def open_ftp(self, url):
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host, file = splithost(url)
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if not host: raise IOError, ('ftp error', 'no host given')
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host, port = splitport(host)
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host = socket.gethostbyname(host)
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if not port:
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import ftplib
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port = ftplib.FTP_PORT
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key = (host, port)
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try:
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if not self.ftpcache.has_key(key):
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self.ftpcache[key] = ftpwrapper(host, port)
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return addinfo(self.ftpcache[key].retrfile(file),
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noheaders())
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except ftperrors(), msg:
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raise IOError, ('ftp error', msg)
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# Utility functions
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# Return the IP address of the magic hostname 'localhost'
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_localhost = None
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def localhost():
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global _localhost
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if not _localhost:
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_localhost = socket.gethostbyname('localhost')
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return _localhost
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# Return the IP address of the current host
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_thishost = None
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def thishost():
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global _thishost
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if not _thishost:
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_thishost = socket.gethostbyname(socket.gethostname())
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return _thishost
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# Return the set of errors raised by the FTP class
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_ftperrors = None
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def ftperrors():
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global _ftperrors
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if not _ftperrors:
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import ftplib
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_ftperrors = (ftplib.error_reply,
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ftplib.error_temp,
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ftplib.error_perm,
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ftplib.error_proto)
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return _ftperrors
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# Return an empty rfc822.Message object
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_noheaders = None
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def noheaders():
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global _noheaders
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if not _noheaders:
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import rfc822
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_noheaders = rfc822.Message(open('/dev/null', 'r'))
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_noheaders.fp.close() # Recycle file descriptor
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return _noheaders
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# Utility classes
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# Class used by open_ftp() for cache of open FTP connections
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class ftpwrapper:
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def __init__(self, host, port):
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self.host = host
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self.port = port
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self.init()
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def init(self):
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import ftplib
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self.ftp = ftplib.FTP()
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self.ftp.connect(self.host, self.port)
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self.ftp.login()
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def retrfile(self, file):
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import ftplib
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try:
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self.ftp.voidcmd('TYPE I')
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except ftplib.all_errors:
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self.init()
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self.ftp.voidcmd('TYPE I')
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conn = None
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if file:
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try:
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cmd = 'RETR ' + file
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conn = self.ftp.transfercmd(cmd)
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except ftplib.error_perm, reason:
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if reason[:3] != '550':
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raise IOError, ('ftp error', reason)
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if not conn:
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# Try a directory listing
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if file: cmd = 'LIST ' + file
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else: cmd = 'LIST'
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conn = self.ftp.transfercmd(cmd)
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return addclosehook(conn.makefile('r'), self.ftp.voidresp)
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# Base class for addinfo and addclosehook
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class addbase:
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def __init__(self, fp):
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self.fp = fp
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self.read = self.fp.read
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self.readline = self.fp.readline
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self.readlines = self.fp.readlines
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self.fileno = self.fp.fileno
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def __repr__(self):
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return '<%s at %s whose fp = %s>' % (
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self.__class__.__name__, `id(self)`, `self.fp`)
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def __del__(self):
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self.close()
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def close(self):
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self.read = None
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self.readline = None
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self.readlines = None
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self.fileno = None
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self.fp = None
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# Class to add a close hook to an open file
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class addclosehook(addbase):
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def __init__(self, fp, closehook, *hookargs):
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addbase.__init__(self, fp)
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self.closehook = closehook
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self.hookargs = hookargs
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def close(self):
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if self.closehook:
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apply(self.closehook, self.hookargs)
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self.closehook = None
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self.hookargs = None
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addbase.close(self)
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# class to add an info() method to an open file
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class addinfo(addbase):
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def __init__(self, fp, headers):
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addbase.__init__(self, fp)
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self.headers = headers
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def info(self):
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return self.headers
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# Utility to combine a URL with a base URL to form a new URL
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def basejoin(base, url):
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type, path = splittype(url)
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if type: return url
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host, path = splithost(path)
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basetype, basepath = splittype(base)
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basehost, basepath = splithost(basepath)
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basepath, basetag = splittag(basepath)
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basepath, basequery = splitquery(basepath)
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type = basetype or 'file'
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if path[:1] != '/':
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import string
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i = string.rfind(basepath, '/')
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if i < 0: basepath = '/'
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else: basepath = basepath[:i+1]
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path = basepath + path
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if not host: host = basehost
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if host: return type + '://' + host + path
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else: return type + ':' + path
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# Utilities to parse URLs:
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# unwrap('<URL:type//host/path>') --> 'type//host/path'
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# splittype('type:opaquestring') --> 'type', 'opaquestring'
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# splithost('//host[:port]/path') --> 'host[:port]', '/path'
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# splitport('host:port') --> 'host', 'port'
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# splitquery('/path?query') --> '/path', 'query'
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# splittag('/path#tag') --> '/path', 'tag'
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# splitgophertype('/Xselector') --> 'X', 'selector'
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def unwrap(url):
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import string
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url = string.strip(url)
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if url[:1] == '<' and url[-1:] == '>':
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url = string.strip(url[1:-1])
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if url[:4] == 'URL:': url = string.strip(url[4:])
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return url
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_typeprog = regex.compile('^\([^/:]+\):\(.*\)$')
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def splittype(url):
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if _typeprog.match(url) >= 0: return _typeprog.group(1, 2)
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return None, url
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_hostprog = regex.compile('^//\([^/]+\)\(.*\)$')
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def splithost(url):
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if _hostprog.match(url) >= 0: return _hostprog.group(1, 2)
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return None, url
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_portprog = regex.compile('^\(.*\):\([0-9]+\)$')
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def splitport(host):
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if _portprog.match(host) >= 0: return _portprog.group(1, 2)
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return host, None
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_queryprog = regex.compile('^\(.*\)\?\([^?]*\)$')
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def splitquery(url):
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if _queryprog.match(url) >= 0: return _queryprog.group(1, 2)
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return url, None
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_tagprog = regex.compile('^\(.*\)#\([^#]*\)$')
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def splittag(url):
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if _tagprog.match(url) >= 0: return _tagprog.group(1, 2)
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return url, None
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def splitgophertype(selector):
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if selector[:1] == '/' and selector[1:2]:
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return selector[1], selector[2:]
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return None, selector
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# Test program
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def test():
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import sys
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import regsub
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args = sys.argv[1:]
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if not args:
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args = [
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'/etc/passwd',
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'file:/etc/passwd',
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'file://localhost/etc/passwd',
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'ftp://ftp.cwi.nl/etc/passwd',
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'gopher://gopher.cwi.nl/11/',
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'http://www.cwi.nl/index.html',
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]
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try:
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for url in args:
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print '-'*10, url, '-'*10
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fn, h = urlretrieve(url)
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print fn, h
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if h:
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print '======'
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for k in h.keys(): print k + ':', h[k]
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print '======'
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fp = open(fn, 'r')
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data = fp.read()
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del fp
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print regsub.gsub('\r', '', data)
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fn, h = None, None
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print '-'*40
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finally:
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urlcleanup()
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# Run test program when run as a script
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if __name__ == '__main__':
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test()
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