cpython/Lib/urlopen.py

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