cpython/Lib/urllib.py
1996-08-26 15:56:12 +00:00

738 lines
20 KiB
Python

# 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
#
# 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 mimetools.Message object which can be
# used to query various info about the object, if available.
# (mimetools.Message objects are queried with the getheader() method.)
import string
import socket
import regex
import os
__version__ = '1.3'
# Helper for non-unix systems
if os.name == 'mac':
from macurl2path import url2pathname, pathname2url
elif os.name == 'nt':
from nturl2path import url2pathname, pathname2url
else:
def url2pathname(pathname):
return pathname
def pathname2url(pathname):
return pathname
# 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):
global _urlopener
if not _urlopener:
_urlopener = FancyURLopener()
return _urlopener.open(url)
def urlretrieve(url, filename=None):
global _urlopener
if not _urlopener:
_urlopener = FancyURLopener()
if filename:
return _urlopener.retrieve(url, filename)
else:
return _urlopener.retrieve(url)
def urlcleanup():
if _urlopener:
_urlopener.cleanup()
# 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.
# Note -- this is a base class for those who don't want the
# automatic handling of errors type 302 (relocated) and 401
# (authorization needed).
ftpcache = {}
class URLopener:
# Constructor
def __init__(self, proxies=None):
if proxies is None:
proxies = getproxies()
self.proxies = proxies
server_version = "Python-urllib/%s" % __version__
self.addheaders = [('User-agent', server_version)]
self.tempcache = None
# Undocumented feature: if you assign {} to tempcache,
# it is used to cache files retrieved with
# self.retrieve(). This is not enabled by default
# since it does not work for changing documents (and I
# haven't got the logic to check expiration headers
# yet).
self.ftpcache = ftpcache
# 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
if self.tempcache:
for url in self.tempcache.keys():
try:
os.unlink(self.tempcache[url][0])
except os.error:
pass
del self.tempcache[url]
# 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)
# External interface
# Use URLopener().open(file) instead of open(file, 'r')
def open(self, fullurl):
fullurl = unwrap(fullurl)
type, url = splittype(fullurl)
if not type: type = 'file'
if self.proxies.has_key(type):
proxy = self.proxies[type]
type, proxy = splittype(proxy)
host, selector = splithost(proxy)
url = (host, fullurl) # Signal special case to open_*()
name = 'open_' + type
if '-' in name:
import regsub
name = regsub.gsub('-', '_', name)
if not hasattr(self, name):
return self.open_unknown(fullurl)
try:
return getattr(self, name)(url)
except socket.error, msg:
raise IOError, ('socket error', msg)
# Overridable interface to open unknown URL type
def open_unknown(self, fullurl):
type, url = splittype(fullurl)
raise IOError, ('url error', 'unknown url type', type)
# External interface
# retrieve(url) returns (filename, None) for a local object
# or (tempfilename, headers) for a remote object
def retrieve(self, url, filename=None):
if self.tempcache and self.tempcache.has_key(url):
return self.tempcache[url]
url1 = unwrap(url)
if self.tempcache and self.tempcache.has_key(url1):
self.tempcache[url] = self.tempcache[url1]
return self.tempcache[url1]
type, url1 = splittype(url1)
if not filename and (not type or type == 'file'):
try:
fp = self.open_local_file(url1)
del fp
return url2pathname(splithost(url1)[1]), None
except IOError, msg:
pass
fp = self.open(url)
headers = fp.info()
if not filename:
import tempfile
filename = tempfile.mktemp()
result = filename, headers
if self.tempcache is not None:
self.tempcache[url] = result
tfp = open(filename, 'w')
bs = 1024*8
block = fp.read(bs)
while block:
tfp.write(block)
block = fp.read(bs)
del fp
del tfp
return result
# Each method named open_<type> knows how to open that type of URL
# Use HTTP protocol
def open_http(self, url):
import httplib
if type(url) is type(""):
host, selector = splithost(url)
else:
host, selector = url
print "proxy via http:", host, selector
if not host: raise IOError, ('http error', 'no host given')
i = string.find(host, '@')
if i >= 0:
user_passwd, host = host[:i], host[i+1:]
else:
user_passwd = None
if user_passwd:
import base64
auth = string.strip(base64.encodestring(user_passwd))
else:
auth = None
h = httplib.HTTP(host)
h.putrequest('GET', selector)
if auth: h.putheader('Authorization: Basic %s' % auth)
for args in self.addheaders: apply(h.putheader, args)
h.endheaders()
errcode, errmsg, headers = h.getreply()
fp = h.getfile()
if errcode == 200:
return addinfo(fp, headers)
else:
return self.http_error(url,
fp, errcode, errmsg, headers)
# Handle http errors.
# Derived class can override this, or provide specific handlers
# named http_error_DDD where DDD is the 3-digit error code
def http_error(self, url, fp, errcode, errmsg, headers):
# First check if there's a specific handler for this error
name = 'http_error_%d' % errcode
if hasattr(self, name):
method = getattr(self, name)
result = method(url, fp, errcode, errmsg, headers)
if result: return result
return self.http_error_default(
url, fp, errcode, errmsg, headers)
# Default http error handler: close the connection and raises IOError
def http_error_default(self, url, fp, errcode, errmsg, headers):
void = fp.read()
fp.close()
raise IOError, ('http error', errcode, errmsg, headers)
# Use Gopher protocol
def open_gopher(self, url):
import gopherlib
host, selector = splithost(url)
if not host: raise IOError, ('gopher error', 'no host given')
type, selector = splitgophertype(selector)
selector, query = splitquery(selector)
selector = unquote(selector)
if query:
query = unquote(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):
if url[:2] == '//':
return self.open_ftp(url)
else:
return self.open_local_file(url)
# Use local file
def open_local_file(self, url):
host, file = splithost(url)
if not host: return addinfo(open(url2pathname(file), 'r'), noheaders())
host, port = splitport(host)
if not port and socket.gethostbyname(host) in (
localhost(), thishost()):
file = unquote(file)
return addinfo(open(url2pathname(file), 'r'), noheaders())
raise IOError, ('local file error', 'not on local host')
# Use FTP protocol
def open_ftp(self, url):
host, path = splithost(url)
if not host: raise IOError, ('ftp error', 'no host given')
host, port = splitport(host)
user, host = splituser(host)
if user: user, passwd = splitpasswd(user)
else: passwd = None
host = socket.gethostbyname(host)
if not port:
import ftplib
port = ftplib.FTP_PORT
path, attrs = splitattr(path)
dirs = string.splitfields(path, '/')
dirs, file = dirs[:-1], dirs[-1]
if dirs and not dirs[0]: dirs = dirs[1:]
key = (user, host, port, string.joinfields(dirs, '/'))
try:
if not self.ftpcache.has_key(key):
self.ftpcache[key] = \
ftpwrapper(user, passwd,
host, port, dirs)
if not file: type = 'D'
else: type = 'I'
for attr in attrs:
attr, value = splitvalue(attr)
if string.lower(attr) == 'type' and \
value in ('a', 'A', 'i', 'I', 'd', 'D'):
type = string.upper(value)
return addinfo(self.ftpcache[key].retrfile(file, type),
noheaders())
except ftperrors(), msg:
raise IOError, ('ftp error', msg)
# Derived class with handlers for errors we can handle (perhaps)
class FancyURLopener(URLopener):
def __init__(self, *args):
apply(URLopener.__init__, (self,) + args)
self.auth_cache = {}
# Default error handling -- don't raise an exception
def http_error_default(self, url, fp, errcode, errmsg, headers):
return addinfo(fp, headers)
# Error 302 -- relocated
def http_error_302(self, url, fp, errcode, errmsg, headers):
# XXX The server can force infinite recursion here!
if headers.has_key('location'):
newurl = headers['location']
elif headers.has_key('uri'):
newurl = headers['uri']
else:
return
void = fp.read()
fp.close()
return self.open(newurl)
# Error 401 -- authentication required
# See this URL for a description of the basic authentication scheme:
# http://www.ics.uci.edu/pub/ietf/http/draft-ietf-http-v10-spec-00.txt
def http_error_401(self, url, fp, errcode, errmsg, headers):
if headers.has_key('www-authenticate'):
stuff = headers['www-authenticate']
p = regex.compile(
'[ \t]*\([^ \t]+\)[ \t]+realm="\([^"]*\)"')
if p.match(stuff) >= 0:
scheme, realm = p.group(1, 2)
if string.lower(scheme) == 'basic':
return self.retry_http_basic_auth(
url, realm)
def retry_http_basic_auth(self, url, realm):
host, selector = splithost(url)
i = string.find(host, '@') + 1
host = host[i:]
user, passwd = self.get_user_passwd(host, realm, i)
if not (user or passwd): return None
host = user + ':' + passwd + '@' + host
newurl = '//' + host + selector
return self.open_http(newurl)
def get_user_passwd(self, host, realm, clear_cache = 0):
key = realm + '@' + string.lower(host)
if self.auth_cache.has_key(key):
if clear_cache:
del self.auth_cache[key]
else:
return self.auth_cache[key]
user, passwd = self.prompt_user_passwd(host, realm)
if user or passwd: self.auth_cache[key] = (user, passwd)
return user, passwd
def prompt_user_passwd(self, host, realm):
# Override this in a GUI environment!
try:
user = raw_input("Enter username for %s at %s: " %
(realm, host))
self.echo_off()
try:
passwd = raw_input(
"Enter password for %s in %s at %s: " %
(user, realm, host))
finally:
self.echo_on()
return user, passwd
except KeyboardInterrupt:
return None, None
def echo_off(self):
import os
os.system("stty -echo")
def echo_on(self):
import os
print
os.system("stty echo")
# 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 mimetools.Message object
_noheaders = None
def noheaders():
global _noheaders
if not _noheaders:
import mimetools
import StringIO
_noheaders = mimetools.Message(StringIO.StringIO(), 0)
_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, user, passwd, host, port, dirs):
self.user = unquote(user or '')
self.passwd = unquote(passwd or '')
self.host = host
self.port = port
self.dirs = []
for dir in dirs:
self.dirs.append(unquote(dir))
self.init()
def init(self):
import ftplib
self.ftp = ftplib.FTP()
self.ftp.connect(self.host, self.port)
self.ftp.login(self.user, self.passwd)
for dir in self.dirs:
self.ftp.cwd(dir)
def retrfile(self, file, type):
import ftplib
if type in ('d', 'D'): cmd = 'TYPE A'; isdir = 1
else: cmd = 'TYPE ' + type; isdir = 0
try:
self.ftp.voidcmd(cmd)
except ftplib.all_errors:
self.init()
self.ftp.voidcmd(cmd)
conn = None
if file and not isdir:
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)
return addclosehook(conn.makefile('rb'), self.ftp.voidresp)
# Base class for addinfo and addclosehook
class addbase:
def __init__(self, fp):
self.fp = fp
self.read = self.fp.read
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 close(self):
self.read = None
self.readline = None
self.readlines = None
self.fileno = None
if self.fp: self.fp.close()
self.fp = None
# 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)
# 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:
# if url is complete (i.e., it contains a type), return it
return url
host, path = splithost(path)
type, basepath = splittype(base) # inherit type from base
if host:
# if url contains host, just inherit type
if type: return type + '://' + host + path
else:
# no type inherited, so url must have started with //
# just return it
return url
host, basepath = splithost(basepath) # inherit host
basepath, basetag = splittag(basepath) # remove extraneuous cruft
basepath, basequery = splitquery(basepath) # idem
if path[:1] != '/':
# non-absolute path name
if path[:1] in ('#', '?'):
# path is just a tag or query, attach to basepath
i = len(basepath)
else:
# else replace last component
i = string.rfind(basepath, '/')
if i < 0:
# basepath not absolute
if host:
# host present, make absolute
basepath = '/'
else:
# else keep non-absolute
basepath = ''
else:
# remove last file component
basepath = basepath[:i+1]
path = basepath + path
if type and host: return type + '://' + host + path
elif type: return type + ':' + path
elif host: return '//' + host + path # don't know what this means
else: return path
# Utilities to parse URLs (most of these return None for missing parts):
# unwrap('<URL:type://host/path>') --> 'type://host/path'
# splittype('type:opaquestring') --> 'type', 'opaquestring'
# splithost('//host[:port]/path') --> 'host[:port]', '/path'
# splituser('user[:passwd]@host[:port]') --> 'user[:passwd]', 'host[:port]'
# splitpasswd('user:passwd') -> 'user', 'passwd'
# splitport('host:port') --> 'host', 'port'
# splitquery('/path?query') --> '/path', 'query'
# splittag('/path#tag') --> '/path', 'tag'
# splitattr('/path;attr1=value1;attr2=value2;...') ->
# '/path', ['attr1=value1', 'attr2=value2', ...]
# splitvalue('attr=value') --> 'attr', 'value'
# splitgophertype('/Xselector') --> 'X', 'selector'
# unquote('abc%20def') -> 'abc def'
# quote('abc def') -> 'abc%20def')
def unwrap(url):
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
_typeprog = regex.compile('^\([^/:]+\):\(.*\)$')
def splittype(url):
if _typeprog.match(url) >= 0: return _typeprog.group(1, 2)
return None, url
_hostprog = regex.compile('^//\([^/]+\)\(.*\)$')
def splithost(url):
if _hostprog.match(url) >= 0: return _hostprog.group(1, 2)
return None, url
_userprog = regex.compile('^\([^@]*\)@\(.*\)$')
def splituser(host):
if _userprog.match(host) >= 0: return _userprog.group(1, 2)
return None, host
_passwdprog = regex.compile('^\([^:]*\):\(.*\)$')
def splitpasswd(user):
if _passwdprog.match(user) >= 0: return _passwdprog.group(1, 2)
return user, None
_portprog = regex.compile('^\(.*\):\([0-9]+\)$')
def splitport(host):
if _portprog.match(host) >= 0: return _portprog.group(1, 2)
return host, None
# Split host and port, returning numeric port.
# Return given default port if no ':' found; defaults to -1.
# Return numerical port if a valid number are found after ':'.
# Return None if ':' but not a valid number.
_nportprog = regex.compile('^\(.*\):\(.*\)$')
def splitnport(host, defport=-1):
if _nportprog.match(host) >= 0:
host, port = _nportprog.group(1, 2)
try:
if not port: raise string.atoi_error, "no digits"
nport = string.atoi(port)
except string.atoi_error:
nport = None
return host, nport
return host, defport
_queryprog = regex.compile('^\(.*\)\?\([^?]*\)$')
def splitquery(url):
if _queryprog.match(url) >= 0: return _queryprog.group(1, 2)
return url, None
_tagprog = regex.compile('^\(.*\)#\([^#]*\)$')
def splittag(url):
if _tagprog.match(url) >= 0: return _tagprog.group(1, 2)
return url, None
def splitattr(url):
words = string.splitfields(url, ';')
return words[0], words[1:]
_valueprog = regex.compile('^\([^=]*\)=\(.*\)$')
def splitvalue(attr):
if _valueprog.match(attr) >= 0: return _valueprog.group(1, 2)
return attr, None
def splitgophertype(selector):
if selector[:1] == '/' and selector[1:2]:
return selector[1], selector[2:]
return None, selector
_quoteprog = regex.compile('%[0-9a-fA-F][0-9a-fA-F]')
def unquote(s):
i = 0
n = len(s)
res = []
while 0 <= i < n:
j = _quoteprog.search(s, i)
if j < 0:
res.append(s[i:])
break
res.append(s[i:j] + chr(string.atoi(s[j+1:j+3], 16)))
i = j+3
return string.joinfields(res, '')
always_safe = string.letters + string.digits + '_,.-'
def quote(s, safe = '/'):
safe = always_safe + safe
res = []
for c in s:
if c in safe:
res.append(c)
else:
res.append('%%%02x' % ord(c))
return string.joinfields(res, '')
# Proxy handling
def getproxies():
"""Return a dictionary of protocol scheme -> proxy server URL mappings.
Scan the environment for variables named <scheme>_proxy;
this seems to be the standard convention. If you need a
different way, you can pass a proxies dictionary to the
[Fancy]URLopener constructor.
"""
proxies = {}
for name, value in os.environ.items():
if value and name[-6:] == '_proxy':
proxies[name[:-6]] = value
return proxies
# Test and time quote() and unquote()
def test1():
import time
s = ''
for i in range(256): s = s + chr(i)
s = s*4
t0 = time.time()
qs = quote(s)
uqs = unquote(qs)
t1 = time.time()
if uqs != s:
print 'Wrong!'
print `s`
print `qs`
print `uqs`
print round(t1 - t0, 3), 'sec'
# Test program
def test():
import sys
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__':
## test1()
test()