Current File : //lib64/python2.7/urllib.py
"""Open an arbitrary URL.

See the following document for more info on URLs:
"Names and Addresses, URIs, URLs, URNs, URCs", at
http://www.w3.org/pub/WWW/Addressing/Overview.html

See also the HTTP spec (from which the error codes are derived):
"HTTP - Hypertext Transfer Protocol", at
http://www.w3.org/pub/WWW/Protocols/

Related standards and specs:
- RFC1808: the "relative URL" spec. (authoritative status)
- RFC1738 - the "URL standard". (authoritative status)
- RFC1630 - the "URI spec". (informational status)

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 a 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 os
import time
import sys
import base64
import re

from urlparse import urljoin as basejoin

__all__ = ["urlopen", "URLopener", "FancyURLopener", "urlretrieve",
           "urlcleanup", "quote", "quote_plus", "unquote", "unquote_plus",
           "urlencode", "url2pathname", "pathname2url", "splittag",
           "localhost", "thishost", "ftperrors", "basejoin", "unwrap",
           "splittype", "splithost", "splituser", "splitpasswd", "splitport",
           "splitnport", "splitquery", "splitattr", "splitvalue",
           "getproxies"]

__version__ = '1.17'    # XXX This version is not always updated :-(

MAXFTPCACHE = 10        # Trim the ftp cache beyond this size

# Helper for non-unix systems
if os.name == 'nt':
    from nturl2path import url2pathname, pathname2url
elif os.name == 'riscos':
    from rourl2path import url2pathname, pathname2url
else:
    def url2pathname(pathname):
        """OS-specific conversion from a relative URL of the 'file' scheme
        to a file system path; not recommended for general use."""
        return unquote(pathname)

    def pathname2url(pathname):
        """OS-specific conversion from a file system path to a relative URL
        of the 'file' scheme; not recommended for general use."""
        return quote(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, data=None, proxies=None):
    """Create a file-like object for the specified URL to read from."""
    from warnings import warnpy3k
    warnpy3k("urllib.urlopen() has been removed in Python 3.0 in "
             "favor of urllib2.urlopen()", stacklevel=2)

    global _urlopener
    if proxies is not None:
        opener = FancyURLopener(proxies=proxies)
    elif not _urlopener:
        opener = FancyURLopener()
        _urlopener = opener
    else:
        opener = _urlopener
    if data is None:
        return opener.open(url)
    else:
        return opener.open(url, data)
def urlretrieve(url, filename=None, reporthook=None, data=None):
    global _urlopener
    if not _urlopener:
        _urlopener = FancyURLopener()
    return _urlopener.retrieve(url, filename, reporthook, data)
def urlcleanup():
    if _urlopener:
        _urlopener.cleanup()
    _safe_quoters.clear()
    ftpcache.clear()

# check for SSL
try:
    import ssl
except:
    _have_ssl = False
else:
    _have_ssl = True

# exception raised when downloaded size does not match content-length
class ContentTooShortError(IOError):
    def __init__(self, message, content):
        IOError.__init__(self, message)
        self.content = content

ftpcache = {}
class URLopener:
    """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)."""

    __tempfiles = None

    version = "Python-urllib/%s" % __version__

    # Constructor
    def __init__(self, proxies=None, **x509):
        if proxies is None:
            proxies = getproxies()
        assert hasattr(proxies, 'has_key'), "proxies must be a mapping"
        self.proxies = proxies
        self.key_file = x509.get('key_file')
        self.cert_file = x509.get('cert_file')
        self.addheaders = [('User-Agent', self.version)]
        self.__tempfiles = []
        self.__unlink = os.unlink # See cleanup()
        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
        # XXX This is not threadsafe.  Bah.

    def __del__(self):
        self.close()

    def close(self):
        self.cleanup()

    def cleanup(self):
        # This code sometimes runs when the rest of this module
        # has already been deleted, so it can't use any globals
        # or import anything.
        if self.__tempfiles:
            for file in self.__tempfiles:
                try:
                    self.__unlink(file)
                except OSError:
                    pass
            del self.__tempfiles[:]
        if self.tempcache:
            self.tempcache.clear()

    def addheader(self, *args):
        """Add a header to be used by the HTTP interface only
        e.g. u.addheader('Accept', 'sound/basic')"""
        self.addheaders.append(args)

    # External interface
    def open(self, fullurl, data=None):
        """Use URLopener().open(file) instead of open(file, 'r')."""
        fullurl = unwrap(toBytes(fullurl))
        # percent encode url, fixing lame server errors for e.g, like space
        # within url paths.
        fullurl = quote(fullurl, safe="%/:=&?~#+!$,;'@()*[]|")
        if self.tempcache and fullurl in self.tempcache:
            filename, headers = self.tempcache[fullurl]
            fp = open(filename, 'rb')
            return addinfourl(fp, headers, fullurl)
        urltype, url = splittype(fullurl)
        if not urltype:
            urltype = 'file'
        if urltype in self.proxies:
            proxy = self.proxies[urltype]
            urltype, proxyhost = splittype(proxy)
            host, selector = splithost(proxyhost)
            url = (host, fullurl) # Signal special case to open_*()
        else:
            proxy = None
        name = 'open_' + urltype
        self.type = urltype
        name = name.replace('-', '_')

        # bpo-35907: disallow the file reading with the type not allowed
        if not hasattr(self, name) or name == 'open_local_file':
            if proxy:
                return self.open_unknown_proxy(proxy, fullurl, data)
            else:
                return self.open_unknown(fullurl, data)
        try:
            if data is None:
                return getattr(self, name)(url)
            else:
                return getattr(self, name)(url, data)
        except socket.error, msg:
            raise IOError, ('socket error', msg), sys.exc_info()[2]

    def open_unknown(self, fullurl, data=None):
        """Overridable interface to open unknown URL type."""
        type, url = splittype(fullurl)
        raise IOError, ('url error', 'unknown url type', type)

    def open_unknown_proxy(self, proxy, fullurl, data=None):
        """Overridable interface to open unknown URL type."""
        type, url = splittype(fullurl)
        raise IOError, ('url error', 'invalid proxy for %s' % type, proxy)

    # External interface
    def retrieve(self, url, filename=None, reporthook=None, data=None):
        """retrieve(url) returns (filename, headers) for a local object
        or (tempfilename, headers) for a remote object."""
        url = unwrap(toBytes(url))
        if self.tempcache and url in self.tempcache:
            return self.tempcache[url]
        type, url1 = splittype(url)
        if filename is None and (not type or type == 'file'):
            try:
                fp = self.open_local_file(url1)
                hdrs = fp.info()
                fp.close()
                return url2pathname(splithost(url1)[1]), hdrs
            except IOError:
                pass
        fp = self.open(url, data)
        try:
            headers = fp.info()
            if filename:
                tfp = open(filename, 'wb')
            else:
                import tempfile
                garbage, path = splittype(url)
                garbage, path = splithost(path or "")
                path, garbage = splitquery(path or "")
                path, garbage = splitattr(path or "")
                suffix = os.path.splitext(path)[1]
                (fd, filename) = tempfile.mkstemp(suffix)
                self.__tempfiles.append(filename)
                tfp = os.fdopen(fd, 'wb')
            try:
                result = filename, headers
                if self.tempcache is not None:
                    self.tempcache[url] = result
                bs = 1024*8
                size = -1
                read = 0
                blocknum = 0
                if "content-length" in headers:
                    size = int(headers["Content-Length"])
                if reporthook:
                    reporthook(blocknum, bs, size)
                while 1:
                    block = fp.read(bs)
                    if block == "":
                        break
                    read += len(block)
                    tfp.write(block)
                    blocknum += 1
                    if reporthook:
                        reporthook(blocknum, bs, size)
            finally:
                tfp.close()
        finally:
            fp.close()

        # raise exception if actual size does not match content-length header
        if size >= 0 and read < size:
            raise ContentTooShortError("retrieval incomplete: got only %i out "
                                       "of %i bytes" % (read, size), result)

        return result

    # Each method named open_<type> knows how to open that type of URL

    def open_http(self, url, data=None):
        """Use HTTP protocol."""
        import httplib
        user_passwd = None
        proxy_passwd= None
        if isinstance(url, str):
            host, selector = splithost(url)
            if host:
                user_passwd, host = splituser(host)
                host = unquote(host)
            realhost = host
        else:
            host, selector = url
            # check whether the proxy contains authorization information
            proxy_passwd, host = splituser(host)
            # now we proceed with the url we want to obtain
            urltype, rest = splittype(selector)
            url = rest
            user_passwd = None
            if urltype.lower() != 'http':
                realhost = None
            else:
                realhost, rest = splithost(rest)
                if realhost:
                    user_passwd, realhost = splituser(realhost)
                if user_passwd:
                    selector = "%s://%s%s" % (urltype, realhost, rest)
                if proxy_bypass(realhost):
                    host = realhost

            #print "proxy via http:", host, selector
        if not host: raise IOError, ('http error', 'no host given')

        if proxy_passwd:
            proxy_passwd = unquote(proxy_passwd)
            proxy_auth = base64.b64encode(proxy_passwd).strip()
        else:
            proxy_auth = None

        if user_passwd:
            user_passwd = unquote(user_passwd)
            auth = base64.b64encode(user_passwd).strip()
        else:
            auth = None
        h = httplib.HTTP(host)
        if data is not None:
            h.putrequest('POST', selector)
            h.putheader('Content-Type', 'application/x-www-form-urlencoded')
            h.putheader('Content-Length', '%d' % len(data))
        else:
            h.putrequest('GET', selector)
        if proxy_auth: h.putheader('Proxy-Authorization', 'Basic %s' % proxy_auth)
        if auth: h.putheader('Authorization', 'Basic %s' % auth)
        if realhost: h.putheader('Host', realhost)
        for args in self.addheaders: h.putheader(*args)
        h.endheaders(data)
        errcode, errmsg, headers = h.getreply()
        fp = h.getfile()
        if errcode == -1:
            if fp: fp.close()
            # something went wrong with the HTTP status line
            raise IOError, ('http protocol error', 0,
                            'got a bad status line', None)
        # According to RFC 2616, "2xx" code indicates that the client's
        # request was successfully received, understood, and accepted.
        if (200 <= errcode < 300):
            return addinfourl(fp, headers, "http:" + url, errcode)
        else:
            if data is None:
                return self.http_error(url, fp, errcode, errmsg, headers)
            else:
                return self.http_error(url, fp, errcode, errmsg, headers, data)

    def http_error(self, url, fp, errcode, errmsg, headers, data=None):
        """Handle http errors.
        Derived class can override this, or provide specific handlers
        named http_error_DDD where DDD is the 3-digit error code."""
        # First check if there's a specific handler for this error
        name = 'http_error_%d' % errcode
        if hasattr(self, name):
            method = getattr(self, name)
            if data is None:
                result = method(url, fp, errcode, errmsg, headers)
            else:
                result = method(url, fp, errcode, errmsg, headers, data)
            if result: return result
        return self.http_error_default(url, fp, errcode, errmsg, headers)

    def http_error_default(self, url, fp, errcode, errmsg, headers):
        """Default error handler: close the connection and raise IOError."""
        fp.close()
        raise IOError, ('http error', errcode, errmsg, headers)

    if _have_ssl:
        def open_https(self, url, data=None):
            """Use HTTPS protocol."""

            import httplib
            user_passwd = None
            proxy_passwd = None
            if isinstance(url, str):
                host, selector = splithost(url)
                if host:
                    user_passwd, host = splituser(host)
                    host = unquote(host)
                realhost = host
            else:
                host, selector = url
                # here, we determine, whether the proxy contains authorization information
                proxy_passwd, host = splituser(host)
                urltype, rest = splittype(selector)
                url = rest
                user_passwd = None
                if urltype.lower() != 'https':
                    realhost = None
                else:
                    realhost, rest = splithost(rest)
                    if realhost:
                        user_passwd, realhost = splituser(realhost)
                    if user_passwd:
                        selector = "%s://%s%s" % (urltype, realhost, rest)
                #print "proxy via https:", host, selector
            if not host: raise IOError, ('https error', 'no host given')
            if proxy_passwd:
                proxy_passwd = unquote(proxy_passwd)
                proxy_auth = base64.b64encode(proxy_passwd).strip()
            else:
                proxy_auth = None
            if user_passwd:
                user_passwd = unquote(user_passwd)
                auth = base64.b64encode(user_passwd).strip()
            else:
                auth = None
            h = httplib.HTTPS(host, 0,
                              key_file=self.key_file,
                              cert_file=self.cert_file)
            if data is not None:
                h.putrequest('POST', selector)
                h.putheader('Content-Type',
                            'application/x-www-form-urlencoded')
                h.putheader('Content-Length', '%d' % len(data))
            else:
                h.putrequest('GET', selector)
            if proxy_auth: h.putheader('Proxy-Authorization', 'Basic %s' % proxy_auth)
            if auth: h.putheader('Authorization', 'Basic %s' % auth)
            if realhost: h.putheader('Host', realhost)
            for args in self.addheaders: h.putheader(*args)
            h.endheaders(data)
            errcode, errmsg, headers = h.getreply()
            fp = h.getfile()
            if errcode == -1:
                if fp: fp.close()
                # something went wrong with the HTTP status line
                raise IOError, ('http protocol error', 0,
                                'got a bad status line', None)
            # According to RFC 2616, "2xx" code indicates that the client's
            # request was successfully received, understood, and accepted.
            if (200 <= errcode < 300):
                return addinfourl(fp, headers, "https:" + url, errcode)
            else:
                if data is None:
                    return self.http_error(url, fp, errcode, errmsg, headers)
                else:
                    return self.http_error(url, fp, errcode, errmsg, headers,
                                           data)

    def open_file(self, url):
        """Use local file or FTP depending on form of URL."""
        if not isinstance(url, str):
            raise IOError, ('file error', 'proxy support for file protocol currently not implemented')
        if url[:2] == '//' and url[2:3] != '/' and url[2:12].lower() != 'localhost/':
            return self.open_ftp(url)
        else:
            return self.open_local_file(url)

    def open_local_file(self, url):
        """Use local file."""
        import mimetypes, mimetools, email.utils
        try:
            from cStringIO import StringIO
        except ImportError:
            from StringIO import StringIO
        host, file = splithost(url)
        localname = url2pathname(file)
        try:
            stats = os.stat(localname)
        except OSError, e:
            raise IOError(e.errno, e.strerror, e.filename)
        size = stats.st_size
        modified = email.utils.formatdate(stats.st_mtime, usegmt=True)
        mtype = mimetypes.guess_type(url)[0]
        headers = mimetools.Message(StringIO(
            'Content-Type: %s\nContent-Length: %d\nLast-modified: %s\n' %
            (mtype or 'text/plain', size, modified)))
        if not host:
            urlfile = file
            if file[:1] == '/':
                urlfile = 'file://' + file
            elif file[:2] == './':
                raise ValueError("local file url may start with / or file:. Unknown url of type: %s" % url)
            return addinfourl(open(localname, 'rb'),
                              headers, urlfile)
        host, port = splitport(host)
        if not port \
           and socket.gethostbyname(host) in (localhost(), thishost()):
            urlfile = file
            if file[:1] == '/':
                urlfile = 'file://' + file
            return addinfourl(open(localname, 'rb'),
                              headers, urlfile)
        raise IOError, ('local file error', 'not on local host')

    def open_ftp(self, url):
        """Use FTP protocol."""
        if not isinstance(url, str):
            raise IOError, ('ftp error', 'proxy support for ftp protocol currently not implemented')
        import mimetypes, mimetools
        try:
            from cStringIO import StringIO
        except ImportError:
            from StringIO import StringIO
        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 = unquote(host)
        user = user or ''
        passwd = passwd or ''
        host = socket.gethostbyname(host)
        if not port:
            import ftplib
            port = ftplib.FTP_PORT
        else:
            port = int(port)
        path, attrs = splitattr(path)
        path = unquote(path)
        dirs = path.split('/')
        dirs, file = dirs[:-1], dirs[-1]
        if dirs and not dirs[0]: dirs = dirs[1:]
        if dirs and not dirs[0]: dirs[0] = '/'
        key = user, host, port, '/'.join(dirs)
        # XXX thread unsafe!
        if len(self.ftpcache) > MAXFTPCACHE:
            # Prune the cache, rather arbitrarily
            for k in self.ftpcache.keys():
                if k != key:
                    v = self.ftpcache[k]
                    del self.ftpcache[k]
                    v.close()
        try:
            if not key in self.ftpcache:
                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 attr.lower() == 'type' and \
                   value in ('a', 'A', 'i', 'I', 'd', 'D'):
                    type = value.upper()
            (fp, retrlen) = self.ftpcache[key].retrfile(file, type)
            mtype = mimetypes.guess_type("ftp:" + url)[0]
            headers = ""
            if mtype:
                headers += "Content-Type: %s\n" % mtype
            if retrlen is not None and retrlen >= 0:
                headers += "Content-Length: %d\n" % retrlen
            headers = mimetools.Message(StringIO(headers))
            return addinfourl(fp, headers, "ftp:" + url)
        except ftperrors(), msg:
            raise IOError, ('ftp error', msg), sys.exc_info()[2]

    def open_data(self, url, data=None):
        """Use "data" URL."""
        if not isinstance(url, str):
            raise IOError, ('data error', 'proxy support for data protocol currently not implemented')
        # ignore POSTed data
        #
        # syntax of data URLs:
        # dataurl   := "data:" [ mediatype ] [ ";base64" ] "," data
        # mediatype := [ type "/" subtype ] *( ";" parameter )
        # data      := *urlchar
        # parameter := attribute "=" value
        import mimetools
        try:
            from cStringIO import StringIO
        except ImportError:
            from StringIO import StringIO
        try:
            [type, data] = url.split(',', 1)
        except ValueError:
            raise IOError, ('data error', 'bad data URL')
        if not type:
            type = 'text/plain;charset=US-ASCII'
        semi = type.rfind(';')
        if semi >= 0 and '=' not in type[semi:]:
            encoding = type[semi+1:]
            type = type[:semi]
        else:
            encoding = ''
        msg = []
        msg.append('Date: %s'%time.strftime('%a, %d %b %Y %H:%M:%S GMT',
                                            time.gmtime(time.time())))
        msg.append('Content-type: %s' % type)
        if encoding == 'base64':
            data = base64.decodestring(data)
        else:
            data = unquote(data)
        msg.append('Content-Length: %d' % len(data))
        msg.append('')
        msg.append(data)
        msg = '\n'.join(msg)
        f = StringIO(msg)
        headers = mimetools.Message(f, 0)
        #f.fileno = None     # needed for addinfourl
        return addinfourl(f, headers, url)


class FancyURLopener(URLopener):
    """Derived class with handlers for errors we can handle (perhaps)."""

    def __init__(self, *args, **kwargs):
        URLopener.__init__(self, *args, **kwargs)
        self.auth_cache = {}
        self.tries = 0
        self.maxtries = 10

    def http_error_default(self, url, fp, errcode, errmsg, headers):
        """Default error handling -- don't raise an exception."""
        return addinfourl(fp, headers, "http:" + url, errcode)

    def http_error_302(self, url, fp, errcode, errmsg, headers, data=None):
        """Error 302 -- relocated (temporarily)."""
        self.tries += 1
        if self.maxtries and self.tries >= self.maxtries:
            if hasattr(self, "http_error_500"):
                meth = self.http_error_500
            else:
                meth = self.http_error_default
            self.tries = 0
            return meth(url, fp, 500,
                        "Internal Server Error: Redirect Recursion", headers)
        result = self.redirect_internal(url, fp, errcode, errmsg, headers,
                                        data)
        self.tries = 0
        return result

    def redirect_internal(self, url, fp, errcode, errmsg, headers, data):
        if 'location' in headers:
            newurl = headers['location']
        elif 'uri' in headers:
            newurl = headers['uri']
        else:
            return
        fp.close()
        # In case the server sent a relative URL, join with original:
        newurl = basejoin(self.type + ":" + url, newurl)

        # For security reasons we do not allow redirects to protocols
        # other than HTTP, HTTPS or FTP.
        newurl_lower = newurl.lower()
        if not (newurl_lower.startswith('http://') or
                newurl_lower.startswith('https://') or
                newurl_lower.startswith('ftp://')):
            raise IOError('redirect error', errcode,
                          errmsg + " - Redirection to url '%s' is not allowed" %
                          newurl,
                          headers)

        return self.open(newurl)

    def http_error_301(self, url, fp, errcode, errmsg, headers, data=None):
        """Error 301 -- also relocated (permanently)."""
        return self.http_error_302(url, fp, errcode, errmsg, headers, data)

    def http_error_303(self, url, fp, errcode, errmsg, headers, data=None):
        """Error 303 -- also relocated (essentially identical to 302)."""
        return self.http_error_302(url, fp, errcode, errmsg, headers, data)

    def http_error_307(self, url, fp, errcode, errmsg, headers, data=None):
        """Error 307 -- relocated, but turn POST into error."""
        if data is None:
            return self.http_error_302(url, fp, errcode, errmsg, headers, data)
        else:
            return self.http_error_default(url, fp, errcode, errmsg, headers)

    def http_error_401(self, url, fp, errcode, errmsg, headers, data=None):
        """Error 401 -- authentication required.
        This function supports Basic authentication only."""
        if not 'www-authenticate' in headers:
            URLopener.http_error_default(self, url, fp,
                                         errcode, errmsg, headers)
        stuff = headers['www-authenticate']
        import re
        match = re.match('[ \t]*([^ \t]+)[ \t]+realm="([^"]*)"', stuff)
        if not match:
            URLopener.http_error_default(self, url, fp,
                                         errcode, errmsg, headers)
        scheme, realm = match.groups()
        if scheme.lower() != 'basic':
            URLopener.http_error_default(self, url, fp,
                                         errcode, errmsg, headers)
        name = 'retry_' + self.type + '_basic_auth'
        if data is None:
            return getattr(self,name)(url, realm)
        else:
            return getattr(self,name)(url, realm, data)

    def http_error_407(self, url, fp, errcode, errmsg, headers, data=None):
        """Error 407 -- proxy authentication required.
        This function supports Basic authentication only."""
        if not 'proxy-authenticate' in headers:
            URLopener.http_error_default(self, url, fp,
                                         errcode, errmsg, headers)
        stuff = headers['proxy-authenticate']
        import re
        match = re.match('[ \t]*([^ \t]+)[ \t]+realm="([^"]*)"', stuff)
        if not match:
            URLopener.http_error_default(self, url, fp,
                                         errcode, errmsg, headers)
        scheme, realm = match.groups()
        if scheme.lower() != 'basic':
            URLopener.http_error_default(self, url, fp,
                                         errcode, errmsg, headers)
        name = 'retry_proxy_' + self.type + '_basic_auth'
        if data is None:
            return getattr(self,name)(url, realm)
        else:
            return getattr(self,name)(url, realm, data)

    def retry_proxy_http_basic_auth(self, url, realm, data=None):
        host, selector = splithost(url)
        newurl = 'http://' + host + selector
        proxy = self.proxies['http']
        urltype, proxyhost = splittype(proxy)
        proxyhost, proxyselector = splithost(proxyhost)
        i = proxyhost.find('@') + 1
        proxyhost = proxyhost[i:]
        user, passwd = self.get_user_passwd(proxyhost, realm, i)
        if not (user or passwd): return None
        proxyhost = quote(user, safe='') + ':' + quote(passwd, safe='') + '@' + proxyhost
        self.proxies['http'] = 'http://' + proxyhost + proxyselector
        if data is None:
            return self.open(newurl)
        else:
            return self.open(newurl, data)

    def retry_proxy_https_basic_auth(self, url, realm, data=None):
        host, selector = splithost(url)
        newurl = 'https://' + host + selector
        proxy = self.proxies['https']
        urltype, proxyhost = splittype(proxy)
        proxyhost, proxyselector = splithost(proxyhost)
        i = proxyhost.find('@') + 1
        proxyhost = proxyhost[i:]
        user, passwd = self.get_user_passwd(proxyhost, realm, i)
        if not (user or passwd): return None
        proxyhost = quote(user, safe='') + ':' + quote(passwd, safe='') + '@' + proxyhost
        self.proxies['https'] = 'https://' + proxyhost + proxyselector
        if data is None:
            return self.open(newurl)
        else:
            return self.open(newurl, data)

    def retry_http_basic_auth(self, url, realm, data=None):
        host, selector = splithost(url)
        i = host.find('@') + 1
        host = host[i:]
        user, passwd = self.get_user_passwd(host, realm, i)
        if not (user or passwd): return None
        host = quote(user, safe='') + ':' + quote(passwd, safe='') + '@' + host
        newurl = 'http://' + host + selector
        if data is None:
            return self.open(newurl)
        else:
            return self.open(newurl, data)

    def retry_https_basic_auth(self, url, realm, data=None):
        host, selector = splithost(url)
        i = host.find('@') + 1
        host = host[i:]
        user, passwd = self.get_user_passwd(host, realm, i)
        if not (user or passwd): return None
        host = quote(user, safe='') + ':' + quote(passwd, safe='') + '@' + host
        newurl = 'https://' + host + selector
        if data is None:
            return self.open(newurl)
        else:
            return self.open(newurl, data)

    def get_user_passwd(self, host, realm, clear_cache=0):
        key = realm + '@' + host.lower()
        if key in self.auth_cache:
            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!"""
        import getpass
        try:
            user = raw_input("Enter username for %s at %s: " % (realm,
                                                                host))
            passwd = getpass.getpass("Enter password for %s in %s at %s: " %
                (user, realm, host))
            return user, passwd
        except KeyboardInterrupt:
            print
            return None, None


# Utility functions

_localhost = None
def localhost():
    """Return the IP address of the magic hostname 'localhost'."""
    global _localhost
    if _localhost is None:
        _localhost = socket.gethostbyname('localhost')
    return _localhost

_thishost = None
def thishost():
    """Return the IP address of the current host."""
    global _thishost
    if _thishost is None:
        _thishost = socket.gethostbyname(socket.gethostname())
    return _thishost

_ftperrors = None
def ftperrors():
    """Return the set of errors raised by the FTP class."""
    global _ftperrors
    if _ftperrors is None:
        import ftplib
        _ftperrors = ftplib.all_errors
    return _ftperrors

_noheaders = None
def noheaders():
    """Return an empty mimetools.Message object."""
    global _noheaders
    if _noheaders is None:
        import mimetools
        try:
            from cStringIO import StringIO
        except ImportError:
            from StringIO import StringIO
        _noheaders = mimetools.Message(StringIO(), 0)
        _noheaders.fp.close()   # Recycle file descriptor
    return _noheaders


# Utility classes

class ftpwrapper:
    """Class used by open_ftp() for cache of open FTP connections."""

    def __init__(self, user, passwd, host, port, dirs,
                 timeout=socket._GLOBAL_DEFAULT_TIMEOUT,
                 persistent=True):
        self.user = user
        self.passwd = passwd
        self.host = host
        self.port = port
        self.dirs = dirs
        self.timeout = timeout
        self.refcount = 0
        self.keepalive = persistent
        self.init()

    def init(self):
        import ftplib
        self.busy = 0
        self.ftp = ftplib.FTP()
        self.ftp.connect(self.host, self.port, self.timeout)
        self.ftp.login(self.user, self.passwd)
        for dir in self.dirs:
            self.ftp.cwd(dir)

    def retrfile(self, file, type):
        import ftplib
        self.endtransfer()
        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 to retrieve as a file
            try:
                cmd = 'RETR ' + file
                conn, retrlen = self.ftp.ntransfercmd(cmd)
            except ftplib.error_perm, reason:
                if str(reason)[:3] != '550':
                    raise IOError, ('ftp error', reason), sys.exc_info()[2]
        if not conn:
            # Set transfer mode to ASCII!
            self.ftp.voidcmd('TYPE A')
            # Try a directory listing. Verify that directory exists.
            if file:
                pwd = self.ftp.pwd()
                try:
                    try:
                        self.ftp.cwd(file)
                    except ftplib.error_perm, reason:
                        raise IOError, ('ftp error', reason), sys.exc_info()[2]
                finally:
                    self.ftp.cwd(pwd)
                cmd = 'LIST ' + file
            else:
                cmd = 'LIST'
            conn, retrlen = self.ftp.ntransfercmd(cmd)
        self.busy = 1
        ftpobj = addclosehook(conn.makefile('rb'), self.file_close)
        self.refcount += 1
        conn.close()
        # Pass back both a suitably decorated object and a retrieval length
        return (ftpobj, retrlen)

    def endtransfer(self):
        if not self.busy:
            return
        self.busy = 0
        try:
            self.ftp.voidresp()
        except ftperrors():
            pass

    def close(self):
        self.keepalive = False
        if self.refcount <= 0:
            self.real_close()

    def file_close(self):
        self.endtransfer()
        self.refcount -= 1
        if self.refcount <= 0 and not self.keepalive:
            self.real_close()

    def real_close(self):
        self.endtransfer()
        try:
            self.ftp.close()
        except ftperrors():
            pass

class addbase:
    """Base class for addinfo and addclosehook."""

    def __init__(self, fp):
        self.fp = fp
        self.read = self.fp.read
        self.readline = self.fp.readline
        if hasattr(self.fp, "readlines"): self.readlines = self.fp.readlines
        if hasattr(self.fp, "fileno"):
            self.fileno = self.fp.fileno
        else:
            self.fileno = lambda: None
        if hasattr(self.fp, "__iter__"):
            self.__iter__ = self.fp.__iter__
            if hasattr(self.fp, "next"):
                self.next = self.fp.next

    def __repr__(self):
        return '<%s at %r whose fp = %r>' % (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 addclosehook(addbase):
    """Class to add a close hook to an open file."""

    def __init__(self, fp, closehook, *hookargs):
        addbase.__init__(self, fp)
        self.closehook = closehook
        self.hookargs = hookargs

    def close(self):
        if self.closehook:
            self.closehook(*self.hookargs)
            self.closehook = None
            self.hookargs = None
        addbase.close(self)

class addinfo(addbase):
    """class to add an info() method to an open file."""

    def __init__(self, fp, headers):
        addbase.__init__(self, fp)
        self.headers = headers

    def info(self):
        return self.headers

class addinfourl(addbase):
    """class to add info() and geturl() methods to an open file."""

    def __init__(self, fp, headers, url, code=None):
        addbase.__init__(self, fp)
        self.headers = headers
        self.url = url
        self.code = code

    def info(self):
        return self.headers

    def getcode(self):
        return self.code

    def geturl(self):
        return self.url


# 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'
# unquote('abc%20def') -> 'abc def'
# quote('abc def') -> 'abc%20def')

try:
    unicode
except NameError:
    def _is_unicode(x):
        return 0
else:
    def _is_unicode(x):
        return isinstance(x, unicode)

def toBytes(url):
    """toBytes(u"URL") --> 'URL'."""
    # Most URL schemes require ASCII. If that changes, the conversion
    # can be relaxed
    if _is_unicode(url):
        try:
            url = url.encode("ASCII")
        except UnicodeError:
            raise UnicodeError("URL " + repr(url) +
                               " contains non-ASCII characters")
    return url

def unwrap(url):
    """unwrap('<URL:type://host/path>') --> 'type://host/path'."""
    url = url.strip()
    if url[:1] == '<' and url[-1:] == '>':
        url = url[1:-1].strip()
    if url[:4] == 'URL:': url = url[4:].strip()
    return url

_typeprog = None
def splittype(url):
    """splittype('type:opaquestring') --> 'type', 'opaquestring'."""
    global _typeprog
    if _typeprog is None:
        import re
        _typeprog = re.compile('^([^/:]+):')

    match = _typeprog.match(url)
    if match:
        scheme = match.group(1)
        return scheme.lower(), url[len(scheme) + 1:]
    return None, url

_hostprog = None
def splithost(url):
    """splithost('//host[:port]/path') --> 'host[:port]', '/path'."""
    global _hostprog
    if _hostprog is None:
        _hostprog = re.compile('//([^/#?]*)(.*)', re.DOTALL)

    match = _hostprog.match(url)
    if match:
        host_port = match.group(1)
        path = match.group(2)
        if path and not path.startswith('/'):
            path = '/' + path
        return host_port, path
    return None, url

_userprog = None
def splituser(host):
    """splituser('user[:passwd]@host[:port]') --> 'user[:passwd]', 'host[:port]'."""
    global _userprog
    if _userprog is None:
        import re
        _userprog = re.compile('^(.*)@(.*)$')

    match = _userprog.match(host)
    if match: return match.group(1, 2)
    return None, host

_passwdprog = None
def splitpasswd(user):
    """splitpasswd('user:passwd') -> 'user', 'passwd'."""
    global _passwdprog
    if _passwdprog is None:
        import re
        _passwdprog = re.compile('^([^:]*):(.*)$',re.S)

    match = _passwdprog.match(user)
    if match: return match.group(1, 2)
    return user, None

# splittag('/path#tag') --> '/path', 'tag'
_portprog = None
def splitport(host):
    """splitport('host:port') --> 'host', 'port'."""
    global _portprog
    if _portprog is None:
        import re
        _portprog = re.compile('^(.*):([0-9]+)$')

    match = _portprog.match(host)
    if match: return match.group(1, 2)
    return host, None

_nportprog = None
def splitnport(host, defport=-1):
    """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."""
    global _nportprog
    if _nportprog is None:
        import re
        _nportprog = re.compile('^(.*):(.*)$')

    match = _nportprog.match(host)
    if match:
        host, port = match.group(1, 2)
        try:
            if not port: raise ValueError, "no digits"
            nport = int(port)
        except ValueError:
            nport = None
        return host, nport
    return host, defport

_queryprog = None
def splitquery(url):
    """splitquery('/path?query') --> '/path', 'query'."""
    global _queryprog
    if _queryprog is None:
        import re
        _queryprog = re.compile('^(.*)\?([^?]*)$')

    match = _queryprog.match(url)
    if match: return match.group(1, 2)
    return url, None

_tagprog = None
def splittag(url):
    """splittag('/path#tag') --> '/path', 'tag'."""
    global _tagprog
    if _tagprog is None:
        import re
        _tagprog = re.compile('^(.*)#([^#]*)$')

    match = _tagprog.match(url)
    if match: return match.group(1, 2)
    return url, None

def splitattr(url):
    """splitattr('/path;attr1=value1;attr2=value2;...') ->
        '/path', ['attr1=value1', 'attr2=value2', ...]."""
    words = url.split(';')
    return words[0], words[1:]

_valueprog = None
def splitvalue(attr):
    """splitvalue('attr=value') --> 'attr', 'value'."""
    global _valueprog
    if _valueprog is None:
        import re
        _valueprog = re.compile('^([^=]*)=(.*)$')

    match = _valueprog.match(attr)
    if match: return match.group(1, 2)
    return attr, None

# urlparse contains a duplicate of this method to avoid a circular import.  If
# you update this method, also update the copy in urlparse.  This code
# duplication does not exist in Python3.

_hexdig = '0123456789ABCDEFabcdef'
_hextochr = dict((a + b, chr(int(a + b, 16)))
                 for a in _hexdig for b in _hexdig)
_asciire = re.compile('([\x00-\x7f]+)')

def unquote(s):
    """unquote('abc%20def') -> 'abc def'."""
    if _is_unicode(s):
        if '%' not in s:
            return s
        bits = _asciire.split(s)
        res = [bits[0]]
        append = res.append
        for i in range(1, len(bits), 2):
            append(unquote(str(bits[i])).decode('latin1'))
            append(bits[i + 1])
        return ''.join(res)

    bits = s.split('%')
    # fastpath
    if len(bits) == 1:
        return s
    res = [bits[0]]
    append = res.append
    for item in bits[1:]:
        try:
            append(_hextochr[item[:2]])
            append(item[2:])
        except KeyError:
            append('%')
            append(item)
    return ''.join(res)

def unquote_plus(s):
    """unquote('%7e/abc+def') -> '~/abc def'"""
    s = s.replace('+', ' ')
    return unquote(s)

always_safe = ('ABCDEFGHIJKLMNOPQRSTUVWXYZ'
               'abcdefghijklmnopqrstuvwxyz'
               '0123456789' '_.-')
_safe_map = {}
for i, c in zip(xrange(256), str(bytearray(xrange(256)))):
    _safe_map[c] = c if (i < 128 and c in always_safe) else '%{:02X}'.format(i)
_safe_quoters = {}

def quote(s, safe='/'):
    """quote('abc def') -> 'abc%20def'

    Each part of a URL, e.g. the path info, the query, etc., has a
    different set of reserved characters that must be quoted.

    RFC 2396 Uniform Resource Identifiers (URI): Generic Syntax lists
    the following reserved characters.

    reserved    = ";" | "/" | "?" | ":" | "@" | "&" | "=" | "+" |
                  "$" | ","

    Each of these characters is reserved in some component of a URL,
    but not necessarily in all of them.

    By default, the quote function is intended for quoting the path
    section of a URL.  Thus, it will not encode '/'.  This character
    is reserved, but in typical usage the quote function is being
    called on a path where the existing slash characters are used as
    reserved characters.
    """
    # fastpath
    if not s:
        if s is None:
            raise TypeError('None object cannot be quoted')
        return s
    cachekey = (safe, always_safe)
    try:
        (quoter, safe) = _safe_quoters[cachekey]
    except KeyError:
        safe_map = _safe_map.copy()
        safe_map.update([(c, c) for c in safe])
        quoter = safe_map.__getitem__
        safe = always_safe + safe
        _safe_quoters[cachekey] = (quoter, safe)
    if not s.rstrip(safe):
        return s
    return ''.join(map(quoter, s))

def quote_plus(s, safe=''):
    """Quote the query fragment of a URL; replacing ' ' with '+'"""
    if ' ' in s:
        s = quote(s, safe + ' ')
        return s.replace(' ', '+')
    return quote(s, safe)

def urlencode(query, doseq=0):
    """Encode a sequence of two-element tuples or dictionary into a URL query string.

    If any values in the query arg are sequences and doseq is true, each
    sequence element is converted to a separate parameter.

    If the query arg is a sequence of two-element tuples, the order of the
    parameters in the output will match the order of parameters in the
    input.
    """

    if hasattr(query,"items"):
        # mapping objects
        query = query.items()
    else:
        # it's a bother at times that strings and string-like objects are
        # sequences...
        try:
            # non-sequence items should not work with len()
            # non-empty strings will fail this
            if len(query) and not isinstance(query[0], tuple):
                raise TypeError
            # zero-length sequences of all types will get here and succeed,
            # but that's a minor nit - since the original implementation
            # allowed empty dicts that type of behavior probably should be
            # preserved for consistency
        except TypeError:
            ty,va,tb = sys.exc_info()
            raise TypeError, "not a valid non-string sequence or mapping object", tb

    l = []
    if not doseq:
        # preserve old behavior
        for k, v in query:
            k = quote_plus(str(k))
            v = quote_plus(str(v))
            l.append(k + '=' + v)
    else:
        for k, v in query:
            k = quote_plus(str(k))
            if isinstance(v, str):
                v = quote_plus(v)
                l.append(k + '=' + v)
            elif _is_unicode(v):
                # is there a reasonable way to convert to ASCII?
                # encode generates a string, but "replace" or "ignore"
                # lose information and "strict" can raise UnicodeError
                v = quote_plus(v.encode("ASCII","replace"))
                l.append(k + '=' + v)
            else:
                try:
                    # is this a sufficient test for sequence-ness?
                    len(v)
                except TypeError:
                    # not a sequence
                    v = quote_plus(str(v))
                    l.append(k + '=' + v)
                else:
                    # loop over the sequence
                    for elt in v:
                        l.append(k + '=' + quote_plus(str(elt)))
    return '&'.join(l)

# Proxy handling
def getproxies_environment():
    """Return a dictionary of 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.

    """
    # Get all variables
    proxies = {}
    for name, value in os.environ.items():
        name = name.lower()
        if value and name[-6:] == '_proxy':
            proxies[name[:-6]] = value

    # CVE-2016-1000110 - If we are running as CGI script, forget HTTP_PROXY
    # (non-all-lowercase) as it may be set from the web server by a "Proxy:"
    # header from the client
    # If "proxy" is lowercase, it will still be used thanks to the next block
    if 'REQUEST_METHOD' in os.environ:
        proxies.pop('http', None)

    return proxies

def proxy_bypass_environment(host):
    """Test if proxies should not be used for a particular host.

    Checks the environment for a variable named no_proxy, which should
    be a list of DNS suffixes separated by commas, or '*' for all hosts.
    """
    no_proxy = os.environ.get('no_proxy', '') or os.environ.get('NO_PROXY', '')
    # '*' is special case for always bypass
    if no_proxy == '*':
        return 1
    # strip port off host
    hostonly, port = splitport(host)
    # check if the host ends with any of the DNS suffixes
    no_proxy_list = [proxy.strip() for proxy in no_proxy.split(',')]
    for name in no_proxy_list:
        if name and (hostonly.endswith(name) or host.endswith(name)):
            return 1
    # otherwise, don't bypass
    return 0


if sys.platform == 'darwin':
    from _scproxy import _get_proxy_settings, _get_proxies

    def proxy_bypass_macosx_sysconf(host):
        """
        Return True iff this host shouldn't be accessed using a proxy

        This function uses the MacOSX framework SystemConfiguration
        to fetch the proxy information.
        """
        import re
        import socket
        from fnmatch import fnmatch

        hostonly, port = splitport(host)

        def ip2num(ipAddr):
            parts = ipAddr.split('.')
            parts = map(int, parts)
            if len(parts) != 4:
                parts = (parts + [0, 0, 0, 0])[:4]
            return (parts[0] << 24) | (parts[1] << 16) | (parts[2] << 8) | parts[3]

        proxy_settings = _get_proxy_settings()

        # Check for simple host names:
        if '.' not in host:
            if proxy_settings['exclude_simple']:
                return True

        hostIP = None

        for value in proxy_settings.get('exceptions', ()):
            # Items in the list are strings like these: *.local, 169.254/16
            if not value: continue

            m = re.match(r"(\d+(?:\.\d+)*)(/\d+)?", value)
            if m is not None:
                if hostIP is None:
                    try:
                        hostIP = socket.gethostbyname(hostonly)
                        hostIP = ip2num(hostIP)
                    except socket.error:
                        continue

                base = ip2num(m.group(1))
                mask = m.group(2)
                if mask is None:
                    mask = 8 * (m.group(1).count('.') + 1)

                else:
                    mask = int(mask[1:])
                mask = 32 - mask

                if (hostIP >> mask) == (base >> mask):
                    return True

            elif fnmatch(host, value):
                return True

        return False

    def getproxies_macosx_sysconf():
        """Return a dictionary of scheme -> proxy server URL mappings.

        This function uses the MacOSX framework SystemConfiguration
        to fetch the proxy information.
        """
        return _get_proxies()

    def proxy_bypass(host):
        if getproxies_environment():
            return proxy_bypass_environment(host)
        else:
            return proxy_bypass_macosx_sysconf(host)

    def getproxies():
        return getproxies_environment() or getproxies_macosx_sysconf()

elif os.name == 'nt':
    def getproxies_registry():
        """Return a dictionary of scheme -> proxy server URL mappings.

        Win32 uses the registry to store proxies.

        """
        proxies = {}
        try:
            import _winreg
        except ImportError:
            # Std module, so should be around - but you never know!
            return proxies
        try:
            internetSettings = _winreg.OpenKey(_winreg.HKEY_CURRENT_USER,
                r'Software\Microsoft\Windows\CurrentVersion\Internet Settings')
            proxyEnable = _winreg.QueryValueEx(internetSettings,
                                               'ProxyEnable')[0]
            if proxyEnable:
                # Returned as Unicode but problems if not converted to ASCII
                proxyServer = str(_winreg.QueryValueEx(internetSettings,
                                                       'ProxyServer')[0])
                if '=' in proxyServer:
                    # Per-protocol settings
                    for p in proxyServer.split(';'):
                        protocol, address = p.split('=', 1)
                        # See if address has a type:// prefix
                        import re
                        if not re.match('^([^/:]+)://', address):
                            address = '%s://%s' % (protocol, address)
                        proxies[protocol] = address
                else:
                    # Use one setting for all protocols
                    if proxyServer[:5] == 'http:':
                        proxies['http'] = proxyServer
                    else:
                        proxies['http'] = 'http://%s' % proxyServer
                        proxies['https'] = 'https://%s' % proxyServer
                        proxies['ftp'] = 'ftp://%s' % proxyServer
            internetSettings.Close()
        except (WindowsError, ValueError, TypeError):
            # Either registry key not found etc, or the value in an
            # unexpected format.
            # proxies already set up to be empty so nothing to do
            pass
        return proxies

    def getproxies():
        """Return a dictionary of scheme -> proxy server URL mappings.

        Returns settings gathered from the environment, if specified,
        or the registry.

        """
        return getproxies_environment() or getproxies_registry()

    def proxy_bypass_registry(host):
        try:
            import _winreg
            import re
        except ImportError:
            # Std modules, so should be around - but you never know!
            return 0
        try:
            internetSettings = _winreg.OpenKey(_winreg.HKEY_CURRENT_USER,
                r'Software\Microsoft\Windows\CurrentVersion\Internet Settings')
            proxyEnable = _winreg.QueryValueEx(internetSettings,
                                               'ProxyEnable')[0]
            proxyOverride = str(_winreg.QueryValueEx(internetSettings,
                                                     'ProxyOverride')[0])
            # ^^^^ Returned as Unicode but problems if not converted to ASCII
        except WindowsError:
            return 0
        if not proxyEnable or not proxyOverride:
            return 0
        # try to make a host list from name and IP address.
        rawHost, port = splitport(host)
        host = [rawHost]
        try:
            addr = socket.gethostbyname(rawHost)
            if addr != rawHost:
                host.append(addr)
        except socket.error:
            pass
        try:
            fqdn = socket.getfqdn(rawHost)
            if fqdn != rawHost:
                host.append(fqdn)
        except socket.error:
            pass
        # make a check value list from the registry entry: replace the
        # '<local>' string by the localhost entry and the corresponding
        # canonical entry.
        proxyOverride = proxyOverride.split(';')
        # now check if we match one of the registry values.
        for test in proxyOverride:
            if test == '<local>':
                if '.' not in rawHost:
                    return 1
            test = test.replace(".", r"\.")     # mask dots
            test = test.replace("*", r".*")     # change glob sequence
            test = test.replace("?", r".")      # change glob char
            for val in host:
                # print "%s <--> %s" %( test, val )
                if re.match(test, val, re.I):
                    return 1
        return 0

    def proxy_bypass(host):
        """Return a dictionary of scheme -> proxy server URL mappings.

        Returns settings gathered from the environment, if specified,
        or the registry.

        """
        if getproxies_environment():
            return proxy_bypass_environment(host)
        else:
            return proxy_bypass_registry(host)

else:
    # By default use environment variables
    getproxies = getproxies_environment
    proxy_bypass = proxy_bypass_environment

# Test and time quote() and unquote()
def test1():
    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 repr(s)
    print repr(qs)
    print repr(uqs)
    print round(t1 - t0, 3), 'sec'


def reporthook(blocknum, blocksize, totalsize):
    # Report during remote transfers
    print "Block number: %d, Block size: %d, Total size: %d" % (
        blocknum, blocksize, totalsize)
A Beginner's Facts Playing Casino Slots

A Beginner’s Facts Playing Casino Slots

How In Order To Play Slots Find Out The Rules Involving Slot Machines

In most modern devices, the number regarding lines that will pay off for” “a gamer depends on the particular number of credits (money or coin-in) wagered on a new particular spin. Those first machines will be paid out based about the mechanical features of the device. However, modern equipment not merely often employ video reels yet also make full use of random number generators instead of mechanical operation to determine champions.

The strategy of progressive jackpots dates back to be able to 1986 when the particular Megabucks machine seemed to be introduced, allowing earnings to accumulate until the player hit the jackpot. Today, many popular progressive slot machines are connected around multiple casinos, more increasing the jackpot feature potential. Classic slot machines, often referred to be able to as 3-reel slot machine games, provide quick plus satisfying action. These games are great for players who appreciate easy and fast-paced game play. With their standard design and mechanics, classic slots charm to both newbies and seasoned gamers. Typically, these slot machines feature one to three paylines, making them easy in order to understand and enjoy.

Slot Tip 4:  Always Enjoy Within Your Budget And Become Willing To Lower Your Guess Or Stop Playing If You Struck A Limit

Bets can be as minimal as 1c each spin, playing with your local on line casino or online is usually easier than at any time to access your bank roll. Modern slot” “equipment games trace to large and unique machines manufactured by an enthusiastic mechanic (and tinkerer) of typically the late 19th millennium, Charles Fey. The machine that Fey created was very simple but complex in concept, and also this machine was the Liberty Bell. Note that these online slot machine game strategies work finest with games that have the lowest volatility since you will need to adjust the dimensions of the gamble as you proceed. Scatter symbols are usually special icons of which can fork out irregardless of their place on the reels, often triggering reward features mostbet.

  • It’s quick to customize amount of credits you’d like to participate in too.
  • Because of the long odds, seeking to win a huge jackpot is most likely unrealistic.
  • You’ll learn what to be able to expect and exactly how to adjust your current playing style to be able to the features of a particular slot device game.
  • For example, the Blood Suckers slot with the RTP of 98% returns to all players $98 of $100 expended inside; $2 is usually the house edge.
  • Therefore, carry out not rush to immediately place actual bets, but initial, get accustomed to the position controls.

Now, your house edge will vary with respect to the” “video game that players opt to play, and typically the total bet amount which is placed. Developers are continually striving to innovate and even create new ways for players to be able to win in a great attempt to retain player interest. One of those innovations seemed to be respins or cascading down symbols – which in turn are certain emblems which cause reels to respin to produce bigger wins or multipliers with outrageous symbols potentially. With all the success and recognition, there is usually one thing which includes always been some sort of given for position machines. In essence, they have been income generators regarding casinos for several years in spite of featuring large plus relatively frequent affiliate payouts. Once you’ve set your desired bet, press the “Spin” button or draw the lever (if available) to trigger the spin.

Beginners Guide: How To Play Slots Regarding Dummies

Keeping with the straightforward nature of playing slots at on the web casinos, if gamers have trouble, these types of websites offer consumer service. The special offers that online casinos offer purely relate with in-game aspects such as bonus money in addition to free spins for slots. The appeal of slot machines is the possiblity to hit big which has a jackpot payday. Over the years, developers have continued to find ways to boost the jackpots regarding players without stopping too much of the edge for your casino.

The most realistic strategy when betting on slot machines is bankroll management; its essence is usually rather simple. Each player can devote a certain amount on bets, in addition to spending it within one evening is a bad concept; a wise option is to split your bankroll volume into several parts. For example, following making a deposit, you can divide it into components simultaneously and use only one piece per day for making bets mostbet app.

Slot Tournaments

Today almost all progressives are linked electronically to other machines, with all credit played in the particular linked machines adding to a typical jackpot. Woe will be the person who hits three jackpot symbols about a buy-a-pay together with only one gold coin played — typically the player gets practically nothing back. On some sort of multiplier, payoffs are proportionate for each coin played — apart from, usually, for that leading jackpot.

  • Their slots selection includes progressive jackpot feature games, as well as a massive selection of all traditional slots you’d count on to find.
  • This is because slot games can be highly addicting and can prospect a player to chase their losses.
  • Nowadays, known because a philanthropist, Bill Redd (also referred to as Si) was among the Bally group’s designers in the 1971s.
  • With all the achievement and popularity, there will be one thing that has always been a new given for slot machine machines.

The wide collection of slot games, like exclusive titles, guarantees a varied plus exciting gaming knowledge. Here are many of the most effective online casinos for slot machine machines and precisely what causes them to be stand out there. A Night Using Cleo transports gamers to the planet of Ancient Egypt, complete with icons such as scarab beetles and the Eye of Horus. This game holds out for its unique bonus models, which add a great extra layer associated with excitement to the gameplay. Players can easily also make use of the chance feature, that allows all of them to attempt in order to double their winnings after any effective spin.

How To Play Slot Machines On-line: Step By Phase Instructions For Beginners

Among other things, site visitors will discover a day-to-day dose of content articles with the newest poker news, reside reporting from tournaments, exclusive videos, podcasts, reviews and bonus deals and so much more. With these kinds of eligibility factors and even any others you might find, your best choice is always in order to game details or even information before a person commit to enjoying. Sean Chaffin can be a longtime freelance article writer, editor, and former high school writing teacher. If you ever feel it’s learning to be a problem, urgently speak to a helpline in your country for immediate” “assistance. From in-depth testimonials and helpful guidelines to the latest reports, we’re here to be able to help you find a very good platforms and create informed decisions every step of the particular way.

They had been featuring three” “re-writing reels operated by way of a handle and a new single slot to be able to place a coin into. This equipment had only one shell out line, with each and every reel featuring several symbols – many you would acknowledge today – spades, hearts, diamonds, a new horseshoe, and the bell. This method requires players to be able to be more involved with every earn, so having some sort of calculator close by is recommended. Instead of changing the particular size of the particular bet based in won or lost rounds, the method has a set bet determined being a percentage of typically the available balance. Using 5% can become convenient, but all of us prefer staying secure and only wagering 3%. Slot machines top the record with regards to the almost all attractive casino game titles for gamblers, the two online and in land-based casinos.

Top Payment Procedures Available On Stake Casino

This feature means that you can spin a slot machine game game without seeking to connect to the particular game, but you is going to take care to be able to ensure you’re not really spending too much per spin. Wilds usually are special symbols that can replace other symbols on paylines to generate benefits. They are typically the most crucial symbols in the particular game and may also sometimes induce bonus features.

  • Additionally, players could unlock bonus capabilities through scatter signs” “that trigger special features.
  • If a person start thinking, “Well, they’re only credit, ” or even, “They’re already paid out for, ” it’s harder to persuade yourself to guard your bankroll.
  • At the core involving every authentic internet gambling platform is gaming software.
  • Players may also withdraw their funds by hitting “Cash Out and about. ” An individual can will certainly then receive a paper voucher together with the balance amount that can become used in another machine.

The user interface is definitely crafted to mirror the appearance and even ambiance of the conventional gambling establishment, featuring intuitive selections and controls. Volatility measures the frequency as well as the size regarding the wins that will the slots spend. For example, in case you prefer big is the winner less often, then you will want to perform an increased volatility slot; in case you prefer a low volatility slot then an individual will get smaller sized, more frequent is the winner. Commonly, this symbol is very totally different from the other symbols, therefore it is easy to distinguish besides making it simpler to understand the gameplay. Depending how many you obtain, could be dependent about the reward an individual are given; but like always, this may also vary per game.

Are There Different Types Of Slot Machines?

That about wraps upward our How in order to Play Slot Devices for Beginners guidebook. If you’ve appreciated it and are ready to try many free slots with regard to yourself, check out our slot reviews web page now. After a new few spins about those, you’ll grasp all of the particular concepts you’ve figured out about here. Paylines often confuse starter slots players the most, and no Exactly how to Play Slot machine Machines for Beginners guide would be full without explaining all of them further. Each symbol has a different worth and exactly how much you win for making combinations will be identified by the value of the symbols.

  • Don’t forget to be able to carefully experience almost all of the great print, because a few terms & situations can limit claiming, usage or cashing out of bonuses.
  • First, you should note that you can always find out exactly what bonus rounds and even special features the game has by viewing the paytable.
  • The goal with this specific strategy for earning at slots is usually to win back our losses.
  • Slot machines have are available a long approach since being simple machines and actually their role since store vending equipment.
  • Once you’ve established your desired gamble, press the “Spin” button or draw the lever (if available) to initiate the spin.

He’s written several books, generally on the topics of card counting and the different blackjack systems they employed over the particular years. He in addition runs a effective YouTube channel wherever he showcases various blackjack scenarios with beginner tips about how to overcome the dealer. Bets can be since little as 1c compared to typically the common minimum levels of $5 in order to $10 that stand and card games require.” “[newline]Please note that Slotsspot. com doesn’t work any gambling companies.

How To Play Slot Machines Inside A Casino

Bonus rounds can befuddle some new participants, so we believed we’d describe all of them here so that this specific How to Play Slot Machines intended for Beginners piece will be complete. When the cheats inserted particular numbers of coins in a certain order, the device would fork out. In jurisdictions with licensed casinos, the law takes a very dim view of cheating the video poker machines. Cheating licensed casinos is a criminal offence and will carry stiff prison terms. A zero-bonus balances the particular possibility of greater wins than you see in pick’em bonuses.

  • Over in britain, they include a couple of names for all of them, fruit machines in England and puggy in Scotland.
  • They are created to offer the chance-based, easy-to-play video gaming experience where gamers” “can go back home with potentially big wins using a simple rewrite.
  • However, you may stick to certain rules when playing particular titles; by using them, you could decrease risks and boost your winning possibilities.
  • The bonus round is usually activated by way of a minimum of three scatter symbols – but this can easily vary slot in order to slot.
  • Just such as the relaxed nature of how to play slot machines, players from all over have similar carefree love towards online game.

A gamer has numerous game titles available, something intended for every taste plus interest. However, whilst we can’t inform you how in order to play slot devices and win every time, we can show a couple of slot machine techniques that will assist you win more often. This is knowledge we’ve gained above decades, so bring it in and create sure you realize that before choosing which usually game to enjoy. Some slot machines in the 1960s and ‘70s had been vulnerable to ordinary magnets. Cheaters could make use of the magnets in order to make the fishing reels float freely alternatively of stopping about a spin.

How To Play Position Machines: A Step By Step Guide

Usually, classic, fruits, 3D, and progressive jackpot slot equipment are available with all online internet casinos. Old-fashioned slot equipment have only one horizontal payline, along which in turn three winning emblems (usually fruit icons or 7s) have to line upwards for you to be paid out. The vast bulk of today’s position machines, however, are multi-payline, with a few featuring up to 100 paylines or more.

  • So, let’s say that we all start with $100, which usually means our 1st bet is 3%.
  • It works generally the same manner regarding all slot devices, although there may become some variations based on the application developer.
  • These are the added features that assist to boost your payout in the particular game.
  • There is enough diversity and choice available amongst the slot machine game games industry.
  • “Each game comes with a unique combo of features like bonus rounds, thrilling varied animation alternatives, modern machines, multiplier machines, wild icons, and more.

The risk is that a new dry run can lead to a large bet that may be difficult in order to sustain. Some slot machine games feature progressive jackpots, where a small portion of each and every bet contributes to be able to a growing goldmine that can always be won by getting a specific combo or at unique. Find out about slot machines, how that they work and how to play slots for actual money with our own full guide.

How Developers Found Ways To Increase Jackpots

The worst factor you can apply at slot machines is always to chase loss by increasing the bet level. The chances are good that you may lose a lot more cash, and probably crazily run through the bankroll. When selecting an ideal bet level for your slot play, your decision is usually a trade-off among risk and payment.

  • The machine became known as the Liberty Bell and Fey spawned an evergrowing industry.
  • There are video games in penny, 2-cent, nickel, 10-cent, 1 fourth, dollar and also $100 denominations, and several machines allow players in order to choose which denomination they want to be able to use.
  • Nearly everyone is guilty associated with not reading Apple or Google words of service, but you shouldn’t are available to a casino with that same mindset.
  • The slot machine machine landscape has always been dependent upon the improvements and innovations involving software companies.
  • These slots are normally great for players who just want to have many fun create typically the most of their particular play.

It’s important to read the cup or help menus and learn precisely what type of device it is. The three major forms of reel-spinning slot machines are the multiplier, the buy-a-pay along with the progressive. Modern movie slots, of program, don’t have real coins but instead use virtual bridal party. To period pay-out odds, simply cash out your own slot credits straight into a real money balance. If you’re gunning for the big bucks, on the other hand, you would end up being wise to stick to high volatility slots.

Slot Hint 10:  Take Benefit Of Bonuses And Even Promotions

In typically the rest, the recognition of attempting to be able to win at slot machines is surging to the point slot machine game play is rivaling table play. On those machines, the particular big payoffs have been $50 or $100 — not like typically the big numbers slot machine game players expect today. On systems of which electronically link equipment in several casinos, progressive jackpots reach huge amount of money. It’s quick — just drop coins into typically the slot and push the button or even pull the handle. Newcomers will find the particular personal interaction along with dealers or additional players at the particular tables intimidating — slot players prevent that. And besides, the greatest, most lifestyle-changing jackpots in typically the casino are available upon the slots.

The game software giant incorporated a 4-tier progressive goldmine with levels called mega, major, slight, and mini. In order to be eligible for the tiny jackpot – the lowest of the bunch, you must bet at least 1 cent on all twenty-five paylines (a minimal total of $0. 25). When this comes to video slots, these generally include multi-tier accelerating jackpots. Every video clip slot usually provides between 2 plus 12 progressive goldmine levels, and every level provides a established max bet an individual have to help to make in order to be able to be eligible.

What Occurs When You” “Get On A Slot Machine?

Each slot machine features a pay stand that shows just what symbols have to line up for a pay out of varying sums. These are organized with the greatest payouts, known because the jackpot, on top of the tables and subsequent payouts below those. A desk also includes an amount paid relying on the amount of credits a new player puts in the machine. A random number generator, or perhaps RNG, is a computer technology that is definitely used to determine payouts and jackpots. An RNG makes a sequence associated with simulated random amounts to determine exactly where those reels may land, and therefore which payouts” “are distributed to participants. Modern slot equipment have become high-tech machines with advanced online video, sound, graphics, in addition to gameplay.

  • So, you should recognize that playing slot machine machines are extremely basic – which is part of the reason players love these games.
  • Ordinarily, a traditional 3-reel slot will be an ideal opt for for the player who else likes a pared-down game with not any frills and everything perform.
  • For example, if you owned four matching emblems on reels one, two, four, in addition to five, and some sort of wild landed throughout the middle, you’d have a 5 symbol combination.
  • Usually, classic, fruit, 3D, and progressive jackpot slot machines are available from all online casinos.
  • You can typically do this inside the ‘account’ or ‘banking’ section of your own casino.

The scam artists would likely remove the magnetic only when the fishing reels had aligned throughout a winning combo. My top slot machine game machine strategy ideas – you’ll learned about below – consist of 12 do’s and even 6 don’ts that may assist you in answering the top ‘how to succeed at slot machines? Changing the developed payback percentage demands opening the device and replacing a computer chip. Server-based slot machines that will allow casinos in order to change payout proportions remotely, but there are still polices around making these kinds of changes. It’s certainly not unusual to proceed 20 or fifty or more draws without a one payout on a reel-spinning slot, although payouts tend to be more repeated on video video poker machines. Nor would it be unusual for a device to pay again 150 percent or more for many dozen pulls.

What Is Responsible Game Playing And What Makes It Essential?

Given that they are games of chance, playing slots has more to perform with luck as compared to strategy. Even so, there are several strategies you can employ to select some sort of slot machine that may likely pay. As you might have got heard before, a person can’t win large payouts at a intensifying slot if you don’t max the wager. A small section of your bet on a modern slot machine game goes straight into a jackpot or perhaps set of jackpots. The more participants wager on typically the progressive lot the bigger its jackpot gets.

  • Not all machines are made the similar way and programmed with the same RTP or payment percentage.
  • To place a bet on the slot machine, simply insert the coins or currency, select your bet size, and take the lever or perhaps press the rotate button.
  • Alternatively, you can start building up a bankroll by keeping aside small amounts through your savings and after that begin gambling after getting saved enough money for a certain variety of slot machines.
  • Let’s consider a closer look at the sorts of bonus icons you’re more likely to find in a regular online” “slot.

Other accelerating slots are connected within a casino, although some are interconnected across all internet casinos featuring that certain game. For a new genuine casino experience from the coziness of your abode, live dealer games certainly are a must consider. These games, including live blackjack, different roulette games, and baccarat, feature real human retailers who interact along with players via reside video streams. Players can participate in current gameplay, detailed with interpersonal interaction, creating a great immersive and genuine casino atmosphere. They” “come in various themes and give a stimulating blend of gameplay, visuals, plus the possibility for significant winnings. Demo methods are available regarding players to train and even familiarize themselves along with the game with out risking real cash.

Starting In Order To Play Slots

Yes, due to the fact demo versions permit you to test slots, check their particular characteristics, and do not risk your own funds. While wagering, it is essential to control yourself, while emotions often usually tend to get free from control. It is incredibly common when you strike a large reward and lose manage, forgetting about caution as well as the strategy you adhere to. Aside coming from these run-of-the-mill strategies, participate in slot machine tournaments whenever feasible.

  • Understanding design and even mechanics in the sport is essential ahead of spinning the fishing reels.
  • Don’t hesitate in order to ask tough queries; other gamblers are usually willing to out a poor apple.
  • The scam artists would remove the magnet only if the reels had aligned within a winning mixture.
  • Video slots are acknowledged for their advanced graphics and several paylines, which will enhance the chances regarding winning.
  • The paytable also shows the value of every symbol, indicating the amount you win intended for matching different icons on a payline.

When playing video poker machines online, you could decrease or raise your stake by simply clicking on typically the BET/STAKE button. For example, classic on the internet slots based about traditional slot equipment have 3 reels. Three-reel slot games put more importance on their leading jackpots but have got a lesser hit regularity with additional losing spins. If you’re pondering how to win at slots, three-reel position games do offer slot players typically the best possiblity to get big, but additionally the particular best chance in order to lose fast. Every good online gambling establishment will have an array of games to attempt at no cost or true money.

How To Experience Video Poker Machines: The Pokernews Guide

The microprocessors driving today’s machines are set with random-number generation devices that govern winning combinations. Many position players pump money into two or more adjacent devices at a time, although if the casino will be crowded and others are having problems finding places to play, limit yourself to one machine. Select your bets and paylines, and get a theme and bonus feature of which interests you. Online slot software will be governed by the Arbitrary Number Generator, or perhaps RNG. As quickly as you struck the ‘Spin’ key, an algorithm can determine where and if the reels can stop. The process is completely unique, and slot designers have their games examined before they hit the casino industry, along with periodically audited with time.

  • This network impact results in massive jackpots, some of which can become truly life-changing.
  • While learning how in order to play casino slot machine games, there are particular factors that you have to always keep in mind when choosing the proper slot machine game game.
  • Added for the paylines and payout structures, deciphering the bet measurements is likewise crucial, as it can have an effect on both the possible winnings and the particular overall game.
  • You may well also get a feeling whether it’s achievable to win in slot games and even if so how to win in slots.

Now, a new payout and goldmine is determined as quickly as the player hits the switch to spin the particular reels. If you’re purely after massive jackpots, you ought to consider playing the subsequent games. These top rated progressive jackpot slots have paid out many of the greatest online slot jackpots of all time.

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