#   This library is free software; you can redistribute it and/or

#   modify it under the terms of the GNU Lesser General Public

#   License as published by the Free Software Foundation; either

#   version 2.1 of the License, or (at your option) any later version.

#

#   This library is distributed in the hope that it will be useful,

#   but WITHOUT ANY WARRANTY; without even the implied warranty of

#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

#   Lesser General Public License for more details.

#

#   You should have received a copy of the GNU Lesser General Public

#   License along with this library; if not, see

#   <http://www.gnu.org/licenses/>.

# This file is part of urlgrabber, a high-level cross-protocol url-grabber

# Copyright 2002-2004 Michael D. Stenner, Ryan Tomayko

# Modified by Benoit Boissinot:

#  - fix for digest auth (inspired from urllib2.py @ Python v2.4)

# Modified by Dirkjan Ochtman:

#  - import md5 function from a local util module

# Modified by Augie Fackler:

#  - add safesend method and use it to prevent broken pipe errors

#    on large POST requests

"""An HTTP handler for urllib2 that supports HTTP 1.1 and keepalive.

>>> import urllib2

>>> from keepalive import HTTPHandler

>>> keepalive_handler = HTTPHandler()

>>> opener = urlreq.buildopener(keepalive_handler)

>>> urlreq.installopener(opener)

>>>

>>> fo = urlreq.urlopen('http://www.python.org')

If a connection to a given host is requested, and all of the existing

connections are still in use, another connection will be opened.  If

the handler tries to use an existing connection but it fails in some

way, it will be closed and removed from the pool.

To remove the handler, simply re-run build_opener with no arguments, and

install that opener.

You can explicitly close connections by using the close_connection()

method of the returned file-like object (described below) or you can

use the handler methods:

  close_connection(host)

  close_all()

  open_connections()

NOTE: using the close_connection and close_all methods of the handler

should be done with care when using multiple threads.

  * there is nothing that prevents another thread from creating new

    connections immediately after connections are closed

  * no checks are done to prevent in-use connections from being closed

>>> keepalive_handler.close_all()

EXTRA ATTRIBUTES AND METHODS

  Upon a status of 200, the object returned has a few additional

  attributes and methods, which should not be used if you want to

  remain consistent with the normal urllib2-returned objects:

    close_connection()  -  close the connection to the host

    readlines()         -  you know, readlines()

    status              -  the return status (i.e. 404)

    reason              -  english translation of status (i.e. 'File not found')

  If you want the best of both worlds, use this inside an

  AttributeError-catching try:

  >>> try: status = fo.status

  >>> except AttributeError: status = None

  Unfortunately, these are ONLY there if status == 200, so it's not

  easy to distinguish between non-200 responses.  The reason is that

  urllib2 tries to do clever things with error codes 301, 302, 401,

  and 407, and it wraps the object upon return.

  For python versions earlier than 2.4, you can avoid this fancy error

  handling by setting the module-level global HANDLE_ERRORS to zero.

  You see, prior to 2.4, it's the HTTP Handler's job to determine what

  to handle specially, and what to just pass up.  HANDLE_ERRORS == 0

  means "pass everything up".  In python 2.4, however, this job no

  longer belongs to the HTTP Handler and is now done by a NEW handler,

  HTTPErrorProcessor.  Here's the bottom line:

    python version < 2.4

        HANDLE_ERRORS == 1  (default) pass up 200, treat the rest as

                            errors

        HANDLE_ERRORS == 0  pass everything up, error processing is

                            left to the calling code

    python version >= 2.4

        HANDLE_ERRORS == 1  pass up 200, treat the rest as errors

        HANDLE_ERRORS == 0  (default) pass everything up, let the

                            other handlers (specifically,

                            HTTPErrorProcessor) decide what to do

  In practice, setting the variable either way makes little difference

  in python 2.4, so for the most consistent behavior across versions,

  you probably just want to use the defaults, which will give you

  exceptions on errors.

"""

# $Id: keepalive.py,v 1.14 2006/04/04 21:00:32 mstenner Exp $

from __future__ import absolute_import, print_function

import errno

import hashlib

import socket

import sys

import threading

from . import (

    util,

)

httplib = util.httplib

urlerr = util.urlerr

urlreq = util.urlreq

DEBUG = None

if sys.version_info < (2, 4):

    HANDLE_ERRORS = 1

else: HANDLE_ERRORS = 0

class ConnectionManager(object):

    """

    The connection manager must be able to:

      * keep track of all existing

      """

    def __init__(self):

        self._lock = threading.Lock()

        self._hostmap = {} # map hosts to a list of connections

        self._connmap = {} # map connections to host

        self._readymap = {} # map connection to ready state

    def add(self, host, connection, ready):

        self._lock.acquire()

        try:

            if host not in self._hostmap:

                self._hostmap[host] = []

            self._hostmap[host].append(connection)

            self._connmap[connection] = host

            self._readymap[connection] = ready

        finally:

            self._lock.release()

    def remove(self, connection):

        self._lock.acquire()

        try:

            try:

                host = self._connmap[connection]

            except KeyError:

                pass

            else:

                del self._connmap[connection]

                del self._readymap[connection]

                self._hostmap[host].remove(connection)

                if not self._hostmap[host]: del self._hostmap[host]

        finally:

            self._lock.release()

    def set_ready(self, connection, ready):

        try:

            self._readymap[connection] = ready

        except KeyError:

            pass

    def get_ready_conn(self, host):

        conn = None

        self._lock.acquire()

        try:

            if host in self._hostmap:

                for c in self._hostmap[host]:

                    if self._readymap[c]:

                        self._readymap[c] = 0

                        conn = c

                        break

        finally:

            self._lock.release()

        return conn

    def get_all(self, host=None):

        if host:

            return list(self._hostmap.get(host, []))

        else:

            return dict(self._hostmap)

class KeepAliveHandler(object):

    def __init__(self):

        self._cm = ConnectionManager()

    #### Connection Management

    def open_connections(self):

        """return a list of connected hosts and the number of connections

        to each.  [('foo.com:80', 2), ('bar.org', 1)]"""

        return [(host, len(li)) for (host, li) in self._cm.get_all().items()]

    def close_connection(self, host):

        """close connection(s) to <host>

        host is the host:port spec, as in 'www.cnn.com:8080' as passed in.

        no error occurs if there is no connection to that host."""

        for h in self._cm.get_all(host):

            self._cm.remove(h)

            h.close()

    def close_all(self):

        """close all open connections"""

        for host, conns in self._cm.get_all().iteritems():

            for h in conns:

                self._cm.remove(h)

                h.close()

    def _request_closed(self, request, host, connection):

        """tells us that this request is now closed and that the

        connection is ready for another request"""

        self._cm.set_ready(connection, 1)

    def _remove_connection(self, host, connection, close=0):

        if close:

            connection.close()

        self._cm.remove(connection)

    #### Transaction Execution

    def http_open(self, req):

        return self.do_open(HTTPConnection, req)

    def do_open(self, http_class, req):

        host = req.get_host()

        if not host:

            raise urlerr.urlerror('no host given')

        try:

            h = self._cm.get_ready_conn(host)

            while h:

                r = self._reuse_connection(h, req, host)

                # if this response is non-None, then it worked and we're

                # done.  Break out, skipping the else block.

                if r:

                    break

                # connection is bad - possibly closed by server

                # discard it and ask for the next free connection

                h.close()

                self._cm.remove(h)

                h = self._cm.get_ready_conn(host)

            else:

                # no (working) free connections were found.  Create a new one.

                h = http_class(host)

                if DEBUG:

                    DEBUG.info("creating new connection to %s (%d)",

                               host, id(h))

                self._cm.add(host, h, 0)

                self._start_transaction(h, req)

                r = h.getresponse()

        except (socket.error, httplib.HTTPException) as err:

            raise urlerr.urlerror(err)

        # if not a persistent connection, don't try to reuse it

        if r.will_close:

            self._cm.remove(h)

        if DEBUG:

            DEBUG.info("STATUS: %s, %s", r.status, r.reason)

        r._handler = self

        r._host = host

        r._url = req.get_full_url()

        r._connection = h

        r.code = r.status

        r.headers = r.msg

        r.msg = r.reason

        if r.status == 200 or not HANDLE_ERRORS:

            return r

        else:

            return self.parent.error('http', req, r,

                                     r.status, r.msg, r.headers)

    def _reuse_connection(self, h, req, host):

        """start the transaction with a re-used connection

        return a response object (r) upon success or None on failure.

        This DOES not close or remove bad connections in cases where

        it returns.  However, if an unexpected exception occurs, it

        will close and remove the connection before re-raising.

        """

        try:

            self._start_transaction(h, req)

            r = h.getresponse()

            # note: just because we got something back doesn't mean it

            # worked.  We'll check the version below, too.

        except (socket.error, httplib.HTTPException):

            r = None

        except: # re-raises

            # adding this block just in case we've missed

            # something we will still raise the exception, but

            # lets try and close the connection and remove it

            # first.  We previously got into a nasty loop

            # where an exception was uncaught, and so the

            # connection stayed open.  On the next try, the

            # same exception was raised, etc.  The trade-off is

            # that it's now possible this call will raise

            # a DIFFERENT exception

            if DEBUG:

                DEBUG.error("unexpected exception - closing "

                            "connection to %s (%d)", host, id(h))

            self._cm.remove(h)

            h.close()

            raise

        if r is None or r.version == 9:

            # httplib falls back to assuming HTTP 0.9 if it gets a

            # bad header back.  This is most likely to happen if

            # the socket has been closed by the server since we

            # last used the connection.

            if DEBUG:

                DEBUG.info("failed to re-use connection to %s (%d)",

                           host, id(h))

            r = None

        else:

            if DEBUG:

                DEBUG.info("re-using connection to %s (%d)", host, id(h))

        return r

    def _start_transaction(self, h, req):

        # What follows mostly reimplements HTTPConnection.request()

        # except it adds self.parent.addheaders in the mix.

        headers = dict((n.lower(), v) for n, v in headers.items())

        skipheaders = {}

        for n in ('host', 'accept-encoding'):

            if n in headers:

                skipheaders['skip_' + n.replace('-', '_')] = 1

        try:

            if req.has_data():

                data = req.get_data()

                h.putrequest('POST', req.get_selector(), **skipheaders)

                if 'content-type' not in headers:

                    h.putheader('Content-type',

                                'application/x-www-form-urlencoded')

                if 'content-length' not in headers:

                    h.putheader('Content-length', '%d' % len(data))

            else:

                h.putrequest('GET', req.get_selector(), **skipheaders)

        except socket.error as err:

            raise urlerr.urlerror(err)

        for k, v in headers.items():

            h.putheader(k, v)

        h.endheaders()

        if req.has_data():

            h.send(data)

class HTTPHandler(KeepAliveHandler, urlreq.httphandler):

    pass

class HTTPResponse(httplib.HTTPResponse):

    # we need to subclass HTTPResponse in order to

    # 1) add readline() and readlines() methods

    # 2) add close_connection() methods

    # 3) add info() and geturl() methods

    # in order to add readline(), read must be modified to deal with a

    # buffer.  example: readline must read a buffer and then spit back

    # one line at a time.  The only real alternative is to read one

    # BYTE at a time (ick).  Once something has been read, it can't be

    # put back (ok, maybe it can, but that's even uglier than this),

    # so if you THEN do a normal read, you must first take stuff from

    # the buffer.

    # the read method wraps the original to accommodate buffering,

    # although read() never adds to the buffer.

    # Both readline and readlines have been stolen with almost no

    # modification from socket.py

    def __init__(self, sock, debuglevel=0, strict=0, method=None):

        httplib.HTTPResponse.__init__(self, sock, debuglevel, method)

        self.fileno = sock.fileno

        self.code = None

        self._rbuf = ''

        self._rbufsize = 8096

        self._handler = None # inserted by the handler later

        self._host = None    # (same)

        self._url = None     # (same)

        self._connection = None # (same)

    _raw_read = httplib.HTTPResponse.read

    def close(self):

        if self.fp:

            self.fp.close()

            self.fp = None

            if self._handler:

                self._handler._request_closed(self, self._host,

                                              self._connection)

    def close_connection(self):

        self._handler._remove_connection(self._host, self._connection, close=1)

        self.close()

    def info(self):

        return self.headers

    def geturl(self):

        return self._url