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"""WebSocket opening handshake processor. This class try to apply available
opening handshake processors for each protocol version until a connection is
successfully established.
"""

from __future__ import absolute_import
import logging

from mod_pywebsocket import common
from mod_pywebsocket.handshake import hybi
# Export AbortedByUserException, HandshakeException, and VersionException
# symbol from this module.
from mod_pywebsocket.handshake._base import AbortedByUserException
from mod_pywebsocket.handshake._base import HandshakeException
from mod_pywebsocket.handshake._base import VersionException

_LOGGER = logging.getLogger(__name__)


def do_handshake(request, dispatcher):
    """Performs WebSocket handshake.

    Args:
        request: mod_python request.
        dispatcher: Dispatcher (dispatch.Dispatcher).

    Handshaker will add attributes such as ws_resource in performing
    handshake.
    """

    _LOGGER.debug('Client\'s opening handshake resource: %r', request.uri)
    # To print mimetools.Message as escaped one-line string, we converts
    # headers_in to dict object. Without conversion, if we use %r, it just
    # prints the type and address, and if we use %s, it prints the original
    # header string as multiple lines.
    #
    # Both mimetools.Message and MpTable_Type of mod_python can be
    # converted to dict.
    #
    # mimetools.Message.__str__ returns the original header string.
    # dict(mimetools.Message object) returns the map from header names to
    # header values. While MpTable_Type doesn't have such __str__ but just
    # __repr__ which formats itself as well as dictionary object.
    _LOGGER.debug('Client\'s opening handshake headers: %r',
                  dict(request.headers_in))

    handshakers = []
    handshakers.append(('RFC 6455', hybi.Handshaker(request, dispatcher)))

    for name, handshaker in handshakers:
        _LOGGER.debug('Trying protocol version %s', name)
        try:
            handshaker.do_handshake()
            _LOGGER.info('Established (%s protocol)', name)
            return
        except HandshakeException as e:
            _LOGGER.debug(
                'Failed to complete opening handshake as %s protocol: %r',
                name, e)
            if e.status:
                raise e
        except AbortedByUserException as e:
            raise
        except VersionException as e:
            raise

    # TODO(toyoshim): Add a test to cover the case all handshakers fail.
    raise HandshakeException(
        'Failed to complete opening handshake for all available protocols',
        status=common.HTTP_STATUS_BAD_REQUEST)


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