Python OpenSSL.SSL.WantReadError() Examples

def _checkHandshakeStatus(self):
        """
        Ask OpenSSL to proceed with a handshake in progress.

        Initially, this just sends the ClientHello; after some bytes have been
        stuffed in to the C{Connection} object by C{dataReceived}, it will then
        respond to any C{Certificate} or C{KeyExchange} messages.
        """
        # The connection might already be aborted (eg. by a callback during
        # connection setup), so don't even bother trying to handshake in that
        # case.
        if self._aborted:
            return
        try:
            self._tlsConnection.do_handshake()
        except WantReadError:
            self._flushSendBIO()
        except Error:
            self._tlsShutdownFinished(Failure())
        else:
            self._handshakeDone = True
            if IHandshakeListener.providedBy(self.wrappedProtocol):
                self.wrappedProtocol.handshakeCompleted() 

def socketRecv(self, packetSize):
        data = self.socket.recv(packetSize)
        if self.tlsSocket is not None:
            dd = ''
            self.tlsSocket.bio_write(data)
            while True:
                try:
                    dd += self.tlsSocket.read(packetSize)
                except SSL.WantReadError:
                    data2 = self.socket.recv(packetSize - len(data) )
                    self.tlsSocket.bio_write(data2)
                    pass
                else:
                    data = dd
                    break
        return data 

def socketRecv(self, packetSize):
        data = self.socksSocket.recv(packetSize)
        if self.tlsSocket is not None:
            dd = b''
            self.tlsSocket.bio_write(data)
            while True:
                try:
                    dd += self.tlsSocket.read(packetSize)
                except SSL.WantReadError:
                    data2 = self.socksSocket.recv(packetSize - len(data) )
                    self.tlsSocket.bio_write(data2)
                    pass
                else:
                    data = dd
                    break
        return data 

def socketRecv(self, packetSize):
        data = self.socksSocket.recv(packetSize)
        if self.tlsSocket is not None:
            dd = ''
            self.tlsSocket.bio_write(data)
            while True:
                try:
                    dd += self.tlsSocket.read(packetSize)
                except SSL.WantReadError:
                    data2 = self.socket.recv(packetSize - len(data) )
                    self.tlsSocket.bio_write(data2)
                    pass
                else:
                    data = dd
                    break
        return data 

def writeSomeData(self, data):
        try:
            return Connection.writeSomeData(self, data)
        except SSL.WantWriteError:
            return 0
        except SSL.WantReadError:
            self.writeBlockedOnRead = 1
            Connection.stopWriting(self)
            Connection.startReading(self)
            return 0
        except SSL.ZeroReturnError:
            return main.CONNECTION_LOST
        except SSL.SysCallError, e:
            if e[0] == -1 and data == "":
                # errors when writing empty strings are expected
                # and can be ignored
                return 0
            else:
                return main.CONNECTION_LOST 

def _checkHandshakeStatus(self):
        """
        Ask OpenSSL to proceed with a handshake in progress.

        Initially, this just sends the ClientHello; after some bytes have been
        stuffed in to the C{Connection} object by C{dataReceived}, it will then
        respond to any C{Certificate} or C{KeyExchange} messages.
        """
        # The connection might already be aborted (eg. by a callback during
        # connection setup), so don't even bother trying to handshake in that
        # case.
        if self._aborted:
            return
        try:
            self._tlsConnection.do_handshake()
        except WantReadError:
            self._flushSendBIO()
        except Error:
            self._tlsShutdownFinished(Failure())
        else:
            self._handshakeDone = True
            if IHandshakeListener.providedBy(self.wrappedProtocol):
                self.wrappedProtocol.handshakeCompleted() 

def doRead(self):
        if self.writeBlockedOnRead:
            self.writeBlockedOnRead = 0
            self._resetReadWrite()
        try:
            return Connection.doRead(self)
        except SSL.ZeroReturnError:
            return main.CONNECTION_DONE
        except SSL.WantReadError:
            return
        except SSL.WantWriteError:
            self.readBlockedOnWrite = 1
            Connection.startWriting(self)
            Connection.stopReading(self)
            return
        except SSL.SysCallError, (retval, desc):
            if ((retval == -1 and desc == 'Unexpected EOF')
                or retval > 0):
                return main.CONNECTION_LOST
            log.err()
            return main.CONNECTION_LOST 

def writeSomeData(self, data):
        try:
            return Connection.writeSomeData(self, data)
        except SSL.WantWriteError:
            return 0
        except SSL.WantReadError:
            self.writeBlockedOnRead = 1
            Connection.stopWriting(self)
            Connection.startReading(self)
            return 0
        except SSL.ZeroReturnError:
            return main.CONNECTION_LOST
        except SSL.SysCallError, e:
            if e[0] == -1 and data == "":
                # errors when writing empty strings are expected
                # and can be ignored
                return 0
            else:
                return main.CONNECTION_LOST 

def socketRecv(self, packetSize):
        data = self.socket.recv(packetSize)
        if self.tlsSocket is not None:
            dd = ''
            self.tlsSocket.bio_write(data)
            while True:
                try:
                    dd += self.tlsSocket.read(packetSize)
                except SSL.WantReadError:
                    data2 = self.socket.recv(packetSize - len(data) )
                    self.tlsSocket.bio_write(data2)
                    pass
                else:
                    data = dd
                    break
        return data 

def recv(self, buffer_size):
            try:
                return super(SSLConnection, self).recv(buffer_size)
            except SSL.WantReadError:
                debug("call: recv(), err: want-read", inst=self)
                self._ssl_want_read = True
                raise RetryError
            except SSL.WantWriteError:
                debug("call: recv(), err: want-write", inst=self)
                self._ssl_want_write = True
                raise RetryError
            except SSL.ZeroReturnError as err:
                debug("call: recv() -> shutdown(), err: zero-return",
                      inst=self)
                super(SSLConnection, self).handle_close()
                return b''
            except SSL.SysCallError as err:
                debug("call: recv(), err: %r" % err, inst=self)
                errnum, errstr = err.args
                if (errnum in _ERRNOS_DISCONNECTED or
                        errstr == 'Unexpected EOF'):
                    super(SSLConnection, self).handle_close()
                    return b''
                else:
                    raise 

def socketRecv(self, packetSize):
        data = self.socksSocket.recv(packetSize)
        if self.tlsSocket is not None:
            dd = b''
            self.tlsSocket.bio_write(data)
            while True:
                try:
                    dd += self.tlsSocket.read(packetSize)
                except SSL.WantReadError:
                    data2 = self.socksSocket.recv(packetSize - len(data) )
                    self.tlsSocket.bio_write(data2)
                    pass
                else:
                    data = dd
                    break
        return data 

def _handle_ssl_want_rw(self):
            prev_row_pending = self._ssl_want_read or self._ssl_want_write
            try:
                yield
            except SSL.WantReadError:
                # we should never get here; it's just for extra safety
                self._ssl_want_read = True
            except SSL.WantWriteError:
                # we should never get here; it's just for extra safety
                self._ssl_want_write = True

            if self._ssl_want_read:
                self.modify_ioloop_events(
                    self._wanted_io_events | self.ioloop.READ, logdebug=True)
            elif self._ssl_want_write:
                self.modify_ioloop_events(
                    self._wanted_io_events | self.ioloop.WRITE, logdebug=True)
            else:
                if prev_row_pending:
                    self.modify_ioloop_events(self._wanted_io_events) 

def recv(self, buffer_size):
            try:
                return super(SSLConnection, self).recv(buffer_size)
            except SSL.WantReadError:
                debug("call: recv(), err: want-read", inst=self)
                self._ssl_want_read = True
                raise RetryError
            except SSL.WantWriteError:
                debug("call: recv(), err: want-write", inst=self)
                self._ssl_want_write = True
                raise RetryError
            except SSL.ZeroReturnError as err:
                debug("call: recv() -> shutdown(), err: zero-return",
                      inst=self)
                super(SSLConnection, self).handle_close()
                return b''
            except SSL.SysCallError as err:
                debug("call: recv(), err: %r" % err, inst=self)
                errnum, errstr = err.args
                if (errnum in _ERRNOS_DISCONNECTED or
                        errstr == 'Unexpected EOF'):
                    super(SSLConnection, self).handle_close()
                    return b''
                else:
                    raise 

def _handle_ssl_want_rw(self):
            prev_row_pending = self._ssl_want_read or self._ssl_want_write
            try:
                yield
            except SSL.WantReadError:
                # we should never get here; it's just for extra safety
                self._ssl_want_read = True
            except SSL.WantWriteError:
                # we should never get here; it's just for extra safety
                self._ssl_want_write = True

            if self._ssl_want_read:
                self.modify_ioloop_events(
                    self._wanted_io_events | self.ioloop.READ, logdebug=True)
            elif self._ssl_want_write:
                self.modify_ioloop_events(
                    self._wanted_io_events | self.ioloop.WRITE, logdebug=True)
            else:
                if prev_row_pending:
                    self.modify_ioloop_events(self._wanted_io_events) 

def socketRecv(self, packetSize):
        data = self.socket.recv(packetSize)
        if self.tlsSocket is not None:
            dd = ''
            self.tlsSocket.bio_write(data)
            while True:
                try:
                    dd += self.tlsSocket.read(packetSize)
                except SSL.WantReadError:
                    data2 = self.socket.recv(packetSize - len(data) )
                    self.tlsSocket.bio_write(data2)
                    pass
                else:
                    data = dd
                    break
        return data 

def socketRecv(self, packetSize):
        data = self.socket.recv(packetSize)
        if self.tlsSocket is not None:
            dd = ''
            self.tlsSocket.bio_write(data)
            while True:
                try:
                    dd += self.tlsSocket.read(packetSize)
                except SSL.WantReadError:
                    data2 = self.socket.recv(packetSize - len(data) )
                    self.tlsSocket.bio_write(data2)
                    pass
                else:
                    data = dd
                    break
        return data 

def initConnection(self):
        self.connect()
        #This is copied from tds.py
        resp = self.preLogin()
        if resp['Encryption'] == TDS_ENCRYPT_REQ or resp['Encryption'] == TDS_ENCRYPT_OFF:
            LOG.debug("Encryption required, switching to TLS")

            # Switching to TLS now
            ctx = SSL.Context(SSL.TLSv1_METHOD)
            ctx.set_cipher_list('RC4, AES256')
            tls = SSL.Connection(ctx,None)
            tls.set_connect_state()
            while True:
                try:
                    tls.do_handshake()
                except SSL.WantReadError:
                    data = tls.bio_read(4096)
                    self.sendTDS(TDS_PRE_LOGIN, data,0)
                    tds = self.recvTDS()
                    tls.bio_write(tds['Data'])
                else:
                    break

            # SSL and TLS limitation: Secure Socket Layer (SSL) and its replacement,
            # Transport Layer Security(TLS), limit data fragments to 16k in size.
            self.packetSize = 16*1024-1
            self.tlsSocket = tls
        self.resp = resp
        return True 

def init_connection(self):
        self.connect()
        #This is copied from tds.py
        resp = self.preLogin()
        if resp['Encryption'] == TDS_ENCRYPT_REQ or resp['Encryption'] == TDS_ENCRYPT_OFF:
            logging.info("Encryption required, switching to TLS")

            # Switching to TLS now
            ctx = SSL.Context(SSL.TLSv1_METHOD)
            ctx.set_cipher_list('RC4')
            tls = SSL.Connection(ctx,None)
            tls.set_connect_state()
            while True:
                try:
                    tls.do_handshake()
                except SSL.WantReadError:
                    data = tls.bio_read(4096)
                    self.sendTDS(TDS_PRE_LOGIN, data,0)
                    tds = self.recvTDS()
                    tls.bio_write(tds['Data'])
                else:
                    break

            # SSL and TLS limitation: Secure Socket Layer (SSL) and its replacement, 
            # Transport Layer Security(TLS), limit data fragments to 16k in size.
            self.packetSize = 16*1024-1
            self.tlsSocket = tls
        self.resp = resp 

def go():
    port = socket()
    port.bind(('', 0))
    port.listen(1)

    called = []
    def info(conn, where, ret):
        print count.next()
        called.append(None)
    context = Context(TLSv1_METHOD)
    context.set_info_callback(info)
    context.use_certificate(
        load_certificate(FILETYPE_PEM, cleartextCertificatePEM))
    context.use_privatekey(
        load_privatekey(FILETYPE_PEM, cleartextPrivateKeyPEM))

    while 1:
        client = socket()
        client.setblocking(False)
        client.connect_ex(port.getsockname())

        clientSSL = Connection(Context(TLSv1_METHOD), client)
        clientSSL.set_connect_state()

        server, ignored = port.accept()
        server.setblocking(False)

        serverSSL = Connection(context, server)
        serverSSL.set_accept_state()

        del called[:]
        while not called:
            for ssl in clientSSL, serverSSL:
                try:
                    ssl.do_handshake()
                except WantReadError:
                    pass 

def go():
    port = socket()
    port.bind(('', 0))
    port.listen(1)

    called = []
    def info(*args):
        print count.next()
        called.append(None)
        return 1
    context = Context(TLSv1_METHOD)
    context.set_verify(VERIFY_PEER, info)
    context.use_certificate(
        load_certificate(FILETYPE_PEM, cleartextCertificatePEM))
    context.use_privatekey(
        load_privatekey(FILETYPE_PEM, cleartextPrivateKeyPEM))

    while 1:
        client = socket()
        client.setblocking(False)
        client.connect_ex(port.getsockname())

        clientSSL = Connection(context, client)
        clientSSL.set_connect_state()

        server, ignored = port.accept()
        server.setblocking(False)

        serverSSL = Connection(context, server)
        serverSSL.set_accept_state()

        del called[:]
        while not called:
            for ssl in clientSSL, serverSSL:
                try:
                    ssl.send('foo')
                except WantReadError, e:
                    pass 

def _safe_call(self, is_reader, call, *args, **kwargs):
        """Wrap the given call with SSL error-trapping.
        
        is_reader: if False EOF errors will be raised. If True, EOF errors
        will return "" (to emulate normal sockets).
        """
        start = time.time()
        while True:
            try:
                return call(*args, **kwargs)
            except SSL.WantReadError:
                # Sleep and try again. This is dangerous, because it means
                # the rest of the stack has no way of differentiating
                # between a "new handshake" error and "client dropped".
                # Note this isn't an endless loop: there's a timeout below.
                time.sleep(self.ssl_retry)
            except SSL.WantWriteError:
                time.sleep(self.ssl_retry)
            except SSL.SysCallError, e:
                if is_reader and e.args == (-1, 'Unexpected EOF'):
                    return ""
                
                errnum = e.args[0]
                if is_reader and errnum in wsgiserver.socket_errors_to_ignore:
                    return ""
                raise socket.error(errnum)
            except SSL.Error, e:
                if is_reader and e.args == (-1, 'Unexpected EOF'):
                    return ""
                
                thirdarg = None
                try:
                    thirdarg = e.args[0][0][2]
                except IndexError:
                    pass
                
                if thirdarg == 'http request':
                    # The client is talking HTTP to an HTTPS server.
                    raise wsgiserver.NoSSLError()
                
                raise wsgiserver.FatalSSLAlert(*e.args) 

def _safe_call(self, is_reader, call, *args, **kwargs):
        """Wrap the given call with SSL error-trapping.
        
        is_reader: if False EOF errors will be raised. If True, EOF errors
        will return "" (to emulate normal sockets).
        """
        start = time.time()
        while True:
            try:
                return call(*args, **kwargs)
            except SSL.WantReadError:
                # Sleep and try again. This is dangerous, because it means
                # the rest of the stack has no way of differentiating
                # between a "new handshake" error and "client dropped".
                # Note this isn't an endless loop: there's a timeout below.
                time.sleep(self.ssl_retry)
            except SSL.WantWriteError:
                time.sleep(self.ssl_retry)
            except SSL.SysCallError, e:
                if is_reader and e.args == (-1, 'Unexpected EOF'):
                    return ""
                
                errnum = e.args[0]
                if is_reader and errnum in wsgiserver.socket_errors_to_ignore:
                    return ""
                raise socket.error(errnum)
            except SSL.Error, e:
                if is_reader and e.args == (-1, 'Unexpected EOF'):
                    return ""
                
                thirdarg = None
                try:
                    thirdarg = e.args[0][0][2]
                except IndexError:
                    pass
                
                if thirdarg == 'http request':
                    # The client is talking HTTP to an HTTPS server.
                    raise wsgiserver.NoSSLError()
                
                raise wsgiserver.FatalSSLAlert(*e.args) 

def _flushSendBIO(self):
        """
        Read any bytes out of the send BIO and write them to the underlying
        transport.
        """
        try:
            bytes = self._tlsConnection.bio_read(2 ** 15)
        except WantReadError:
            # There may be nothing in the send BIO right now.
            pass
        else:
            self.transport.write(bytes) 

def makeConnection(self, transport):
        """
        Connect this wrapper to the given transport and initialize the
        necessary L{OpenSSL.SSL.Connection} with a memory BIO.
        """
        tlsContext = self.factory._contextFactory.getContext()
        self._tlsConnection = Connection(tlsContext, None)
        if self.factory._isClient:
            self._tlsConnection.set_connect_state()
        else:
            self._tlsConnection.set_accept_state()
        self._appSendBuffer = []

        # Intentionally skip ProtocolWrapper.makeConnection - it might call
        # wrappedProtocol.makeConnection, which we want to make conditional.
        Protocol.makeConnection(self, transport)
        self.factory.registerProtocol(self)
        if self._connectWrapped:
            # Now that the TLS layer is initialized, notify the application of
            # the connection.
            ProtocolWrapper.makeConnection(self, transport)

        # Now that we ourselves have a transport (initialized by the
        # ProtocolWrapper.makeConnection call above), kick off the TLS
        # handshake.
        try:
            self._tlsConnection.do_handshake()
        except WantReadError:
            # This is the expected case - there's no data in the connection's
            # input buffer yet, so it won't be able to complete the whole
            # handshake now.  If this is the speak-first side of the
            # connection, then some bytes will be in the send buffer now; flush
            # them.
            self._flushSendBIO() 

def doRead(self):
        if self.disconnected:
            # See the comment in the similar check in doWrite below.
            # Additionally, in order for anything other than returning
            # CONNECTION_DONE here to make sense, it will probably be necessary
            # to implement a way to switch back to TCP from TLS (actually, if
            # we did something other than return CONNECTION_DONE, that would be
            # a big part of implementing that feature).  In other words, the
            # expectation is that doRead will be called when self.disconnected
            # is True only when the connection has been lost.  It's possible
            # that the other end could stop speaking TLS and then send us some
            # non-TLS data.  We'll end up ignoring that data and dropping the
            # connection.  There's no unit tests for this check in the cases
            # where it makes a difference.  The test suite only hits this
            # codepath when it would have otherwise hit the SSL.ZeroReturnError
            # exception handler below, which has exactly the same behavior as
            # this conditional.  Maybe that's the only case that can ever be
            # triggered, I'm not sure.  -exarkun
            return main.CONNECTION_DONE
        if self.writeBlockedOnRead:
            self.writeBlockedOnRead = 0
            self._resetReadWrite()
        try:
            return Connection.doRead(self)
        except SSL.ZeroReturnError:
            return main.CONNECTION_DONE
        except SSL.WantReadError:
            return
        except SSL.WantWriteError:
            self.readBlockedOnWrite = 1
            Connection.startWriting(self)
            Connection.stopReading(self)
            return
        except SSL.SysCallError, (retval, desc):
            if ((retval == -1 and desc == 'Unexpected EOF')
                or retval > 0):
                return main.CONNECTION_LOST
            log.err()
            return main.CONNECTION_LOST 

def _safe_call(self, is_reader, call, *args, **kwargs):
        """Wrap the given call with SSL error-trapping.
        
        is_reader: if False EOF errors will be raised. If True, EOF errors
        will return "" (to emulate normal sockets).
        """
        start = time.time()
        while True:
            try:
                return call(*args, **kwargs)
            except SSL.WantReadError:
                # Sleep and try again. This is dangerous, because it means
                # the rest of the stack has no way of differentiating
                # between a "new handshake" error and "client dropped".
                # Note this isn't an endless loop: there's a timeout below.
                time.sleep(self.ssl_retry)
            except SSL.WantWriteError:
                time.sleep(self.ssl_retry)
            except SSL.SysCallError, e:
                if is_reader and e.args == (-1, 'Unexpected EOF'):
                    return ""
                
                errnum = e.args[0]
                if is_reader and errnum in wsgiserver.socket_errors_to_ignore:
                    return ""
                raise socket.error(errnum)
            except SSL.Error, e:
                if is_reader and e.args == (-1, 'Unexpected EOF'):
                    return ""
                
                thirdarg = None
                try:
                    thirdarg = e.args[0][0][2]
                except IndexError:
                    pass
                
                if thirdarg == 'http request':
                    # The client is talking HTTP to an HTTPS server.
                    raise wsgiserver.NoSSLError()
                
                raise wsgiserver.FatalSSLAlert(*e.args) 

def _flushReceiveBIO(self):
        """
        Try to receive any application-level bytes which are now available
        because of a previous write into the receive BIO.  This will take
        care of delivering any application-level bytes which are received to
        the protocol, as well as handling of the various exceptions which
        can come from trying to get such bytes.
        """
        # Keep trying this until an error indicates we should stop or we
        # close the connection.  Looping is necessary to make sure we
        # process all of the data which was put into the receive BIO, as
        # there is no guarantee that a single recv call will do it all.
        while not self._lostTLSConnection:
            try:
                bytes = self._tlsConnection.recv(2 ** 15)
            except WantReadError:
                # The newly received bytes might not have been enough to produce
                # any application data.
                break
            except ZeroReturnError:
                # TLS has shut down and no more TLS data will be received over
                # this connection.
                self._shutdownTLS()
                # Passing in None means the user protocol's connnectionLost
                # will get called with reason from underlying transport:
                self._tlsShutdownFinished(None)
            except Error:
                # Something went pretty wrong.  For example, this might be a
                # handshake failure during renegotiation (because there were no
                # shared ciphers, because a certificate failed to verify, etc).
                # TLS can no longer proceed.
                failure = Failure()
                self._tlsShutdownFinished(failure)
            else:
                if not self._aborted:
                    ProtocolWrapper.dataReceived(self, bytes)

        # The received bytes might have generated a response which needs to be
        # sent now.  For example, the handshake involves several round-trip
        # exchanges without ever producing application-bytes.
        self._flushSendBIO() 

def init_connection(self):
        self.connect()
        #This is copied from tds.py
        resp = self.preLogin()
        if resp['Encryption'] == TDS_ENCRYPT_REQ or resp['Encryption'] == TDS_ENCRYPT_OFF:
            logging.info("Encryption required, switching to TLS")

            # Switching to TLS now
            ctx = SSL.Context(SSL.TLSv1_METHOD)
            ctx.set_cipher_list('RC4')
            tls = SSL.Connection(ctx,None)
            tls.set_connect_state()
            while True:
                try:
                    tls.do_handshake()
                except SSL.WantReadError:
                    data = tls.bio_read(4096)
                    self.sendTDS(TDS_PRE_LOGIN, data,0)
                    tds = self.recvTDS()
                    tls.bio_write(tds['Data'])
                else:
                    break

            # SSL and TLS limitation: Secure Socket Layer (SSL) and its replacement, 
            # Transport Layer Security(TLS), limit data fragments to 16k in size.
            self.packetSize = 16*1024-1
            self.tlsSocket = tls
        self.resp = resp 

def _safe_call(self, is_reader, call, *args, **kwargs):
        """Wrap the given call with SSL error-trapping.
        
        is_reader: if False EOF errors will be raised. If True, EOF errors
        will return "" (to emulate normal sockets).
        """
        start = time.time()
        while True:
            try:
                return call(*args, **kwargs)
            except SSL.WantReadError:
                # Sleep and try again. This is dangerous, because it means
                # the rest of the stack has no way of differentiating
                # between a "new handshake" error and "client dropped".
                # Note this isn't an endless loop: there's a timeout below.
                time.sleep(self.ssl_retry)
            except SSL.WantWriteError:
                time.sleep(self.ssl_retry)
            except SSL.SysCallError, e:
                if is_reader and e.args == (-1, 'Unexpected EOF'):
                    return ""
                
                errnum = e.args[0]
                if is_reader and errnum in wsgiserver.socket_errors_to_ignore:
                    return ""
                raise socket.error(errnum)
            except SSL.Error, e:
                if is_reader and e.args == (-1, 'Unexpected EOF'):
                    return ""
                
                thirdarg = None
                try:
                    thirdarg = e.args[0][0][2]
                except IndexError:
                    pass
                
                if thirdarg == 'http request':
                    # The client is talking HTTP to an HTTPS server.
                    raise wsgiserver.NoSSLError()
                
                raise wsgiserver.FatalSSLAlert(*e.args) 

def _safe_call(self, is_reader, call, *args, **kwargs):
        """Wrap the given call with SSL error-trapping.
        
        is_reader: if False EOF errors will be raised. If True, EOF errors
        will return "" (to emulate normal sockets).
        """
        start = time.time()
        while True:
            try:
                return call(*args, **kwargs)
            except SSL.WantReadError:
                # Sleep and try again. This is dangerous, because it means
                # the rest of the stack has no way of differentiating
                # between a "new handshake" error and "client dropped".
                # Note this isn't an endless loop: there's a timeout below.
                time.sleep(self.ssl_retry)
            except SSL.WantWriteError:
                time.sleep(self.ssl_retry)
            except SSL.SysCallError, e:
                if is_reader and e.args == (-1, 'Unexpected EOF'):
                    return ""
                
                errnum = e.args[0]
                if is_reader and errnum in wsgiserver.socket_errors_to_ignore:
                    return ""
                raise socket.error(errnum)
            except SSL.Error, e:
                if is_reader and e.args == (-1, 'Unexpected EOF'):
                    return ""
                
                thirdarg = None
                try:
                    thirdarg = e.args[0][0][2]
                except IndexError:
                    pass
                
                if thirdarg == 'http request':
                    # The client is talking HTTP to an HTTPS server.
                    raise wsgiserver.NoSSLError()
                
                raise wsgiserver.FatalSSLAlert(*e.args)