ipc/ipc.py

#  Copyright 2014 Linaro Limited
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#
#  This program 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 General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software
#  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
#  MA 02110-1301, USA.
#
#  Simple VLANd IPC module

import socket
import json
import time
import datetime
import os
import sys
import logging

vlandpath = os.path.abspath(os.path.normpath(os.path.dirname(sys.argv[0])))
sys.path.insert(0, vlandpath)
from errors import CriticalError, InputError, ConfigError, SocketError

class VlanIpc:
    """VLANd IPC class"""

    def __init__(self):
        self.conn = None
        self.socket = None

    def server_init(self, host, port):
        self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        self.conn = None

        while True:
            try:
                self.socket.bind((host, port))
                break
            except socket.error as e:
                print "Can't bind to port %d: %s" % (port, e)
                time.sleep(1)

    def server_listen(self):
        if self.socket is None:
            raise SocketError("Server can't receive data: no socket")
        self.socket.listen(1)

    def server_recv(self):
        if self.socket is None:
            raise SocketError("Server can't receive data: no socket")

        self.conn, addr = self.socket.accept()
        logging.debug("server: Connection from")
        logging.debug(addr)
        data = self.conn.recv(8)  # 32bit limit
        count = int(data, 16)
        c = 0
        data = ''
        while c < count:
            data += self.conn.recv(1)
            c += 1
        try:
            json_data = json.loads(data)
        except ValueError:
            self.conn.close()
            self.conn = None
            raise SocketError("Server unable to decode receieved data: corrupt?")

        if 'client_name' not in json_data:
            self.conn.close()
            self.conn = None
            raise SocketError("Server unable to detect client name: corrupt packet?")

        return json_data

    def server_reply(self, json_data):
        if self.conn is None:
            raise SocketError("Server can't send data: no connection")

        data = self._format_message(json_data)
        if not data:
            self.conn.close()
            self.conn = None
            raise SocketError("Server unable to format reply data")

        # send the actual number of bytes to read.
        self.conn.send(data[0])
        # now send the bytes.
        self.conn.send(data[1])

    def server_close(self):
        if self.conn is not None:
            self.conn.shutdown(socket.SHUT_RDWR)
            self.conn.close()

    def client_connect(self, host, port):
        self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        while True:
            try:
                ret = self.socket.connect_ex((host, port))
                if ret:
                    self.socket.close()
                    self.socket = None
                    raise SocketError("Client can't send connect: %s" % ret)
                else:
                    break
            except socket.error:
                time.sleep(1)
        return True

    def client_send(self, json_data):
        if self.socket is None:
            raise SocketError("Client can't send data: no socket")

        data = self._format_message(json_data)
        if not data:
            self.socket.shutdown(socket.SHUT_RDWR)
            self.socket.close()
            self.socket = None
            raise SocketError("Client unable to send data")

        # send the actual number of bytes to read.
        self.socket.send(data[0])
        # now send the bytes.
        self.socket.send(data[1])

    def client_recv_and_close(self):
        if self.socket is None:
            raise SocketError("Client can't receieve data: no socket")

        data = self.socket.recv(8)  # 32bit limit
        count = int(data, 16)
        c = 0
        data = ''
        while c < count:
            data += self.socket.recv(1)
            c += 1
        try:
            json_data = json.loads(data)
        except ValueError:
            self.socket.close()
            self.socket = None
            raise SocketError("Client unable to decode receieved data: corrupt?")

        self.socket.shutdown(socket.SHUT_RDWR)
        self.socket.close()

        return json_data

    # The default JSON serialiser code can't deal with datetime
    # objects by default, so let's tell it how to.
    def _json_serial(self, obj):
        """JSON serializer for objects not serialisable by default json code"""
        if isinstance(obj, datetime.datetime):
            serial = obj.isoformat()
            return serial

    def _format_message(self, json_data):
        try:
            msgstr = json.dumps(json_data, default=self._json_serial)
        except ValueError:
            return None
        # "header" calculation
        msglen = "%08X" % len(msgstr)
        return (msglen, msgstr)