PyBitmessage-2021-04-27/src/network/udp.py

"""
src/network/udp.py
==================
"""
import time
import socket

import state
import protocol
from bmproto import BMProto
from debug import logger
from objectracker import ObjectTracker
from queues import receiveDataQueue


class UDPSocket(BMProto):           # pylint: disable=too-many-instance-attributes
    """Bitmessage protocol over UDP (class)"""
    port = 8444
    announceInterval = 60

    def __init__(self, host=None, sock=None, announcing=False):
        super(BMProto, self).__init__(sock=sock)        # pylint: disable=bad-super-call
        self.verackReceived = True
        self.verackSent = True
        # .. todo:: sort out streams
        self.streams = [1]
        self.fullyEstablished = True
        self.connectedAt = 0
        self.skipUntil = 0
        if sock is None:
            if host is None:
                host = ''
            self.create_socket(
                socket.AF_INET6 if ":" in host else socket.AF_INET,
                socket.SOCK_DGRAM
            )
            self.set_socket_reuse()
            logger.info("Binding UDP socket to %s:%i", host, self.port)
            self.socket.bind((host, self.port))
        else:
            self.socket = sock
            self.set_socket_reuse()
        self.listening = state.Peer(*self.socket.getsockname())
        self.destination = state.Peer(*self.socket.getsockname())
        ObjectTracker.__init__(self)
        self.connecting = False
        self.connected = True
        self.announcing = announcing
        self.set_state("bm_header", expectBytes=protocol.Header.size)

    def set_socket_reuse(self):
        """Set socket reuse option"""
        self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
        self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        try:
            self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)
        except AttributeError:
            pass

    # disable most commands before doing research / testing
    # only addr (peer discovery), error and object are implemented

    def bm_command_getdata(self):
        # return BMProto.bm_command_getdata(self)
        return True

    def bm_command_inv(self):
        # return BMProto.bm_command_inv(self)
        return True

    def bm_command_addr(self):
        addresses = self._decode_addr()
        # only allow peer discovery from private IPs in order to avoid
        # attacks from random IPs on the internet
        if not self.local:
            return True
        remoteport = False
        for seenTime, stream, services, ip, port in addresses:
            decodedIP = protocol.checkIPAddress(str(ip))
            if stream not in state.streamsInWhichIAmParticipating:
                continue
            if (seenTime < time.time() - self.maxTimeOffset or seenTime > time.time() + self.maxTimeOffset):
                continue
            if decodedIP is False:
                # if the address isn't local, interpret it as
                # the host's own announcement
                remoteport = port
        if remoteport is False:
            return True
        logger.debug(
            "received peer discovery from %s:%i (port %i):",
            self.destination.host, self.destination.port, remoteport)
        if self.local:
            state.discoveredPeers[
                state.Peer(self.destination.host, remoteport)
            ] = time.time()
        return True

    def bm_command_portcheck(self):
        return True

    def bm_command_ping(self):
        return True

    def bm_command_pong(self):
        return True

    def bm_command_verack(self):
        return True

    def bm_command_version(self):
        return True

    def handle_connect(self):
        return

    def writable(self):
        return self.write_buf

    def readable(self):
        return len(self.read_buf) < self._buf_len

    def handle_read(self):
        try:
            (recdata, addr) = self.socket.recvfrom(self._buf_len)
        except socket.error as e:
            logger.error("socket error: %s", e)
            return

        self.destination = state.Peer(*addr)
        encodedAddr = protocol.encodeHost(addr[0])
        self.local = bool(protocol.checkIPAddress(encodedAddr, True))
        # overwrite the old buffer to avoid mixing data and so that
        # self.local works correctly
        self.read_buf[0:] = recdata
        self.bm_proto_reset()
        receiveDataQueue.put(self.listening)

    def handle_write(self):
        try:
            retval = self.socket.sendto(
                self.write_buf, ('<broadcast>', self.port))
        except socket.error as e:
            logger.error("socket error on sendato: %s", e)
            retval = 0
        self.slice_write_buf(retval)