PyBitmessage-2024-12-20/src/network/udp.py

"""
UDP protocol handler
"""
import logging
import socket
import time

import protocol
from network.bmproto import BMProto
from network.objectracker import ObjectTracker
from .node import Peer
import state

from queues import receiveDataQueue

logger = logging.getLogger('default')


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):
        # pylint: disable=bad-super-call
        super(BMProto, self).__init__(sock=sock)
        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 = Peer(*self.socket.getsockname())
        self.destination = 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 True

    def 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
        self.local = True
        remoteport = False

        for seenTime, stream, _, ip, port in addresses:
            decodedIP = protocol.checkIPAddress(bytes(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 {}:{} (port {}):".format(
                self.destination.host, self.destination.port, remoteport))
        if self.local:
            state.discoveredPeers[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 = 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 sendto: %s", e)
            if e.errno == 101:
                self.announcing = False
                self.socket.close()
            retval = 0
        self.slice_write_buf(retval)