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294 lines
10 KiB
C++
294 lines
10 KiB
C++
/*
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* This file is part of OpenTTD.
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* OpenTTD 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, version 2.
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* OpenTTD 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.
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* See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file core/udp.cpp Basic functions to receive and send UDP packets.
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*/
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#include "../../stdafx.h"
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#include "../../date_func.h"
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#include "../../debug.h"
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#include "../../core/random_func.hpp"
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#include "udp.h"
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#include "../../safeguards.h"
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/**
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* Create an UDP socket but don't listen yet.
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* @param bind the addresses to bind to.
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*/
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NetworkUDPSocketHandler::NetworkUDPSocketHandler(NetworkAddressList *bind)
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{
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if (bind != nullptr) {
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for (NetworkAddress &addr : *bind) {
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this->bind.push_back(addr);
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}
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} else {
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/* As an empty hostname and port 0 don't go well when
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* resolving it we need to add an address for each of
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* the address families we support. */
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this->bind.emplace_back("", 0, AF_INET);
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this->bind.emplace_back("", 0, AF_INET6);
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}
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this->fragment_token = ((uint64) InteractiveRandom()) | (((uint64) InteractiveRandom()) << 32);
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}
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/**
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* Start listening on the given host and port.
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* @return true if at least one port is listening
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*/
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bool NetworkUDPSocketHandler::Listen()
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{
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/* Make sure socket is closed */
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this->CloseSocket();
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for (NetworkAddress &addr : this->bind) {
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addr.Listen(SOCK_DGRAM, &this->sockets);
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}
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return this->sockets.size() != 0;
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}
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/**
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* Close the actual UDP socket.
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*/
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void NetworkUDPSocketHandler::CloseSocket()
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{
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for (auto &s : this->sockets) {
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closesocket(s.first);
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}
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this->sockets.clear();
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}
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/**
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* Send a packet over UDP
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* @param p the packet to send
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* @param recv the receiver (target) of the packet
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* @param all send the packet using all sockets that can send it
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* @param broadcast whether to send a broadcast message
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*/
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void NetworkUDPSocketHandler::SendPacket(Packet *p, NetworkAddress *recv, bool all, bool broadcast, bool short_mtu)
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{
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if (this->sockets.size() == 0) this->Listen();
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const uint MTU = short_mtu ? UDP_MTU_SHORT : UDP_MTU;
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if (p->Size() > MTU) {
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p->PrepareToSend();
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uint64 token = this->fragment_token++;
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const uint PAYLOAD_MTU = MTU - (1 + 2 + 8 + 1 + 1 + 2);
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const size_t packet_size = p->Size();
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const uint8 frag_count = (uint8)((packet_size + PAYLOAD_MTU - 1) / PAYLOAD_MTU);
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Packet frag(PACKET_UDP_EX_MULTI);
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uint8 current_frag = 0;
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size_t offset = 0;
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while (offset < packet_size) {
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uint16 payload_size = (uint16)std::min<size_t>(PAYLOAD_MTU, packet_size - offset);
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frag.Send_uint64(token);
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frag.Send_uint8 (current_frag);
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frag.Send_uint8 (frag_count);
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frag.Send_uint16 (payload_size);
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frag.Send_binary(p->GetBufferData() + offset, payload_size);
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current_frag++;
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offset += payload_size;
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this->SendPacket(&frag, recv, all, broadcast, short_mtu);
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frag.ResetState(PACKET_UDP_EX_MULTI);
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}
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assert_msg(current_frag == frag_count, "%u, %u", current_frag, frag_count);
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return;
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}
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for (auto &s : this->sockets) {
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/* Make a local copy because if we resolve it we cannot
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* easily unresolve it so we can resolve it later again. */
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NetworkAddress send(*recv);
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/* Not the same type */
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if (!send.IsFamily(s.second.GetAddress()->ss_family)) continue;
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p->PrepareToSend();
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if (broadcast) {
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/* Enable broadcast */
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unsigned long val = 1;
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if (setsockopt(s.first, SOL_SOCKET, SO_BROADCAST, (char *) &val, sizeof(val)) < 0) {
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DEBUG(net, 1, "Setting broadcast mode failed: %s", NetworkError::GetLast().AsString());
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}
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}
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/* Send the buffer */
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ssize_t res = p->TransferOut<int>(sendto, s.first, 0, (const struct sockaddr *)send.GetAddress(), send.GetAddressLength());
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DEBUG(net, 7, "sendto(%s)", NetworkAddressDumper().GetAddressAsString(&send));
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/* Check for any errors, but ignore it otherwise */
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if (res == -1) DEBUG(net, 1, "sendto(%s) failed with: %s", NetworkAddressDumper().GetAddressAsString(&send), NetworkError::GetLast().AsString());
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if (!all) break;
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}
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}
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/**
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* Receive a packet at UDP level
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*/
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void NetworkUDPSocketHandler::ReceivePackets()
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{
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for (auto &s : this->sockets) {
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for (int i = 0; i < 1000; i++) { // Do not infinitely loop when DoSing with UDP
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struct sockaddr_storage client_addr;
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memset(&client_addr, 0, sizeof(client_addr));
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/* The limit is UDP_MTU, but also allocate that much as we need to read the whole packet in one go. */
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Packet p(this, UDP_MTU, UDP_MTU);
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socklen_t client_len = sizeof(client_addr);
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/* Try to receive anything */
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SetNonBlocking(s.first); // Some OSes seem to lose the non-blocking status of the socket
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ssize_t nbytes = p.TransferIn<int>(recvfrom, s.first, 0, (struct sockaddr *)&client_addr, &client_len);
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/* Did we get the bytes for the base header of the packet? */
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if (nbytes <= 0) break; // No data, i.e. no packet
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if (nbytes <= 2) continue; // Invalid data; try next packet
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#ifdef __EMSCRIPTEN__
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client_len = FixAddrLenForEmscripten(client_addr);
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#endif
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NetworkAddress address(client_addr, client_len);
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/* If the size does not match the packet must be corrupted.
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* Otherwise it will be marked as corrupted later on. */
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if (!p.ParsePacketSize() || (size_t)nbytes != p.Size()) {
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DEBUG(net, 1, "received a packet with mismatching size from %s, (%u, %u)", NetworkAddressDumper().GetAddressAsString(&address), (uint)nbytes, (uint)p.Size());
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continue;
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}
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p.PrepareToRead();
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/* Handle the packet */
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this->HandleUDPPacket(&p, &address);
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}
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}
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}
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/**
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* Handle an incoming packets by sending it to the correct function.
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* @param p the received packet
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* @param client_addr the sender of the packet
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*/
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void NetworkUDPSocketHandler::HandleUDPPacket(Packet *p, NetworkAddress *client_addr)
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{
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PacketUDPType type;
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/* New packet == new client, which has not quit yet */
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this->Reopen();
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type = (PacketUDPType)p->Recv_uint8();
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switch (this->HasClientQuit() ? PACKET_UDP_END : type) {
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case PACKET_UDP_CLIENT_FIND_SERVER: this->Receive_CLIENT_FIND_SERVER(p, client_addr); break;
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case PACKET_UDP_SERVER_RESPONSE: this->Receive_SERVER_RESPONSE(p, client_addr); break;
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case PACKET_UDP_EX_MULTI: this->Receive_EX_MULTI(p, client_addr); break;
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case PACKET_UDP_EX_SERVER_RESPONSE: this->Receive_EX_SERVER_RESPONSE(p, client_addr); break;
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default:
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if (this->HasClientQuit()) {
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DEBUG(net, 0, "[udp] received invalid packet type %d from %s", type, NetworkAddressDumper().GetAddressAsString(client_addr));
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} else {
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DEBUG(net, 0, "[udp] received illegal packet from %s", NetworkAddressDumper().GetAddressAsString(client_addr));
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}
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break;
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}
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}
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void NetworkUDPSocketHandler::Receive_EX_MULTI(Packet *p, NetworkAddress *client_addr)
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{
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uint64 token = p->Recv_uint64();
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uint8 index = p->Recv_uint8 ();
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uint8 total = p->Recv_uint8 ();
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uint16 payload_size = p->Recv_uint16();
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DEBUG(net, 6, "[udp] received multi-part packet from %s: " OTTD_PRINTFHEX64 ", %u/%u, %u bytes",
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NetworkAddressDumper().GetAddressAsString(client_addr), token, index, total, payload_size);
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if (total == 0 || index >= total) return;
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if (!p->CanReadFromPacket(payload_size)) return;
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time_t cur_time = time(nullptr);
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auto add_to_fragment = [&](FragmentSet &fs) {
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fs.fragments[index].assign((const char *) p->GetBufferData() + p->GetRawPos(), payload_size);
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uint total_payload = 0;
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for (auto &frag : fs.fragments) {
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if (!frag.size()) return;
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total_payload += (uint)frag.size();
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}
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DEBUG(net, 6, "[udp] merged multi-part packet from %s: " OTTD_PRINTFHEX64 ", %u bytes",
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NetworkAddressDumper().GetAddressAsString(client_addr), token, total_payload);
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Packet merged(this, SHRT_MAX, 0);
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merged.ReserveBuffer(total_payload);
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for (auto &frag : fs.fragments) {
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merged.Send_binary((const byte *)frag.data(), frag.size());
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}
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merged.ParsePacketSize();
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merged.PrepareToRead();
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/* If the size does not match the packet must be corrupted.
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* Otherwise it will be marked as corrupted later on. */
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if (total_payload != merged.ReadRawPacketSize()) {
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DEBUG(net, 1, "received an extended packet with mismatching size from %s, (%u, %u)",
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NetworkAddressDumper().GetAddressAsString(client_addr), (uint)total_payload, (uint)merged.ReadRawPacketSize());
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} else {
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this->HandleUDPPacket(&merged, client_addr);
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}
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fs = this->fragments.back();
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this->fragments.pop_back();
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};
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uint i = 0;
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while (i < this->fragments.size()) {
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FragmentSet &fs = this->fragments[i];
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if (fs.create_time < cur_time - 10) {
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fs = this->fragments.back();
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this->fragments.pop_back();
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continue;
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}
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if (fs.token == token && fs.address == *client_addr && fs.fragments.size() == total) {
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add_to_fragment(fs);
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return;
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}
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i++;
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}
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this->fragments.push_back({ token, *client_addr, cur_time, {} });
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this->fragments.back().fragments.resize(total);
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add_to_fragment(this->fragments.back());
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}
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/**
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* Helper for logging receiving invalid packets.
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* @param type The received packet type.
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* @param client_addr The address we received the packet from.
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*/
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void NetworkUDPSocketHandler::ReceiveInvalidPacket(PacketUDPType type, NetworkAddress *client_addr)
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{
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DEBUG(net, 0, "[udp] received packet type %d on wrong port from %s", type, NetworkAddressDumper().GetAddressAsString(client_addr));
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}
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void NetworkUDPSocketHandler::Receive_CLIENT_FIND_SERVER(Packet *p, NetworkAddress *client_addr) { this->ReceiveInvalidPacket(PACKET_UDP_CLIENT_FIND_SERVER, client_addr); }
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void NetworkUDPSocketHandler::Receive_SERVER_RESPONSE(Packet *p, NetworkAddress *client_addr) { this->ReceiveInvalidPacket(PACKET_UDP_SERVER_RESPONSE, client_addr); }
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void NetworkUDPSocketHandler::Receive_EX_SERVER_RESPONSE(Packet *p, NetworkAddress *client_addr) { this->ReceiveInvalidPacket(PACKET_UDP_EX_SERVER_RESPONSE, client_addr); }
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