mirror of https://github.com/OpenTTD/OpenTTD.git
Codechange: move more logic about packet size validity and reading into Packet
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470d8b6637
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@ -181,13 +181,32 @@ bool Packet::CanReadFromPacket(uint bytes_to_read)
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}
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/**
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* Reads the packet size from the raw packet and stores it in the packet->size
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* Check whether the packet, given the position of the "write" pointer, has read
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* enough of the packet to contain its size.
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* @return True iff there is enough data in the packet to contain the packet's size.
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*/
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void Packet::ReadRawPacketSize()
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bool Packet::HasPacketSizeData() const
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{
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return this->pos >= sizeof(PacketSize);
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}
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/**
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* Reads the packet size from the raw packet and stores it in the packet->size
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* @return True iff the packet size seems plausible.
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*/
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bool Packet::ParsePacketSize()
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{
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assert(this->cs != nullptr && this->next == nullptr);
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this->size = (PacketSize)this->buffer[0];
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this->size += (PacketSize)this->buffer[1] << 8;
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/* If the size of the packet is less than the bytes required for the size and type of
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* the packet, or more than the allowed limit, then something is wrong with the packet.
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* In those cases the packet can generally be regarded as containing garbage data. */
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if (this->size < sizeof(PacketSize) + sizeof(PacketType) || this->size > SEND_MTU) return false;
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this->pos = sizeof(PacketSize);
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return true;
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}
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/**
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@ -195,8 +214,6 @@ void Packet::ReadRawPacketSize()
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*/
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void Packet::PrepareToRead()
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{
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this->ReadRawPacketSize();
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/* Put the position on the right place */
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this->pos = sizeof(PacketSize);
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}
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@ -71,7 +71,8 @@ public:
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void Send_string(const char *data);
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/* Reading/receiving of packets */
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void ReadRawPacketSize();
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bool HasPacketSizeData() const;
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bool ParsePacketSize();
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void PrepareToRead();
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bool CanReadFromPacket (uint bytes_to_read);
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@ -155,8 +155,8 @@ Packet *NetworkTCPSocketHandler::ReceivePacket()
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Packet *p = this->packet_recv;
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/* Read packet size */
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if (p->pos < sizeof(PacketSize)) {
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while (p->pos < sizeof(PacketSize)) {
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if (!p->HasPacketSizeData()) {
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while (!p->HasPacketSizeData()) {
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/* Read the size of the packet */
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res = recv(this->sock, (char*)p->buffer + p->pos, sizeof(PacketSize) - p->pos, 0);
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if (res == -1) {
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@ -178,10 +178,8 @@ Packet *NetworkTCPSocketHandler::ReceivePacket()
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p->pos += res;
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}
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/* Read the packet size from the received packet */
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p->ReadRawPacketSize();
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if (p->size > SEND_MTU) {
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/* Parse the size in the received packet and if not valid, close the connection. */
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if (!p->ParsePacketSize()) {
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this->CloseConnection();
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return nullptr;
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}
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@ -134,14 +134,14 @@ void NetworkUDPSocketHandler::ReceivePackets()
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#endif
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NetworkAddress address(client_addr, client_len);
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p.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 (nbytes != p.size) {
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if (!p.ParsePacketSize() || nbytes != p.size) {
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DEBUG(net, 1, "received a packet with mismatching size from %s", address.GetAddressAsString().c_str());
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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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