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/*
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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 packet.cpp Basic functions to create, fill and read packets.
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*/
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#include "../../stdafx.h"
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#include "../../string_func.h"
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#include "packet.h"
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#include "../../safeguards.h"
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/**
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* Create a packet that is used to read from a network socket
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* @param cs the socket handler associated with the socket we are reading from
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*/
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Packet::Packet(NetworkSocketHandler *cs)
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{
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assert(cs != nullptr);
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this->cs = cs;
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this->next = nullptr;
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this->pos = 0; // We start reading from here
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this->size = 0;
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this->buffer = MallocT<byte>(SEND_MTU);
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}
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/**
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* Creates a packet to send
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* @param type of the packet to send
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*/
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Packet::Packet(PacketType type)
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{
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this->cs = nullptr;
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this->next = nullptr;
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/* Skip the size so we can write that in before sending the packet */
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this->pos = 0;
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this->size = sizeof(PacketSize);
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this->buffer = MallocT<byte>(SEND_MTU);
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this->buffer[this->size++] = type;
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}
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/**
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* Free the buffer of this packet.
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*/
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Packet::~Packet()
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{
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free(this->buffer);
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}
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/**
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* Writes the packet size from the raw packet from packet->size
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*/
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void Packet::PrepareToSend()
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{
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assert(this->cs == nullptr && this->next == nullptr);
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this->buffer[0] = GB(this->size, 0, 8);
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this->buffer[1] = GB(this->size, 8, 8);
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this->pos = 0; // We start reading from here
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}
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/**
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* Is it safe to write to the packet, i.e. didn't we run over the buffer?
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* @param bytes_to_write The amount of bytes we want to try to write.
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* @return True iff the given amount of bytes can be written to the packet.
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*/
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bool Packet::CanWriteToPacket(size_t bytes_to_write)
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{
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return this->size + bytes_to_write < SEND_MTU;
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}
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/*
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* The next couple of functions make sure we can send
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* uint8, uint16, uint32 and uint64 endian-safe
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* over the network. The least significant bytes are
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* sent first.
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*
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* So 0x01234567 would be sent as 67 45 23 01.
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*
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* A bool is sent as a uint8 where zero means false
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* and non-zero means true.
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*/
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/**
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* Package a boolean in the packet.
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* @param data The data to send.
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*/
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void Packet::Send_bool(bool data)
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{
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this->Send_uint8(data ? 1 : 0);
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}
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/**
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* Package a 8 bits integer in the packet.
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* @param data The data to send.
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*/
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void Packet::Send_uint8(uint8 data)
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{
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assert(this->CanWriteToPacket(sizeof(data)));
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this->buffer[this->size++] = data;
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}
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/**
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* Package a 16 bits integer in the packet.
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* @param data The data to send.
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*/
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void Packet::Send_uint16(uint16 data)
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{
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assert(this->CanWriteToPacket(sizeof(data)));
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this->buffer[this->size++] = GB(data, 0, 8);
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this->buffer[this->size++] = GB(data, 8, 8);
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}
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/**
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* Package a 32 bits integer in the packet.
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* @param data The data to send.
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*/
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void Packet::Send_uint32(uint32 data)
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{
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assert(this->CanWriteToPacket(sizeof(data)));
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this->buffer[this->size++] = GB(data, 0, 8);
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this->buffer[this->size++] = GB(data, 8, 8);
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this->buffer[this->size++] = GB(data, 16, 8);
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this->buffer[this->size++] = GB(data, 24, 8);
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}
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/**
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* Package a 64 bits integer in the packet.
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* @param data The data to send.
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*/
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void Packet::Send_uint64(uint64 data)
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{
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assert(this->CanWriteToPacket(sizeof(data)));
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this->buffer[this->size++] = GB(data, 0, 8);
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this->buffer[this->size++] = GB(data, 8, 8);
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this->buffer[this->size++] = GB(data, 16, 8);
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this->buffer[this->size++] = GB(data, 24, 8);
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this->buffer[this->size++] = GB(data, 32, 8);
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this->buffer[this->size++] = GB(data, 40, 8);
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this->buffer[this->size++] = GB(data, 48, 8);
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this->buffer[this->size++] = GB(data, 56, 8);
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}
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/**
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* Sends a string over the network. It sends out
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* the string + '\0'. No size-byte or something.
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* @param data The string to send
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*/
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void Packet::Send_string(const char *data)
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{
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assert(data != nullptr);
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/* Length of the string + 1 for the '\0' termination. */
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assert(this->CanWriteToPacket(strlen(data) + 1));
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while ((this->buffer[this->size++] = *data++) != '\0') {}
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}
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/*
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* Receiving commands
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* Again, the next couple of functions are endian-safe
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* see the comment before Send_bool for more info.
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*/
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/**
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* Is it safe to read from the packet, i.e. didn't we run over the buffer?
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* In case \c close_connection is true, the connection will be closed when one would
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* overrun the buffer. When it is false, the connection remains untouched.
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* @param bytes_to_read The amount of bytes we want to try to read.
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* @param close_connection Whether to close the connection if one cannot read that amount.
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* @return True if that is safe, otherwise false.
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*/
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bool Packet::CanReadFromPacket(size_t bytes_to_read, bool close_connection)
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{
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/* Don't allow reading from a quit client/client who send bad data */
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if (this->cs->HasClientQuit()) return false;
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/* Check if variable is within packet-size */
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if (this->pos + bytes_to_read > this->size) {
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if (close_connection) this->cs->NetworkSocketHandler::CloseConnection();
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return false;
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}
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return true;
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}
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/**
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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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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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* Prepares the packet so it can be read
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*/
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void Packet::PrepareToRead()
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{
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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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/**
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* Read a boolean from the packet.
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* @return The read data.
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*/
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bool Packet::Recv_bool()
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{
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return this->Recv_uint8() != 0;
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}
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/**
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* Read a 8 bits integer from the packet.
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* @return The read data.
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*/
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uint8 Packet::Recv_uint8()
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{
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uint8 n;
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if (!this->CanReadFromPacket(sizeof(n), true)) return 0;
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n = this->buffer[this->pos++];
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return n;
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}
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/**
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* Read a 16 bits integer from the packet.
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* @return The read data.
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*/
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uint16 Packet::Recv_uint16()
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{
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uint16 n;
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if (!this->CanReadFromPacket(sizeof(n), true)) return 0;
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n = (uint16)this->buffer[this->pos++];
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n += (uint16)this->buffer[this->pos++] << 8;
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return n;
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}
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/**
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* Read a 32 bits integer from the packet.
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* @return The read data.
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*/
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uint32 Packet::Recv_uint32()
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{
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uint32 n;
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if (!this->CanReadFromPacket(sizeof(n), true)) return 0;
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n = (uint32)this->buffer[this->pos++];
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n += (uint32)this->buffer[this->pos++] << 8;
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n += (uint32)this->buffer[this->pos++] << 16;
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n += (uint32)this->buffer[this->pos++] << 24;
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return n;
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}
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/**
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* Read a 64 bits integer from the packet.
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* @return The read data.
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*/
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uint64 Packet::Recv_uint64()
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{
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uint64 n;
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if (!this->CanReadFromPacket(sizeof(n), true)) return 0;
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n = (uint64)this->buffer[this->pos++];
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n += (uint64)this->buffer[this->pos++] << 8;
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n += (uint64)this->buffer[this->pos++] << 16;
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n += (uint64)this->buffer[this->pos++] << 24;
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n += (uint64)this->buffer[this->pos++] << 32;
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n += (uint64)this->buffer[this->pos++] << 40;
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n += (uint64)this->buffer[this->pos++] << 48;
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n += (uint64)this->buffer[this->pos++] << 56;
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return n;
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}
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/**
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* Reads a string till it finds a '\0' in the stream.
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* @param buffer The buffer to put the data into.
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* @param size The size of the buffer.
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* @param settings The string validation settings.
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*/
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void Packet::Recv_string(char *buffer, size_t size, StringValidationSettings settings)
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{
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PacketSize pos;
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char *bufp = buffer;
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const char *last = buffer + size - 1;
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/* Don't allow reading from a closed socket */
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if (cs->HasClientQuit()) return;
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pos = this->pos;
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while (--size > 0 && pos < this->size && (*buffer++ = this->buffer[pos++]) != '\0') {}
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if (size == 0 || pos == this->size) {
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*buffer = '\0';
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/* If size was sooner to zero then the string in the stream
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* skip till the \0, so than packet can be read out correctly for the rest */
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while (pos < this->size && this->buffer[pos] != '\0') pos++;
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pos++;
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}
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this->pos = pos;
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str_validate(bufp, last, settings);
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}
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