src/network/core/packet.h

   1 /* $Id$ */
   2
   3 /*
   4  * This file is part of OpenTTD.
   5  * 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.
   6  * 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.
   7  * 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/>.
   8  */
   9
  10 /**
  11  * @file packet.h Basic functions to create, fill and read packets.
  12  */
  13
  14 #ifndef NETWORK_CORE_PACKET_H
  15 #define NETWORK_CORE_PACKET_H
  16
  17 #include "config.h"
  18 #include "core.h"
  19 #include "../../string_type.h"
  20
  21 #ifdef ENABLE_NETWORK
  22
  23 typedef uint16 PacketSize; ///< Size of the whole packet.
  24 typedef uint8  PacketType; ///< Identifier for the packet
  25
  26 /**
  27  * Internal entity of a packet. As everything is sent as a packet,
  28  * all network communication will need to call the functions that
  29  * populate the packet.
  30  * Every packet can be at most SEND_MTU bytes. Overflowing this
  31  * limit will give an assertion when sending (i.e. writing) the
  32  * packet. Reading past the size of the packet when receiving
  33  * will return all 0 values and "" in case of the string.
  34  *
  35  * --- Points of attention ---
  36  *  - all > 1 byte integral values are written in little endian,
  37  *    unless specified otherwise.
  38  *      Thus, 0x01234567 would be sent as {0x67, 0x45, 0x23, 0x01}.
  39  *  - all sent strings are of variable length and terminated by a '\0'.
  40  *      Thus, the length of the strings is not sent.
  41  *  - years that are leap years in the 'days since X' to 'date' calculations:
  42  *     (year % 4 == 0) and ((year % 100 != 0) or (year % 400 == 0))
  43  */
  44 struct Packet {
  45         /** The next packet. Used for queueing packets before sending. */
  46         Packet *next;
  47         /**
  48          * The size of the whole packet for received packets. For packets
  49          * that will be sent, the value is filled in just before the
  50          * actual transmission.
  51          */
  52         PacketSize size;
  53         /** The current read/write position in the packet */
  54         PacketSize pos;
  55         /** The buffer of this packet, of basically variable length up to SEND_MTU. */
  56         byte *buffer;
  57
  58 private:
  59         /** Socket we're associated with. */
  60         NetworkSocketHandler *cs;
  61
  62 public:
  63         Packet(NetworkSocketHandler *cs);
  64         Packet(PacketType type);
  65         ~Packet();
  66
  67         /* Sending/writing of packets */
  68         void PrepareToSend();
  69
  70         void Send_bool  (bool   data);
  71         void Send_uint8 (uint8  data);
  72         void Send_uint16(uint16 data);
  73         void Send_uint32(uint32 data);
  74         void Send_uint64(uint64 data);
  75         void Send_string(const char *data);
  76
  77         /* Reading/receiving of packets */
  78         void ReadRawPacketSize();
  79         void PrepareToRead();
  80
  81         bool   CanReadFromPacket (uint bytes_to_read);
  82         bool   Recv_bool  ();
  83         uint8  Recv_uint8 ();
  84         uint16 Recv_uint16();
  85         uint32 Recv_uint32();
  86         uint64 Recv_uint64();
  87         void   Recv_string(char *buffer, size_t size, StringValidationSettings settings = SVS_REPLACE_WITH_QUESTION_MARK);
  88 };
  89
  90 #endif /* ENABLE_NETWORK */
  91
  92 #endif /* NETWORK_CORE_PACKET_H */