src/network/core/packet.h

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