chat.h

/*
 *      This is the include-file for both the chat-user-
 *      interface and the chat-server. Modifications can
 *      be done -- dont forget to recompile both the
 *      server and the user-interface ( or use 'make' )
 *      Last revision: Hans Korneder, May 1987
 */

/*
 *      NUSERS reflects the table-size within the server.
 *      It's the maximum number of user-interfaces, that can
 *      be served from the server. The tables are searched
 *      sequentially -- increasing NUSERS might slow down
 *      the server.
 */
#define NUSERS  30

/*
 *      TEXTLEN reflects the maximum number of characters
 *      that can be transferred within one chat-packet.
 *      it should be at least 96 ( 8+32+40+16 within the
 *      startup-packet for: logname, nickname, pfrom, from )
 *      Increasing the TEXTLEN above 118 might cause problems
 *      for x.25-users: the packetlength will exceed 128,
 *      thus more than one x.25-packet has to be sent
 *      for one chat-packet.
 */
#define TEXTLEN  118

/*
 *      Some magic numbers: They are used to identify incoming
 *      packets to the server ( and to reject garbage being
 *      sent to the server from a hacker's program )
 *      The magic numbers are stored in signed short integers,
 *      and they must be unique.
 */
#define UMAGIC1   27001 /* user calls for the first time */
#define UMAGICL   27002 /* user calls for the last  time */
#define UMAGIC    27003 /* user sends some text          */

/*
 *      The packet, that is sent from the user-interface
 *      to the server. The magic number and the pid are
 *      transferred as ascii-characters. i once had a
 *      version running, using binary figures...
 *      ... and then someone came and wanted to connect
 *          a Motorola to an Intel machine
 *      ... and then someone came, and just had a 7-bit-line
 *      ... and then i gave it up
 *
 *      use even number of bytes for cp_magic and cp_pid
 *      ( as some compilers do word-alignments for structure-
 *      members. yes, it's true! )
 */
struct chat_packet
{
  char cp_magic[6];      /* magic number of the packet          */
  char cp_pid[6];        /* pid-- to identify sender            */
  char cp_text[TEXTLEN]; /* the text                            */
};

/*
 *      SERVER_PIPE is the name of a fifo-file, that must be
 *      writable by everybody ( to transfer packets to the
 *      server ). Thus the directories on the path to it
 *      must have at least the x-flag set for everybody.
 */
#define SERVER_PIPE  "/usr/lib/chat_server"