#pragma module TCPIP$SCTP_SELECT_SERVER "V5.7-00"

/*
** BUILD ENVIRONMENT:
**
**   If the current version of DECC does not suport SCTP, then you must
**   manually configure the environment as follows:
**
**	$ define netinet tcpip$examples
**
** BUILD INSTRUCTIONS:
**
**	$ cc tcpip$sctp_select_server
**	$ link tcpip$sctp_select_server
**
** SYNTAX:
**
**      sctp_server [port]
**
** EXAMPLE:
**
**   Define a foreign symbol to point at the application.
**
**	$ sctp_sel :== $TCPIP$EXAMPLES:tcpip$sctp_select_server
**	$ sctp_sel
*/
#define _SOCKADDR_LEN

#include <stdio.h>
#include <stdlib.h>
#include <sys/errno.h>
#include <string.h>
#ifndef __VMS
#include <unixio.h>
#else
#include <unistd.h>
#endif

typedef unsigned int socklen_t; /* usually defined in socket.h */

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <netinet/sctp.h> /* SCTP */

#ifndef IPPROTO_SCTP
#define IPPROTO_SCTP            132             /* SCTP */
#endif

#define MAXCLIENTS 5
#define DEF_PORT 55555
#define SA(x) ((struct sockaddr *)x)

typedef struct client_s
{
   int  sd;
   char name[INET6_ADDRSTRLEN];
   int  port;
} client_t;

void clear_socket(int sd, fd_set *fds, client_t *cli)
{
   printf("Closed connection to: %s:%d\n", cli->name, cli->port);
   close(sd);
   FD_CLR(sd, fds);
   cli->sd = -1;
}

int main(int argc, char *argv[])
{
   int listen_sd, sd, maxfd, cc, status, port, i;
   fd_set rset, wset, eset, allset; /* masks for select */
   struct sockaddr_in local, peer;
   socklen_t peerlen = sizeof(peer);
   client_t client[MAXCLIENTS];
   char buf[128];

   if(argc == 2) port = atoi(argv[1]);
   else          port = DEF_PORT;

   /* init to no clients connected */
   for(i = 0; i < MAXCLIENTS; i++) client[i].sd = -1;

   /* setup the local address that we will bind to and listen on */
   local.sin_len = sizeof(local);
   local.sin_family = AF_INET;
   local.sin_port = htons(port);
   local.sin_addr.s_addr = INADDR_ANY;

   /* create an SCTP listen socket */
   listen_sd = socket(AF_INET, SOCK_STREAM, IPPROTO_SCTP);
   if(listen_sd == -1) {perror("STREAM socket"); return 1;}

   maxfd = listen_sd; /* for select mask */

   /* bind to local port and address(es) */
   if(bind(listen_sd, SA(&local), local.sin_len) == -1)
   {perror("bind"); return 1;}

   /* prepare to accept connections */
   if(listen(listen_sd, 5) == -1) {perror("listen"); return 1;}

   /* prepare for select loop */

   /* Set bits for all the listener sockets. */
   FD_ZERO(&allset);
   FD_SET(listen_sd, &allset);
   FD_ZERO(&wset); /* not interested in write events for now */

   printf("Waiting for connections on SCTP port %d ...\n", port);

   /* select loop */
   for(;;) {
      rset = eset = allset;

      if((status = select(maxfd + 1, &rset, &wset, &eset, NULL)) < 0) {
	 if(errno == EINTR) {printf("select returned EINTR\n"); continue;}
	 else               {perror("select"); return 1;}
      }

      if(FD_ISSET(listen_sd, &eset)) printf("Exception on listen socket\n");

      /* new connection */
      if(FD_ISSET(listen_sd, &rset)) {
	 peerlen = sizeof(peer);

	 if((sd = accept(listen_sd, (struct sockaddr *)&peer, &peerlen)) == -1)
	 {perror("accept"); continue;}

	 /* add new client to client array. */
	 for(i = 0; i < MAXCLIENTS; i++) {
	    if(client[i].sd < 0) {
	       client[i].sd = sd;
	       break;
	    }
	 }
	 if(i == MAXCLIENTS)
	 {printf("Too many clients\n"); close(sd); continue;}

	 /* save client's address and port number */
	 inet_ntop(AF_INET, &peer.sin_addr.s_addr,
		   &client[i].name[0], INET6_ADDRSTRLEN);
	 client[i].port = ntohs(peer.sin_port);

	 printf("Accepted connection from: %s:%d\n",
		client[i].name, client[i].port);

	 if(sd > maxfd) maxfd = sd;

	 FD_SET(sd, &allset); /* add connected socket to select mask */
      }

      /* check all clients for newly-arrived data */
      for(i = 0; i < MAXCLIENTS; i++) {
	 if((sd = client[i].sd) < 0) continue;

	 if(FD_ISSET(sd, &eset))
	   printf("Exception on connected socket:%d\n", sd);

	 if(FD_ISSET(sd, &rset)) { /* data arrived on socket */
	    cc = read(sd, &buf, sizeof(buf));
	    switch(cc) {
	    case -1:  /* error on socket */
	       perror("read");
	       clear_socket(sd, &allset, &client[i]);
	       break;

	    case 0: /* peer disconnect */
	       printf("%s closed connection.", client[i].name);
	       clear_socket(sd, &allset, &client[i]);
	       break;

	    default: /* data available */
	       buf[cc] = '\0';
	       printf("%s:%d says: %s\n", client[i].name, client[i].port, buf);
	       if(buf[0] == 'Q') clear_socket(sd, &allset, &client[i]);

	    } /* end switch */
	 } /* client read ready */
      } /* for all clients */
   } /* select() for ever */
}