/* By Hans Henrik Happe
 *
 * compile: gcc -o ring-sctp ring-sctp.c -lsctp
 *
 * usage: ring-sctp <# processes> <# forwards>
 */

#include <asm/msr.h>

#include <stdio.h>
#include <poll.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/tcp.h>
#include <fcntl.h>
#include <netdb.h>

#include <netinet/sctp.h>
#include <sys/time.h>


double second() {


  struct timeval tv;
  struct timezone tz;
  double t;

  gettimeofday(&tv,&tz);

  t= (double)(tv.tv_sec)+(double)(tv.tv_usec/1.0e6);

  return t;
}

typedef struct {
    struct sockaddr sockadr;
    int len;    
} adr_t;

int get_adr(adr_t *adr, int port) {
   int n;
   struct addrinfo hints, *res;
   char str[6];
    
   memset(&hints, 0, sizeof(struct addrinfo));
    
   hints.ai_flags    = AI_PASSIVE;
   hints.ai_family   = PF_UNSPEC;
   hints.ai_socktype = SOCK_STREAM;

   sprintf(str, "%d", port);
   n = getaddrinfo("localhost", str, &hints, &res);

   if (n != 0) {
       fprintf(stderr,
               "getaddrinfo error: [%s]\n",
               gai_strerror(n));
       return -1;    
   }
   
   memcpy(&adr->sockadr, res->ai_addr, sizeof(*res->ai_addr));
   adr->len = sizeof(*res->ai_addr);
      
   freeaddrinfo(res);

   return 0;
}

int init_listen(int port) {
    int n, on=1;
    int sock;    
    struct sockaddr_in name;
   
        
    sock = socket(PF_INET, SOCK_SEQPACKET, IPPROTO_SCTP);
    if (sock == -1) {
        perror("socket");
        return -1;
    }
    
    name.sin_family = PF_INET;
    name.sin_port = htons (port);
    name.sin_addr.s_addr = htonl (INADDR_ANY);
    
    if (bind (sock, (struct sockaddr *) &name, sizeof (name)) == -1) {
        perror("bind");
        return -1;
    }      
    
    if (listen(sock, 10) == -1) {
        perror("listen");
        return -1;
    }

    return sock;  
}

int do_recv(int sock, void *buf, int n) {
    struct sockaddr sa;
    struct sctp_sndrcvinfo info;
    int slen, flags, res;
    slen = sizeof(sa);
    
    res = sctp_recvmsg(sock, buf, n, &sa, &slen, &info, &flags);
    if (res == -1) {
        perror("recv");    
    }
    if (res != n) {
        fprintf(stderr, "recv incomplete\n");    
    }
    return res;
}

int do_send(int sock, adr_t *adr, void *buf, int n) {
    int res;
    
    res = sctp_sendmsg(sock, buf, n, &adr->sockadr, adr->len, 666, MSG_ADDR_OVER, 0, 0, 444);
    if (res == -1) {
        perror("send");    
    }
    if (res != n) {
        fprintf(stderr, "send incomplete\n");    
    }
    return res;
}


int main(int argc, char *argv[]) {
    int i, cnt, pid, src, dest, its;
    int lsock;
    char id, rank, data;
    int port = 11100;
    double t0, t1;
        
    /* # processes */
    cnt = atoi(argv[1]);
    
    /* # forwards */
    its = atoi(argv[2]);

    {
        adr_t dests[cnt];
           
        /* Create processes */
        rank = 0;
        for (i=1; i<cnt; i++) {
            pid = fork();
            if (pid == 0) {
                rank=cnt-i;
                break;    
            }
        }

        /* Listen */
        lsock = init_listen(port+rank);

        
        sleep(2); /* "Ensure" that all processes are listening, HACK!!! */
                
        
        for (i=0; i<cnt; i++) {
            get_adr(dests+i, port+i);
        }
                
                
        srandom(666);        
        src = 0;
        dest = 1;
        
        /* Send startup message */
        if (rank == src) {
            do_send(lsock, &dests[dest], &data, 1);
        }
        
        
        /* Receive message and forward to a random destination */
        
        t0 = second();
        for (i=0; i < its; i++) {
                    
            if (rank == dest) {
                do_recv(lsock, &data, 1);
            }

            src = dest;                    
                    
            dest = (dest+1)%cnt;    
                    
            if (src == rank) {                   
                do_send(lsock, &dests[dest], &data, 1);
            }
        }
        
        if (rank == 0) {
            for (i=1; i<cnt; i++) {
                wait(&dest);    
            }
            t1 = second();
            printf("avg forwarding time: %lf\n", ((t1-t0)/its));
        }
    }    
    
    return 0;
}