Stream Control Transmission Protocol (SCTP) Associations

Listing 4. streamsend_echo_client.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

#include <netinet/sctp.h>

#define SIZE 1024
char buf[SIZE];
#define ECHO_PORT 2013

char *usage_msg = "usage: streamsend_echo_client ip-addr istreams
ostreams stream";

void usage() {
        fprintf(stderr, "%s\n", usage_msg);
        exit(1);
}


int main(int argc, char *argv[]) {
        int sockfd;
        int len;
        struct sockaddr_in serv_addr;
        struct sockaddr_in *addresses;
        int addr_size = sizeof(struct sockaddr_in);
        int addr_count = argc - 1;
        int port = ECHO_PORT;

        char *message = "hello\n";
        struct sctp_initmsg initmsg;
        struct sctp_status status;
        struct sctp_sndrcvinfo sinfo;
        int ochannel;

        if (argc != 5) usage();

        /* create endpoint */
        sockfd = socket(AF_INET, SOCK_STREAM,
                        IPPROTO_SCTP
                );

        if (sockfd < 0) {
                perror(NULL);
                exit(2); }
        /* connect to server */
        addresses = malloc(addr_size);
        if (addresses == NULL) {
                exit(1);
        }

        serv_addr.sin_family = AF_INET;
        serv_addr.sin_addr.s_addr = inet_addr(argv[1]);
        serv_addr.sin_port = htons(port);

        memcpy(addresses, &serv_addr, addr_size);

        memset(&initmsg, 0, sizeof(initmsg));
        initmsg.sinit_max_instreams = atoi(argv[2]);
        initmsg.sinit_num_ostreams = atoi(argv[3]);
        printf("Asking for: input streams: %d, output streams: %d\n",
               initmsg.sinit_max_instreams,
               initmsg.sinit_num_ostreams);

        if (setsockopt(sockfd, IPPROTO_SCTP,
                       SCTP_INITMSG, &initmsg, sizeof(initmsg))) {
                perror("set sock opt\n");
        }

        if (sctp_connectx(sockfd, (struct sockaddr *) addresses, 1) < 0)
{
                perror("connectx");
                exit(3);
        }

        memset(&status, 0, sizeof(status));
        len = sizeof(status);
        status.sstat_assoc_id = 1;

        if (getsockopt(sockfd, IPPROTO_SCTP,
                       SCTP_STATUS, &status, &len) == -1) {
                perror("get sock opt\n");
        }
        printf("Got: input streams: %d, output streams: %d\n",
               status.sstat_instrms,
               status.sstat_outstrms);

        /* sanity check channel */
        ochannel = atoi(argv[4]);
        if (ochannel >= status.sstat_outstrms)
                printf("Writing on illegal channel %d\n", ochannel);

        /* transfer data */
        bzero(&sinfo, sizeof(sinfo));
        sinfo.sinfo_stream = ochannel;
        sctp_send(sockfd, message, strlen(message),
                  &sinfo, 0);

        sinfo.sinfo_flags = SCTP_EOF;
        sctp_send(sockfd, NULL, 0,
                  &sinfo, 0);

        close(sockfd);
        exit(0);
}

Listing 5. streamsend_echo_server.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

#include <netinet/sctp.h>

#define SIZE 1024
char buf[SIZE];
#define TIME_PORT 2013

char *usage_msg = "usage: app ip-addr istreams ostreams";

void usage() {
  fprintf(stderr, "%s\n", usage_msg);
  exit(1);
}


int main(int argc, char *argv[]) {
  int sockfd, client_sockfd;
  int nread, len;
  struct sockaddr_in serv_addr, client_addr;
  time_t t;
  struct sockaddr_in *addresses;
  int addr_size = sizeof(struct sockaddr_in);
  int addr_count = 1;
  int port = TIME_PORT;
  int n;
  struct sctp_initmsg initmsg;
  struct sctp_status status;
  sctp_assoc_t associd;
  struct sctp_sndrcvinfo sinfo;
  struct sctp_event_subscribe events;

  int flags;

  if (argc != 4) usage();

  /* create endpoint */
  sockfd = socket(AF_INET, SOCK_STREAM,
                 IPPROTO_SCTP
  );
  if (sockfd < 0) {
    perror(NULL);
    exit(2);
  }

  serv_addr.sin_family = AF_INET;
  serv_addr.sin_addr.s_addr = inet_addr(argv[1]);
  serv_addr.sin_port = htons(port);

  if (sctp_bindx(sockfd, (struct sockaddr *) &serv_addr, addr_count,
                 SCTP_BINDX_ADD_ADDR) == -1) {
    perror("sctp bindx");
    exit(2);
  }

  memset(&initmsg, 0, sizeof(initmsg));
  initmsg.sinit_max_instreams = atoi(argv[2]);
  initmsg.sinit_num_ostreams = atoi(argv[3]);
  printf("Asking for: input streams: %d, output streams: %d\n",
         initmsg.sinit_max_instreams,
         initmsg.sinit_num_ostreams);

  if (setsockopt(sockfd, IPPROTO_SCTP,
                 SCTP_INITMSG, &initmsg, sizeof(initmsg))) {
    perror("set sock opt\n");
  }



  /* specify queue */
  listen(sockfd, 5);
  for (;;) {
    len = sizeof(client_addr);
    client_sockfd = accept(sockfd, (struct sockaddr *) &client_addr,
&len);
    if (client_sockfd == -1) {
      perror(NULL); continue;
    }



    memset(&status, 0, sizeof(status));
    len = sizeof(status);
    status.sstat_assoc_id = 0;

    if (getsockopt(client_sockfd, IPPROTO_SCTP,
                   SCTP_STATUS, &status, &len) == -1) {
      perror("get sock opt\n");
    }

    printf("Got: input streams: %d, output streams: %d\n",
           status.sstat_instrms,
           status.sstat_outstrms);


    for(;;) {
      /* transfer data */
      len = sizeof(client_addr);
      bzero(&sinfo, sizeof(sinfo));
      nread = sctp_recvmsg(client_sockfd, buf, SIZE,
                           (struct sockaddr *) &client_addr, &len,
                         &sinfo, &flags);

      if (nread == 0) {
        break;
      }

      printf("read %d bytes on channel %hd\n", nread,
sinfo.sinfo_stream);
      printf("sinfo flags: %d\n", sinfo.sinfo_flags);
      write(1, buf, nread);
    }
    close(client_sockfd);
  }
}