Listing 1. chat_client.c

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

#include <netinet/sctp.h>

#define SIZE 1024
char buf[SIZE];
#define STDIN 0
char *msg = "hello\n";
#define ECHO_PORT 2013

int main(int argc, char *argv[]) {
        int sockfd;
        int nread, nsent;
        int flags, len;
        struct sockaddr_in serv_addr;
        struct sctp_sndrcvinfo sinfo;
        fd_set readfds;

        if (argc != 2) {
                fprintf(stderr, "usage: %s IPaddr\n", argv[0]);
                exit(1);
        }
        /* create endpoint using  SCTP */
        sockfd = socket(AF_INET, SOCK_SEQPACKET,
                        IPPROTO_SCTP);
        if (sockfd < 0) {
                perror("socket creation failed");
                exit(2); }
        /* connect to server */
        serv_addr.sin_family = AF_INET;
        serv_addr.sin_addr.s_addr = inet_addr(argv[1]);
        serv_addr.sin_port = htons(ECHO_PORT);

        if (connect(sockfd,
                    (struct sockaddr *) &serv_addr,
                    sizeof(serv_addr)) < 0) {
                perror("connect to server failed");
                exit(3);
        }
        printf("Connected\n");

        while (1) {
                /* we need to select between messages FROM the user
                   on the console and messages TO the user from the
                   socket
                */
                FD_CLR(sockfd, &readfds);
                FD_SET(sockfd, &readfds);
                FD_SET(STDIN, &readfds);
                printf("Selecting\n");
                select(sockfd+1, &readfds, NULL, NULL, NULL);

                if (FD_ISSET(STDIN, &readfds)) {
                        printf("reading from stdin\n");
                        nread = read(0, buf, SIZE);
                        if (nread <= 0 )
                                break;
                        sendto(sockfd, buf, nread, 0,
                               (struct sockaddr *) &serv_addr,
                               sizeof(serv_addr));
                } else if (FD_ISSET(sockfd, &readfds)) {
                        printf("Reading from socket\n");
                        len = sizeof(serv_addr);
                        nread = sctp_recvmsg(sockfd, buf, SIZE,
                                     (struct sockaddr *) &serv_addr,
                                     &len,
                                     &sinfo, &flags);
                        write(1, buf, nread);
                }
        }
        close(sockfd);
        exit(0);
}