//sample SCTP client application using lksctp
//alexkr.com

#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netinet/sctp.h>
#include <arpa/inet.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

#define RECVBUFSIZE     4096
#define PPID            1234

int main(int argc, char * argv[])
{
       int SctpScocket, in, flags;
       socklen_t opt_len;
       char * szAddress;
       int iPort;
       char * szMsg;
       int iMsgSize;

       //forget about memset(,0,);
       struct sockaddr_in servaddr = {0};
       struct sctp_status status = {0};
       struct sctp_sndrcvinfo sndrcvinfo = {0};
       struct sctp_event_subscribe events = {0};
       struct sctp_initmsg initmsg = {0};
       char * szRecvBuffer[RECVBUFSIZE + 1] = {0};
       socklen_t from_len = (socklen_t) sizeof(struct sockaddr_in);

       if (argc < 3)
       {
               printf("Use parameters: send_to_address port message\n");
               return 0;
       }

       //get the arguments
       szAddress = argv[1];
       iPort = atoi(argv[2]);
       szMsg = argv[3];
       iMsgSize = strlen(szMsg);
       if (iMsgSize > 1024)
       {
         printf("Message is too big for this test\n");
         return 0;
       }

       printf("Starting SCTP client connection to %s:%u\n", szAddress, iPort);

       //here we fail when Linux does not support SCTP
       if ((SctpScocket = socket(AF_INET, SOCK_STREAM, IPPROTO_SCTP)) < 0) {
               printf("After socket errno: %d\n", errno);
               perror("Description: ");
               return 0;
       }
       printf("socket created...\n");

       //set the association options
       initmsg.sinit_num_ostreams = 1;  //number of output streams can be greater
       if (setsockopt( SctpScocket, IPPROTO_SCTP, SCTP_INITMSG, &initmsg,
sizeof(initmsg))<0 )
       {
               printf("After setsockopt errno: %d\n", errno);
               perror("Description: ");
               return 0;
       }
       printf("setsockopt succeeded...\n");

       //other endpoint to make association with
       bzero( (void *)&servaddr, sizeof(servaddr) );
       servaddr.sin_family = AF_INET;
       servaddr.sin_port = htons(iPort);
       servaddr.sin_addr.s_addr = inet_addr( szAddress );

       //establish SCTP association
       if (connect( SctpScocket, (struct sockaddr *)&servaddr, sizeof(servaddr) ) < 0)
       {
               printf("After connect errno: %d\n", errno);
               perror("Description: ");
               return 0;
       }
       printf("connect succeeded...\n");

       //check status
       opt_len = (socklen_t) sizeof(struct sctp_status);
       if (getsockopt(SctpScocket, IPPROTO_SCTP, SCTP_STATUS, &status, &opt_len) < 0)
       {
               printf("After getsockopt errno: %d\n", errno);
               perror("Description: ");
               return 0;
       }else
       {
               printf("Association ID\t\t= %d\n", status.sstat_assoc_id );
               printf("Receiver window size\t= %d\n", status.sstat_rwnd );
       }

       //send message to server
       printf("Sending to server: %s\n", szMsg);
       if (sctp_sendmsg(SctpScocket, (const void *)szMsg, iMsgSize, NULL, 0,
htonl(PPID), 0, 0 /*stream 0*/, 0, 0) < 0)
       {
               printf("After sctp_sendmsg errno: %d\n", errno);
               perror("Description: ");
               return 0;
       }

       //read response from test server
       in = sctp_recvmsg(SctpScocket, (void*)szRecvBuffer, RECVBUFSIZE,
(struct sockaddr *)&servaddr, &from_len, &sndrcvinfo, &flags);
       if (in > 0 && in < RECVBUFSIZE - 1)
       {
               szRecvBuffer[in] = 0;
               printf("Received from server: %s\n", szRecvBuffer);
               return 0;
       }
       else
       {
               printf("After sctp_recvmsg errno: %d\n", errno);
               perror("Description: ");
               printf("Return: %d\n", in);
       }

       if (close(SctpScocket) < 0) {
               printf("After close errno: %d\n", errno);
               perror("Description: ");
       }

       printf("exiting...\n");

       //cleanup
       close(SctpScocket);
       return 0;
}