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

#include <sys/types.h>
#include <sys/socket.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, n, flags;
       socklen_t from_len;

       //forget about memset(,0,)
       struct sockaddr_in addr = {0};
       struct sctp_sndrcvinfo sinfo = {0};
       struct sctp_event_subscribe event = {0};
       char pRecvBuffer[RECVBUFSIZE + 1] = {0};

       char * szAddress;
       int iPort;
       char * szMsg;
       int iMsgSize;

       if (argc < 3)
       {
         printf("Use parameters: bind_to_address port response\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;
       }

       //here we may fail if sctp is not supported
       if ((SctpScocket = socket(AF_INET, SOCK_SEQPACKET, IPPROTO_SCTP)) < 0)
       {
               printf("After socket errno: %d\n", errno);
               perror("Description: ");
               return 0;
       }
       printf("socket created...\n");

       //make sure we receive MSG_NOTIFICATION
       if (setsockopt(SctpScocket, IPPROTO_SCTP, SCTP_EVENTS, &event,
sizeof(struct sctp_event_subscribe)) < 0)
       {
               printf("After setsockopt errno: %d\n", errno);
               perror("Description: ");
               return 0;
       }
       printf("setsockopt succeeded...\n");

       addr.sin_family = AF_INET;
       addr.sin_port = htons(iPort);
       addr.sin_addr.s_addr = inet_addr(szAddress);

       //bind to specific server address and port
       if (bind(SctpScocket, (struct sockaddr *)&addr, sizeof(struct
sockaddr_in)) < 0)
       {
               printf("After bind errno: %d\n", errno);
               perror("Description: ");
               return 0;
       }
       printf("bind succeeded...\n");

       //wait for connections
       if (listen(SctpScocket, 1) < 0) {
               printf("After listen errno: %d\n", errno);
               perror("Description: ");
               return 0;
       }
       printf("listen succeeded...\n");

       while(true)
       {
               //each time erase the stuff
               flags = 0;
               memset((void *)&addr, 0, sizeof(struct sockaddr_in));
               from_len = (socklen_t)sizeof(struct sockaddr_in);
               memset((void *)&sinfo, 0, sizeof(struct sctp_sndrcvinfo));

               n = sctp_recvmsg(SctpScocket, (void*)pRecvBuffer, RECVBUFSIZE,
(struct sockaddr *)&addr, &from_len, &sinfo, &flags);
               if (-1 == n)
               {
                       printf("Error with sctp_recvmsg: -1... waiting\n");
                       printf("errno: %d\n", errno);
                       perror("Description: ");
                       sleep(1);
                       continue;
               }

               if (flags & MSG_NOTIFICATION)
               {
                       printf("Notification received!\n");
                       printf("From %s:%u\n", inet_ntoa(addr.sin_addr), ntohs(addr.sin_port));
               }
               else
               {
                       printf("Received from %s:%u on stream %d, PPID %d.: %s\n",
                               inet_ntoa(addr.sin_addr),
                               ntohs(addr.sin_port),
                               sinfo.sinfo_stream,
                               ntohl(sinfo.sinfo_ppid),
                               pRecvBuffer
                       );
               }

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

               //close server when exit is received
               if (0 == strcmp(pRecvBuffer, "exit"))
               {
                       break;
               }
       }//while

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

       if (close(SctpScocket) < 0) {
               perror("close");
       }
       return (0);
}