/*
   File		: sctp_client_send_receive_echo_messages_from_one_stream.c
   Programmer	: Nasif Ekiz
   Date 	: 9/27/2006
   Description	: This is a SCTP client application which establishes an association with server. It reads 
		  a message from the user and sends it to the server. The server than echoes the read 
		  message to client. 
		 
		  This program is a SCTP one-to-many style application. 
*/

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

#define SERV_PORT 7000
#define MAXLINE 4096
#define SCTP_MAXLINE 800

// this function is used to send and receive messages on one stream in the association
void sctpstr_cli(FILE *fp, int sock_fd, struct sockaddr *to, socklen_t tolen) {
	
	struct sockaddr_in peeraddr; 		 	 	
	struct sctp_sndrcvinfo sri;			// sctp_sndrcvinfo structure used to set default parameters for the association
	char sendline[MAXLINE], recvline[MAXLINE];	// send and receive message buffers
	socklen_t len;					
	int out_sz, rd_sz;
	int msg_flags;

	// clear sctp_sndrcvinfo structure
	memset(&sri, 0, sizeof(sri));
	
	while(fgets(sendline, MAXLINE, fp) != NULL) {
		
		// if stream number is not presented in [streamnum] format
		if(sendline[0] != '[') {
			printf("Error, line must be of the form '[streamnum]text' \n");
			continue;
		}

		// set the stream number that the message will be sent
		sri.sinfo_stream = strtol(&sendline[1], NULL, 0);
	
		out_sz = strlen(sendline);
	
		// send a message that will be echoed by the server
		sctp_sendmsg(sock_fd, sendline, out_sz, to, tolen, 0, 0, sri.sinfo_stream, 0, 0);

		len = sizeof(peeraddr);
		
		// read the echoed message from the server
		rd_sz = sctp_recvmsg(sock_fd, recvline, sizeof(recvline), (struct sockaddr *) &peeraddr, &len, &sri, &msg_flags);

		// print stream number, stream sequence number and association id
		printf("From str:%d seq:%d (assoc:0x%x):", sri.sinfo_stream, sri.sinfo_ssn, (u_int) sri.sinfo_assoc_id);
		
		// print the received echoed message
		printf("%.*s", rd_sz, recvline);
	}
}
int main(int argc, char **argv)
{
	int sock_fd;				// socket identifier
	struct sockaddr_in servaddr;		// address structure to keep server's IPv4 address info
	struct sctp_event_subscribe evnts; 	// this structure is used to enable/disable various SCTP 
						// notifications	
	int echo_to_all=0;			// variable used to determine wheather to send data from 
						// one or multiple streams 

	// server address is missing
	if(argc < 2)
		printf("Missing host argument - use '%s host [echo]'\n", argv[0]);

	// open a socket
	// AF_INET - IPv4 protocol
	// SOCK_SEQPACKET - sequenced packet socket
	// IPPROTO_SCTP - SCTP transport protocol	
        sock_fd = socket(AF_INET, SOCK_SEQPACKET, IPPROTO_SCTP);

	// check for error
	if (sock_fd < 0) {
		perror("Client can't open socket!");
		exit(1);
	}

	// clear server address structure
	memset(&servaddr, 0, sizeof(servaddr));

	// set server address information
	servaddr.sin_family = AF_INET;			 // IPv4 protocol
	servaddr.sin_addr.s_addr = htonl(INADDR_ANY);	 // in the case of multiple interfaces accept 
							 // connection on any host interface
	servaddr.sin_port = htons(SERV_PORT);		 // server application port number
	inet_pton(AF_INET, argv[1], &servaddr.sin_addr); // convert the string server address(argv[1]) to 
							 // host byte order (servaddr.sin_addr)	 

	// clear sctp_event_subscribe structure 
	memset(&evnts, 0, sizeof(evnts));
	
	// enable sctp_sndrcvinfo to come with each sctp_recvmsg function
	evnts.sctp_data_io_event = 1;

	// set the options for the socket
	// SCTP_EVENTS option allows a caller to fetch, enable/disable various SCTP notifications
	if ((setsockopt(sock_fd,IPPROTO_SCTP, SCTP_EVENTS, &evnts, sizeof(evnts))) < 0) {
		perror("Error in setsockopt!");
		exit(1);
	}

	// message is echoed on just one stream
	if(echo_to_all == 0)
		sctpstr_cli(stdin,sock_fd,(struct sockaddr *)&servaddr,sizeof(servaddr));
	

	// close the socket
	if ((close(sock_fd)) < 0) {
		perror("Can't close socket!");
		exit(1);
	}

	return(0);
}