I'm trying to connect to a remote peer (which I don't have directory access other than connecting to it via socket and ping) via SCTP. Assuming that I have connected succesfully, what should be the value of my sctp_status.sstate if I try calling getsocktopt()? Mine is SCTP_COOKIE_ECHOED(3) according to sctp.h. Is it correct? Shouldn't it be SCTP_ESTABLISHED?
Because I tried sending message to the remote peer with this code:
ret = sctp_sendmsg (connSock, (void *) data, (size_t) strlen (data), (struct sockaddr *) &servaddr, sizeof (servaddr), 46, 0, 0, 0, 0);
It returned the number of bytes I tried sending. Then when I tried catching if there's any response:
ret = sctp_recvmsg (connSock, (void *) reply, sizeof (reply), NULL,
NULL, NULL, &flags);
It returns -1 with errno of ECONNRESET(104). What are the possible mistakes in my code, or maybe in my flow? Did I miss something?
Thanks in advance for answering. Will gladly appreciate that. :)
Update: Here down below is my client code in connecting to the remote peer. It's actually a node addon for me to use since SCTP is not fully supported in node. Using lksctp-tools package to include the headers.
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netinet/sctp.h>
#include <arpa/inet.h>
#include <signal.h>
#define MAX_BUFFER 1024
int connSock = 0;
int connect(char host[], int port, char remote_host[], int remote_port, int timeout) {
int ret, flags;
fd_set rset, wset;
struct sockaddr_in servaddr;
struct sockaddr_in locaddr;
struct sctp_initmsg initmsg;
struct timeval tval;
struct sctp_status status;
socklen_t opt_len;
errno = 0;
connSock = socket (AF_INET, SOCK_STREAM, IPPROTO_SCTP);
flags = fcntl(connSock, F_GETFL, 0);
fcntl(connSock, F_SETFL, flags | O_NONBLOCK);
if (connSock == -1)
{
return (-1);
}
memset(&locaddr, 0, sizeof(locaddr));
locaddr.sin_family = AF_INET;
locaddr.sin_port = htons(port);
locaddr.sin_addr.s_addr = inet_addr(host);
ret = bind(connSock, (struct sockaddr *)&locaddr, sizeof(locaddr));
if (ret == -1)
{
return (-1);
}
memset (&initmsg, 0, sizeof (initmsg));
initmsg.sinit_num_ostreams = 5;
initmsg.sinit_max_instreams = 5;
initmsg.sinit_max_attempts = 10;
ret = setsockopt(connSock, IPPROTO_SCTP, SCTP_INITMSG, &initmsg, sizeof(initmsg));
if (ret == -1)
{
return (-1);
}
memset (&servaddr, 0, sizeof (servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons (remote_port);
servaddr.sin_addr.s_addr = inet_addr (remote_host);
if((ret = connect (connSock, (struct sockaddr *) &servaddr, sizeof (servaddr))) < 0)
if (errno != EINPROGRESS)
return (-1);
if (ret == 0) {
fcntl(connSock, F_SETFL, flags);
return 0;
}
FD_ZERO(&rset);
FD_SET(connSock, &rset);
wset = rset;
tval.tv_sec = timeout;
tval.tv_usec = 0;
ret = select(connSock+1, &rset, &wset, NULL, timeout ? &tval : NULL);
if (ret == 0) {
close(connSock);
errno = ETIMEDOUT;
return(-1);
}
else if (ret < 0) {
return(-1);
}
fcntl(connSock, F_SETFL, flags);
opt_len = (socklen_t) sizeof(struct sctp_status);
getsockopt(connSock, IPPROTO_SCTP, SCTP_STATUS, &status, &opt_len);
printf ("assoc id = %d\n", status.sstat_assoc_id);
printf ("state = %d\n", status.sstat_state);
printf ("instrms = %d\n", status.sstat_instrms);
printf ("outstrms = %d\n", status.sstat_outstrms);
return 0;
}
int sendMessage(char remote_host[], int remote_port, char data[]) {
int ret, flags;
struct sockaddr_in servaddr;
char reply[1024];
errno = 0;
memset (&servaddr, 0, sizeof (servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons (remote_port);
servaddr.sin_addr.s_addr = inet_addr (remote_host);
printf("\nSending %s (%li bytes)", data, strlen(data));
ret = sctp_sendmsg (connSock, (void *) data, (size_t) strlen (data),
(struct sockaddr *) &servaddr, sizeof (servaddr), 46, 0, 0, 0, 0);
if (ret == -1)
{
printf("\nError sending errno(%d)", errno);
return -1;
}
else {
ret = sctp_recvmsg (connSock, (void *) reply, sizeof (reply), NULL,
NULL, NULL, &flags);
if (ret == -1)
{
printf("\nError receiving errno(%d)", errno);
return -1;
}
else {
printf("\nServer replied with %s", reply);
return 0;
}
}
}
int getSocket() {
return connSock;
}
I don't know if there's anything significant I need to set first before connecting that I missed out. I got the snippet from different sources so it's quite messy.
Another update, here's the tshark log of that code when executed:
3336.919408 local -> remote SCTP 82 INIT
3337.006690 remote -> local SCTP 810 INIT_ACK
3337.006727 local -> remote SCTP 774 COOKIE_ECHO
3337.085390 remote -> local SCTP 50 COOKIE_ACK
3337.086650 local -> remote SCTP 94 DATA
3337.087277 remote -> local SCTP 58 ABORT
3337.165266 remote -> local SCTP 50 ABORT
Detailed tshark log of this here.
Looks like the remote sent its COOKIE_ACK chunk but my client failed to set its state to ESTABLISHED (I double checked the sstate value of 3 here).
