Transport end already connected error : 106 with connect() - c

Question

I have started implementing a server-client model with UNIX domain sockets of SOCK_STREAM type.
Thanks in advance

Answer 1

You need to avoid connecting again if your socket is already connected, you can keep some flag in your client code that indicates your client socket is already connected or not, based on that skip connecting again.
I have edited your server code below to show what I am trying to say in comments(You need to put accepted fd in select read set too, so that you can check any of clients posted any data, also you have multiple clients connected to you so you will have to keep accepted sockets in an array):
int cltfdlen = 0;
int cltfds[FD_SETSIZE];
int maxFD = sockfd;
int sun_path_size = sizeof(client_address.sun_path);
client_address.sun_family = AF_UNIX;
strncpy(client_address.sun_path, SOCKET_NAME, sun_path_size);
client_len = sizeof(client_address);
cli_interval.tv_sec = 60;
cli_interval.tv_usec = 0;
while (1) {
FD_ZERO(&read_fds);
FD_SET(sockfd, &read_fds);
for(i=0;i<cltfdlen;cltfdlen++)
FD_SET(cltfds[i], &read_fds);
int activity = select(maxFD + 1, &read_fds, NULL, NULL, &cli_interval);
if ((activity < 0) && (errno !=EINTR)) {
printf("socket select failed errno %d\n", errno);
return 1;
}
if (FD_ISSET(sockfd, &read_fds)) {
cli_sockfd = accept(sockfd,
(struct sockaddr *)&client_address,
&client_len);
if(cli_sockfd < 0) {
printf("accept from IPC socket failed");
return 1;
}
else
{
cltfds[cltfdlen++] = cli_sockfd;
if(maxFD < cli_sockfd)
maxFD = cli_sockfd
continue;
}
}
msg = (msg_t *) malloc(sizeof(msg_t));
if (msg == NULL) {
printf("Memory allocation failed for msg");
close(ipc_sockfd);
ipc_sockfd = -1;
return 1;
}
memset(msg, 0, sizeof(msg));
for(i=0;i<cltfdlen;i++)
{
if(FD_ISSET(cltfds[i], &read_fds))
{
if (read(cltfds[i], (void *)msg, sizeof(msg_t)) == -1) {
printf("Read from IPC socket failed");
return 1;
}
}
}
close(cli_sockfd);
cli_sockfd = -1;
}