Unix socket loops - c++

Question

I'm trying to implement a pair server/client programs that is able to exchange information through Unix Sockets. Problem is the client is constantly being reset and re-run by the server in a loop, and I'm having trouble sending/receiving data to and from the socket after the first time. Right now I have something like this:
Server:
int main(int argc, char const *argv[]){
unix_socket server;
server.initSocket(DEFAULT_SOCKET_PATH,SERVER_MODE);
server.wait();
bool first=true;
for (int i = 0; i < 30; ++i)
{
//send & receive data
server.closeSocket();
first=false;
}
return 0;
}
Client:
int loop_controller(){
unix_socket client;
client.initSocket(DEFAULT_SOCKET_PATH,CLIENT_MODE);
// receive & send data
client.closeSocket();
}
int main () {
for (int i = 0; i < 30; ++i){
loop_controller();
}
return 0;
}
The initSocket(), wait() and closeSocket() members of unix_socket class (mode 0 for servers, mode 1 for clients):
void unix_socket::initSocket(const char* sock_path, const int sc_mode){
if (sc_mode==0){
if (mode != sc_mode) mode=sc_mode;
if ((sock = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
perror("socket");
//exit(1);
}
// ---
local.sun_family = AF_UNIX;
strcpy(local.sun_path, sock_path);
unlink(local.sun_path);
len = strlen(local.sun_path) + sizeof(local.sun_family);
if (bind(sock, (struct sockaddr *)&local, len) == -1) {
close(sock);
perror("bind");
//exit(1);
}
// ---
} else if(sc_mode==1) {
if (mode != sc_mode) mode=sc_mode;
if ((client_sock = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
perror("socket");
//exit(1);
}
// ---
remote.sun_family = AF_UNIX;
strcpy(remote.sun_path, sock_path);
len = strlen(remote.sun_path) + sizeof(remote.sun_family);
if (connect(client_sock, (struct sockaddr *)&remote, len) == -1) {
perror("connect");
//exit(1);
}
// ---
} else printf("Invalid sc_mode argument: %d\n",sc_mode);
}
//...
void unix_socket::wait(){
if (mode==0){
if (listen(sock, 5) == -1) {
perror("listen");
//exit(1);
}
t = sizeof(remote);
if ((client_sock = accept(sock, (struct sockaddr *)&remote, &t)) == -1) {
perror("accept");
//exit(1);
}
} else printf("Invalid call to wait(): mode %d\n, must be 0",mode);
}
//...
void unix_socket::closeSocket(){
//close(sock);
close(client_sock);
}
//...
When running both programs with Valgrind, however, I'm getting SIGPIPE errors:
==5384==
==5384== Process terminating with default action of signal 13 (SIGPIPE)
==5384== at 0x573DDA2: send (send.c:28)
==5384== by 0x405910: unix_socket::sendMsg(char, double) (in .../server)
==5384== by 0x405B6C: unix_socket::sendVectorXd(Eigen::Matrix<double, -1, 1, 0, -1, 1> const&) (in .../server)
==5384== by 0x402044: main (in .../server)
==5384==
I'm guessing that something is not being done correctly when closing/reopening socket. What would be the right procedure?

Answer 1

In your loop, you are only accept()ing once. The end of the loop body indicates the client socket being closed, but yet it is never accept()ed again for the next iteration.
Your loop should be something like:
server.startListening(); // bind, listen and friends
for (int i = 0; i < 30; i++) {
server.acceptClient(); // Call accept
// insert byte pushing routines here..
server.closeSocket(); // call close() on socket returned by accept()
}