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/*
* psocksxx - A C++ wrapper for POSIX sockets
* Copyright (C) 2013 Uditha Atukorala
*
* This software library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This software library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this software library. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include "lecho.h"
#include <iostream>
#include <sys/socket.h>
#include <sys/un.h>
#include <cstring>
#include <cstdlib>
#include <signal.h>
lecho::lecho( const char * path ) :
_sockfd( -1 ), _lsock_path( path ) {
// fork
_cpid = fork();
if ( _cpid == -1 ) {
std::cerr << "failed to fork out child process" << std::endl;
} else if ( _cpid == 0 ) {
// child - initialise echo server on a local socket
init_listener();
// serve requests
serve_requests();
// exit - should never get here
exit( 0 );
} else {
// parent - wait for the child to create the socket and return
wait_connect();
}
}
lecho::~lecho() {
// cleanup
shutdown();
}
void lecho::init_listener() {
// initialise socket
if ( ( _sockfd = socket( PF_LOCAL, SOCK_STREAM, 0 ) ) < 0 ) {
std::cerr << "failed to setup local socket" << std::endl;
exit( -1 );
}
// socket address
sockaddr_un saddr;
bzero( (void *) &saddr, sizeof( saddr ) );
saddr.sun_family = AF_LOCAL;
strcpy( saddr.sun_path, _lsock_path );
// bind
if ( bind( _sockfd, (::sockaddr *) &saddr,
sizeof( sockaddr_un ) ) != 0 ) {
std::cerr << "failed to bind to local socket" << std::endl;
exit( -1 );
}
// listen
if ( listen( _sockfd, 2 ) != 0 ) {
std::cerr << "failed to listen on local socket" << std::endl;
exit( -1 );
}
}
void lecho::serve_requests() {
int peer_sockfd;
sockaddr_un peer_addr;
socklen_t addrlen = sizeof( peer_addr );
int n = 0;
char cbuffer[64];
bool close_peer;
for (;;) {
if ( ( peer_sockfd = accept( _sockfd, (sockaddr *) &peer_addr, &addrlen ) ) == -1 ) {
continue;
}
close_peer = false;
do {
// read from the socket
n = recv( peer_sockfd, cbuffer, sizeof( cbuffer ), 0 );
// sanity check - did we receive anything?
if ( n <= 0 ) {
close_peer = true;
} else {
// send back what we received
if ( send( peer_sockfd, cbuffer, n, 0 ) < 0 ) {
close_peer = true;
}
}
} while (! close_peer );
// close peer
close( peer_sockfd );
}
}
void lecho::shutdown() {
if ( _cpid == 0 ) {
// child - should never get here
} else {
// parent - send kill to child
kill( _cpid, SIGTERM );
}
// unlink
unlink( _lsock_path );
}
void lecho::wait_connect() {
int sockfd = -1;
unsigned int max_tries = 10;
sockaddr_un saddr;
// initialise socket
if ( ( sockfd = socket( PF_LOCAL, SOCK_STREAM, 0 ) ) < 0 ) {
std::cerr << "failed to setup local socket" << std::endl;
exit( -1 );
}
// socket address structure
bzero( (void *) &saddr, sizeof( saddr ) );
saddr.sun_family = AF_LOCAL;
strcpy( saddr.sun_path, _lsock_path );
// loop until we can establish a connection or
// we exhaust our attempts
for ( int i = 0; i < max_tries; i++ ) {
// try to connect
if ( ( connect( sockfd, (sockaddr *) &saddr, sizeof( sockaddr_un ) ) == -1 ) ) {
// connect failed - sleep for a bit
usleep( 500 );
} else {
// connect successful - break out of the loop
break;
}
}
// close socket
close( sockfd );
}
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