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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 "necho.h"
#include <iostream>
#include <cstdlib>
#include <cstring>
#include <csignal>
#include <netdb.h>
#include <cerrno>
#include <sys/wait.h>
static int sockfd = -1;
void sigterm_handler( int sig, siginfo_t *siginfo, void *context ) {
// close any open sockets
if ( sockfd > -1 ) {
close( sockfd );
}
exit( EXIT_SUCCESS );
}
necho::necho( const char * node, const char * service, int socket_type ) :
_sockfd( -1 ), _nsock_node( node ), _nsock_service( service ),
_socket_type( socket_type ) {
// fork
_cpid = fork();
if ( _cpid == -1 ) {
std::cerr << "failed to fork out child process" << std::endl;
} else if ( _cpid == 0 ) {
// child - initialise signal handlers
init_signal_handlers();
// echo 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();
}
}
necho::~necho() {
// cleanup
shutdown();
}
void necho::init_signal_handlers() {
struct sigaction sa;
sigfillset( &sa.sa_mask );
sa.sa_sigaction = &sigterm_handler;
sa.sa_flags = SA_SIGINFO;
if ( sigaction( SIGTERM, &sa, 0 ) < 0 ) {
std::cerr << "sigaction() failed: " << strerror( errno ) << std::endl;
exit( EXIT_FAILURE );
}
}
void necho::init_listener() {
addrinfo hints, * saddr_info;
int status = 0;
// setup hints
memset( &hints, 0, sizeof ( hints ) );
hints.ai_family = AF_INET;
hints.ai_socktype = _socket_type;
if ( ( status = getaddrinfo( _nsock_node, _nsock_service, &hints, &saddr_info ) ) != 0 ) {
std::cerr << "getaddrinfo() failed: " << gai_strerror( status ) << std::endl;
exit( EXIT_FAILURE );
}
// initialise socket
if ( ( _sockfd = socket( saddr_info->ai_family, saddr_info->ai_socktype, saddr_info->ai_protocol ) ) < 0 ) {
std::cerr << "failed to setup network socket" << std::endl;
exit( EXIT_FAILURE );
}
// update static variable used by signal handlers
sockfd = _sockfd;
// set SO_REUSEADDR to true so we can reuse the socket
int optval = 1;
if ( setsockopt( _sockfd, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof( optval ) ) != 0 ) {
std::cerr << "setsockopt() failed: " << strerror( errno ) << std::endl;
exit( EXIT_FAILURE );
}
// bind
if ( bind( _sockfd, saddr_info->ai_addr, saddr_info->ai_addrlen ) != 0 ) {
std::cerr << "bind() failed: " << strerror( errno ) << std::endl;
exit( EXIT_FAILURE );
}
// listen
if ( listen( _sockfd, 5 ) != 0 ) {
std::cerr << "listen() failed: " << strerror( errno ) << std::endl;
exit( EXIT_FAILURE );
}
// cleanup
freeaddrinfo( saddr_info );
}
void necho::serve_requests() {
int peer_sockfd;
int n = 0;
char cbuffer[64];
bool close_peer;
for (;;) {
if ( ( peer_sockfd = accept( _sockfd, 0, 0 ) ) == -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 necho::wait_connect() {
int sockfd = -1;
int status = 0;
unsigned int max_tries = 10;
addrinfo hints, * saddr_info;
// setup hints
memset( &hints, 0, sizeof ( hints ) );
hints.ai_family = AF_INET;
hints.ai_socktype = _socket_type;
if ( ( status = getaddrinfo( _nsock_node, _nsock_service, &hints, &saddr_info ) ) != 0 ) {
std::cerr << "getaddrinfo() failed: " << gai_strerror( status ) << std::endl;
exit( EXIT_FAILURE );
}
// 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, saddr_info->ai_addr, saddr_info->ai_addrlen ) == -1 ) ) {
// connect failed - sleep for a bit
usleep( 500 );
} else {
// connect successful - break out of the loop
break;
}
}
// close socket
close( sockfd );
}
void necho::shutdown() {
if ( _cpid == 0 ) {
// child - should never get here
} else {
// parent - send kill to child
kill( _cpid, SIGTERM );
// wait for the child
waitpid( _cpid, 0, 0 );
}
}
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