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/* micro_inetd - simple network service spawner
**
** Copyright (C)1996,2000 by Jef Poskanzer <jef@mail.acme.com>.
** All rights reserved.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
** 1. Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** 2. Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in the
** documentation and/or other materials provided with the distribution.
**
** THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
** ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
** OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
** HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
** SUCH DAMAGE.
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <signal.h>
#include <memory.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#if defined(AF_INET6) && defined(IN6_IS_ADDR_V4MAPPED)
#define USE_IPV6
#endif
static void usage();
static int initialize_listen_socket( int pf, int af, unsigned short port );
static void child_handler( int sig );
static char* argv0;
int
main( int argc, char* argv[] )
{
unsigned short port;
char** child_argv;
int listen_fd, conn_fd;
struct sockaddr_in sin;
int sz;
fd_set lfdset;
int maxfd;
argv0 = argv[0];
/* Get arguments. */
if ( argc < 3 )
usage();
port = (unsigned short) atoi( argv[1] );
child_argv = argv + 2;
/* Initialize listen socket. If we have v6 use that, since its sockets
** will accept v4 connections too. Otherwise just use v4.
*/
#ifdef USE_IPV6
listen_fd = initialize_listen_socket( PF_INET6, AF_INET6, port );
#else /* USE_IPV6 */
listen_fd = initialize_listen_socket( PF_INET, AF_INET, port );
#endif /* USE_IPV6 */
/* Set up a signal handler for child reaping. */
(void) signal( SIGCHLD, child_handler );
for (;;)
{
/* Accept a new connection. */
sz = sizeof(sin);
conn_fd = accept( listen_fd, (struct sockaddr*) &sin, &sz );
if ( conn_fd < 0 )
{
if ( errno == EINTR ) /* because of SIGCHLD (or ptrace) */
continue;
perror( "accept" );
exit( 1 );
}
/* Fork a sub-process. */
if ( fork() == 0 )
{
/* Close standard descriptors and the listen socket. */
(void) close( 0 );
(void) close( 1 );
(void) close( 2 );
(void) close( listen_fd );
/* Dup the connection onto the standard descriptors. */
(void) dup2( conn_fd, 0 );
(void) dup2( conn_fd, 1 );
(void) dup2( conn_fd, 2 );
(void) close( conn_fd );
/* Run the program. */
(void) execv( child_argv[0], child_argv );
/* Something went wrong. */
perror( "execl" );
exit( 1 );
}
/* Parent process. */
(void) close( conn_fd );
}
}
static
void usage()
{
(void) fprintf( stderr, "usage: %s port program [args...]\n", argv0 );
exit( 1 );
}
static void
child_handler( int sig )
{
pid_t pid;
int status;
/* Set up the signal handler again. Don't need to do this on BSD
** systems, but it doesn't hurt.
*/
(void) signal( SIGCHLD, child_handler );
/* Reap defunct children until there aren't any more. */
for (;;)
{
pid = waitpid( (pid_t) -1, &status, WNOHANG );
if ( (int) pid == 0 ) /* none left */
break;
if ( (int) pid < 0 )
{
if ( errno == EINTR ) /* because of ptrace */
continue;
/* ECHILD shouldn't happen with the WNOHANG option, but with
** some kernels it does anyway. Ignore it.
*/
if ( errno != ECHILD )
perror( "waitpid" );
break;
}
}
}
static int
initialize_listen_socket( int pf, int af, unsigned short port )
{
int listen_fd;
int on;
#ifdef USE_IPV6
struct sockaddr_in6 sa;
#else /* USE_IPV6 */
struct sockaddr_in sa;
#endif /* USE_IPV6 */
/* Create socket. */
listen_fd = socket( pf, SOCK_STREAM, 0 );
if ( listen_fd < 0 )
{
perror( "socket" );
exit( 1 );
}
/* Allow reuse of local addresses. */
on = 1;
if ( setsockopt(
listen_fd, SOL_SOCKET, SO_REUSEADDR, (char*) &on, sizeof(on) ) < 0 )
{
perror( "setsockopt SO_REUSEADDR" );
exit( 1 );
}
/* Set up the sockaddr. */
(void) memset( (char*) &sa, 0, sizeof(sa) );
#ifdef USE_IPV6
sa.sin6_family = af;
sa.sin6_addr = in6addr_any;
sa.sin6_port = htons( port );
#else /* USE_IPV6 */
sa.sin_family = af;
sa.sin_addr.s_addr = htonl( INADDR_ANY );
sa.sin_port = htons( port );
#endif /* USE_IPV6 */
/* Bind it to the socket. */
if ( bind( listen_fd, (struct sockaddr*) &sa, sizeof(sa) ) < 0 )
{
perror( "bind" );
exit( 1 );
}
/* Start a listen going. */
if ( listen( listen_fd, 1024 ) < 0 )
{
perror( "listen" );
exit( 1 );
}
return listen_fd;
}
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