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/* ==================================================================
* DAEMON.C
*
* This file provides the 'daemon' implementation of
* xtell.
*
*
* Daemon-
* Regular daemon which waits for connections
* forks, handles connections, cleans up,
* dies, etc.
*
* =============================================================== */
#include "xtelld.h"
/* the entry point is daemon_service (last function, at the bottom) */
unsigned long open_connections;
/* ------------------------------------
* child_reaper:
* free resources of child service
* as well as close the descriptor
* on the parent end
* ------------------------------------
*/
static void child_reaper (int s)
{
int status;
wait (&status);
if (WIFEXITED(status)) /* exit value is a socket descriptor */
killsock (WEXITSTATUS(status));
signal (SIGCHLD, child_reaper);
if (open_connections > 0)
open_connections--;
}
/* ------------------------------------------------------------------
* daemon_core:
* this maintains a standalone -forking- daemon
* it basically waits for a connection, forks off
* a handler for it, and cleans up when it dies.
* results in much smaller code, but also a wee bit more
* overhead.
* ------------------------------------------------------------------
*/
static void daemon_core (int sd)
{
struct sockaddr_in sin;
int sinsize, sd_peal;
sinsize = sizeof (struct sockaddr);
signal (SIGCHLD, child_reaper);
while (1) {
sd_peal = accept (sd, (struct sockaddr *)&sin, &sinsize);
if (sd_peal == -1) {
if (errno == EINTR)
continue;
else
break;
}
else if (open_connections < max_connections) {
switch (fork ()) {
case 0:
alarm (client_timeout);
signal (SIGALRM, xtell_killtic);
/* we trick the inetd service handler into
* thinking it was spawned by inetd, rather
* than this process. harmless prank. */
inetd_service (sd_peal, sd_peal);
killsock (sd_peal);
exit (sd_peal);
case -1:
fprintf(stderr, "daemon_service: could not fork!!\n");
syslog(LOG_ERR, "daemon_service: could not fork!!");
break;
default:
open_connections++;
break;
}
}
else
killsock (sd_peal);
}
fprintf(stderr, "accept() returned error: %s\n", strerror (errno));
syslog(LOG_ERR, "accept() returned error: %s", strerror (errno));
}
/* ------------------------------------------------------------------
* daemon_service :
* ------------------------------------------------------------------
*/
void daemon_service (void)
{
int sd, err;
struct sockaddr_in sin;
open_connections = 0;
openlog ("xtell", LOG_PID, LOG_AUTH);
setsid ();
if (fork ()) /* daemonize */
exit (0);
chdir ("/");
sd = socket (PF_INET, SOCK_STREAM, 0);
if (sd == -1) {
syslog(LOG_ERR, "Cannot allocate socket: %s", strerror (errno));
fprintf(stderr, "Cannot allocate socket: %s\n", strerror (errno));
exit (-1);
}
sin.sin_family = AF_INET;
sin.sin_port = htons (xtell_port);
sin.sin_addr.s_addr = INADDR_ANY;
err = bind (sd, (struct sockaddr *)&sin, sizeof (sin));
if (err == -1) {
syslog(LOG_ERR, "Cannot bind to port %d: %s",
xtell_port, strerror (errno));
fprintf(stderr, "Cannot bind to port %d: %s\n",
xtell_port, strerror (errno));
exit (-1);
}
if (-1 == listen (sd, 5)) {
syslog(LOG_ERR, "Cannot listen on port %d: %s",
xtell_port, strerror (errno));
fprintf(stderr, "Cannot listen on port %d: %s\n",
xtell_port, strerror (errno));
exit (-1);
}
syslog (LOG_NOTICE, "xtell services started [ %s ]",
VERSION);
daemon_core (sd);
syslog(LOG_ERR, "xtell services terminated (exiting on internal error)");
fprintf(stderr, "xtell services terminated (exiting on internal error)\n");
closelog ();
killsock (sd);
}
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