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server.c
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server.c
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/******************************************************
* tunelizador http
* server.c
*******************************************************/
#include <stdio.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <signal.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/wait.h>
#include "config.h"
#include "common.h"
/******************
* macros aux
*******************/
#undef PROMPT
#define PROMPT "(server) "
/******************
* variables globales
*******************/
int fifo, sock, f_log, pid_s, f_port, verbose = VERBOSE;
char f_host[SZ_HOST], f_send[SZ_FILE], f_recv[SZ_FILE], f_pid[SZ_FILE];
/******************
* funciones
*******************/
// libera recursos
void clean()
{
MSG("exiting...\n");
// matamos hijo
MSG("killing server\n");
kill(pid_s, SIGTERM);
// cerramos sockets
MSG("closing sockets...\n");
close(sock);
// cerramos fifos
MSG("closing fifos...\n");
close(fifo);
// y borramos
MSG("removing fifos...\n");
unlink(f_recv);
unlink(f_send);
// fuera pid
MSG("removing files...\n");
unlink(f_pid);
// cerramos log
MSG("closing files\n");
close(f_log);
MSG(">>> done <<<\n\n");
}
// uso
void usage()
{
printf("Usage: server [host [port]]\n\n");
exit(-1);
}
// server
void server()
{
char sbuf[SZ_SBUF];
struct sockaddr_in a;
struct hostent *host;
int sz, conn = 0;
MSG("running server...\n");
// creamos fifos si no existen
MSG("creating fifos...\n");
mknod(f_recv, S_IFIFO | F_MOD, 0);
mknod(f_send, S_IFIFO | F_MOD, 0);
// creamos socket
MSG("creating socket...\n");
TRY(sock = socket(AF_INET, SOCK_STREAM, 0));
// resolucion host
MSG("resolving remote host...\n");
host = gethostbyname(f_host);
// parameros conexion
memset(&a, 0, sizeof(a));
a.sin_family = AF_INET;
a.sin_port = htons(f_port);
a.sin_addr = *((struct in_addr *)host->h_addr);
// hasta CTRL+C
while (1)
{
// abrimos fifo
MSG("reading http_tunnel...\n");
TRY(fifo = open(f_recv, O_RDONLY));
TRY(sz = read(fifo, sbuf, SZ_SBUF));
close(fifo);
// copiamos a socket (si > 0)
if (sz)
{
// reconectamos a server
if (! conn)
{
MSG("connecting to %s:%d...\n", f_host, f_port);
TRY(conn = !connect(sock, (struct sockaddr *)&a, sizeof(a)));
}
// enviamos datos
TRY(send(sock, sbuf, sz, 0));
}
MSG("http_tunnel -> socket: %d bytes\n", sz);
// leemos de socket
MSG("reading socket...\n");
TRY(sz = xrecv(sock, sbuf, SZ_SBUF, RECV_TIMEOUT));
// copiamos de socket (aunque 0)
TRY(fifo = open(f_send, O_WRONLY));
TRY(write(fifo, sbuf, sz));
close(fifo);
MSG("socket -> http_tunnel: %d bytes\n", sz);
}
}
// monit server
void watchdog()
{
struct stat st;
int status, intv;
time_t t_fi, t_fo, ti_fi, ti_fo;
unsigned int t;
MSG("checking server...\n");
// fecha mod inicial fifos
stat(f_recv, &st); ti_fi = st.st_ctime;
stat(f_send, &st); ti_fo = st.st_ctime;
// crono
t = crono();
// esperamos hasta salida
while (! waitpid(pid_s, &status, WNOHANG))
{
// intervalo ?
intv = crono() - t;
// fecha modificacion act fifos
stat(f_recv, &st); t_fi = st.st_ctime;
stat(f_send, &st); t_fo = st.st_ctime;
// algun cambio ?
if ((t_fi == ti_fi) && (t_fo == ti_fo))
{
// max time inactiv
if (intv > MAX_TIME) ABORT("timeout\n");
}
// reset crono
else t = crono();
// guardamos ultimo valor
ti_fi = t_fi;
ti_fo = t_fo;
MSG("waiting (%d/%d)...\n", intv, MAX_TIME);
// esperamos 1 seg.
sleep(1);
}
}
// funcion principal
int main(int argc, char *argv[])
{
int sid, pid, f;
char s_pid[7];
// desactivamos buffer salida
setbuf(stdout, 0);
// banner
printf("%s\n", BANNER);
printf("Starting server...\n\n");
//
// usage
//
// server
if (argc == 1)
{
strncpy(f_host, F_HOST, SZ_HOST);
f_port = F_PORT;
}
// server host
else if (argc == 2)
{
strncpy(f_host, argv[1], SZ_HOST);
f_port = F_PORT;
}
// server host port
else if (argc == 3)
{
strncpy(f_host, argv[1], SZ_HOST);
f_port = atoi(argv[2]);
}
// error ?
else usage();
//
// end usage
//
// filenames
sprintf(f_send, "%s.%d", F_SEND, f_port);
sprintf(f_recv, "%s.%d", F_RECV, f_port);
sprintf(f_pid, "%s.%d", F_PID, f_port);
// borramos pipes antiguos
unlink(f_recv);
unlink(f_send);
// server corriendo ?
TRY(f = open(f_pid, O_RDWR | O_CREAT, F_MOD));
// si existe, paramos
if (read(f, s_pid, sizeof(s_pid)))
{
pid = atoi(s_pid);
kill(pid, SIGTERM);
}
// lanzamos fork
TRY(pid = fork());
// hijo, daemonizamos
if (!pid)
{
// manejador int
set_handlers();
// default mask
umask(0);
// cambiamos sesion
TRY(sid = setsid());
// directorio por defecto
chdir(WORK_DIR);
// ajusta prioridad a baja
nice(PRIO);
// abrimos fichero logs
TRY(f_log = open(F_LOG, O_WRONLY |
O_CREAT | O_APPEND, F_MOD));
// stdout y stderr -> f
dup2(f_log, 1);
dup2(f_log, 2);
// no stdin
close(0);
MSG(">>> http_tunnel sever <<<\n");
MSG("initializing...\n");
// lanzamos fork
MSG("fork...\n");
TRY(pid_s = fork());
// lanzamos server y watchdog
if (pid_s == 0) server();
else watchdog();
}
// padre
else
{
// guardamos pid
sprintf(s_pid, "%d", pid);
lseek(f, 0, SEEK_SET);
write(f, s_pid, strlen(s_pid));
close(f);
}
return 0;
}