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/*
* Sample program to be used as a transparent proxy.
*
* Must be executed with permission enough to do an ioctl on /dev/ipl
* or equivalent. This is just a sample and is only alpha quality.
* - Darren Reed (8 April 1996)
*/
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/errno.h>
#include <sys/syslog.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <net/if.h>
#include <sys/socket.h>
#include "ip_nat.h"
#define RELAY_BUFSZ 8192
char ibuff[RELAY_BUFSZ];
char obuff[RELAY_BUFSZ];
int relay(ifd, ofd, rfd)
int ifd, ofd, rfd;
{
fd_set rfds, wfds;
char *irh, *irt, *rrh, *rrt;
char *iwh, *iwt, *rwh, *rwt;
int nfd, n, rw;
irh = irt = ibuff;
iwh = iwt = obuff;
nfd = ifd;
if (nfd < ofd)
nfd = ofd;
if (nfd < rfd)
nfd = rfd;
while (1) {
FD_ZERO(&rfds);
FD_ZERO(&wfds);
if (irh > irt)
FD_SET(rfd, &wfds);
if (irh < (ibuff + RELAY_BUFSZ))
FD_SET(ifd, &rfds);
if (iwh > iwt)
FD_SET(ofd, &wfds);
if (iwh < (obuff + RELAY_BUFSZ))
FD_SET(rfd, &rfds);
switch ((n = select(nfd + 1, &rfds, &wfds, NULL, NULL)))
{
case -1 :
case 0 :
return -1;
default :
if (FD_ISSET(ifd, &rfds)) {
rw = read(ifd, irh, ibuff + RELAY_BUFSZ - irh);
if (rw == -1)
return -1;
if (rw == 0)
return 0;
irh += rw;
n--;
}
if (n && FD_ISSET(ofd, &wfds)) {
rw = write(ofd, iwt, iwh - iwt);
if (rw == -1)
return -1;
iwt += rw;
n--;
}
if (n && FD_ISSET(rfd, &rfds)) {
rw = read(rfd, iwh, obuff + RELAY_BUFSZ - iwh);
if (rw == -1)
return -1;
if (rw == 0)
return 0;
iwh += rw;
n--;
}
if (n && FD_ISSET(rfd, &wfds)) {
rw = write(rfd, irt, irh - irt);
if (rw == -1)
return -1;
irt += rw;
n--;
}
if (irh == irt)
irh = irt = ibuff;
if (iwh == iwt)
iwh = iwt = obuff;
}
}
}
main(argc, argv)
int argc;
char *argv[];
{
struct sockaddr_in sin;
natlookup_t nl;
natlookup_t *nlp = &nl;
int fd, sl = sizeof(sl), se;
openlog(argv[0], LOG_PID|LOG_NDELAY, LOG_DAEMON);
if ((fd = open("/dev/ipnat", O_RDONLY)) == -1) {
se = errno;
perror("open");
errno = se;
syslog(LOG_ERR, "open: %m\n");
exit(-1);
}
bzero(&nl, sizeof(nl));
nl.nl_flags = IPN_TCP;
bzero(&sin, sizeof(sin));
sin.sin_family = AF_INET;
sl = sizeof(sin);
if (getsockname(0, (struct sockaddr *)&sin, &sl) == -1) {
se = errno;
perror("getsockname");
errno = se;
syslog(LOG_ERR, "getsockname: %m\n");
exit(-1);
} else {
nl.nl_inip.s_addr = sin.sin_addr.s_addr;
nl.nl_inport = sin.sin_port;
}
bzero(&sin, sizeof(sin));
sin.sin_family = AF_INET;
sl = sizeof(sin);
if (getpeername(0, (struct sockaddr *)&sin, &sl) == -1) {
se = errno;
perror("getpeername");
errno = se;
syslog(LOG_ERR, "getpeername: %m\n");
exit(-1);
} else {
nl.nl_outip.s_addr = sin.sin_addr.s_addr;
nl.nl_outport = sin.sin_port;
}
if (ioctl(fd, SIOCGNATL, &nlp) == -1) {
se = errno;
perror("ioctl");
errno = se;
syslog(LOG_ERR, "ioctl: %m\n");
exit(-1);
}
sin.sin_port = nl.nl_realport;
sin.sin_addr = nl.nl_realip;
sl = sizeof(sin);
fd = socket(AF_INET, SOCK_STREAM, 0);
if (connect(fd, (struct sockaddr *)&sin, sl) == -1) {
se = errno;
perror("connect");
errno = se;
syslog(LOG_ERR, "connect: %m\n");
exit(-1);
}
(void) ioctl(fd, F_SETFL, ioctl(fd, F_GETFL, 0)|O_NONBLOCK);
(void) ioctl(0, F_SETFL, ioctl(fd, F_GETFL, 0)|O_NONBLOCK);
(void) ioctl(1, F_SETFL, ioctl(fd, F_GETFL, 0)|O_NONBLOCK);
syslog(LOG_NOTICE, "connected to %s,%d\n", inet_ntoa(sin.sin_addr),
ntohs(sin.sin_port));
if (relay(0, 1, fd) == -1) {
se = errno;
perror("relay");
errno = se;
syslog(LOG_ERR, "relay: %m\n");
exit(-1);
}
exit(0);
}
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