#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <errno.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <string.h>
#define QLEN 5
int LISTEN_ON = 23;
int JUMP_TO = 3000;
const char *JUMP_ADDR = "127.0.0.1";
char sbuf[2048],
cbuf[2048];
void telcli(int source);
void communicate(int sfd, int cfd);
int main(int argc, const char **argv)
{
int srv_fd,
rem_fd;
unsigned int rem_len; /* , opt = 1; */
struct sockaddr_in rem_addr,
srv_addr;
if (argc != 4) {
fprintf(stderr, "Usage: bounce <source port #> <target IP address> <target port #>\n");
exit(-1);
}
LISTEN_ON = atoi(argv[1]);
JUMP_ADDR = argv[2];
JUMP_TO = atoi(argv[3]);
bzero((char *)&rem_addr, sizeof(rem_addr));
bzero((char *)&srv_addr, sizeof(srv_addr));
srv_addr.sin_family = AF_INET;
srv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
srv_addr.sin_port = htons(LISTEN_ON);
srv_fd = socket(PF_INET, SOCK_STREAM, 0);
if (bind(srv_fd, (struct sockaddr *)&srv_addr, sizeof(srv_addr)) == -1) {
perror("bind");
exit(-1);
}
listen(srv_fd, QLEN);
close(0);
close(1);
close(2);
#ifdef TIOCNOTTY
if ((rem_fd = open("/dev/tty", O_RDWR)) >= 0) {
ioctl(rem_fd, TIOCNOTTY, (char *)0);
close(rem_fd);
}
#endif
if (fork())
exit(0);
while (1) {
rem_len = sizeof(rem_addr);
rem_fd = accept(srv_fd, (struct sockaddr *)&rem_addr, &rem_len);
if (rem_fd < 0) {
if (errno == EINTR)
continue;
exit(-1);
}
switch (fork()) {
case 0: /* child process */
close(srv_fd); /* close original socket */
telcli(rem_fd); /* process the request */
close(rem_fd);
exit(0);
break;
default:
close(rem_fd); /* parent process */
if (fork())
exit(0); /* let init worry about children */
break;
case -1:
fprintf(stderr, "\n\rfork: %s\n\r", strerror(errno));
break;
}
}
}
void telcli(int source)
{
int dest;
/*
* int found;
*/
struct sockaddr_in sa;
/*
* struct hostent *hp;
*/
/*
* struct servent *sp;
*/
/*
* char string[100];
*/
sa.sin_addr.s_addr = inet_addr(JUMP_ADDR);
sa.sin_family = AF_INET;
sa.sin_port = htons((unsigned)JUMP_TO);
if ((dest = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
perror("telcli: socket");
exit(1);
}
connect(dest, (struct sockaddr *)&sa, sizeof(sa));
#ifdef FNDELAY
fcntl(source, F_SETFL, fcntl(source, F_GETFL, 0) | FNDELAY);
fcntl(dest, F_SETFL, fcntl(dest, F_GETFL, 0) | FNDELAY);
#else
fcntl(source, F_SETFL, O_NDELAY);
fcntl(dest, F_SETFL, O_NDELAY);
#endif
communicate(dest, source);
close(dest);
exit(0);
}
void communicate(int sfd, int cfd)
{
char *chead,
*ctail,
*shead,
*stail;
int num,
nfd,
spos,
cpos;
/*
* extern int errno;
*/
fd_set rd,
wr;
chead = ctail = cbuf;
cpos = 0;
shead = stail = sbuf;
spos = 0;
while (1) {
FD_ZERO(&rd);
FD_ZERO(&wr);
if (spos < sizeof(sbuf) - 1)
FD_SET(sfd, &rd);
if (ctail > chead)
FD_SET(sfd, &wr);
if (cpos < sizeof(cbuf) - 1)
FD_SET(cfd, &rd);
if (stail > shead)
FD_SET(cfd, &wr);
nfd = select(256, &rd, &wr, 0, 0);
if (nfd <= 0)
continue;
if (FD_ISSET(sfd, &rd)) {
num = read(sfd, stail, sizeof(sbuf) - spos);
if ((num == -1) && (errno != EWOULDBLOCK))
return;
if (num == 0)
return;
if (num > 0) {
spos += num;
stail += num;
if (!--nfd)
continue;
}
}
if (FD_ISSET(cfd, &rd)) {
num = read(cfd, ctail, sizeof(cbuf) - cpos);
if ((num == -1) && (errno != EWOULDBLOCK))
return;
if (num == 0)
return;
if (num > 0) {
cpos += num;
ctail += num;
if (!--nfd)
continue;
}
}
if (FD_ISSET(sfd, &wr)) {
num = write(sfd, chead, ctail - chead);
if ((num == -1) && (errno != EWOULDBLOCK))
return;
if (num > 0) {
chead += num;
if (chead == ctail) {
chead = ctail = cbuf;
cpos = 0;
}
if (!--nfd)
continue;
}
}
if (FD_ISSET(cfd, &wr)) {
num = write(cfd, shead, stail - shead);
if ((num == -1) && (errno != EWOULDBLOCK))
return;
if (num > 0) {
shead += num;
if (shead == stail) {
shead = stail = sbuf;
spos = 0;
}
if (!--nfd)
continue;
}
}
}
}
