#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/types.h>
#include <string.h>
#include <signal.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#define BUF_SIZE 1024
#undef max
#define max(x,y) ((x) > (y) ? (x) : (y))
#define SHUT_FD1 { \
if (fd1 >= 0) 
{ \
shutdown (fd1, SHUT_RDWR); \
close (fd1); \
fd1 = -1; \
} \
}
#define SHUT_FD2 { \
if (fd2 >= 0) { \
shutdown (fd2, SHUT_RDWR); \
close (fd2); \
fd2 = -1; \
} \
}
int rely(int fd1, int fd2);
static int accept_socket(int sockid);
static int listen_socket (int listen_port);
static int connect_socket (int connect_port, char *address);
int main (int argc, char **argv)
{
int h;
char buf1[BUF_SIZE], buf2[BUF_SIZE];
int buf1_avail, buf1_written;
int buf2_avail, buf2_written;
int forward_port;
static char forward_addr[100];
if (argc != 4)
{
printf ("Usage: %s localport forwardport forwardaddr\n", argv[0]);
exit (1);
}
signal (SIGPIPE, SIG_IGN);
signal (SIGCLD, SIG_IGN);
forward_port = atoi (argv[2]);
strcpy(forward_addr, argv[3]);
h = listen_socket (atoi (argv[1]));
if (h < 0) exit (1);
for (;;)
{
int r;
int pid;
r = accept_socket(h);
if (r < 0)
{
perror ("accept()");
continue;
}
pid = fork();
if ( pid < 0 )
{
perror("fork()");
continue;
}
else if ( pid > 0)
{
printf("process %d forked a child %d\n", getpid(), pid);
continue;
}
else if ( pid == 0 )
{
printf("child process %d was forked\n", getpid());
int fd1 = -1, fd2 = -1;
fd1 = r;
fd2 = connect_socket (forward_port, forward_addr);
if (fd2 < 0)
{
SHUT_FD1;
}
else
{
printf ("connect to %s:%d\n", forward_addr, forward_port);
rely(fd1, fd2);
/**//*SHUT_FD1;
SHUT_FD2;*/
}
printf("child process %d is exiting\n", getpid());
exit(0);
}
}
printf("programe terminated\n");
return 0;
}
static int accept_socket(int sockid)
{
int lengthc ;
struct sockaddr_in client;
int newsockid;
memset((char *) &client, 0, sizeof(struct sockaddr_in));
lengthc = sizeof(client);
newsockid = accept(sockid, (struct sockaddr *) & client, (int *) & lengthc);
printf ("connect from %s\n", inet_ntoa(client.sin_addr));
return (newsockid);
}
static int accept_socket1(int sockid)
{
return 0;
/**//*
FD_SET (h, &rd);
nfds = max (nfds, h);
if (FD_ISSET (h, &rd)) {
unsigned int l;
struct sockaddr_in client_address;
memset (&client_address, 0, l = sizeof (client_address));
r = accept (h, (struct sockaddr *)&client_address, &l);
if (r < 0) {
perror ("accept()");
} else {
SHUT_FD1;
SHUT_FD2;
buf1_avail = buf1_written = 0;
buf2_avail = buf2_written = 0;
fd1 = r;
fd2 = connect_socket (forward_port, argv[3]);
if (fd2 < 0) {
SHUT_FD1;
} else
printf ("connect from %s\n", inet_ntoa(client_address.sin_addr));
}
}
*/
}
static int listen_socket (int listen_port)
{
struct sockaddr_in a;
int s;
int yes;
if ((s = socket (AF_INET, SOCK_STREAM, 0)) < 0)
{
perror ("socket");
return -1;
}
yes = 1;
if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *) &yes, sizeof (yes)) < 0)
{
perror ("setsockopt");
close (s);
return -1;
}
memset (&a, 0, sizeof (a));
a.sin_port = htons (listen_port);
a.sin_family = AF_INET;
if (bind(s, (struct sockaddr *) &a, sizeof (a)) < 0)
{
perror ("bind");
close (s);
return -1;
}
printf ("accepting connections on port %d\n", (int) listen_port);
listen (s, 10);
return s;
}
static int connect_socket (int connect_port, char *address)
{
struct sockaddr_in a;
int s;
if ((s = socket (AF_INET, SOCK_STREAM, 0)) < 0)
{
perror ("socket");
close (s);
return -1;
}
memset (&a, 0, sizeof (a));
a.sin_port = htons (connect_port);
a.sin_family = AF_INET;
if (!inet_aton(address, (struct in_addr *) &a.sin_addr.s_addr))
{
perror ("bad IP address format");
close (s);
return -1;
}
if (connect(s, (struct sockaddr *) &a, sizeof (a)) < 0)
{
perror ("connect()");
shutdown (s, SHUT_RDWR);
close (s);
return -1;
}
return s;
}
int rely(int fd1, int fd2)
{
char buf1[BUF_SIZE], buf2[BUF_SIZE];
int buf1_avail, buf1_written;
int buf2_avail, buf2_written;
buf1_avail = buf1_written = 0;
buf2_avail = buf2_written = 0;
for (;;)
{
int r, nfds = 0;
fd_set rd, wr, er;
FD_ZERO (&rd);
FD_ZERO (&wr);
FD_ZERO (&er);
/**//*可读socket一起放入select的可读句柄列表里*/
if (fd1 > 0 && buf1_avail < BUF_SIZE)
{
FD_SET (fd1, &rd);
nfds = max (nfds, fd1);
}
if (fd2 > 0 && buf2_avail < BUF_SIZE)
{
FD_SET (fd2, &rd);
nfds = max (nfds, fd2);
}
/**//*把可写socket两个一起放入select的可写句柄列表里*/
if (fd1 > 0 && buf2_avail - buf2_written > 0)
{
FD_SET (fd1, &wr);
nfds = max (nfds, fd1);
}
if (fd2 > 0 && buf1_avail - buf1_written > 0)
{
FD_SET (fd2, &wr);
nfds = max (nfds, fd2);
}
/**//*把有异常数据的socket两个一起放入select的异常句柄列表里*/
if (fd1 > 0)
{
FD_SET (fd1, &er);
nfds = max (nfds, fd1);
}
if (fd2 > 0)
{
FD_SET (fd2, &er);
nfds = max (nfds, fd2);
}
/**//*开始select*/
r = select (nfds + 1, &rd, &wr, &er, NULL);
if (r == -1 && errno == EINTR) continue;
if (r < 0)
{
perror ("select()");
return -1;
}
/**//* NB: read oob data before normal reads */
if (fd1 > 0)
if (FD_ISSET (fd1, &er))
{
char c;
errno = 0;
r = recv (fd1, &c, 1, MSG_OOB);
if (r < 1)
{
SHUT_FD1;
}
else
send (fd2, &c, 1, MSG_OOB);
}
if (fd2 > 0)
if (FD_ISSET (fd2, &er))
{
char c;
errno = 0;
r = recv (fd2, &c, 1, MSG_OOB);
if (r < 1)
{
SHUT_FD1;
}
else
send (fd1, &c, 1, MSG_OOB);
}
/**//* NB: read data from fd1 */
if (fd1 > 0)
if (FD_ISSET (fd1, &rd))
{
r = read (fd1, buf1 + buf1_avail, BUF_SIZE - buf1_avail);
if (r < 1)
{
SHUT_FD1;
}
else
buf1_avail += r;
}
/**//* NB: read data from fd2 */
if (fd2 > 0)
if (FD_ISSET (fd2, &rd))
{
r = read (fd2, buf2 + buf2_avail, BUF_SIZE - buf2_avail);
if (r < 1)
{
SHUT_FD2;
}
else
buf2_avail += r;
}
/**//* NB: write data to fd1 */
if (fd1 > 0)
if (FD_ISSET (fd1, &wr))
{
r = write (fd1, buf2 + buf2_written, buf2_avail - buf2_written);
if (r < 1)
{
SHUT_FD1;
}
else
buf2_written += r;
}
/**//* NB: write data to fd1 */
if (fd2 > 0)
if (FD_ISSET (fd2, &wr))
{
r = write (fd2, buf1 + buf1_written, buf1_avail - buf1_written);
if (r < 1)
{
SHUT_FD2;
}
else
buf1_written += r;
}
/**//* check if write data has caught read data */
if (buf1_written == buf1_avail) buf1_written = buf1_avail = 0;
if (buf2_written == buf2_avail) buf2_written = buf2_avail = 0;
/**//* one side has closed the connection, keep writing to the other side until empty */
if (fd1 < 0 && buf1_avail - buf1_written == 0)
{
SHUT_FD2;
}
if (fd2 < 0 && buf2_avail - buf2_written == 0)
{
SHUT_FD1;
}
if (fd1 < 0 && fd2 < 0 )
return 0;
}
return 0;
}
posted on 2008-08-05 16:35 dragonimp 阅读(312)
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