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tcp-proxy.c
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tcp-proxy.c
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#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <event.h>
#define MAX_CACHED 8000
#define MAX_CONNECTIONS 2
unsigned int daddr;
unsigned short dport;
char *host;
struct maps{
evutil_socket_t *self_sock;
evutil_socket_t *other_sock;
struct bufferevent *other_bev;
};
void read_cb(struct bufferevent *bev, void *ctx);
//Sets a socket descriptor to nonblocking mode
void setnonblock(int fd)
{
int flags;
flags = fcntl(fd, F_GETFL);
flags |= O_NONBLOCK;
fcntl(fd, F_SETFL, flags);
}
//Translates hostname to IP address
int hostname_to_ip(char *hostname , char *ip)
{
struct hostent *he;
struct in_addr **addr_list;
int i;
if((he = gethostbyname(hostname)) == NULL)
{
// get the host info
herror("gethostbyname");
return 1;
}
addr_list = (struct in_addr **) he->h_addr_list;
for(i = 0; addr_list[i] != NULL; i++)
{
//Return the first one;
strcpy(ip , inet_ntoa(*addr_list[i]) );
return 0;
}
return 1;
}
void error_cb(struct bufferevent *bev, short error, void *map_b)
{
struct maps *map = ((struct maps *)map_b);
if ((error & BEV_EVENT_EOF) || (error & BEV_EVENT_READING)) {
/* EOF */
if(*map->other_sock > 0){
//Says eof has been reached
//checks if mapped sock is at eof
shutdown(*map->other_sock, SHUT_RD);
*map->self_sock = -1;
free(map);
} else {
close(*map->self_sock);
close(bufferevent_getfd(map->other_bev));
bufferevent_free(bev);
bufferevent_free(map->other_bev);
free(map);
}
} else if ((error & BEV_EVENT_WRITING) || (error & BEV_EVENT_ERROR)){
close(*map->self_sock);
close(bufferevent_getfd(map->other_bev));
bufferevent_free(bev);
bufferevent_free(map->other_bev);
free(map);
}
}
void write_cb(struct bufferevent *bev, void *map_b)
{
struct bufferevent *partner = ((struct maps *)map_b)->other_bev;
bufferevent_setcb(bev, read_cb, NULL, error_cb, partner);
bufferevent_setwatermark(bev, EV_WRITE, 0, MAX_CACHED);
if (partner)
bufferevent_enable(partner, EV_READ);
}
void read_cb(struct bufferevent *bev, void *map_b)
{
struct bufferevent *partner = ((struct maps *)map_b)->other_bev;
struct evbuffer *src;
size_t len;
src = bufferevent_get_input(bev);
if (!partner) {
len = evbuffer_get_length(src);
evbuffer_drain(src, len);
return;
}
bufferevent_write_buffer(partner, src);
if (evbuffer_get_length(src) >= MAX_CACHED) {
bufferevent_setcb(partner, read_cb, write_cb, error_cb, bev);
bufferevent_setwatermark(partner, EV_WRITE, MAX_CACHED/2, MAX_CACHED);
bufferevent_disable(bev, EV_READ);
}
}
void accept_cb(evutil_socket_t fd, short what, void *base_b)
{
struct event_base *base = event_base_new();
struct evdns_base *dns_base;
struct sockaddr_storage ss;
socklen_t slen = sizeof(ss);
//sem_wait(&connections);
evutil_socket_t source_sock = accept(fd, (struct sockaddr *)&ss, &slen);
if (source_sock < 0) {
perror("accept");
} else if (source_sock > FD_SETSIZE) {
close(fd);
} else {
setnonblock(source_sock);
struct bufferevent *bev_in, *bev_out;
bev_in = bufferevent_socket_new(base_b, source_sock, BEV_OPT_CLOSE_ON_FREE);
bev_out = bufferevent_socket_new(base_b, -1, BEV_OPT_CLOSE_ON_FREE);
dns_base = evdns_base_new(base_b, 1);
bufferevent_socket_connect_hostname(bev_out, dns_base, AF_INET, host, dport);
evutil_socket_t server_sock = bufferevent_getfd(bev_out);
setnonblock(server_sock);
struct maps *map_in, *map_out;
map_in = (struct maps *)malloc(sizeof(struct maps));
map_out = (struct maps *)malloc(sizeof(struct maps));
map_in->self_sock = &source_sock;
map_in->other_sock = &server_sock;
map_in->other_bev = bev_out;
map_out->self_sock = &server_sock;
map_out->other_sock = &source_sock;
map_out->other_bev = bev_in;
bufferevent_setcb(bev_in, read_cb, NULL, error_cb, map_in);
bufferevent_setwatermark(bev_in, EV_READ|EV_WRITE, 0, MAX_CACHED);
bufferevent_setcb(bev_out, read_cb, NULL, error_cb, map_out);
bufferevent_setwatermark(bev_out, EV_READ|EV_WRITE, 0, MAX_CACHED);
struct timeval *timeout = (struct timeval *)malloc(sizeof(struct timeval));
timeout->tv_usec = 0;
timeout->tv_sec = 10;
bufferevent_set_timeouts(bev_in, NULL, timeout);
bufferevent_set_timeouts(bev_out, NULL, timeout);
bufferevent_priority_set(bev_in, 0);
bufferevent_priority_set(bev_out, 0);
bufferevent_enable(bev_out, EV_READ|EV_WRITE);
bufferevent_enable(bev_in, EV_READ|EV_WRITE);
event_base_dispatch(base);
free(timeout);
}
}
int main(int argc, char **argv)
{
int socketlisten;
struct sockaddr_in addresslisten;
int reuse = 1;
if(argc != 4)
{
printf("Usage: %s destination-host destination-port listening-port\n", argv[0]);
return 0;
}
//sem_init(&connections, 0, MAX_CONNECTIONS);
daddr = inet_addr(argv[1]);
host = argv[1];
if(daddr == INADDR_NONE)
{
char temp[100];
hostname_to_ip(argv[1], temp);
daddr = inet_addr(temp);
}
dport = atoi(argv[2]);
event_init();
struct event_base *base = event_base_new();
//Create listening socket
socketlisten = socket(AF_INET, SOCK_STREAM, 0);
if (socketlisten < 0)
{
fprintf(stderr,"Failed to create listen socket");
return 1;
}
//Init listening structure
memset(&addresslisten, 0, sizeof(addresslisten));
addresslisten.sin_family = AF_INET;
addresslisten.sin_addr.s_addr = INADDR_ANY;
addresslisten.sin_port = htons(atoi(argv[3]));
//Binding
if (bind(socketlisten,
(struct sockaddr *)&addresslisten,
sizeof(addresslisten)) < 0)
{
fprintf(stderr,"Failed to bind\n");
return 1;
}
//Listen
if (listen(socketlisten, 5) < 0)
{
fprintf(stderr,"Failed to listen to socket\n");
return 1;
}
//Set some socket properties
setsockopt(socketlisten, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse));
setnonblock(socketlisten);
//Add accept callback
struct event *accept_event = event_new(base, socketlisten, EV_READ | EV_PERSIST, accept_cb, base);
event_add(accept_event, NULL);
event_base_dispatch(base);
//If dispatch returns for some reason....
event_free(accept_event);
close(socketlisten);
return 0;
}