basic-proxy/main.c

#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>
#include "easysock.h"

void forward_data(int from_fd, int to_fd) {
	int n = 0;
        char* buffer = malloc(3000*sizeof(char));
	while ((n = recv(from_fd, buffer, 3000, 0)) > 0) { // read data from input socket
        	send(to_fd, buffer, n, 0); // send data to output socket
	}
}

int check_ip_ver(char* address) {
	char buffer[16]; /* 16 chars - 128 bits - is enough to hold an ipv6 address */
	if (inet_pton(AF_INET,address,buffer) == 1) {
		return 4;
	} else if (inet_pton(AF_INET6,address,buffer) == 1) {
		return 6;
	} else {
		return -1;
	}
}


int main(int argc,char* argv[]) {

/* argv[1] = local address
   argv[2] = local port
   argv[3] = remote address
   argv[4] = remote port */

	char* local_addr = argv[1];
	int local_port = strtol(argv[2],NULL,10);
	char* remote_addr = argv[3];
	int remote_port = strtol(argv[4],NULL,10);

	int preferred_local_network = check_ip_ver(local_addr);
	int preferred_remote_network = check_ip_ver(remote_addr);
	printf("Using %d for local\nUsing %d for remote\n",preferred_local_network,preferred_remote_network);
	
	if ((preferred_local_network == -1) || (preferred_remote_network == -1)) {
		exit(-7);
	}

	char preferred_transport = 'T';
	struct sockaddr addr_struct;
	int server_sock = create_local(preferred_local_network,preferred_transport,local_addr,local_port,&addr_struct);
	int addrlen = sizeof(addr_struct);

	listen(server_sock,50);  /* Arbitrary number, change later */

	printf("Listening on %s:%d\n",local_addr,local_port);
	while (1) {
	int from_client = accept(server_sock,&addr_struct,(socklen_t *)&addrlen);	
	int to_server = create_remote(preferred_remote_network,preferred_transport,remote_addr,remote_port);

	printf("Connection established to %s:%d\n",remote_addr,remote_port);
	if (fork() == 0) {

	/* fork returns 0 for a child, so we're in the child's execution
	   right now */
		close(server_sock);
		if (fork() == 0) {
			forward_data(from_client,to_server);
			exit(0);
		}
		if (fork() == 0) {
			forward_data(to_server,from_client);
			exit(0);
		}
		exit(0);


	}
//	recv(from_client,buffer,3000,0);
			

//	printf("%s",buffer);
	

	}

}