#include<signal.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/ip.h>
#include<netdb.h>
#include<arpa/inet.h>
#include<stdio.h>
#include<unistd.h>
#include<stdlib.h>
#include<pthread.h>

short from_inside_port = 6000;
short local_port = 22;

struct pt_param {
	int in_fd;
	int out_fd;
};

void* pass_through(void *p){
	struct pt_param *ptp = p;
	char buffer[2048];
	ssize_t readlen;
	while(1){
		readlen = read(ptp->in_fd, buffer, 2048); 
		printf("Read %ld bytes, passing from fd %d to %d\n", readlen, ptp->in_fd, ptp->out_fd);
		if(readlen < 1)
			break;
		if(write(ptp->out_fd, buffer, readlen) != readlen)
			break;
	}
	printf("Terminating forward from fd %d to fd %d\n", ptp->in_fd, ptp->out_fd);
}

int main(int argc, char ** argv){
	struct sockaddr_in sad;
	if(argc > 2)
		from_inside_port = atoi(argv[2]);
	sad.sin_port = htons(from_inside_port);
	sad.sin_family = AF_INET;

	int skt = socket(AF_INET, SOCK_STREAM, 0);

	// do a dns lookup
	struct hostent* entry = gethostbyname(argv[1]);
	if(!entry){
		if(h_errno == HOST_NOT_FOUND){
			printf("This is our own message that says the host wasn't found\n");
		}
		herror("gethostbyname");
		return 1;
	}
	struct in_addr **addr_list = (struct in_addr**)entry->h_addr_list;
	struct in_addr* c_addr = addr_list[0];
	char* ip_string = inet_ntoa(*c_addr);
	sad.sin_addr = *c_addr; // copy the address we found into sad
									// Finally done with DNS!
	printf("Connecting to:  %s\n", ip_string);

	if( connect(skt, (struct sockaddr*)&sad, sizeof(struct sockaddr_in)) ){
		perror("connect");
		return 1;
	}
	printf("Inside connection is ready!\n");
	// skt is the outside connection

	sad.sin_port = htons(local_port);
	sad.sin_family = AF_INET;

	int lskt = socket(AF_INET, SOCK_STREAM, 0);

	sad.sin_addr.s_addr = 0x0100007F;
	printf("We think localhost is %s\n", inet_ntoa(sad.sin_addr));

	if( connect(lskt, (struct sockaddr*)&sad, sizeof(struct sockaddr_in)) ){
		perror("connect");
		return 1;
	}
	printf("Local connection is ready!\n");

	// Pass to inside loop
	// But it should go both directions!
	pthread_t threads[2];
	struct pt_param outside_to_inside = {skt, lskt};
	struct pt_param inside_to_outside = {lskt, skt};

	pthread_create(&threads[0], 0, pass_through, &outside_to_inside);
	pthread_create(&threads[1], 0, pass_through, &inside_to_outside);

	for(int i = 0; i < 2; i++)
		pthread_join(threads[i], 0);

	close(skt);
	close(lskt);
	return 0;
}