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114 lines
3.3 KiB
C
114 lines
3.3 KiB
C
#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include "easysock.h"
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#define PROG_NAME "basicproxy"
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#define PROG_VER "0.01"
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void forward_data(int from_fd, int to_fd) {
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int n = 0;
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char* buffer = malloc(3000*sizeof(char));
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while ((n = recv(from_fd, buffer, 3000, 0)) > 0) { // read data from input socket
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send(to_fd, buffer, n, 0); // send data to output socket
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}
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}
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void print_prog_info() {
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printf("%s [Local IP address] [local port] [remote IP address] [remote port]\n",PROG_NAME);
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}
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void print_version_info() {
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printf("%s %s\n",PROG_NAME,PROG_VER);
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}
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void print_help_info() {
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printf("\n%s - A simple TCP proxy written in C.\n\n",PROG_NAME);
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printf("Syntax - ");
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print_prog_info();
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printf("[Local IP address] - The local address to bind to\n"
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"[local port] - The local port to listen on\n"
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"[remote IP address] - The remote IP to connect to\n"
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"[remote port] - The remote port to connect to\n");
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printf("\nExample: %s 127.0.0.1 3000 1.2.3.4 5000 - Listen on '127.0.0.1:3000', and forward all data from there to '1.2.3.4:5000'\n\n",PROG_NAME);
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}
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int main(int argc,char* argv[]) {
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/* argv[1] = local address
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argv[2] = local port
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argv[3] = remote address
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argv[4] = remote port */
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if (argc == 2) {
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if (strcmp(argv[1],"-v") == 0 || strcmp(argv[1],"--version") == 0) {
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print_version_info();
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exit(0);
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} else if (strcmp(argv[1],"-h") == 0 || strcmp(argv[1],"--help") == 0) {
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print_help_info();
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exit(0);
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}
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}
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if (argc != 5) {
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print_prog_info();
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exit(230);
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}
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char* local_addr = argv[1];
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int local_port = strtol(argv[2],NULL,10);
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char* remote_addr = argv[3];
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int remote_port = strtol(argv[4],NULL,10);
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int preferred_local_network = check_ip_ver(local_addr);
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int preferred_remote_network = check_ip_ver(remote_addr);
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if (preferred_remote_network < 0) { /* This value will be less than 0 if the remote address is a domain name */
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printf("Using %d for local\nUsing hostname for remote\n",preferred_local_network);
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} else {
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printf("Using %d for local\nUsing %d for remote\n",preferred_local_network,preferred_remote_network);
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}
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if (preferred_local_network == -1) {
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exit(207); /* If the _local_ address isn't an IP address, then we've got problems. */
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}
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char preferred_transport = 'T';
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struct sockaddr addr_struct;
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int server_sock = create_local(preferred_local_network,preferred_transport,local_addr,local_port,&addr_struct);
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int addrlen;
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if (check_ip_ver(local_addr) == 4) {
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addrlen = sizeof(struct sockaddr_in);
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} else if (check_ip_ver(local_addr) == 6) {
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addrlen = sizeof(struct sockaddr_in6);
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} else {
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exit(207);
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}
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listen(server_sock,50); /* Arbitrary number, change later */
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printf("Listening on %s:%d\n",local_addr,local_port);
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struct sockaddr remote_addr_struct;
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while (1) {
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int from_client = accept(server_sock,&addr_struct,(socklen_t *)&addrlen);
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int to_server = create_remote(preferred_remote_network,preferred_transport,remote_addr,remote_port,&remote_addr_struct);
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printf("Connection established to %s:%d\n",remote_addr,remote_port);
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if (fork() == 0) {
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/* fork returns 0 for a child, so we're in the child's execution
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right now */
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close(server_sock);
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if (fork() == 0) {
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forward_data(from_client,to_server);
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exit(0);
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}
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if (fork() == 0) {
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forward_data(to_server,from_client);
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exit(0);
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}
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exit(0);
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}
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}
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}
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