Three of Socks5 Proxy (GCC) for your QQ

This article uses QQ as an object, teach you how to write a SOCKS5 Proxy this chapter mainly introduces the working principle of launch_udp ()

First, SOCKS5 UDP package structure =========================== order: 2 bytes reserved word, must be 0x01 bytes current fragment number1 bytes Address Type X bytes Destination Address 2 Bytes Destination Port number n bytes Data

Second, source code ============================

void Launch_UDP (int udp_proxy_port, const char * udp_proxy_ip, int clt_udp_port) {// port is NOT network orders // record the machine, client, server, and the distal end of the packet the source address struct sockaddr_in servaddr, clientaddr, remoteaddr, inaddr; int inlen INT listenfd; int N; fd_set set; // After writing the received data in the buffer 11th byte, the first 10 Bytes is used to store Header char * thisbuf = & buf [10]; int thissize = bufsz - 10;

Printf (" / n / n");

// create a UDP SOCKET, UDP protocol does not need to pay attention to listen, accept and conenct memset (& servaddr, 0, sizeof (servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_port = htons (udp_proxy_port); servaddr.sin_addr.s_addr = HTONL (INADDR_Any);

Memset (Remoteaddr, 0, SizeOf (RemoteAddr)); RemoteAddr.sin_Family = AF_INET; Listenfd = Socket (AF_INET, SOCK_DGRAM, 0); if (listenfd <0) {p_ERROR ("socket error"); exit (-1); }

IF (Bind (Struct SockAddr *) & Servaddr, SizeOf (Servaddr)) <0) {p_error ("bind error"); exit (-1);

// Use SELECT to monitor if there is information to read FD_ZERO (& Set); FD_SET (Listenfd, & Set);

While (1) {

IF (SELECT (Listenfd 1, & set, NULL, NULL, NULL) <0) {p_error ("select error"); exit (-1);} if (fd_isset (listenfd, & set)) {// UDP protocol Use RECVFROM () to receive data, and obtain the source address N = Recvfrom (Listenfd, thisbuf, thissize, 0, (strunt sockaddr *) & inaddr, & inlen; if (n> = 0) {Debug_Showip (& INADDR, "Received from "," / n "); // Information from client IF ((Thisbuf [0] == 0x0) && (Thisbuf [1] == 0x0) && (htons (inaddr.sin_port) == CLT_UDP_PORT)) {/ / Save the client's address Memcpy (& ClientAddr); if (thisbuf [3]! = 0x1) {// If the destination address type is domain name, advance row resolution Get IP and send Struct Hostent * h; CHAR TMP [256]; Int Seg; Strncpy (TMP, & thisbuf [5], Thisbuf [4]); TMP [thisbuf [4]] = 0;

H = gethostByname (TMP); // if (h == null) p_ERROR ("unknown domain name / n"); else {remoteaddr.sin_addr.s_addr = (* (struct in_addr *) h-> h_addr; seg = thisbuf [4] 1; Memcpy (& Remoteaddr.sin_Port, & thisbuf [4 seg], 2); debug_showbin (thisbuf, 4 seg 2, "Recv client [header]," / N "); debug_showbin (& thisbuf [4 seg 2], N- (4 seg 2)," Recv client [data] "," / n "); debug_showip (& Remoteaddr," Send to Domain "," / N / N "); SendTo (Listenfd, & Thisbuf [4 Seg 2], N- (4 Seg 2), 0, (Struct SockAddr *) & Remoteaddr, SizeOf (RemoteAdddd);}} else {/ / Destination address is IPv4, send data directly to Memcpy (& Remoteaddr.SIN_PORT, & THISBUF [8], 2); Memcpy (& Remoteaddr.sin_addr.s_addr, & thisbuf [4], 4); debug_showbin (thisbuf, 10, "RECV Client [header], "/ n"); debug_showbin (& thisbuf [10], N-10, "Recv client [data]", "/ n"); debug_showip (& RemoteAddr, "Send to IP", "/ N / n "); sendto (list Enfd, & Thisbuf [10], N-10, 0, (Struct SockAddr *) & RemoteAddr, SizeOf (RemoteAddr));}} else {// Data from remote server debug_showbin (thisbuf, n, "recv remote", "/ N "); debug_showip (& ClientAddr," Send to CLT "," / N "); // Write Header BUF [0] = 0x0; BUF [1] = 0x0; BUF [2] = 0x0; buf [3 ] = 0x1; Memcpy (& BUF [4], & UDP_Proxy_IP, 4); Memcpy (& Buf [8], & UDP_Proxy_Port, 2);

// Send to the client Sendto (Listenfd, BUF, N 10, 0, (Struct Sockaddr *) & Clientaddr, SizeOf (ClientAddr));}}}}}}}; printfd); Printf (" ​​/ n / n ");} III, test =================== to now, the entire proxy has been completed, you can test it with QQ, after the connection QQ and far The information transmitted between the end servers will be displayed on the screen, we can also intercept the data, thus bringing annoying ads to :)

Download the source code of this chapter → mysocks5.c