3proxy/src/socks.c

/*
   3APA3A simpliest proxy server
   (c) 2002-2016 by Vladimir Dubrovin <3proxy@3proxy.ru>

   please read License Agreement

*/

#include "proxy.h"
#define RETURN(xxx) { param->res = xxx; goto CLEANRET; }

char * commands[] = {"UNKNOWN", "CONNECT", "BIND", "UDPMAP"};

#define BUFSIZE 1024
#define LARGEBUFSIZE 67000

void * sockschild(struct clientparam* param) {
 int res;
 unsigned i=0;
 SOCKET s;
 unsigned size;
 SASIZETYPE sasize;
 unsigned short port = 0;
 char * buf=NULL;
 char c;
 char command=0;
 struct pollfd fds[3];
 int ver=0;
 int havepass = 0;
#ifndef NOIPV6
 struct sockaddr_in6 sin = {AF_INET6};
#else
 struct sockaddr_in sin = {AF_INET};
#endif
 int len;
 int heur = 0;


 param->service = S_SOCKS;

 if(!(buf = myalloc(BUFSIZE))) {RETURN(21);}
 memset(buf, 0, BUFSIZE);
 if ((ver = sockgetcharcli(param, conf.timeouts[SINGLEBYTE_L], 0)) != 5 && ver != 4) {
	RETURN(401);
 } /* version */
 param->service = ver;
 if(ver == 5){
	 if ((i = sockgetcharcli(param, conf.timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(441);} /* nmethods */
	 for (; i; i--) {
		if ((res = sockgetcharcli(param, conf.timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(441);}
		if (res == 2 && param->srv->needuser) {
			havepass = res;
		}
	 }
	 buf[0] = 5;
	 buf[1] = (param->srv->needuser > 1 && !havepass)? 255 : havepass;
	 if(socksend(param->clisock, buf, 2, conf.timeouts[STRING_S])!=2){RETURN(401);}
	 if (param->srv->needuser > 1 && !havepass) RETURN(4);
	 if (havepass) {
		if (((res = sockgetcharcli(param, conf.timeouts[SINGLEBYTE_L], 0))) != 1) {
			RETURN(412);
		}
		if ((i = sockgetcharcli(param, conf.timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(451);}
		if (i && (unsigned)(res = sockgetlinebuf(param, CLIENT, buf, i, 0, conf.timeouts[STRING_S])) != i){RETURN(441);};
		buf[i] = 0;
		if(!param->username)param->username = mystrdup(buf);
		if ((i = sockgetcharcli(param, conf.timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(445);}
		if (i && (unsigned)(res = sockgetlinebuf(param, CLIENT, buf, i, 0, conf.timeouts[STRING_S])) != i){RETURN(441);};
		buf[i] = 0;
		if(!param->password)param->password = mystrdup(buf);
		buf[0] = 1;
		buf[1] = 0;
		if(socksend(param->clisock, buf, 2, conf.timeouts[STRING_S])!=2){RETURN(481);}
	 }
	 if ((c = sockgetcharcli(param, conf.timeouts[SINGLEBYTE_L], 0)) != 5) {
		RETURN(421);
         } /* version */
 }
 if( (command = sockgetcharcli(param, conf.timeouts[SINGLEBYTE_S], 0)) < 1 || command > 3){command = 0; RETURN(407);} /* command */
 if(ver == 5){
	 if (sockgetcharcli(param, conf.timeouts[SINGLEBYTE_S], 0) == EOF) {RETURN(447);} /* reserved */
	 c = sockgetcharcli(param, conf.timeouts[SINGLEBYTE_S], 0); /* atype */
 }
 else {
	if ((res = sockgetcharcli(param, conf.timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(441);}
	buf[0] = (unsigned char) res;
	if ((res = sockgetcharcli(param, conf.timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(441);}
	buf[1] = (unsigned char) res;
	port = *(unsigned short*)buf;
	c = 1;
 }
 
 size = 4;
 *SAFAMILY(&param->sinsr) = *SAFAMILY(&param->req) = AF_INET;
 switch(c) {
#ifndef NOIPV6
	case 4:
		if(param->srv->family == 4) RETURN(997);
		size = 16;
		*SAFAMILY(&param->sinsr) = *SAFAMILY(&param->req) = AF_INET6;
#endif
	case 1:
		for (i = 0; i<size; i++){
			if ((res = sockgetcharcli(param, conf.timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(441);}
			buf[i] = (unsigned char)res;
		}
#ifndef NOIPV6
		if (c == 1 && param->srv->family==6){
			char prefix[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 255, 255};
			*SAFAMILY(&param->sinsr) = *SAFAMILY(&param->req) = AF_INET6;
			memcpy(SAADDR(&param->sinsr), prefix, 12);
			memcpy(12 + (char *)SAADDR(&param->sinsr), buf, 4);
			memcpy(SAADDR(&param->req), prefix, 12);
			memcpy(12 + (char *)SAADDR(&param->req), buf, 4);
		}
		else {
#endif
			memcpy(SAADDR(&param->sinsr), buf, size);
			memcpy(SAADDR(&param->req), buf, size);
#ifndef NOIPV6
		}
#endif
		if(command == 1 && SAISNULL(&param->req)) {
			RETURN(431);
		}
		myinet_ntop(*SAFAMILY(&param->sinsr), SAADDR(&param->sinsr), buf, 64);
		if(command == 3){
			if(*SAFAMILY(&param->req) == *SAFAMILY(&param->sincr) && !memcmp(SAADDR(&param->req),SAADDR(&param->sincr), SAADDRLEN(&param->req))){
				heur = 1;
			}
			else if (!SAISNULL(&param->req)){
				heur = 2;
			}
		}

		break;
	case 3:
		if ((size = sockgetcharcli(param, conf.timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(451);} /* nmethods */
		for (i=0; i<size; i++){ /* size < 256 */
			if ((res = sockgetcharcli(param, conf.timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(451);}
			buf[i] = (unsigned char)res;
		}
		buf[i] = 0;
		if(!getip46(param->srv->family, buf, (struct sockaddr *) &param->req)) RETURN(100);
		param->sinsr = param->req;
		break;
	default:
		RETURN(997);
 }
 if(param->hostname)myfree(param->hostname);
 param->hostname = mystrdup(buf);
 if (ver == 5) {
	 if ((res = sockgetcharcli(param, conf.timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(441);}
	 buf[0] = (unsigned char) res;
	 if ((res = sockgetcharcli(param, conf.timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(441);}
	 buf[1] = (unsigned char) res;
	 port = *(unsigned short*)buf;

 }
 else {
	sockgetlinebuf(param, CLIENT, buf, BUFSIZE - 1, 0, conf.timeouts[STRING_S]);
	buf[127] = 0;
	if(param->srv->needuser && *buf && !param->username)param->username = mystrdup(buf);
	if(!memcmp(SAADDR(&param->req), "\0\0\0", 3)){
		param->service = S_SOCKS45;
		sockgetlinebuf(param, CLIENT, buf, BUFSIZE - 1, 0, conf.timeouts[STRING_S]);
		buf[127] = 0;
		if(param->hostname)myfree(param->hostname);
		param->hostname = mystrdup(buf);
		if(!getip46(param->srv->family, buf, (struct sockaddr *) &param->req)) RETURN(100);
		param->sinsr = param->req;
	}
 }

 *SAPORT(&param->sinsr) = *SAPORT(&param->req) = port;
 if(command == 1 && !*SAPORT(&param->sinsr)) {RETURN(461);}
 switch(command) { 
	case 1:
	 param->operation = CONNECT;
	 break;
 	case 2:
	case 3:

#ifndef NOIPV6	 
	 param->sinsl = *SAFAMILY(&param->req)==AF_INET6? param->srv->extsa6 : (SAISNULL(&param->srv->extNat)?param->srv->extsa:param->srv->extNat);
#else
	 param->sinsl = SAISNULL(&param->srv->extNat)?param->srv->extsa:param->srv->extNat;
#endif
	 if ((param->remsock=so._socket(SASOCK(&param->req), command == 2? SOCK_STREAM:SOCK_DGRAM, command == 2?IPPROTO_TCP:IPPROTO_UDP)) == INVALID_SOCKET) {RETURN (11);}
	 param->operation = command == 2?BIND:UDPASSOC;
#ifdef REUSE
	if (command == 2){
		int opt;

#ifdef SO_REUSEADDR
		opt = 1;
		so._setsockopt(param->remsock, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(int));
#endif
#ifdef SO_REUSEPORT
		opt = 1;
		so._setsockopt(param->remsock, SOL_SOCKET, SO_REUSEPORT, &opt, sizeof(int));
#endif
	}
#endif
	 break;

	default:
	 RETURN(997);
 }

 if((res = (*param->srv->authfunc)(param))) {
	RETURN(res);
 }

 if(command > 1) {
	if(so._bind(param->remsock,(struct sockaddr *)&param->sinsl,SASIZE(&param->sinsl))) {
		*SAPORT(&param->sinsl) = 0;
		if(so._bind(param->remsock,(struct sockaddr *)&param->sinsl,SASIZE(&param->sinsl)))RETURN (12);
#if SOCKSTRACE > 0
fprintf(stderr, "%hu bound to communicate with server\n", *SAPORT(&param->sins));
fflush(stderr);
#endif
	}
	sasize = SASIZE(&param->sinsl);
	so._getsockname(param->remsock, (struct sockaddr *)&param->sinsl,  &sasize);
	if(command == 3) {
		param->ctrlsock = param->clisock;
		param->clisock = so._socket(SASOCK(&param->sincr), SOCK_DGRAM, IPPROTO_UDP);
		if(param->clisock == INVALID_SOCKET) {RETURN(11);}
		sin = param->sincl;
		*SAPORT(&sin) = 0;
		if(so._bind(param->clisock,(struct sockaddr *)&sin,SASIZE(&sin))) {RETURN (12);}
#if SOCKSTRACE > 0
fprintf(stderr, "%hu binded to communicate with client\n",
			ntohs(*SAPORT(&sin))
	);
fflush(stderr);
#endif
	}
 }
 param->res = 0;

CLEANRET:

 if(param->clisock != INVALID_SOCKET){
	int repcode;

	sasize = sizeof(sin);
	if(command != 3 && param->remsock != INVALID_SOCKET) so._getsockname(param->remsock, (struct sockaddr *)&sin,  &sasize);
	else so._getsockname(param->clisock, (struct sockaddr *)&sin,  &sasize);
#if SOCKSTRACE > 0
fprintf(stderr, "Sending confirmation to client with code %d for %s with %s:%hu\n",
			param->res,
			commands[command],
			inet_ntoa(sin.sin_addr),
			ntohs(sin.sin_port)
	);
fflush(stderr);
#endif
	if(!param->res) repcode = 0;
	else if(param->res <= 10) repcode = 2;
	else if (param->res < 20) repcode = 5;
	else if (param->res < 30) repcode = 1;
	else if (param->res < 100) repcode = 4;
	else repcode = param->res%10;

	if(ver == 5){
		buf[0] = 5;
		buf[1] = repcode;
		buf[2] = 0;
		buf[3] = (*SAFAMILY(&sin) == AF_INET)?1:4;
		memcpy(buf+4, SAADDR(&sin), SAADDRLEN(&sin));
		memcpy(buf+4+SAADDRLEN(&sin), SAPORT(&sin), 2);
		socksend((command == 3)?param->ctrlsock:param->clisock, buf, 6+SAADDRLEN(&sin), conf.timeouts[STRING_S]);
	}
	else{
		buf[0] = 0;
		buf[1] = 90 + !!(repcode);
		memcpy(buf+2, SAPORT(&sin), 2);
		memcpy(buf+4, SAADDR(&sin), 4);
		socksend(param->clisock, buf, 8, conf.timeouts[STRING_S]);
	}

	if (param->res == 0) {
		switch(command) {
			case 1:
				if(param->redirectfunc){
					if(buf)myfree(buf);
					return (*param->redirectfunc)(param);
				}
				param->res = mapsocket(param, conf.timeouts[CONNECTION_L]);
				break;
			case 2:
				so._listen (param->remsock, 1);
				
				fds[0].fd = param->remsock;
				fds[1].fd = param->clisock;
				fds[0].events = fds[1].events = POLLIN;
				res = so._poll(fds, 2, conf.timeouts[CONNECTION_L] * 1000);
				if (res < 1 || fds[1].revents) {
					res = 460;
					break;
				}
				sasize = sizeof(param->sinsr);
				s = so._accept(param->remsock, (struct sockaddr *)&param->sinsr, &sasize);
				so._closesocket(param->remsock);
				param->remsock = s;
				if(s == INVALID_SOCKET) {
					param->res = 462;
					break;
				}
				if(SAISNULL(&param->req) &&
				 memcmp(SAADDR(&param->req),SAADDR(&param->sinsr),SAADDRLEN(&param->req))) {
					param->res = 470;
					break;
				}
#if SOCKSTRACE > 0
fprintf(stderr, "Sending incoming connection to client with code %d for %s with %hu\n",
			param->res,
			commands[command],
			*SAPORT(param->sins);
	);
fflush(stderr);
#endif
				if(ver == 5){
					buf[3] = (*SAFAMILY(&param->sinsr) == AF_INET)?1:4;
					memcpy(buf+4, SAADDR(&param->sinsr), SAADDRLEN(&param->sinsr));
					memcpy(buf+4+SAADDRLEN(&param->sinsr), SAPORT(&param->sinsr), 2);
					socksend(param->clisock, buf, 6+SAADDRLEN(&param->sinsr), conf.timeouts[STRING_S]);
				}
				else {
					memcpy (buf+2, SAPORT(&param->sinsr), 2);
					memcpy (buf+4, SAADDR(&param->sinsr), 4);
					socksend(param->clisock, buf, 8, conf.timeouts[STRING_S]);
				}

				param->res = mapsocket(param, conf.timeouts[CONNECTION_S]);
				break;
			case 3:
				param->sinsr = param->req;
				myfree(buf);
				if(!(buf = myalloc(LARGEBUFSIZE))) {RETURN(21);}
				sin = (heur == 1)?param->req:param->sincr;

				fds[2].events = fds[1].events = fds[0].events = 0;
				fds[0].fd = param->remsock;
				fds[1].fd = param->clisock;
				fds[2].fd = param->ctrlsock;
				for(;;){

					if(!fds[1].events || fds[1].revents){
						sasize = sizeof(sin);
						len = so._recvfrom(param->clisock, (char *)buf, 65535, 0, (struct sockaddr *)&sin, &sasize);
						if(len >= 0) {
							fds[1].events = fds[1].revents = 0;
							if(len < 10) continue;

							sasize = sizeof(sin);
							if(len <= 10) {
								param->res = 464;
								break;
							}
							if(SAADDRLEN(&sin) != SAADDRLEN(&param->sincr) || memcmp(SAADDR(&sin), SAADDR(&param->sincr), SAADDRLEN(&sin)) || (heur == 1 && *SAPORT(&param->sincr)!=*SAPORT(&sin))){
								if(heur == 1){
#if SOCKSTRACE > 0
fprintf(stderr, "internal UDP packet ignored\n");
fflush(stderr);
#endif
									sin = param->req;
									continue;
								}

								param->res = 465;
								break;
							}
							if(buf[0] || buf[1] || buf[2]) {
								param->res = 466;
								break;
							}
							size = 4;
							switch(buf[3]) {
								case 4:
									size = 16;
								case 1:
									i = 4+size;
									memcpy(SAADDR(&param->sinsr), buf+4, size);
									*SAFAMILY(&param->sinsr) = (size == 4)?AF_INET:AF_INET6;
									break;
								case 3:
									size = buf[4];
									for (i=4; size; i++, size--){
										buf[i] = buf[i+1];
									}
									buf[i++] = 0;
									if(!getip46(param->srv->family, buf+4, (struct sockaddr *) &param->sinsr)) RETURN(100);
									break;
								default:
									RETURN(997);
							 }

							memcpy(SAPORT(&param->sinsr), buf+i, 2);
							i+=2;

							sasize = sizeof(param->sinsr);
							if(len > (int)i){
								socksendto(param->remsock, (struct sockaddr *)&param->sinsr, buf+i, len - i, conf.timeouts[SINGLEBYTE_L]*1000);
								param->statscli64+=(len - i);
								param->nwrites++;
#if SOCKSTRACE > 1
fprintf(stderr, "UDP packet relayed from client to %s:%hu size %d, header %d\n",
			inet_ntoa(param->sins.sin_addr),
			ntohs(param->sins.sin_port),
			(len - i),
			i
	);
fprintf(stderr, "client address is assumed to be %s:%hu\n",
			inet_ntoa(sin.sin_addr),
			ntohs(sin.sin_port)
	);
fflush(stderr);
#endif
							}
							continue;
						}
						else if(len ==0 || (len <0 && errno != EINTR && errno != EAGAIN)){
							param->res = 464;
							break;
						}
						fds[1].events = POLLIN;
					}
					if (!fds[0].events || fds[0].revents) {
						sasize = sizeof(param->sinsr);
						buf[0]=buf[1]=buf[2]=0;
						buf[3]=(*SAFAMILY(&param->sinsl) == AF_INET)?1:4;
						len = so._recvfrom(param->remsock, (char *)buf+6+SAADDRLEN(&param->sinsl), 65535 - (6+SAADDRLEN(&param->sinsl)), 0, (struct sockaddr *)&param->sinsr, &sasize);
						if(len == 0 || (len < 0 && errno != EAGAIN && errno !=EINTR)) {
							param->res = 468;
							break;
						}
						else if(len > 0){
							fds[0].events = fds[0].revents = 0;
							param->statssrv64+=len;
							param->nreads++;
							if(!*SAPORT(&sin) || (heur == 2 && (*SAFAMILY(&param->sinsr) != *SAFAMILY(&param->req) || memcmp(SAADDR(&param->sinsr),SAADDR(&param->req), SAADDRLEN(&param->req))))){
#if SOCKSTRACE > 0
fprintf(stderr, "external UDP packet ignored\n");
fflush(stderr);
#endif
									continue;
							}
							memcpy(buf+4, SAADDR(&param->sinsr), SAADDRLEN(&param->sinsr));
							memcpy(buf+4+SAADDRLEN(&param->sinsr), SAPORT(&param->sinsr), 2);
							sasize = sizeof(sin);
							socksendto(param->clisock, (struct sockaddr *)&sin, buf, len + 6 + SAADDRLEN(&param->sinsr), conf.timeouts[SINGLEBYTE_L]*1000);
#if SOCKSTRACE > 1
fprintf(stderr, "UDP packet relayed to client from %hu size %d\n",
			ntohs(*SAPORT(&param->sinsr)),
			len
	);
fflush(stderr);
#endif

							continue;
						}
						fds[0].events = POLLIN;
					}
	
					if (fds[2].revents) {
						param->res = 0;
						break;
					}

					fds[0].revents = fds[1].revents = fds[2].revents = 0;
					fds[2].events = POLLIN;
					res = so._poll(fds, 3, conf.timeouts[CONNECTION_L]*1000);
					if(res == 0 || (res < 0 && errno != EAGAIN && errno != EINTR)) {
						param->res = 463;
						break;
					}
				}
				break;
			default:
				param->res = 417;
				break;
		}
	}
 }
 
 if(command > 3) command = 0;
 if(buf){
	 sprintf((char *)buf, "%s ", commands[command]);
	 if(param->hostname){
	  sprintf((char *)buf + strlen((char *)buf), "%.265s", param->hostname);
	 }
	 else 
		myinet_ntop(*SAFAMILY(&param->req), SAADDR(&param->req), (char *)buf + strlen((char *)buf), 64);
         sprintf((char *)buf+strlen((char *)buf), ":%hu", ntohs(*SAPORT(&param->req)));
	 dolog(param, buf);
	 myfree(buf);
 }
 freeparam(param);
 return (NULL);
}

#ifdef WITHMAIN
struct proxydef childdef = {
	sockschild,
	1080,
	0,
	S_SOCKS,
	"-N(EXTERNAL_IP) External NAT address to report to client for BIND\n"
};
#include "proxymain.c"
#include "log.c"
#endif