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3proxy/src/socks.c
Vladimir Dubrovin 3d20e1104e
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resolver: per service, defaultresolve, fakeresolve or sysresolve 
Each service resolves names the way the last of defaultresolve (the name
servers in force, configured or the system's with the hosts file),
fakeresolve (127.0.0.2) and sysresolve (the C library) read before it
says; the last one in the configuration also applies outside services.
defaultresolve is the new command, and the default.

The name servers and the hosts file no longer depend on the mode: nserver
lines, or the system's, are always in force, so dnspr keeps forwarding;
with fakeresolve it does not, as before. fakeresolver moves to common.c,
which the standalone services link without resolve.c.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-21 18:45:48 +03:00

440 lines
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/*
3APA3A simplest proxy server
(c) 2002-2026 by Vladimir Dubrovin <vlad@3proxy.org>
please read License Agreement
*/
#include "proxy.h"
#define RETURN(xxx) { param->res = xxx; goto CLEANRET; }
unsigned char * commands[] = {(unsigned char *)"UNKNOWN", (unsigned char *)"CONNECT", (unsigned char *)"BIND", (unsigned char *)"UDPMAP"};
#define BUFSIZE 1024
#if SOCKSTRACE > 0
char tracebuf[256];
#endif
static void printcommand(unsigned char * buf, int command, struct clientparam *param){
sprintf((char *)buf, "%s ", commands[command]);
if(*param->hostname){
sprintf((char *)buf + strlen((char *)buf), "%.256s", 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)));
}
void * sockschild(struct clientparam* param) {
int res;
unsigned i=0;
SOCKET s;
unsigned size;
SASIZETYPE sasize;
uint16_t port = 0;
/* a filter may hand back a buffer of its own in place of this one */
unsigned char * buf = param->tmpbuf;
/* the line logged, made apart from buf: logging makes its own line in
the scratch buffer */
unsigned char logline[340];
unsigned char c;
unsigned char command=0;
struct pollfd fds[3];
int ver=0;
int havepass = 0;
PROXYSOCKADDRTYPE sin;
param->service = S_SOCKS;
memset(buf, 0, BUFSIZE);
if ((ver = sockgetcharcli(param, param->srv->timeouts[SINGLEBYTE_L], 0)) != 5 && ver != 4) {
RETURN(401);
} /* version */
param->service = ver;
if(ver == 5){
if ((i = sockgetcharcli(param, param->srv->timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(441);} /* nmethods */
for (; i; i--) {
if ((res = sockgetcharcli(param, param->srv->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, param->clisock, buf, 2, param->srv->timeouts[STRING_S])!=2){RETURN(401);}
if (param->srv->needuser > 1 && !havepass) RETURN(4);
if (havepass) {
if (((res = sockgetcharcli(param, param->srv->timeouts[SINGLEBYTE_L], 0))) != 1) {
RETURN(412);
}
if ((i = sockgetcharcli(param, param->srv->timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(451);}
if (i && (res = sockgetlinebuf(param, CLIENT, buf, i, 0, param->srv->timeouts[STRING_S])) != (int)i) {RETURN(441);}
buf[i] = 0;
if(!*param->username) {
if(PARAMSTR(param, username, buf)){RETURN(21);}
}
if ((i = sockgetcharcli(param, param->srv->timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(445);}
if (i && (res = sockgetlinebuf(param, CLIENT, buf, i, 0, param->srv->timeouts[STRING_S])) != (int)i) {RETURN(441);}
buf[i] = 0;
if(!*param->password) {
if(PARAMSTR(param, password, buf)){RETURN(21);}
}
buf[0] = 1;
buf[1] = 0;
if(socksend(param, param->clisock, buf, 2, param->srv->timeouts[STRING_S])!=2){RETURN(481);}
}
if ((c = sockgetcharcli(param, param->srv->timeouts[SINGLEBYTE_L], 0)) != 5) {
RETURN(421);
}
}
if( (command = sockgetcharcli(param, param->srv->timeouts[SINGLEBYTE_S], 0)) < 1 || command > 3){command = 0; RETURN(407);} /* command */
if(ver == 5){
if (sockgetcharcli(param, param->srv->timeouts[SINGLEBYTE_S], 0) == EOF) {RETURN(447);} /* reserved */
c = sockgetcharcli(param, param->srv->timeouts[SINGLEBYTE_S], 0); /* atype */
}
else {
if ((res = sockgetcharcli(param, param->srv->timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(441);}
buf[0] = (unsigned char) res;
if ((res = sockgetcharcli(param, param->srv->timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(441);}
buf[1] = (unsigned char) res;
memcpy(&port, buf, 2);
c = 1;
}
size = 4;
switch(c) {
#ifndef NOIPV6
case 4:
size = 16;
#endif
case 1:
for (i = 0; i<size; i++){
if ((res = sockgetcharcli(param, param->srv->timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(441);}
buf[i] = (unsigned char)res;
}
res = socks5_setaddr(param->srv->family, c, buf, &param->req);
if(res == 1) {RETURN(997);}
if(res == 2 && command == 1) {RETURN(431);}
param->sinsr = param->req;
myinet_ntop(*SAFAMILY(&param->sinsr), SAADDR(&param->sinsr), (char *)buf, 64);
break;
case 3:
if ((size = sockgetcharcli(param, param->srv->timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(451);} /* nmethods */
for (i=0; i<size; i++){ /* size < 256 */
if ((res = sockgetcharcli(param, param->srv->timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(451);}
buf[i] = (unsigned char)res;
}
buf[i] = 0;
if(command == 2 && param->srv->family != 6 && (!strcmp((char *)buf, "0.0.0.0") || !strcmp((char *)buf, "0"))) param->req = param->srv->extsa;
else if(!getip46m(param->srv->resolvmode, param->srv->family, buf, (struct sockaddr *) &param->req)) RETURN(100);
param->sinsr = param->req;
break;
default:
RETURN(997);
}
if(PARAMSTR(param, hostname, buf)){RETURN(21);}
if (ver == 5) {
if ((res = sockgetcharcli(param, param->srv->timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(441);}
buf[0] = (unsigned char) res;
if ((res = sockgetcharcli(param, param->srv->timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(441);}
buf[1] = (unsigned char) res;
memcpy(&port, buf, 2);
}
else {
if(sockgetlinebuf(param, CLIENT, buf, BUFSIZE - 1, 0, param->srv->timeouts[STRING_S]) < 0) {RETURN(441);}
buf[127] = 0;
if(param->srv->needuser && *buf && !*param->username) {
if(PARAMSTR(param, username, buf)){RETURN(21);}
}
if(!memcmp(SAADDR(&param->req), "\0\0\0", 3)){
param->service = S_SOCKS45;
if(sockgetlinebuf(param, CLIENT, buf, BUFSIZE - 1, 0, param->srv->timeouts[STRING_S]) < 0) {RETURN(441);}
buf[127] = 0;
if(PARAMSTR(param, hostname, buf)){RETURN(21);}
if(!getip46m(param->srv->resolvmode, 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 : param->srv->extsa;
#else
param->sinsl = param->srv->extsa;
#endif
param->operation = command == 2?BIND:UDPASSOC;
if(command == 2){
if ((param->remsock=nssocket(param->srv, &param->srv->so, param->sostate, NS_OUT, SASOCK(&param->req), SOCK_STREAM, IPPROTO_TCP)) == INVALID_SOCKET) {RETURN (11);}
setopts(param->remsock, &param->srv->lissockopts, param->srv->maxseg);
if(extbindtodevice(param, param->remsock)) {RETURN (12);}
}
break;
default:
RETURN(997);
}
if(command == 3) param->preauth = 1;
res = (*param->srv->authfunc)(param);
param->preauth = 0;
if(command == 3 && res == 2) res = 0;
if(res) {
RETURN(res);
}
#ifndef WITHMAIN
if(param->nreqfilters && buf){
int reqbufsize = BUFSIZE, reqsize, action;
printcommand(buf, command, param);
reqsize = strlen((char *)buf);
action = handlereqfilters(param, &buf, &reqbufsize, 0, &reqsize);
if(action == HANDLED){
RETURN(0);
}
if(action != PASS) RETURN(517);
}
#endif
if(command == 3) {
if((res = udpbind(param))) {RETURN(res);}
}
else if(command == 2) {
if(bindwithrange(param, param->remsock, &param->sinsl, param->extport)) {
/* a range has already been searched, retrying on any port would
ignore what was asked for */
if(param->extport) RETURN (12);
*SAPORT(&param->sinsl) = 0;
if(param->srv->so._bind(param->sostate, 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->sinsl));
fflush(stderr);
#endif
}
sasize = sizeof(param->sinsl);
param->srv->so._getsockname(param->sostate, param->remsock, (struct sockaddr *)&param->sinsl, &sasize);
}
if(command == 3) {
param->ctrlsock = param->clisock;
param->clisock = nssocket(param->srv, &param->srv->so, param->sostate, NS_IN, SASOCK(&param->sincr), SOCK_DGRAM, IPPROTO_UDP);
if(param->clisock == INVALID_SOCKET) {RETURN(11);}
#ifdef _WIN32
{ unsigned long ul = 1; ioctlsocket(param->clisock, FIONBIO, &ul); }
#else
fcntl(param->clisock, F_SETFL, O_NONBLOCK | fcntl(param->clisock, F_GETFL));
#endif
if(intbindtodevice(param, param->clisock)) {RETURN (12);}
sin = param->sincl;
*SAPORT(&sin) = 0;
/* the port the client is told to send its datagrams to */
if(bindwithrange(param, param->clisock, &sin, param->intport)) {RETURN (12);}
sasize = sizeof(sin);
param->srv->so._getsockname(param->sostate, param->clisock, (struct sockaddr *)&sin, &sasize);
#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 && buf){
int repcode;
sasize = sizeof(sin);
/* CONNECT and BIND report the address of the socket towards the
destination, UDP ASSOCIATE the one the client sends its datagrams
to, as does a request which never got a socket of its own */
if(command != 3 && param->remsock != INVALID_SOCKET){
param->srv->so._getsockname(param->sostate, param->remsock, (struct sockaddr *)&sin, &sasize);
if(!SAISNULL(&param->srv->extNat)){
uint16_t port;
port = *SAPORT(&sin);
sin = param->srv->extNat;
*SAPORT(&sin) = port;
}
}
else {
param->srv->so._getsockname(param->sostate, param->clisock, (struct sockaddr *)&sin, &sasize);
if(command == 3 && !SAISNULL(&param->srv->intNat)){
uint16_t port;
port = *SAPORT(&sin);
sin = param->srv->intNat;
*SAPORT(&sin) = port;
}
}
#if SOCKSTRACE > 0
myinet_ntop(*SAFAMILY(&sin), SAADDR(&sin), tracebuf, SASIZE(&sin));
fprintf(stderr, "Sending confirmation to client with code %d for %s with %s:%hu\n",
param->res,
commands[command],
tracebuf,
ntohs(*SAPORT(&sin))
);
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 if (param->res == 100) repcode = 4;
else if (param->res == 997) repcode = 8;
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(param, (command == 3)?param->ctrlsock:param->clisock, buf, 6+SAADDRLEN(&sin), param->srv->timeouts[STRING_S]);
}
else{
buf[0] = 0;
buf[1] = 90 + !!(repcode);
if(*SAFAMILY(&sin) == AF_INET){
memcpy(buf+2, SAPORT(&sin), 2);
memcpy(buf+4, SAADDR(&sin), 4);
} else {
memset(buf+2, 0, 6);
param->res = 997;
}
socksend(param, param->clisock, buf, 8, param->srv->timeouts[STRING_S]);
}
if (param->npredatfilters){
int action;
action = handlepredatflt(param);
if(action == HANDLED){
param->res = 0;
}
if(action != PASS){
param->res = 19;
}
}
if (param->res == 0) {
switch(command) {
case 1:
if(param->redirectfunc){
if(buf != param->tmpbuf) free(buf);
return (void *)param->redirectfunc;
}
param->res = mapsocket(param, param->srv->timeouts[CONNECTION_L]);
break;
case 2:
param->srv->so._listen (param->sostate, param->remsock, 1);
fds[0].fd = param->remsock;
fds[1].fd = param->clisock;
fds[0].events = fds[1].events = POLLIN;
res = param->srv->so._poll(param->sostate, fds, 2, param->srv->timeouts[CONNECTION_L] * 1000);
if (res < 1 || fds[1].revents) {
res = 460;
break;
}
sasize = sizeof(param->sinsr);
s = param->srv->so._accept(param->sostate, param->remsock, (struct sockaddr *)&param->sinsr, &sasize);
param->srv->so._closesocket(param->sostate, 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;
}
{
#ifdef _WIN32
unsigned long ul=1;
ioctlsocket(param->remsock, FIONBIO, &ul);
#else
{
int flags = fcntl(param->remsock, F_GETFL);
if(flags != -1) fcntl(param->remsock, F_SETFL, O_NONBLOCK | flags);
}
#endif
}
#if SOCKSTRACE > 0
fprintf(stderr, "Sending incoming connection to client with code %d for %s with %hu\n",
param->res,
commands[command],
*SAPORT(&param->sinsr)
);
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, param->clisock, buf, 6+SAADDRLEN(&param->sinsr), param->srv->timeouts[STRING_S]);
}
else {
memcpy (buf+2, SAPORT(&param->sinsr), 2);
memcpy (buf+4, SAADDR(&param->sinsr), 4);
socksend(param, param->clisock, buf, 8, param->srv->timeouts[STRING_S]);
}
param->res = mapsocket(param, param->srv->timeouts[CONNECTION_S]);
break;
case 3:
param->sinsr = param->req;
param->res = udpsockmap(param, param->srv->timeouts[CONNECTION_L]);
break;
default:
param->res = 417;
break;
}
}
}
if(command > 3) command = 0;
printcommand(logline, command, param);
dolog(param, logline);
if(buf != param->tmpbuf) free(buf);
return (NULL);
}
#ifdef WITHMAIN
struct proxydef childdef = {
sockschild,
1080,
0,
S_SOCKS,
"-Ne(EXTERNAL_IP) External NAT address (between 3proxy and destination server) to report to client for CONNECT / BIND\n"
"-Ni(INTERNAL_IP) Internal NAT address (between client and 3proxy) to report to client for UDPASSOC\n"
"NAT is required to map IP-to-IP without port translation\n"
};
#include "proxymain.c"
#endif
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