/*
   3APA3A simplest proxy server
   (c) 2002-2026 by Vladimir Dubrovin <vlad@3proxy.org>

   please read License Agreement

*/

#include "proxy.h"

#ifdef WITH_FTP

#define RETURN(xxx) { param->res = xxx; goto CLEANRET; }
#define BUFSIZE 2048

void * ftpprchild(struct clientparam* param) {
 int i=0, res;
 unsigned char *buf;
 unsigned char *se;
 int status = 0;
 int inbuf;
 int pasv = 0;
 SOCKET sc = INVALID_SOCKET, ss = INVALID_SOCKET, clidatasock = INVALID_SOCKET;
 SASIZETYPE sasize;
 char * req = NULL;
#ifndef _WIN32
 struct linger lg;
#endif
 struct pollfd fds;

 if(!(buf = malloc(BUFSIZE))) RETURN(876);
 param->ctrlsock = param->clisock;
 param->operation = CONNECT;
#ifndef _WIN32
 lg.l_onoff = 1;
 lg.l_linger = conf.timeouts[STRING_L];
#endif
 if(socksend(param, param->ctrlsock, (unsigned char *)"220 Ready\r\n", 11, conf.timeouts[STRING_S])!=11) {RETURN (801);}
 for(;;){
	i = sockgetlinebuf(param, CLIENT, buf, BUFSIZE - 10, '\n', conf.timeouts[CONNECTION_S]);
	if(!i) {
		RETURN(0);
	}
	if(i<4) {RETURN(802);}
	buf[i] = 0;
	if ((se=(unsigned char *)strchr((char *)buf, '\r'))) *se = 0;
	if (req) free (req);
	req = NULL;

	if (!strncasecmp((char *)buf, "OPEN ", 5)){
		if(parsehostname((char *)buf+5, param, 21)){RETURN(803);}
		if(param->remsock != INVALID_SOCKET) {
			param->srv->so._shutdown(param->sostate, param->remsock, SHUT_RDWR);
			param->srv->so._closesocket(param->sostate, param->remsock);
			param->remsock = INVALID_SOCKET;
		}
		if((res = (*param->srv->authfunc)(param))) {RETURN(res);}
		param->ctrlsocksrv = param->remsock;
		if(socksend(param, param->ctrlsock, (unsigned char *)"220 Ready\r\n", 11, conf.timeouts[STRING_S])!=11) {RETURN (801);}
		status = 1;
	}
	else if (!strncasecmp((char *)buf, "USER ", 5)){
		if(parseconnusername((char *)buf +5, param, 0, 21)){RETURN(804);}
		if(!status){
			if((res = (*param->srv->authfunc)(param))) {RETURN(res);}
			param->ctrlsocksrv = param->remsock;
		}
		if(socksend(param, param->ctrlsock, (unsigned char *)"331 ok\r\n", 8, conf.timeouts[STRING_S])!=8) {RETURN (807);}
		status = 2;

	}
	else if (!strncasecmp((char *)buf, "PASS ", 5)){
		/* The user name carries the server to log in to, and it arrives
		   with USER. Without it there is nothing to log in to, and what
		   follows would read the name and the host as if there were. */
		if(!param->hostname || !param->extusername){
			socksend(param, param->ctrlsock, (unsigned char *)"503 Login with USER first\r\n", 27, conf.timeouts[STRING_S]);
			RETURN(805);
		}
		param->extpassword = (unsigned char *)strdup((char *)buf+5);
		inbuf = BUFSIZE;
		res = ftplogin(param, (char *)buf, &inbuf);
		param->res = res;
		if(inbuf && inbuf != BUFSIZE && socksend(param, param->ctrlsock, buf, inbuf, conf.timeouts[STRING_S])!=inbuf) {RETURN (807);}
		if(!res) status = 3;
		sprintf((char *)buf, "%.128s@%.128s%c%hu", param->extusername, param->hostname, (ntohs(*SAPORT(&param->sinsr))==21)?0:':', ntohs(*SAPORT(&param->sinsr)));
		req = strdup((char *)buf);
#ifndef WITHMAIN
		{
			int action, reqbufsize, reqsize;
			reqbufsize = BUFSIZE;
			reqsize = (int)strlen((char *)buf) + 1;
			
			action = handlereqfilters(param, &buf, &reqbufsize, 0, &reqsize);
			if(action == HANDLED){
				RETURN(0);
			}
			if(action != PASS) RETURN(877);
		}
#endif
	}
	else if (status >= 3 && (
			(!strncasecmp((char *)buf, "PASV", 4) && (pasv = 1)) ||
			(!strncasecmp((char *)buf, "EPSV", 4) && (pasv = 2)) ||
			(!strncasecmp((char *)buf, "PORT ", 5) && !(pasv = 0))
		)){
#ifndef WITHMAIN
		{
			int action, reqbufsize, reqsize;
			reqbufsize = BUFSIZE;
			reqsize = (int)strlen((char *)buf) + 1;
			
			action = handlehdrfilterscli(param, &buf, &reqbufsize, 0, &reqsize);
			if(action == HANDLED){
				RETURN(0);
			}
			if(action != PASS) RETURN(878);
		}
#endif
		if(sc != INVALID_SOCKET) {
			param->srv->so._shutdown(param->sostate, sc, SHUT_RDWR);
			param->srv->so._closesocket(param->sostate, sc);
			sc = INVALID_SOCKET;
		}
		if(ss != INVALID_SOCKET) {
			param->srv->so._shutdown(param->sostate, ss, SHUT_RDWR);
			param->srv->so._closesocket(param->sostate, ss);
			ss = INVALID_SOCKET;
		}
		if(clidatasock != INVALID_SOCKET) {
			param->srv->so._shutdown(param->sostate, clidatasock, SHUT_RDWR);
			param->srv->so._closesocket(param->sostate, clidatasock);
			clidatasock = INVALID_SOCKET;
		}
		if ((clidatasock=socket(SASOCK(&param->sincl), SOCK_STREAM, IPPROTO_TCP)) == INVALID_SOCKET) {RETURN(821);}
		if(intbindtodevice(param, clidatasock)){RETURN(822);}
		*SAPORT(&param->sincl) = 0;
		if(bindwithrange(param, clidatasock, &param->sincl, param->intport)){RETURN(822);}
		if (pasv) {
			if(param->srv->so._listen(param->sostate, clidatasock, 1)) {RETURN(823);}
			sasize = sizeof(param->sincl);
			if(param->srv->so._getsockname(param->sostate, clidatasock, (struct sockaddr *)&param->sincl, &sasize)){RETURN(824);}
			if(pasv == 1){
				if(*SAFAMILY(&param->sincl) == AF_INET)
					sprintf((char *)buf, "227 OK (%u,%u,%u,%u,%u,%u)\r\n",
					 (unsigned)(((unsigned char *)(SAADDR(&param->sincl)))[0]),
					 (unsigned)(((unsigned char *)(SAADDR(&param->sincl)))[1]),
					 (unsigned)(((unsigned char *)(SAADDR(&param->sincl)))[2]),
					 (unsigned)(((unsigned char *)(SAADDR(&param->sincl)))[3]),
					 (unsigned)(((unsigned char *)(SAPORT(&param->sincl)))[0]),
					 (unsigned)(((unsigned char *)(SAPORT(&param->sincl)))[1])
					);
				else sprintf((char *)buf, "227 OK (127,0,0,1,%u,%u)\r\n", 
					 (unsigned)(((unsigned char *)(SAPORT(&param->sincl)))[0]),
					 (unsigned)(((unsigned char *)(SAPORT(&param->sincl)))[1])
					);
			}
			else {
				sprintf((char *)buf, "229 OK (|||%u|)\r\n", 
					 (unsigned)ntohs(*SAPORT(&param->sincl))
					);
			}
		}
		else {
			unsigned long b1, b2, b3, b4;
			unsigned short b5, b6;

			if(sscanf((char *)buf+5, "%lu,%lu,%lu,%lu,%hu,%hu", &b1, &b2, &b3, &b4, &b5, &b6)!=6) {RETURN(828);}
			*SAPORT(&param->sincr) = htons((uint16_t)((b5<<8)^b6));
			if(connectwithpoll(param, clidatasock, (struct sockaddr *)&param->sincr, SASIZE(&param->sincr),conf.timeouts[CONNECT_TO])) {
				param->srv->so._closesocket(param->sostate, clidatasock);
				clidatasock = INVALID_SOCKET;
				RETURN(826);
			}
			sprintf((char *)buf, "200 OK\r\n");
		}
#ifndef WITHMAIN
		{
			int action, reqbufsize, reqsize;
			reqbufsize = BUFSIZE;
			reqsize = (int)strlen((char *)buf) + 1;
			
			action = handlehdrfilterssrv(param, &buf, &reqbufsize, 0, &reqsize);
			if(action == HANDLED){
				RETURN(0);
			}
			if(action != PASS) RETURN(879);
		}
#endif
		if(socksend(param, param->ctrlsock, buf, (int)strlen((char *)buf), conf.timeouts[STRING_S])!=(int)strlen((char *)buf)) {RETURN (825);}
		status = 4;
	}
	else if (status == 4 && (
		!(strncasecmp((char *)buf, "RETR ", 5) && (param->operation = FTP_GET)) ||
		!(strncasecmp((char *)buf, "LIST", 4) && (param->operation = FTP_LIST))||
		!(strncasecmp((char *)buf, "NLST ", 5) && (param->operation = FTP_LIST)) ||
		!(strncasecmp((char *)buf, "MLSD", 4) && (param->operation = FTP_LIST)) ||
		!(strncasecmp((char *)buf, "APPE ", 5) && (param->operation = FTP_PUT)) ||
		!(strncasecmp((char *)buf, "STOR ", 5) && (param->operation = FTP_PUT))
	)){
		int arg = (buf[4] && buf[5])? 1:0;
		int ressent = 0;


#ifndef WITHMAIN
		{
			int action, reqbufsize, reqsize;
			reqbufsize = BUFSIZE;
			reqsize = (int)strlen((char *)buf) + 1;
			
			action = handlehdrfilterscli(param, &buf, &reqbufsize, 0, &reqsize);
			if(action == HANDLED){
				RETURN(0);
			}
			if(action != PASS) RETURN(880);
		}
#endif
		if(clidatasock == INVALID_SOCKET) { RETURN (829);}
		if(pasv){

			memset(&fds, 0, sizeof(fds));
			fds.fd = clidatasock;
			fds.events = POLLIN;

			res = param->srv->so._poll (param->sostate, &fds, 1, conf.timeouts[STRING_L]*1000);
			if(res != 1) {
				RETURN(857);
			}
			sasize = sizeof(param->sincr);
			ss = param->srv->so._accept(param->sostate, clidatasock, (struct sockaddr *)&param->sincr, &sasize);
			if (ss == INVALID_SOCKET) { RETURN (858);}
#ifdef _WIN32
			{ unsigned long ul = 1; ioctlsocket(ss, FIONBIO, &ul); }
#else
			fcntl(ss, F_SETFL, O_NONBLOCK | fcntl(ss, F_GETFL));
#endif
			param->srv->so._shutdown(param->sostate, clidatasock, SHUT_RDWR);
			param->srv->so._closesocket(param->sostate, clidatasock);
			clidatasock = ss;
			ss = INVALID_SOCKET;
		}
		if(clidatasock == INVALID_SOCKET){RETURN(828);}
		req = strdup((char *)buf);
		buf[4] = 0;
		status = 3;
		ss = ftpcommand(param, buf, arg? buf+5 : NULL);
		if (ss == INVALID_SOCKET) {
			param->srv->so._shutdown(param->sostate, clidatasock, SHUT_RDWR);
			param->srv->so._closesocket(param->sostate, clidatasock);
			clidatasock = INVALID_SOCKET;
			
			if(socksend(param, param->ctrlsock, (unsigned char *)"550 err\r\n", 9, conf.timeouts[STRING_S])!=9) {RETURN (831);}
			continue;
		}

		if(socksend(param, param->ctrlsock, (unsigned char *)"125 data\r\n", 10, conf.timeouts[STRING_S]) != 10) {
			param->remsock = INVALID_SOCKET;
			RETURN (832);
		}
		if(param->srvoffset < param->srvinbuf)while((i = sockgetlinebuf(param, SERVER, buf, BUFSIZE, '\n', 0)) > 3){
			if(socksend(param, param->ctrlsock, buf, i, conf.timeouts[STRING_S])!=i) {RETURN(833);}
			if(isnumber(*buf) && buf[3] != '-') {
				ressent = 1;
				break;
			}
		}
		sc = param->remsock;
		param->remsock = ss;
#ifndef _WIN32
		/* not on Windows, see the accepting side in proxymain.c */
		param->srv->so._setsockopt(param->sostate, param->remsock, SOL_SOCKET, SO_LINGER, (char *)&lg, sizeof(lg));
		param->srv->so._setsockopt(param->sostate, clidatasock, SOL_SOCKET, SO_LINGER, (char *)&lg, sizeof(lg));
#endif
		param->clisock = clidatasock;
		res = mapsocket(param, conf.timeouts[CONNECTION_S]);
		if(param->remsock != INVALID_SOCKET) {
			param->srv->so._shutdown (param->sostate, param->remsock, SHUT_RDWR);
			param->srv->so._closesocket(param->sostate, param->remsock);
		}
		if(param->clisock != INVALID_SOCKET) {
			param->srv->so._shutdown (param->sostate, param->clisock, SHUT_RDWR);
			param->srv->so._closesocket(param->sostate, param->clisock);
		}
		param->clisock = param->ctrlsock;
		param->remsock = sc;
		sc = INVALID_SOCKET;
		ss = INVALID_SOCKET;
		clidatasock = INVALID_SOCKET;
		if(!ressent){
			while((i = sockgetlinebuf(param, SERVER, buf, BUFSIZE, '\n', conf.timeouts[STRING_L])) > 3){
				if(socksend(param, param->ctrlsock, buf, i, conf.timeouts[STRING_S])!=i) {RETURN(833);}
				if(isnumber(*buf) && buf[3] != '-') break;
			}
			if(i < 3) {RETURN(834);}
		}
	}
	else {
		if(status < 3) {
			if(socksend(param, param->remsock, (unsigned char *)"530 login\r\n", 11, conf.timeouts[STRING_S])!=1) {RETURN (810);}
			continue;
		}
		if(!strncasecmp((char *)buf, "QUIT", 4)) status = 5;
		if(!strncasecmp((char *)buf, "CWD ", 4)) req = strdup((char *)buf);
		i = (int)strlen((char *)buf);
		buf[i++] = '\r';
		buf[i++] = '\n';
		if(socksend(param, param->remsock, buf, i, conf.timeouts[STRING_S])!=i) {RETURN (811);}
 param->statscli64+=(i);
		param->nwrites++;
		while((i = sockgetlinebuf(param, SERVER, buf, BUFSIZE, '\n', conf.timeouts[STRING_L])) > 0){
			if(socksend(param, param->ctrlsock, buf, i, conf.timeouts[STRING_S])!=i) {RETURN (812);}
			if(i > 4 && isnumber(*buf) && buf[3] != '-') break;
		}
		if(status == 5) {RETURN (0);}
		if(i < 3) {RETURN (813);}
	}
	sasize = sizeof(param->sincr);
	if(param->srv->so._getpeername(param->sostate, param->ctrlsock, (struct sockaddr *)&param->sincr, &sasize)){RETURN(819);}
	if(req && (param->statscli64 || param->statssrv64)){
		dolog(param, (unsigned char *)req);
	}
 }

CLEANRET:

 if(sc != INVALID_SOCKET) {
	param->srv->so._shutdown(param->sostate, sc, SHUT_RDWR);
	param->srv->so._closesocket(param->sostate, sc);
 }
 if(ss != INVALID_SOCKET) {
	param->srv->so._shutdown(param->sostate, ss, SHUT_RDWR);
	param->srv->so._closesocket(param->sostate, ss);
 }
 if(clidatasock != INVALID_SOCKET) {
	param->srv->so._shutdown(param->sostate, clidatasock, SHUT_RDWR);
	param->srv->so._closesocket(param->sostate, clidatasock);
 }
 sasize = sizeof(param->sincr);
 param->srv->so._getpeername(param->sostate, param->ctrlsock, (struct sockaddr *)&param->sincr, &sasize);
 if(param->res != 0 || param->statscli64 || param->statssrv64 ){
	dolog(param, (unsigned char *)((req && (param->res > 802))? req:NULL));
 }
 if(req) free(req);
 if(buf) free(buf);
 return (NULL);
}

#ifdef WITHMAIN
struct proxydef childdef = {
	ftpprchild,
	21,
	0,
	S_FTPPR,
	" -hdefault_host[:port] - use this host and port as default if no host specified\n"
};
#include "proxymain.c"
#endif

#else

/* Built without FTP support. The service and the redirect naming it are
   still known, so a configuration carrying them is read rather than
   refused, and a client reaching one is turned away. */
void * ftpprchild(struct clientparam * param){
	param->res = 878;
	dolog(param, (unsigned char *)"ftp support is not built in");
	return NULL;
}

#endif