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/*
* Utility routines.
*
* Copyright (C) 2018 Denys Vlasenko
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
//kbuild:lib-$(CONFIG_FTPGET) += parse_pasv_epsv.o
//kbuild:lib-$(CONFIG_FTPPUT) += parse_pasv_epsv.o
//kbuild:lib-$(CONFIG_WGET) += parse_pasv_epsv.o
#include "libbb.h"
int FAST_FUNC parse_pasv_epsv(char *buf)
{
/*
* PASV command will not work for IPv6. RFC2428 describes
* IPv6-capable "extended PASV" - EPSV.
*
* "EPSV [protocol]" asks server to bind to and listen on a data port
* in specified protocol. Protocol is 1 for IPv4, 2 for IPv6.
* If not specified, defaults to "same as used for control connection".
* If server understood you, it should answer "229 <some text>(|||port|)"
* where "|" are literal pipe chars and "port" is ASCII decimal port#.
*
* There is also an IPv6-capable replacement for PORT (EPRT),
* but we don't need that.
*
* NB: PASV may still work for some servers even over IPv6.
* For example, vsftp happily answers
* "227 Entering Passive Mode (0,0,0,0,n,n)" and proceeds as usual.
*/
char *ptr;
int port;
if (!ENABLE_FEATURE_IPV6 || buf[2] == '7' /* "227" */) {
/* Response is "227 garbageN1,N2,N3,N4,P1,P2[)garbage]"
* Server's IP is N1.N2.N3.N4 (we ignore it)
* Server's port for data connection is P1*256+P2 */
ptr = strrchr(buf, ')');
if (!ptr) ptr = strrchr(buf, '\r'); /* for PASV responses not ending with ')' */
if (!ptr) ptr = strrchr(buf, '\n'); /* for PASV responses not ending with ')' */
if (ptr) *ptr = '\0';
ptr = strrchr(buf, ',');
if (!ptr) return -1;
*ptr = '\0';
port = xatou_range(ptr + 1, 0, 255);
ptr = strrchr(buf, ',');
if (!ptr) return -1;
*ptr = '\0';
port += xatou_range(ptr + 1, 0, 255) * 256;
} else {
/* Response is "229 garbage(|||P1|)"
* Server's port for data connection is P1 */
ptr = strrchr(buf, '|');
if (!ptr) return -1;
*ptr = '\0';
ptr = strrchr(buf, '|');
if (!ptr) return -1;
*ptr = '\0';
port = xatou_range(ptr + 1, 0, 65535);
}
return port;
}
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