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getnameinfo.c revision 1.57 
      1 /*	$NetBSD: getnameinfo.c,v 1.57 2015/09/03 15:01:19 christos Exp $	*/
      2 /*	$KAME: getnameinfo.c,v 1.45 2000/09/25 22:43:56 itojun Exp $	*/
      3 
      4 /*
      5  * Copyright (c) 2000 Ben Harris.
      6  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
      7  * All rights reserved.
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. Redistributions in binary form must reproduce the above copyright
     15  *    notice, this list of conditions and the following disclaimer in the
     16  *    documentation and/or other materials provided with the distribution.
     17  * 3. Neither the name of the project nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 /*
     35  * Issues to be discussed:
     36  * - Thread safe-ness must be checked
     37  * - RFC2553 says that we should raise error on short buffer.  X/Open says
     38  *   we need to truncate the result.  We obey RFC2553 (and X/Open should be
     39  *   modified).  ipngwg rough consensus seems to follow RFC2553.
     40  * - What is "local" in NI_FQDN?
     41  * - NI_NAMEREQD and NI_NUMERICHOST conflict with each other.
     42  * - (KAME extension) always attach textual scopeid (fe80::1%lo0), if
     43  *   sin6_scope_id is filled - standardization status?
     44  *   XXX breaks backward compat for code that expects no scopeid.
     45  *   beware on merge.
     46  */
     47 
     48 #include <sys/cdefs.h>
     49 #if defined(LIBC_SCCS) && !defined(lint)
     50 __RCSID("$NetBSD: getnameinfo.c,v 1.57 2015/09/03 15:01:19 christos Exp $");
     51 #endif /* LIBC_SCCS and not lint */
     52 
     53 #ifndef RUMP_ACTION
     54 #include "namespace.h"
     55 #endif
     56 #include <sys/types.h>
     57 #include <sys/socket.h>
     58 #include <sys/un.h>
     59 #include <net/if.h>
     60 #include <net/if_dl.h>
     61 #include <net/if_ieee1394.h>
     62 #include <net/if_types.h>
     63 #include <netatalk/at.h>
     64 #include <netinet/in.h>
     65 #include <arpa/inet.h>
     66 #include <arpa/nameser.h>
     67 #include <assert.h>
     68 #include <limits.h>
     69 #include <netdb.h>
     70 #include <resolv.h>
     71 #include <stddef.h>
     72 #include <string.h>
     73 
     74 #include "servent.h"
     75 #include "hostent.h"
     76 
     77 #ifndef RUMP_ACTION
     78 #ifdef __weak_alias
     79 __weak_alias(getnameinfo,_getnameinfo)
     80 #endif
     81 #endif
     82 
     83 static const struct afd {
     84 	int		a_af;
     85 	socklen_t	a_addrlen;
     86 	socklen_t	a_socklen;
     87 	int		a_off;
     88 } afdl [] = {
     89 #ifdef INET6
     90 	{PF_INET6, sizeof(struct in6_addr), sizeof(struct sockaddr_in6),
     91 		offsetof(struct sockaddr_in6, sin6_addr)},
     92 #endif
     93 	{PF_INET, sizeof(struct in_addr), sizeof(struct sockaddr_in),
     94 		offsetof(struct sockaddr_in, sin_addr)},
     95 	{0, 0, 0, 0},
     96 };
     97 
     98 struct sockinet {
     99 	u_char	si_len;
    100 	u_char	si_family;
    101 	u_short	si_port;
    102 };
    103 
    104 static int getnameinfo_inet(const struct sockaddr *, socklen_t, char *,
    105     socklen_t, char *, socklen_t, int);
    106 #ifdef INET6
    107 static int ip6_parsenumeric(const struct sockaddr *, const char *, char *,
    108 				 socklen_t, int);
    109 static int ip6_sa2str(const struct sockaddr_in6 *, char *, size_t, int);
    110 #endif
    111 static int getnameinfo_atalk(const struct sockaddr *, socklen_t, char *,
    112     socklen_t, char *, socklen_t, int);
    113 static int getnameinfo_local(const struct sockaddr *, socklen_t, char *,
    114     socklen_t, char *, socklen_t, int);
    115 
    116 static int getnameinfo_link(const struct sockaddr *, socklen_t, char *,
    117     socklen_t, char *, socklen_t, int);
    118 static int hexname(const uint8_t *, size_t, char *, socklen_t);
    119 
    120 /*
    121  * Top-level getnameinfo() code.  Look at the address family, and pick an
    122  * appropriate function to call.
    123  */
    124 int
    125 getnameinfo(const struct sockaddr *sa, socklen_t salen,
    126 	char *host, socklen_t hostlen,
    127 	char *serv, socklen_t servlen,
    128 	int flags)
    129 {
    130 
    131 	switch (sa->sa_family) {
    132 	case AF_APPLETALK:
    133 		return getnameinfo_atalk(sa, salen, host, hostlen,
    134 		    serv, servlen, flags);
    135 	case AF_INET:
    136 	case AF_INET6:
    137 		return getnameinfo_inet(sa, salen, host, hostlen,
    138 		    serv, servlen, flags);
    139 	case AF_LINK:
    140 		return getnameinfo_link(sa, salen, host, hostlen,
    141 		    serv, servlen, flags);
    142 	case AF_LOCAL:
    143 		return getnameinfo_local(sa, salen, host, hostlen,
    144 		    serv, servlen, flags);
    145 	default:
    146 		return EAI_FAMILY;
    147 	}
    148 }
    149 
    150 /*
    151  * getnameinfo_atalk():
    152  * Format an AppleTalk address into a printable format.
    153  */
    154 /* ARGSUSED */
    155 static int
    156 getnameinfo_atalk(const struct sockaddr *sa, socklen_t salen,
    157     char *host, socklen_t hostlen, char *serv, socklen_t servlen,
    158     int flags)
    159 {
    160 	char numserv[8];
    161 	int n, m=0;
    162 
    163 	const struct sockaddr_at *sat =
    164 	    (const struct sockaddr_at *)(const void *)sa;
    165 
    166 	if (serv != NULL && servlen > 0) {
    167 		snprintf(numserv, sizeof(numserv), "%u", sat->sat_port);
    168 		if (strlen(numserv) + 1 > servlen)
    169 			return EAI_MEMORY;
    170 		strlcpy(serv, numserv, servlen);
    171 	}
    172 
    173         n = snprintf(host, hostlen, "%u.%u",
    174 	    ntohs(sat->sat_addr.s_net), sat->sat_addr.s_node);
    175 
    176 	if (n < 0 || (socklen_t)(m+n) >= hostlen)
    177 		goto errout;
    178 
    179 	m += n;
    180 
    181 	if (sat->sat_range.r_netrange.nr_phase) {
    182         	n = snprintf(host+m, hostlen-m, " phase %u",
    183 			sat->sat_range.r_netrange.nr_phase);
    184 
    185 		if (n < 0 || (socklen_t)(m+n) >= hostlen)
    186 			goto errout;
    187 
    188 		m += n;
    189 	}
    190 	if (sat->sat_range.r_netrange.nr_firstnet) {
    191         	n = snprintf(host+m, hostlen-m, " range %u - %u",
    192 			ntohs(sat->sat_range.r_netrange.nr_firstnet),
    193 			ntohs(sat->sat_range.r_netrange.nr_lastnet ));
    194 
    195 		if (n < 0 || (socklen_t)(m+n) >= hostlen)
    196 			goto errout;
    197 
    198 		m += n;
    199 	}
    200 
    201 	return 0;
    202 
    203 errout:
    204 	if (host && hostlen>0)
    205 		host[m] = '\0';	/* XXX ??? */
    206 
    207 	return EAI_MEMORY;
    208 }
    209 
    210 /*
    211  * getnameinfo_local():
    212  * Format an local address into a printable format.
    213  */
    214 /* ARGSUSED */
    215 static int
    216 getnameinfo_local(const struct sockaddr *sa, socklen_t salen,
    217     char *host, socklen_t hostlen, char *serv, socklen_t servlen,
    218     int flags)
    219 {
    220 	const struct sockaddr_un *sun =
    221 	    (const struct sockaddr_un *)(const void *)sa;
    222 
    223 	if (serv != NULL && servlen > 0)
    224 		serv[0] = '\0';
    225 
    226 	if (host && hostlen > 0)
    227 		strlcpy(host, sun->sun_path,
    228 		    MIN(sizeof(sun->sun_path) + 1, hostlen));
    229 
    230 	return 0;
    231 }
    232 
    233 /*
    234  * getnameinfo_inet():
    235  * Format an IPv4 or IPv6 sockaddr into a printable string.
    236  */
    237 static int
    238 getnameinfo_inet(const struct sockaddr *sa, socklen_t salen,
    239 	char *host, socklen_t hostlen,
    240 	char *serv, socklen_t servlen,
    241 	int flags)
    242 {
    243 	const struct afd *afd;
    244 	struct servent *sp;
    245 	struct hostent *hp;
    246 	u_short port;
    247 	int family, i;
    248 	const char *addr;
    249 	uint32_t v4a;
    250 	char numserv[512];
    251 	char numaddr[512];
    252 
    253 	/* sa is checked below */
    254 	/* host may be NULL */
    255 	/* serv may be NULL */
    256 
    257 	if (sa == NULL)
    258 		return EAI_FAIL;
    259 
    260 	family = sa->sa_family;
    261 	for (i = 0; afdl[i].a_af; i++)
    262 		if (afdl[i].a_af == family) {
    263 			afd = &afdl[i];
    264 			goto found;
    265 		}
    266 	return EAI_FAMILY;
    267 
    268  found:
    269 	if (salen != afd->a_socklen)
    270 		return EAI_FAIL;
    271 
    272 	/* network byte order */
    273 	port = ((const struct sockinet *)(const void *)sa)->si_port;
    274 	addr = (const char *)(const void *)sa + afd->a_off;
    275 
    276 	if (serv == NULL || servlen == 0) {
    277 		/*
    278 		 * do nothing in this case.
    279 		 * in case you are wondering if "&&" is more correct than
    280 		 * "||" here: rfc2553bis-03 says that serv == NULL OR
    281 		 * servlen == 0 means that the caller does not want the result.
    282 		 */
    283 	} else {
    284 		struct servent_data svd;
    285 		struct servent sv;
    286 
    287 		if (flags & NI_NUMERICSERV)
    288 			sp = NULL;
    289 		else {
    290 			(void)memset(&svd, 0, sizeof(svd));
    291 			sp = getservbyport_r(port,
    292 				(flags & NI_DGRAM) ? "udp" : "tcp", &sv, &svd);
    293 		}
    294 		if (sp) {
    295 			if (strlen(sp->s_name) + 1 > servlen) {
    296 				endservent_r(&svd);
    297 				return EAI_MEMORY;
    298 			}
    299 			strlcpy(serv, sp->s_name, servlen);
    300 			endservent_r(&svd);
    301 		} else {
    302 			snprintf(numserv, sizeof(numserv), "%u", ntohs(port));
    303 			if (strlen(numserv) + 1 > servlen)
    304 				return EAI_MEMORY;
    305 			strlcpy(serv, numserv, servlen);
    306 		}
    307 	}
    308 
    309 	switch (sa->sa_family) {
    310 	case AF_INET:
    311 		v4a = (uint32_t)
    312 		    ntohl(((const struct sockaddr_in *)
    313 		    (const void *)sa)->sin_addr.s_addr);
    314 		if (IN_MULTICAST(v4a) || IN_EXPERIMENTAL(v4a))
    315 			flags |= NI_NUMERICHOST;
    316 		v4a >>= IN_CLASSA_NSHIFT;
    317 		if (v4a == 0)
    318 			flags |= NI_NUMERICHOST;
    319 		break;
    320 #ifdef INET6
    321 	case AF_INET6:
    322 	    {
    323 		const struct sockaddr_in6 *sin6;
    324 		sin6 = (const struct sockaddr_in6 *)(const void *)sa;
    325 		switch (sin6->sin6_addr.s6_addr[0]) {
    326 		case 0x00:
    327 			if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
    328 				;
    329 			else if (IN6_IS_ADDR_LOOPBACK(&sin6->sin6_addr))
    330 				;
    331 			else
    332 				flags |= NI_NUMERICHOST;
    333 			break;
    334 		default:
    335 			if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) {
    336 				flags |= NI_NUMERICHOST;
    337 			}
    338 			else if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
    339 				flags |= NI_NUMERICHOST;
    340 			break;
    341 		}
    342 	    }
    343 		break;
    344 #endif
    345 	}
    346 	if (host == NULL || hostlen == 0) {
    347 		/*
    348 		 * do nothing in this case.
    349 		 * in case you are wondering if "&&" is more correct than
    350 		 * "||" here: rfc2553bis-03 says that host == NULL or
    351 		 * hostlen == 0 means that the caller does not want the result.
    352 		 */
    353 	} else if (flags & NI_NUMERICHOST) {
    354 		size_t numaddrlen;
    355 
    356 		/* NUMERICHOST and NAMEREQD conflicts with each other */
    357 		if (flags & NI_NAMEREQD)
    358 			return EAI_NONAME;
    359 
    360 		switch(afd->a_af) {
    361 #ifdef INET6
    362 		case AF_INET6:
    363 		{
    364 			int error;
    365 
    366 			if ((error = ip6_parsenumeric(sa, addr, host,
    367 						      hostlen, flags)) != 0)
    368 				return(error);
    369 			break;
    370 		}
    371 #endif
    372 		default:
    373 			if (inet_ntop(afd->a_af, addr, numaddr,
    374 			    (socklen_t)sizeof(numaddr)) == NULL)
    375 				return EAI_SYSTEM;
    376 			numaddrlen = strlen(numaddr);
    377 			if (numaddrlen + 1 > hostlen) /* don't forget terminator */
    378 				return EAI_MEMORY;
    379 			strlcpy(host, numaddr, hostlen);
    380 			break;
    381 		}
    382 	} else {
    383 		struct hostent hent;
    384 		char hbuf[4096];
    385 		int he;
    386 		hp = gethostbyaddr_r(addr, afd->a_addrlen, afd->a_af, &hent,
    387 		    hbuf, sizeof(hbuf), &he);
    388 
    389 		if (hp) {
    390 #if 0
    391 			/*
    392 			 * commented out, since "for local host" is not
    393 			 * implemented here - see RFC2553 p30
    394 			 */
    395 			if (flags & NI_NOFQDN) {
    396 				char *p;
    397 				p = strchr(hp->h_name, '.');
    398 				if (p)
    399 					*p = '\0';
    400 			}
    401 #endif
    402 			if (strlen(hp->h_name) + 1 > hostlen) {
    403 				return EAI_MEMORY;
    404 			}
    405 			strlcpy(host, hp->h_name, hostlen);
    406 		} else {
    407 			if (flags & NI_NAMEREQD)
    408 				return EAI_NONAME;
    409 			switch(afd->a_af) {
    410 #ifdef INET6
    411 			case AF_INET6:
    412 			{
    413 				int error;
    414 
    415 				if ((error = ip6_parsenumeric(sa, addr, host,
    416 							      hostlen,
    417 							      flags)) != 0)
    418 					return(error);
    419 				break;
    420 			}
    421 #endif
    422 			default:
    423 				if (inet_ntop(afd->a_af, addr, host,
    424 				    hostlen) == NULL)
    425 					return EAI_SYSTEM;
    426 				break;
    427 			}
    428 		}
    429 	}
    430 	return(0);
    431 }
    432 
    433 #ifdef INET6
    434 static int
    435 ip6_parsenumeric(const struct sockaddr *sa, const char *addr, char *host,
    436 	socklen_t hostlen, int flags)
    437 {
    438 	size_t numaddrlen;
    439 	char numaddr[512];
    440 
    441 	_DIAGASSERT(sa != NULL);
    442 	_DIAGASSERT(addr != NULL);
    443 	_DIAGASSERT(host != NULL);
    444 
    445 	if (inet_ntop(AF_INET6, addr, numaddr, (socklen_t)sizeof(numaddr))
    446 	    == NULL)
    447 		return EAI_SYSTEM;
    448 
    449 	numaddrlen = strlen(numaddr);
    450 	if (numaddrlen + 1 > hostlen) /* don't forget terminator */
    451 		return EAI_OVERFLOW;
    452 	strlcpy(host, numaddr, hostlen);
    453 
    454 	if (((const struct sockaddr_in6 *)(const void *)sa)->sin6_scope_id) {
    455 		char zonebuf[MAXHOSTNAMELEN];
    456 		int zonelen;
    457 
    458 		zonelen = ip6_sa2str(
    459 		    (const struct sockaddr_in6 *)(const void *)sa,
    460 		    zonebuf, sizeof(zonebuf), flags);
    461 		if (zonelen < 0)
    462 			return EAI_OVERFLOW;
    463 		if ((size_t) zonelen + 1 + numaddrlen + 1 > hostlen)
    464 			return EAI_OVERFLOW;
    465 		/* construct <numeric-addr><delim><zoneid> */
    466 		memcpy(host + numaddrlen + 1, zonebuf,
    467 		    (size_t)zonelen);
    468 		host[numaddrlen] = SCOPE_DELIMITER;
    469 		host[numaddrlen + 1 + zonelen] = '\0';
    470 	}
    471 
    472 	return 0;
    473 }
    474 
    475 /* ARGSUSED */
    476 static int
    477 ip6_sa2str(const struct sockaddr_in6 *sa6, char *buf, size_t bufsiz, int flags)
    478 {
    479 	unsigned int ifindex;
    480 	const struct in6_addr *a6;
    481 	int n;
    482 
    483 	_DIAGASSERT(sa6 != NULL);
    484 	_DIAGASSERT(buf != NULL);
    485 
    486 	ifindex = (unsigned int)sa6->sin6_scope_id;
    487 	a6 = &sa6->sin6_addr;
    488 
    489 #ifdef NI_NUMERICSCOPE
    490 	if ((flags & NI_NUMERICSCOPE) != 0) {
    491 		n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
    492 		if (n < 0 || (size_t)n >= bufsiz)
    493 			return -1;
    494 		else
    495 			return n;
    496 	}
    497 #endif
    498 
    499 	/* if_indextoname() does not take buffer size.  not a good api... */
    500 	if ((IN6_IS_ADDR_LINKLOCAL(a6) || IN6_IS_ADDR_MC_LINKLOCAL(a6)) &&
    501 	    bufsiz >= IF_NAMESIZE) {
    502 		char *p = if_indextoname(ifindex, buf);
    503 		if (p) {
    504 			return (int)strlen(p);
    505 		}
    506 	}
    507 
    508 	/* last resort */
    509 	n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
    510 	if (n < 0 || (size_t) n >= bufsiz)
    511 		return -1;
    512 	else
    513 		return n;
    514 }
    515 #endif /* INET6 */
    516 
    517 
    518 /*
    519  * getnameinfo_link():
    520  * Format a link-layer address into a printable format, paying attention to
    521  * the interface type.
    522  */
    523 /* ARGSUSED */
    524 static int
    525 getnameinfo_link(const struct sockaddr *sa, socklen_t salen,
    526     char *host, socklen_t hostlen, char *serv, socklen_t servlen,
    527     int flags)
    528 {
    529 	const struct sockaddr_dl *sdl =
    530 	    (const struct sockaddr_dl *)(const void *)sa;
    531 	const struct ieee1394_hwaddr *iha;
    532 	int n;
    533 
    534 	if (serv != NULL && servlen > 0)
    535 		*serv = '\0';
    536 
    537 	if (sdl->sdl_nlen == 0 && sdl->sdl_alen == 0 && sdl->sdl_slen == 0) {
    538 		n = snprintf(host, hostlen, "link#%u", sdl->sdl_index);
    539 		goto out;
    540 	}
    541 
    542 	switch (sdl->sdl_type) {
    543 #ifdef IFT_ECONET
    544 	case IFT_ECONET:
    545 		if (sdl->sdl_alen < 2)
    546 			return EAI_FAMILY;
    547 		if (CLLADDR(sdl)[1] == 0)
    548 			n = snprintf(host, hostlen, "%u", CLLADDR(sdl)[0]);
    549 		else
    550 			n = snprintf(host, hostlen, "%u.%u",
    551 			    CLLADDR(sdl)[1], CLLADDR(sdl)[0]);
    552 		goto out;
    553 #endif
    554 	case IFT_IEEE1394:
    555 		if (sdl->sdl_alen < sizeof(iha->iha_uid))
    556 			return EAI_FAMILY;
    557 		iha =
    558 		    (const struct ieee1394_hwaddr *)(const void *)CLLADDR(sdl);
    559 		return hexname(iha->iha_uid, sizeof(iha->iha_uid),
    560 		    host, hostlen);
    561 	/*
    562 	 * The following have zero-length addresses.
    563 	 * IFT_ATM	(net/if_atmsubr.c)
    564 	 * IFT_FAITH	(net/if_faith.c)
    565 	 * IFT_GIF	(net/if_gif.c)
    566 	 * IFT_LOOP	(net/if_loop.c)
    567 	 * IFT_PPP	(net/if_ppp.c, net/if_spppsubr.c)
    568 	 * IFT_SLIP	(net/if_sl.c, net/if_strip.c)
    569 	 * IFT_STF	(net/if_stf.c)
    570 	 * IFT_L2VLAN	(net/if_vlan.c)
    571 	 * IFT_PROPVIRTUAL (net/if_bridge.h>
    572 	 */
    573 	/*
    574 	 * The following use IPv4 addresses as link-layer addresses:
    575 	 * IFT_OTHER	(net/if_gre.c)
    576 	 */
    577 	case IFT_ARCNET: /* default below is believed correct for all these. */
    578 	case IFT_ETHER:
    579 	case IFT_FDDI:
    580 	case IFT_HIPPI:
    581 	case IFT_ISO88025:
    582 	default:
    583 		return hexname((const uint8_t *)CLLADDR(sdl),
    584 		    (size_t)sdl->sdl_alen, host, hostlen);
    585 	}
    586 out:
    587 	if (n < 0 || (socklen_t) n >= hostlen) {
    588 		*host = '\0';
    589 		return EAI_MEMORY;
    590 	}
    591 	return 0;
    592 }
    593 
    594 static int
    595 hexname(const uint8_t *cp, size_t len, char *host, socklen_t hostlen)
    596 {
    597 	int n;
    598 	size_t i;
    599 	char *outp = host;
    600 
    601 	*outp = '\0';
    602 	for (i = 0; i < len; i++) {
    603 		n = snprintf(outp, hostlen, "%s%02x",
    604 		    i ? ":" : "", cp[i]);
    605 		if (n < 0 || (socklen_t) n >= hostlen) {
    606 			*host = '\0';
    607 			return EAI_MEMORY;
    608 		}
    609 		outp += n;
    610 		hostlen -= n;
    611 	}
    612 	return 0;
    613 }
    614