getaddrinfo.c

Newlib 嵌入式 C库 标准实现代码

/*	$KAME: getaddrinfo.c,v 1.15 2000/07/09 04:37:24 itojun Exp $	*/

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * "#ifdef FAITH" part is local hack for supporting IPv4-v6 translator.
 *
 * Issues to be discussed:
 * - Thread safe-ness must be checked.
 * - Return values.  There are nonstandard return values defined and used
 *   in the source code.  This is because RFC2553 is silent about which error
 *   code must be returned for which situation.
 * - freeaddrinfo(NULL).  RFC2553 is silent about it.  XNET 5.2 says it is
 *   invalid.
 *   current code - SEGV on freeaddrinfo(NULL)
 * Note:
 * - We use getipnodebyname() just for thread-safeness.  There's no intent
 *   to let it do PF_UNSPEC (actually we never pass PF_UNSPEC to
 *   getipnodebyname().
 * - The code filters out AFs that are not supported by the kernel,
 *   when globbing NULL hostname (to loopback, or wildcard).  Is it the right
 *   thing to do?  What is the relationship with post-RFC2553 AI_ADDRCONFIG
 *   in ai_flags?
 * - (post-2553) semantics of AI_ADDRCONFIG itself is too vague.
 *   (1) what should we do against numeric hostname (2) what should we do
 *   against NULL hostname (3) what is AI_ADDRCONFIG itself.  AF not ready?
 *   non-loopback address configured?  global address configured?
 * - To avoid search order issue, we have a big amount of code duplicate
 *   from gethnamaddr.c and some other places.  The issues that there's no
 *   lower layer function to lookup "IPv4 or IPv6" record.  Calling
 *   gethostbyname2 from getaddrinfo will end up in wrong search order, as
 *   follows:
 *	- The code makes use of following calls when asked to resolver with
 *	  ai_family  = PF_UNSPEC:
 *		getipnodebyname(host, AF_INET6);
 *		getipnodebyname(host, AF_INET);
 *	  This will result in the following queries if the node is configure to
 *	  prefer /etc/hosts than DNS:
 *		lookup /etc/hosts for IPv6 address
 *		lookup DNS for IPv6 address
 *		lookup /etc/hosts for IPv4 address
 *		lookup DNS for IPv4 address
 *	  which may not meet people's requirement.
 *	  The right thing to happen is to have underlying layer which does
 *	  PF_UNSPEC lookup (lookup both) and return chain of addrinfos.
 *	  This would result in a bit of code duplicate with _dns_ghbyname() and
 *	  friends.
 */
/*
 * diffs with other KAME platforms:
 * - other KAME platforms already nuked FAITH ($GAI), but as FreeBSD
 *   4.0-RELEASE supplies it, we still have the code here.
 * - AI_ADDRCONFIG support is supplied
 * - some of FreeBSD style (#define tabify and others)
 * - classful IPv4 numeric (127.1) is allowed.
 */

#include <sys/cdefs.h>
#include <machine/endian.h>

#include "namespace.h"
#include <sys/types.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <net/if.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <rpc/rpc.h>
#include <rpcsvc/yp_prot.h>
#include <rpcsvc/ypclnt.h>
#include <netdb.h>
#include <resolv.h>
#include <string.h>
#include <stdlib.h>
#include <stddef.h>
#include <ctype.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#ifdef DEBUG
#include <syslog.h>
#endif

#include <syslog.h>
#include <stdarg.h>
#include <nsswitch.h>
#include "un-namespace.h"

#if defined(__KAME__) && defined(INET6)
# define FAITH
#endif

#define	SUCCESS 0
#define	ANY 0
#define	YES 1
#define	NO  0

static const char in_addrany[] = { 0, 0, 0, 0 };
static const char in6_addrany[] = {
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};
static const char in_loopback[] = { 127, 0, 0, 1 };
static const char in6_loopback[] = {
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
};

static const struct afd {
	int a_af;
	int a_addrlen;
	int a_socklen;
	int a_off;
	const char *a_addrany;
	const char *a_loopback;
	int a_scoped;
} afdl [] = {
#ifdef INET6
#define	N_INET6 0
	{PF_INET6, sizeof(struct in6_addr),
	 sizeof(struct sockaddr_in6),
	 offsetof(struct sockaddr_in6, sin6_addr),
	 in6_addrany, in6_loopback, 1},
#define	N_INET 1
#else
#define	N_INET 0
#endif
	{PF_INET, sizeof(struct in_addr),
	 sizeof(struct sockaddr_in),
	 offsetof(struct sockaddr_in, sin_addr),
	 in_addrany, in_loopback, 0},
	{0, 0, 0, 0, NULL, NULL, 0},
};

struct explore {
	int e_af;
	int e_socktype;
	int e_protocol;
	const char *e_protostr;
	int e_wild;
#define	WILD_AF(ex)		((ex)->e_wild & 0x01)
#define	WILD_SOCKTYPE(ex)	((ex)->e_wild & 0x02)
#define	WILD_PROTOCOL(ex)	((ex)->e_wild & 0x04)
};

static const struct explore explore[] = {
#if 0
	{ PF_LOCAL, 0, ANY, ANY, NULL, 0x01 },
#endif
#ifdef INET6
	{ PF_INET6, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07 },
	{ PF_INET6, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07 },
	{ PF_INET6, SOCK_RAW, ANY, NULL, 0x05 },
#endif
	{ PF_INET, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07 },
	{ PF_INET, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07 },
	{ PF_INET, SOCK_RAW, ANY, NULL, 0x05 },
	{ PF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07 },
	{ PF_UNSPEC, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07 },
	{ PF_UNSPEC, SOCK_RAW, ANY, NULL, 0x05 },
	{ -1, 0, 0, NULL, 0 },
};

#ifdef INET6
#define	PTON_MAX	16
#else
#define	PTON_MAX	4
#endif

static const ns_src default_dns_files[] = {
	{ NSSRC_FILES, 	NS_SUCCESS },
	{ NSSRC_DNS, 	NS_SUCCESS },
	{ 0 }
};

#if PACKETSZ > 1024
#define MAXPACKET	PACKETSZ
#else
#define MAXPACKET	1024
#endif

typedef union {
	HEADER hdr;
	u_char buf[MAXPACKET];
} querybuf;

struct res_target {
	struct res_target *next;
	const char *name;	/* domain name */
	int qclass, qtype;	/* class and type of query */
	u_char *answer;		/* buffer to put answer */
	int anslen;		/* size of answer buffer */
	int n;			/* result length */
};

static int str_isnumber(const char *);
static int explore_fqdn(const struct addrinfo *, const char *,
	const char *, struct addrinfo **);
static int explore_null(const struct addrinfo *,
	const char *, struct addrinfo **);
static int explore_numeric(const struct addrinfo *, const char *,
	const char *, struct addrinfo **);
static int explore_numeric_scope(const struct addrinfo *, const char *,
	const char *, struct addrinfo **);
static int get_canonname(const struct addrinfo *,
	struct addrinfo *, const char *);
static struct addrinfo *get_ai(const struct addrinfo *,
	const struct afd *, const char *);
static int get_portmatch(const struct addrinfo *, const char *);
static int get_port(struct addrinfo *, const char *, int);
static const struct afd *find_afd(int);
static int addrconfig(struct addrinfo *);
#ifdef INET6
static int ip6_str2scopeid(char *, struct sockaddr_in6 *);
#endif

static struct addrinfo *getanswer(const querybuf *, int, const char *, int,
	const struct addrinfo *);
static int _dns_getaddrinfo(void *, void *, va_list);
static void _sethtent(void);
static void _endhtent(void);
static struct addrinfo *_gethtent(const char *, const struct addrinfo *);
static int _files_getaddrinfo(void *, void *, va_list);
#ifdef YP
static struct addrinfo *_yphostent(char *, const struct addrinfo *);
static int _yp_getaddrinfo(void *, void *, va_list);
extern int _yp_check(char **);
#endif

u_int16_t _getshort(const u_char *src);

static int res_queryN(const char *, struct res_target *);
static int res_searchN(const char *, struct res_target *);
static int res_querydomainN(const char *, const char *,
	struct res_target *);

static char *ai_errlist[] = {
	"Success",
	"Address family for hostname not supported",	/* EAI_ADDRFAMILY */
	"Temporary failure in name resolution",		/* EAI_AGAIN      */
	"Invalid value for ai_flags",		       	/* EAI_BADFLAGS   */
	"Non-recoverable failure in name resolution", 	/* EAI_FAIL       */
	"ai_family not supported",			/* EAI_FAMILY     */
	"Memory allocation failure", 			/* EAI_MEMORY     */
	"No address associated with hostname", 		/* EAI_NODATA     */
	"hostname nor servname provided, or not known",	/* EAI_NONAME     */
	"servname not supported for ai_socktype",	/* EAI_SERVICE    */
	"ai_socktype not supported", 			/* EAI_SOCKTYPE   */
	"System error returned in errno", 		/* EAI_SYSTEM     */
	"Invalid value for hints",			/* EAI_BADHINTS	  */
	"Resolved protocol is unknown",			/* EAI_PROTOCOL   */
	"Unknown error", 				/* EAI_MAX        */
};

/* XXX macros that make external reference is BAD. */

#define	GET_AI(ai, afd, addr) \
do { \
	/* external reference: pai, error, and label free */ \
	(ai) = get_ai(pai, (afd), (addr)); \
	if ((ai) == NULL) { \
		error = EAI_MEMORY; \
		goto free; \
	} \
} while (/*CONSTCOND*/0)

#define	GET_PORT(ai, serv) \
do { \
	/* external reference: error and label free */ \
	error = get_port((ai), (serv), 0); \
	if (error != 0) \
		goto free; \
} while (/*CONSTCOND*/0)

#define	GET_CANONNAME(ai, str) \
do { \
	/* external reference: pai, error and label free */ \
	error = get_canonname(pai, (ai), (str)); \
	if (error != 0) \
		goto free; \
} while (/*CONSTCOND*/0)

#define	ERR(err) \
do { \
	/* external reference: error, and label bad */ \
	error = (err); \
	goto bad; \
	/*NOTREACHED*/ \
} while (/*CONSTCOND*/0)

#define	MATCH_FAMILY(x, y, w) \
	((x) == (y) || (/*CONSTCOND*/(w) && ((x) == PF_UNSPEC || (y) == PF_UNSPEC)))
#define	MATCH(x, y, w) \
	((x) == (y) || (/*CONSTCOND*/(w) && ((x) == ANY || (y) == ANY)))

char *
gai_strerror(ecode)
	int ecode;
{
	if (ecode < 0 || ecode > EAI_MAX)
		ecode = EAI_MAX;
	return ai_errlist[ecode];
}

void
freeaddrinfo(ai)
	struct addrinfo *ai;
{
	struct addrinfo *next;

	do {
		next = ai->ai_next;
		if (ai->ai_canonname)
			free(ai->ai_canonname);
		/* no need to free(ai->ai_addr) */
		free(ai);
		ai = next;
	} while (ai);
}

static int
str_isnumber(p)
	const char *p;
{
	char *ep;

	if (*p == '\0')
		return NO;
	ep = NULL;
	(void)strtoul(p, &ep, 10);
	if (ep && *ep == '\0')
		return YES;
	else
		return NO;
}

int
getaddrinfo(hostname, servname, hints, res)
	const char *hostname, *servname;
	const struct addrinfo *hints;
	struct addrinfo **res;
{
	struct addrinfo sentinel;
	struct addrinfo *cur;
	int error = 0;
	struct addrinfo ai;
	struct addrinfo ai0;
	struct addrinfo *pai;
	const struct explore *ex;

	memset(&sentinel, 0, sizeof(sentinel));
	cur = &sentinel;
	pai = &ai;
	pai->ai_flags = 0;
	pai->ai_family = PF_UNSPEC;
	pai->ai_socktype = ANY;
	pai->ai_protocol = ANY;
	pai->ai_addrlen = 0;
	pai->ai_canonname = NULL;
	pai->ai_addr = NULL;
	pai->ai_next = NULL;

	if (hostname == NULL && servname == NULL)
		return EAI_NONAME;
	if (hints) {
		/* error check for hints */
		if (hints->ai_addrlen || hints->ai_canonname ||
		    hints->ai_addr || hints->ai_next)
			ERR(EAI_BADHINTS); /* xxx */
		if (hints->ai_flags & ~AI_MASK)
			ERR(EAI_BADFLAGS);
		switch (hints->ai_family) {
		case PF_UNSPEC:
		case PF_INET:
#ifdef INET6
		case PF_INET6:
#endif
			break;
		default:
			ERR(EAI_FAMILY);
		}
		memcpy(pai, hints, sizeof(*pai));

		/*
		 * if both socktype/protocol are specified, check if they
		 * are meaningful combination.
		 */
		if (pai->ai_socktype != ANY && pai->ai_protocol != ANY) {
			for (ex = explore; ex->e_af >= 0; ex++) {
				if (pai->ai_family != ex->e_af)
					continue;
				if (ex->e_socktype == ANY)
					continue;
				if (ex->e_protocol == ANY)
					continue;
				if (pai->ai_socktype == ex->e_socktype
				 && pai->ai_protocol != ex->e_protocol) {
					ERR(EAI_BADHINTS);
				}
			}
		}
	}

	/*
	 * post-2553: AI_ALL and AI_V4MAPPED are effective only against
	 * AF_INET6 query.  They needs to be ignored if specified in other
	 * occassions.
	 */
	switch (pai->ai_flags & (AI_ALL | AI_V4MAPPED)) {
	case AI_V4MAPPED:
	case AI_ALL | AI_V4MAPPED:
		if (pai->ai_family != AF_INET6)
			pai->ai_flags &= ~(AI_ALL | AI_V4MAPPED);
		break;
	case AI_ALL:
#if 1
		/* illegal */
		ERR(EAI_BADFLAGS);
#else
		pai->ai_flags &= ~(AI_ALL | AI_V4MAPPED);
#endif
		break;
	}

	/*
	 * check for special cases.  (1) numeric servname is disallowed if
	 * socktype/protocol are left unspecified. (2) servname is disallowed
	 * for raw and other inet{,6} sockets.
	 */
	if (MATCH_FAMILY(pai->ai_family, PF_INET, 1)
#ifdef PF_INET6
	    || MATCH_FAMILY(pai->ai_family, PF_INET6, 1)
#endif
	    ) {
		ai0 = *pai;	/* backup *pai */

		if (pai->ai_family == PF_UNSPEC) {
#ifdef PF_INET6
			pai->ai_family = PF_INET6;
#else
			pai->ai_family = PF_INET;
#endif
		}
		error = get_portmatch(pai, servname);
		if (error)
			ERR(error);

		*pai = ai0;
	}

	ai0 = *pai;

	/* NULL hostname, or numeric hostname */
	for (ex = explore; ex->e_af >= 0; ex++) {
		*pai = ai0;

		/* PF_UNSPEC entries are prepared for DNS queries only */
		if (ex->e_af == PF_UNSPEC)
			continue;

		if (!MATCH_FAMILY(pai->ai_family, ex->e_af, WILD_AF(ex)))
			continue;
		if (!MATCH(pai->ai_socktype, ex->e_socktype, WILD_SOCKTYPE(ex)))
			continue;
		if (!MATCH(pai->ai_protocol, ex->e_protocol, WILD_PROTOCOL(ex)))
			continue;

		if (pai->ai_family == PF_UNSPEC)