getipnode.c

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/*
 * Copyright (C) 2004, 2005  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 1999-2003  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

/* $Id: getipnode.c,v 1.37.18.3 2005/04/29 00:17:18 marka Exp $ */

/*! \file */

/**
 *    These functions perform thread safe, protocol independent
 *    nodename-to-address and address-to-nodename translation as defined in
 *    RFC2553.  This use a struct hostent which is defined in namedb.h:
 * 
 * \code
 * struct  hostent {
 *         char    *h_name;        // official name of host
 *         char    **h_aliases;    // alias list
 *         int     h_addrtype;     // host address type
 *         int     h_length;       // length of address
 *         char    **h_addr_list;  // list of addresses from name server
 * };
 * #define h_addr  h_addr_list[0]  // address, for backward compatibility
 * \endcode
 * 
 *    The members of this structure are:
 * 
 * \li   h_name:
 *           The official (canonical) name of the host.
 * 
 * \li   h_aliases:
 *           A NULL-terminated array of alternate names (nicknames) for the
 *           host.
 * 
 * \li   h_addrtype:
 *           The type of address being returned - usually PF_INET or
 *           PF_INET6.
 * 
 * \li   h_length:
 *           The length of the address in bytes.
 * 
 * \li   h_addr_list:
 *           A NULL terminated array of network addresses for the host. Host
 *           addresses are returned in network byte order.
 * 
 *    lwres_getipnodebyname() looks up addresses of protocol family af for
 *    the hostname name. The flags parameter contains ORed flag bits to
 *    specify the types of addresses that are searched for, and the types of
 *    addresses that are returned. The flag bits are:
 * 
 * \li   #AI_V4MAPPED:
 *           This is used with an af of #AF_INET6, and causes IPv4 addresses
 *           to be returned as IPv4-mapped IPv6 addresses.
 * 
 * \li   #AI_ALL:
 *           This is used with an af of #AF_INET6, and causes all known
 *           addresses (IPv6 and IPv4) to be returned. If #AI_V4MAPPED is
 *           also set, the IPv4 addresses are return as mapped IPv6
 *           addresses.
 * 
 * \li   #AI_ADDRCONFIG:
 *           Only return an IPv6 or IPv4 address if here is an active
 *           network interface of that type. This is not currently
 *           implemented in the BIND 9 lightweight resolver, and the flag is
 *           ignored.
 * 
 * \li   #AI_DEFAULT:
 *           This default sets the #AI_V4MAPPED and #AI_ADDRCONFIG flag bits.
 * 
 *    lwres_getipnodebyaddr() performs a reverse lookup of address src which
 *    is len bytes long. af denotes the protocol family, typically PF_INET
 *    or PF_INET6.
 * 
 *    lwres_freehostent() releases all the memory associated with the struct
 *    hostent pointer. Any memory allocated for the h_name, h_addr_list
 *    and h_aliases is freed, as is the memory for the hostent structure
 *    itself.
 * 
 * \section getipnode_return Return Values
 * 
 *    If an error occurs, lwres_getipnodebyname() and
 *    lwres_getipnodebyaddr() set *error_num to an appropriate error code
 *    and the function returns a NULL pointer. The error codes and their
 *    meanings are defined in \link netdb.h <lwres/netdb.h>\endlink:
 * 
 * \li   #HOST_NOT_FOUND:
 *           No such host is known.
 * 
 * \li   #NO_ADDRESS:
 *           The server recognised the request and the name but no address
 *           is available. Another type of request to the name server for
 *           the domain might return an answer.
 * 
 * \li   #TRY_AGAIN:
 *           A temporary and possibly transient error occurred, such as a
 *           failure of a server to respond. The request may succeed if
 *           retried.
 * 
 * \li   #NO_RECOVERY:
 *           An unexpected failure occurred, and retrying the request is
 *           pointless.
 * 
 *    lwres_hstrerror() translates these error codes to suitable error
 *    messages.
 * 
 * \section getipnode_see See Also
 * 
 * getaddrinfo.c, gethost.c, getnameinfo.c, herror.c, RFC2553  
 */

#include <config.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#include <lwres/lwres.h>
#include <lwres/net.h>
#include <lwres/netdb.h>	/* XXX #include <netdb.h> */

#include "assert_p.h"

#ifndef INADDRSZ
#define INADDRSZ 4
#endif
#ifndef IN6ADDRSZ
#define IN6ADDRSZ 16
#endif

#ifdef LWRES_PLATFORM_NEEDIN6ADDRANY
LIBLWRES_EXTERNAL_DATA const struct in6_addr in6addr_any = IN6ADDR_ANY_INIT;
#endif

#ifndef IN6_IS_ADDR_V4COMPAT
static const unsigned char in6addr_compat[12] = {
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};
#define IN6_IS_ADDR_V4COMPAT(x) (!memcmp((x)->s6_addr, in6addr_compat, 12) && \
                                 ((x)->s6_addr[12] != 0 || \
                                  (x)->s6_addr[13] != 0 || \
                                  (x)->s6_addr[14] != 0 || \
                                   ((x)->s6_addr[15] != 0 && \
                                    (x)->s6_addr[15] != 1)))
#endif
#ifndef IN6_IS_ADDR_V4MAPPED
#define IN6_IS_ADDR_V4MAPPED(x) (!memcmp((x)->s6_addr, in6addr_mapped, 12))
#endif

static const unsigned char in6addr_mapped[12] = {
        0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0xff, 0xff
};

/***
 ***	Forward declarations.
 ***/

static int
scan_interfaces(int *, int *);

static struct hostent *
copyandmerge(struct hostent *, struct hostent *, int, int *);

static struct hostent *
hostfromaddr(lwres_gnbaresponse_t *addr, int af, const void *src);

static struct hostent *
hostfromname(lwres_gabnresponse_t *name, int af);

/***
 ***	Public functions.
 ***/

/*!
 *	AI_V4MAPPED + AF_INET6
 *	If no IPv6 address then a query for IPv4 and map returned values.
 *
 *	AI_ALL + AI_V4MAPPED + AF_INET6
 *	Return IPv6 and IPv4 mapped.
 *
 *	AI_ADDRCONFIG
 *	Only return IPv6 / IPv4 address if there is an interface of that
 *	type active.
 */

struct hostent *
lwres_getipnodebyname(const char *name, int af, int flags, int *error_num) {
	int have_v4 = 1, have_v6 = 1;
	struct in_addr in4;
	struct in6_addr in6;
	struct hostent he, *he1 = NULL, *he2 = NULL, *he3 = NULL;
	int v4 = 0, v6 = 0;
	int tmp_err;
	lwres_context_t *lwrctx = NULL;
	lwres_gabnresponse_t *by = NULL;
	int n;

	/*
	 * If we care about active interfaces then check.
	 */
	if ((flags & AI_ADDRCONFIG) != 0)
		if (scan_interfaces(&have_v4, &have_v6) == -1) {
			*error_num = NO_RECOVERY;
			return (NULL);
		}

	/* Check for literal address. */
	if ((v4 = lwres_net_pton(AF_INET, name, &in4)) != 1)
		v6 = lwres_net_pton(AF_INET6, name, &in6);

	/*
	 * Impossible combination?
	 */
	if ((af == AF_INET6 && (flags & AI_V4MAPPED) == 0 && v4 == 1) ||
	    (af == AF_INET && v6 == 1) ||
	    (have_v4 == 0 && v4 == 1) ||
	    (have_v6 == 0 && v6 == 1) ||
	    (have_v4 == 0 && af == AF_INET) ||
	    (have_v6 == 0 && af == AF_INET6 &&
	     (((flags & AI_V4MAPPED) != 0 && have_v4) ||
	      (flags & AI_V4MAPPED) == 0))) {
		*error_num = HOST_NOT_FOUND;
		return (NULL);
	}

	/*
	 * Literal address?
	 */
	if (v4 == 1 || v6 == 1) {
		char *addr_list[2];
		char *aliases[1];
		char mappedname[sizeof("::ffff:123.123.123.123")];
		union {
			const char *const_name;
			char *deconst_name;
		} u;

		u.const_name = name;
		if (v4 == 1 && af == AF_INET6) {
			strcpy(mappedname, "::ffff:");
			lwres_net_ntop(AF_INET, (char *)&in4,
				       mappedname + sizeof("::ffff:") - 1,
				       sizeof(mappedname) - sizeof("::ffff:")
				       + 1);
			he.h_name = mappedname;
		} else
			he.h_name = u.deconst_name;
		he.h_addr_list = addr_list;
		he.h_addr_list[0] = (v4 == 1) ? (char *)&in4 : (char *)&in6;
		he.h_addr_list[1] = NULL;
		he.h_aliases = aliases;
		he.h_aliases[0] = NULL;
		he.h_length = (v4 == 1) ? INADDRSZ : IN6ADDRSZ;
		he.h_addrtype = (v4 == 1) ? AF_INET : AF_INET6;
		return (copyandmerge(&he, NULL, af, error_num));
	}

	n = lwres_context_create(&lwrctx, NULL, NULL, NULL, 0);
	if (n != 0) {
		*error_num = NO_RECOVERY;
		goto cleanup;
	}
	(void) lwres_conf_parse(lwrctx, lwres_resolv_conf);
	tmp_err = NO_RECOVERY;
	if (have_v6 && af == AF_INET6) {

		n = lwres_getaddrsbyname(lwrctx, name, LWRES_ADDRTYPE_V6, &by);
		if (n == 0) {
			he1 = hostfromname(by, AF_INET6);
			lwres_gabnresponse_free(lwrctx, &by);
			if (he1 == NULL) {
				*error_num = NO_RECOVERY;
				goto cleanup;
			}
		} else {
			tmp_err = HOST_NOT_FOUND;
		}
	}

	if (have_v4 &&
	    ((af == AF_INET) ||
	     (af == AF_INET6 && (flags & AI_V4MAPPED) != 0 &&
	      (he1 == NULL || (flags & AI_ALL) != 0)))) {
		n = lwres_getaddrsbyname(lwrctx, name, LWRES_ADDRTYPE_V4, &by);
		if (n == 0) {
			he2 = hostfromname(by, AF_INET);
			lwres_gabnresponse_free(lwrctx, &by);
			if (he2 == NULL) {
				*error_num = NO_RECOVERY;
				goto cleanup;
			}
		} else if (he1 == NULL) {
			if (n == LWRES_R_NOTFOUND)
				*error_num = HOST_NOT_FOUND;
			else
				*error_num = NO_RECOVERY;
			goto cleanup;
		}
	} else
		*error_num = tmp_err;

	he3 = copyandmerge(he1, he2, af, error_num);

 cleanup:
	if (he1 != NULL)
		lwres_freehostent(he1);
	if (he2 != NULL)
		lwres_freehostent(he2);
	if (lwrctx != NULL) {
		lwres_conf_clear(lwrctx);
		lwres_context_destroy(&lwrctx);
	}
	return (he3);
}

/*% performs a reverse lookup of address src which is len bytes long. af denotes the protocol family, typically #PF_INET or PF_INET6. */
struct hostent *
lwres_getipnodebyaddr(const void *src, size_t len, int af, int *error_num) {
	struct hostent *he1, *he2;
	lwres_context_t *lwrctx = NULL;
	lwres_gnbaresponse_t *by = NULL;
	lwres_result_t n;
	union {
		const void *konst;
		struct in6_addr *in6;
	} u;

	/*
	 * Sanity checks.
	 */
	if (src == NULL) {
		*error_num = NO_RECOVERY;
		return (NULL);
	}

	switch (af) {
	case AF_INET:
		if (len != (unsigned int)INADDRSZ) {
			*error_num = NO_RECOVERY;
			return (NULL);
		}
		break;
	case AF_INET6:
		if (len != (unsigned int)IN6ADDRSZ) {
			*error_num = NO_RECOVERY;
			return (NULL);
		}
		break;
	default:
		*error_num = NO_RECOVERY;
		return (NULL);
	}

	/*
	 * The de-"const"-ing game is done because at least one
	 * vendor's system (RedHat 6.0) defines the IN6_IS_ADDR_*
	 * macros in such a way that they discard the const with
	 * internal casting, and gcc ends up complaining.  Rather
	 * than replacing their own (possibly optimized) definitions
	 * with our own, cleanly discarding the const is the easiest
	 * thing to do.
	 */
	u.konst = src;

	/*
	 * Look up IPv4 and IPv4 mapped/compatible addresses.
	 */
	if ((af == AF_INET6 && IN6_IS_ADDR_V4COMPAT(u.in6)) ||
	    (af == AF_INET6 && IN6_IS_ADDR_V4MAPPED(u.in6)) ||
	    (af == AF_INET)) {
		const unsigned char *cp = src;

		if (af == AF_INET6)
			cp += 12;
		n = lwres_context_create(&lwrctx, NULL, NULL, NULL, 0);
		if (n == LWRES_R_SUCCESS)
			(void) lwres_conf_parse(lwrctx, lwres_resolv_conf);
		if (n == LWRES_R_SUCCESS)
			n = lwres_getnamebyaddr(lwrctx, LWRES_ADDRTYPE_V4,
						INADDRSZ, cp, &by);
		if (n != LWRES_R_SUCCESS) {
			lwres_conf_clear(lwrctx);
			lwres_context_destroy(&lwrctx);
			if (n == LWRES_R_NOTFOUND)
				*error_num = HOST_NOT_FOUND;
			else
				*error_num = NO_RECOVERY;
			return (NULL);
		}
		he1 = hostfromaddr(by, AF_INET, cp);
		lwres_gnbaresponse_free(lwrctx, &by);
		lwres_conf_clear(lwrctx);
		lwres_context_destroy(&lwrctx);
		if (af != AF_INET6)
			return (he1);

		/*
		 * Convert from AF_INET to AF_INET6.
		 */
		he2 = copyandmerge(he1, NULL, af, error_num);
		lwres_freehostent(he1);
		if (he2 == NULL)
			return (NULL);
		/*
		 * Restore original address.
		 */
		memcpy(he2->h_addr, src, len);
		return (he2);
	}

	/*
	 * Lookup IPv6 address.
	 */
	if (memcmp(src, &in6addr_any, IN6ADDRSZ) == 0) {
		*error_num = HOST_NOT_FOUND;
		return (NULL);
	}

	n = lwres_context_create(&lwrctx, NULL, NULL, NULL, 0);
	if (n == LWRES_R_SUCCESS)
		(void) lwres_conf_parse(lwrctx, lwres_resolv_conf);
	if (n == LWRES_R_SUCCESS)
		n = lwres_getnamebyaddr(lwrctx, LWRES_ADDRTYPE_V6, IN6ADDRSZ,
					src, &by);
	if (n != 0) {
		lwres_conf_clear(lwrctx);
		lwres_context_destroy(&lwrctx);
		*error_num = HOST_NOT_FOUND;
		return (NULL);
	}
	he1 = hostfromaddr(by, AF_INET6, src);
	lwres_gnbaresponse_free(lwrctx, &by);
	if (he1 == NULL)
		*error_num = NO_RECOVERY;
	lwres_conf_clear(lwrctx);
	lwres_context_destroy(&lwrctx);
	return (he1);
}

/*% releases all the memory associated with the struct hostent pointer */
void
lwres_freehostent(struct hostent *he) {
	char **cpp;
	int names = 1;
	int addresses = 1;

	free(he->h_name);

	cpp = he->h_addr_list;
	while (*cpp != NULL) {
		free(*cpp);
		*cpp = NULL;
		cpp++;
		addresses++;
	}

	cpp = he->h_aliases;
	while (*cpp != NULL) {
		free(*cpp);
		cpp++;
		names++;
	}

	free(he->h_aliases);
	free(he->h_addr_list);
	free(he);
}

/*
 * Private
 */

/*
 * Scan the interface table and set have_v4 and have_v6 depending
 * upon whether there are IPv4 and IPv6 interface addresses.
 *
 * Returns:
 *	0 on success
 *	-1 on failure.
 */

#if defined(SIOCGLIFCONF) && defined(SIOCGLIFADDR) && \
    !defined(IRIX_EMUL_IOCTL_SIOCGIFCONF) 

#ifdef __hpux
#define lifc_len iflc_len
#define lifc_buf iflc_buf
#define lifc_req iflc_req
#define LIFCONF if_laddrconf
#else
#define ISC_HAVE_LIFC_FAMILY 1
#define ISC_HAVE_LIFC_FLAGS 1
#define LIFCONF lifconf
#endif
 
#ifdef __hpux
#define lifr_addr iflr_addr
#define lifr_name iflr_name
#define lifr_dstaddr iflr_dstaddr
#define lifr_flags iflr_flags
#define ss_family sa_family
#define LIFREQ if_laddrreq
#else
#define LIFREQ lifreq
#endif

static int
scan_interfaces6(int *have_v4, int *have_v6) {
	struct LIFCONF lifc;
	struct LIFREQ lifreq;
	struct in_addr in4;
	struct in6_addr in6;
	char *buf = NULL, *cp, *cplim;
	static unsigned int bufsiz = 4095;
	int s, cpsize, n;

	/*
	 * Set to zero.  Used as loop terminators below.
	 */
	*have_v4 = *have_v6 = 0;

	/*
	 * Get interface list from system.
	 */
	if ((s = socket(AF_INET6, SOCK_DGRAM, 0)) == -1)
		goto err_ret;

	/*
	 * Grow buffer until large enough to contain all interface
	 * descriptions.
	 */
	for (;;) {
		buf = malloc(bufsiz);
		if (buf == NULL)
			goto err_ret;
#ifdef ISC_HAVE_LIFC_FAMILY
		lifc.lifc_family = AF_UNSPEC;	/* request all families */
#endif
#ifdef ISC_HAVE_LIFC_FLAGS
		lifc.lifc_flags = 0;
#endif
		lifc.lifc_len = bufsiz;
		lifc.lifc_buf = buf;
		if ((n = ioctl(s, SIOCGLIFCONF, (char *)&lifc)) != -1) {
			/*
			 * Some OS's just return what will fit rather
			 * than set EINVAL if the buffer is too small
			 * to fit all the interfaces in.  If 
			 * lifc.lifc_len is too near to the end of the
			 * buffer we will grow it just in case and
			 * retry.
			 */
			if (lifc.lifc_len + 2 * sizeof(lifreq) < bufsiz)
				break;
		}
		if ((n == -1) && errno != EINVAL)