[thirdparty/systemd.git] / src / nss-myhostname / nss-myhostname.c

/* SPDX-License-Identifier: LGPL-2.1+ */
/***
  This file is part of systemd.

  Copyright 2008-2011 Lennart Poettering
***/

#include <errno.h>
#include <net/if.h>
#include <netdb.h>
#include <nss.h>
#include <stdlib.h>
#include <string.h>

#include "alloc-util.h"
#include "hostname-util.h"
#include "local-addresses.h"
#include "macro.h"
#include "nss-util.h"
#include "signal-util.h"
#include "string-util.h"
#include "util.h"

/* We use 127.0.0.2 as IPv4 address. This has the advantage over
 * 127.0.0.1 that it can be translated back to the local hostname. For
 * IPv6 we use ::1 which unfortunately will not translate back to the
 * hostname but instead something like "localhost" or so. */

#define LOCALADDRESS_IPV4 (htobe32(0x7F000002))
#define LOCALADDRESS_IPV6 &in6addr_loopback

NSS_GETHOSTBYNAME_PROTOTYPES(myhostname);
NSS_GETHOSTBYADDR_PROTOTYPES(myhostname);

enum nss_status _nss_myhostname_gethostbyname4_r(
                const char *name,
                struct gaih_addrtuple **pat,
                char *buffer, size_t buflen,
                int *errnop, int *h_errnop,
                int32_t *ttlp) {

        struct gaih_addrtuple *r_tuple, *r_tuple_prev = NULL;
        _cleanup_free_ struct local_address *addresses = NULL;
        _cleanup_free_ char *hn = NULL;
        const char *canonical = NULL;
        int n_addresses = 0;
        uint32_t local_address_ipv4;
        struct local_address *a;
        size_t l, idx, ms;
        char *r_name;
        unsigned n;

        BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);

        assert(name);
        assert(pat);
        assert(buffer);
        assert(errnop);
        assert(h_errnop);

        if (is_localhost(name)) {
                /* We respond to 'localhost', so that /etc/hosts
                 * is optional */

                canonical = "localhost";
                local_address_ipv4 = htobe32(INADDR_LOOPBACK);

        } else if (is_gateway_hostname(name)) {

                n_addresses = local_gateways(NULL, 0, AF_UNSPEC, &addresses);
                if (n_addresses <= 0) {
                        *errnop = ENOENT;
                        *h_errnop = HOST_NOT_FOUND;
                        return NSS_STATUS_NOTFOUND;
                }

                canonical = "_gateway";

        } else {
                hn = gethostname_malloc();
                if (!hn) {
                        *errnop = ENOMEM;
                        *h_errnop = NO_RECOVERY;
                        return NSS_STATUS_TRYAGAIN;
                }

                /* We respond to our local host name, our hostname suffixed with a single dot. */
                if (!streq(name, hn) && !streq_ptr(startswith(name, hn), ".")) {
                        *errnop = ENOENT;
                        *h_errnop = HOST_NOT_FOUND;
                        return NSS_STATUS_NOTFOUND;
                }

                n_addresses = local_addresses(NULL, 0, AF_UNSPEC, &addresses);
                if (n_addresses < 0)
                        n_addresses = 0;

                canonical = hn;
                local_address_ipv4 = LOCALADDRESS_IPV4;
        }

        l = strlen(canonical);
        ms = ALIGN(l+1) + ALIGN(sizeof(struct gaih_addrtuple)) * (n_addresses > 0 ? n_addresses : 2);
        if (buflen < ms) {
                *errnop = ERANGE;
                *h_errnop = NETDB_INTERNAL;
                return NSS_STATUS_TRYAGAIN;
        }

        /* First, fill in hostname */
        r_name = buffer;
        memcpy(r_name, canonical, l+1);
        idx = ALIGN(l+1);

        assert(n_addresses >= 0);
        if (n_addresses == 0) {
                /* Second, fill in IPv6 tuple */
                r_tuple = (struct gaih_addrtuple*) (buffer + idx);
                r_tuple->next = r_tuple_prev;
                r_tuple->name = r_name;
                r_tuple->family = AF_INET6;
                memcpy(r_tuple->addr, LOCALADDRESS_IPV6, 16);
                r_tuple->scopeid = 0;

                idx += ALIGN(sizeof(struct gaih_addrtuple));
                r_tuple_prev = r_tuple;

                /* Third, fill in IPv4 tuple */
                r_tuple = (struct gaih_addrtuple*) (buffer + idx);
                r_tuple->next = r_tuple_prev;
                r_tuple->name = r_name;
                r_tuple->family = AF_INET;
                *(uint32_t*) r_tuple->addr = local_address_ipv4;
                r_tuple->scopeid = 0;

                idx += ALIGN(sizeof(struct gaih_addrtuple));
                r_tuple_prev = r_tuple;
        }

        /* Fourth, fill actual addresses in, but in backwards order */
        for (a = addresses + n_addresses - 1, n = 0; (int) n < n_addresses; n++, a--) {
                r_tuple = (struct gaih_addrtuple*) (buffer + idx);
                r_tuple->next = r_tuple_prev;
                r_tuple->name = r_name;
                r_tuple->family = a->family;
                r_tuple->scopeid = a->family == AF_INET6 && IN6_IS_ADDR_LINKLOCAL(&a->address.in6) ? a->ifindex : 0;
                memcpy(r_tuple->addr, &a->address, 16);

                idx += ALIGN(sizeof(struct gaih_addrtuple));
                r_tuple_prev = r_tuple;
        }

        /* Verify the size matches */
        assert(idx == ms);

        /* Nscd expects us to store the first record in **pat. */
        if (*pat)
                **pat = *r_tuple_prev;
        else
                *pat = r_tuple_prev;

        if (ttlp)
                *ttlp = 0;

        /* Explicitly reset all error variables */
        *errnop = 0;
        *h_errnop = NETDB_SUCCESS;
        h_errno = 0;

        return NSS_STATUS_SUCCESS;
}

static enum nss_status fill_in_hostent(
                const char *canonical, const char *additional,
                int af,
                struct local_address *addresses, unsigned n_addresses,
                uint32_t local_address_ipv4,
                struct hostent *result,
                char *buffer, size_t buflen,
                int *errnop, int *h_errnop,
                int32_t *ttlp,
                char **canonp) {

        size_t l_canonical, l_additional, idx, ms, alen;
        char *r_addr, *r_name, *r_aliases, *r_alias = NULL, *r_addr_list;
        struct local_address *a;
        unsigned n, c;

        assert(canonical);
        assert(result);
        assert(buffer);
        assert(errnop);
        assert(h_errnop);

        alen = FAMILY_ADDRESS_SIZE(af);

        for (a = addresses, n = 0, c = 0; n < n_addresses; a++, n++)
                if (af == a->family)
                        c++;

        l_canonical = strlen(canonical);
        l_additional = strlen_ptr(additional);
        ms = ALIGN(l_canonical+1)+
                (additional ? ALIGN(l_additional+1) : 0) +
                sizeof(char*) +
                (additional ? sizeof(char*) : 0) +
                (c > 0 ? c : 1) * ALIGN(alen) +
                (c > 0 ? c+1 : 2) * sizeof(char*);

        if (buflen < ms) {
                *errnop = ERANGE;
                *h_errnop = NETDB_INTERNAL;
                return NSS_STATUS_TRYAGAIN;
        }

        /* First, fill in hostnames */
        r_name = buffer;
        memcpy(r_name, canonical, l_canonical+1);
        idx = ALIGN(l_canonical+1);

        if (additional) {
                r_alias = buffer + idx;
                memcpy(r_alias, additional, l_additional+1);
                idx += ALIGN(l_additional+1);
        }

        /* Second, create aliases array */
        r_aliases = buffer + idx;
        if (additional) {
                ((char**) r_aliases)[0] = r_alias;
                ((char**) r_aliases)[1] = NULL;
                idx += 2*sizeof(char*);
        } else {
                ((char**) r_aliases)[0] = NULL;
                idx += sizeof(char*);
        }

        /* Third, add addresses */
        r_addr = buffer + idx;
        if (c > 0) {
                unsigned i = 0;

                for (a = addresses, n = 0; n < n_addresses; a++, n++) {
                        if (af != a->family)
                                continue;

                        memcpy(r_addr + i*ALIGN(alen), &a->address, alen);
                        i++;
                }

                assert(i == c);
                idx += c*ALIGN(alen);
        } else {
                if (af == AF_INET)
                        *(uint32_t*) r_addr = local_address_ipv4;
                else
                        memcpy(r_addr, LOCALADDRESS_IPV6, 16);

                idx += ALIGN(alen);
        }

        /* Fourth, add address pointer array */
        r_addr_list = buffer + idx;
        if (c > 0) {
                unsigned i;

                for (i = 0; i < c; i++)
                        ((char**) r_addr_list)[i] = r_addr + i*ALIGN(alen);

                ((char**) r_addr_list)[i] = NULL;
                idx += (c+1) * sizeof(char*);

        } else {
                ((char**) r_addr_list)[0] = r_addr;
                ((char**) r_addr_list)[1] = NULL;
                idx += 2 * sizeof(char*);
        }

        /* Verify the size matches */
        assert(idx == ms);

        result->h_name = r_name;
        result->h_aliases = (char**) r_aliases;
        result->h_addrtype = af;
        result->h_length = alen;
        result->h_addr_list = (char**) r_addr_list;

        if (ttlp)
                *ttlp = 0;

        if (canonp)
                *canonp = r_name;

        /* Explicitly reset all error variables */
        *errnop = 0;
        *h_errnop = NETDB_SUCCESS;
        h_errno = 0;

        return NSS_STATUS_SUCCESS;
}

enum nss_status _nss_myhostname_gethostbyname3_r(
                const char *name,
                int af,
                struct hostent *host,
                char *buffer, size_t buflen,
                int *errnop, int *h_errnop,
                int32_t *ttlp,
                char **canonp) {

        _cleanup_free_ struct local_address *addresses = NULL;
        const char *canonical, *additional = NULL;
        _cleanup_free_ char *hn = NULL;
        uint32_t local_address_ipv4 = 0;
        int n_addresses = 0;

        BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);

        assert(name);
        assert(host);
        assert(buffer);
        assert(errnop);
        assert(h_errnop);

        if (af == AF_UNSPEC)
                af = AF_INET;

        if (!IN_SET(af, AF_INET, AF_INET6)) {
                *errnop = EAFNOSUPPORT;
                *h_errnop = NO_DATA;
                return NSS_STATUS_UNAVAIL;
        }

        if (is_localhost(name)) {
                canonical = "localhost";
                local_address_ipv4 = htobe32(INADDR_LOOPBACK);

        } else if (is_gateway_hostname(name)) {

                n_addresses = local_gateways(NULL, 0, af, &addresses);
                if (n_addresses <= 0) {
                        *errnop = ENOENT;
                        *h_errnop = HOST_NOT_FOUND;
                        return NSS_STATUS_NOTFOUND;
                }

                canonical = "_gateway";

        } else {
                hn = gethostname_malloc();
                if (!hn) {
                        *errnop = ENOMEM;
                        *h_errnop = NO_RECOVERY;
                        return NSS_STATUS_TRYAGAIN;
                }

                if (!streq(name, hn) && !streq_ptr(startswith(name, hn), ".")) {
                        *errnop = ENOENT;
                        *h_errnop = HOST_NOT_FOUND;
                        return NSS_STATUS_NOTFOUND;
                }

                n_addresses = local_addresses(NULL, 0, af, &addresses);
                if (n_addresses < 0)
                        n_addresses = 0;

                canonical = hn;
                additional = n_addresses <= 0 && af == AF_INET6 ? "localhost" : NULL;
                local_address_ipv4 = LOCALADDRESS_IPV4;
        }

        return fill_in_hostent(
                        canonical, additional,
                        af,
                        addresses, n_addresses,
                        local_address_ipv4,
                        host,
                        buffer, buflen,
                        errnop, h_errnop,
                        ttlp,
                        canonp);
}

enum nss_status _nss_myhostname_gethostbyaddr2_r(
                const void* addr, socklen_t len,
                int af,
                struct hostent *host,
                char *buffer, size_t buflen,
                int *errnop, int *h_errnop,
                int32_t *ttlp) {

        const char *canonical = NULL, *additional = NULL;
        uint32_t local_address_ipv4 = LOCALADDRESS_IPV4;
        _cleanup_free_ struct local_address *addresses = NULL;
        _cleanup_free_ char *hn = NULL;
        int n_addresses = 0;
        struct local_address *a;
        bool additional_from_hostname = false;
        unsigned n;

        BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);

        assert(addr);
        assert(host);
        assert(buffer);
        assert(errnop);
        assert(h_errnop);

        if (!IN_SET(af, AF_INET, AF_INET6)) {
                *errnop = EAFNOSUPPORT;
                *h_errnop = NO_DATA;
                return NSS_STATUS_UNAVAIL;
        }

        if (len != FAMILY_ADDRESS_SIZE(af)) {
                *errnop = EINVAL;
                *h_errnop = NO_RECOVERY;
                return NSS_STATUS_UNAVAIL;
        }

        if (af == AF_INET) {
                if ((*(uint32_t*) addr) == LOCALADDRESS_IPV4)
                        goto found;

                if ((*(uint32_t*) addr) == htobe32(INADDR_LOOPBACK)) {
                        canonical = "localhost";
                        local_address_ipv4 = htobe32(INADDR_LOOPBACK);
                        goto found;
                }

        } else {
                assert(af == AF_INET6);

                if (memcmp(addr, LOCALADDRESS_IPV6, 16) == 0) {
                        canonical = "localhost";
                        additional_from_hostname = true;
                        goto found;
                }
        }

        n_addresses = local_addresses(NULL, 0, AF_UNSPEC, &addresses);
        for (a = addresses, n = 0; (int) n < n_addresses; n++, a++) {
                if (af != a->family)
                        continue;

                if (memcmp(addr, &a->address, FAMILY_ADDRESS_SIZE(af)) == 0)
                        goto found;
        }

        addresses = mfree(addresses);

        n_addresses = local_gateways(NULL, 0, AF_UNSPEC, &addresses);
        for (a = addresses, n = 0; (int) n < n_addresses; n++, a++) {
                if (af != a->family)
                        continue;

                if (memcmp(addr, &a->address, FAMILY_ADDRESS_SIZE(af)) == 0) {
                        canonical = "_gateway";
                        goto found;
                }
        }

        *errnop = ENOENT;
        *h_errnop = HOST_NOT_FOUND;
        return NSS_STATUS_NOTFOUND;

found:
        if (!canonical || additional_from_hostname) {
                hn = gethostname_malloc();
                if (!hn) {
                        *errnop = ENOMEM;
                        *h_errnop = NO_RECOVERY;
                        return NSS_STATUS_TRYAGAIN;
                }

                if (!canonical)
                        canonical = hn;
                else
                        additional = hn;
        }

        return fill_in_hostent(
                        canonical, additional,
                        af,
                        addresses, n_addresses,
                        local_address_ipv4,
                        host,
                        buffer, buflen,
                        errnop, h_errnop,
                        ttlp,
                        NULL);
}

NSS_GETHOSTBYNAME_FALLBACKS(myhostname);
NSS_GETHOSTBYADDR_FALLBACKS(myhostname);
Commit	Line	Data
53e1b683	1	/* SPDX-License-Identifier: LGPL-2.1+ */
4e8c8252	2	/***
cbc06dcd	3	This file is part of systemd.
4e8c8252	4
8041b5ba	5	Copyright 2008-2011 Lennart Poettering
4e8c8252	6	***/
6b21f0cf	7
6b21f0cf	8	#include <errno.h>
4e8c8252	9	#include <net/if.h>
07630cea LP	10	#include <netdb.h>
07630cea LP	11	#include <nss.h>
8041b5ba	12	#include <stdlib.h>
07630cea	13	#include <string.h>
8041b5ba	14
b5efdb8a	15	#include "alloc-util.h"
07630cea	16	#include "hostname-util.h"
e80af1bd	17	#include "local-addresses.h"
1c633045	18	#include "macro.h"
c9fdc26e	19	#include "nss-util.h"
0c5eb056	20	#include "signal-util.h"
07630cea	21	#include "string-util.h"
c9fdc26e	22	#include "util.h"
4e8c8252 LP	23
	24	/* We use 127.0.0.2 as IPv4 address. This has the advantage over
	25	* 127.0.0.1 that it can be translated back to the local hostname. For
	26	* IPv6 we use ::1 which unfortunately will not translate back to the
3fdcecc8	27	* hostname but instead something like "localhost" or so. */
4e8c8252	28
8e38570e	29	#define LOCALADDRESS_IPV4 (htobe32(0x7F000002))
4e8c8252	30	#define LOCALADDRESS_IPV6 &in6addr_loopback
4e8c8252	31
c9fdc26e LP	32	NSS_GETHOSTBYNAME_PROTOTYPES(myhostname);
c9fdc26e LP	33	NSS_GETHOSTBYADDR_PROTOTYPES(myhostname);
8041b5ba	34
4e8c8252 LP	35	enum nss_status _nss_myhostname_gethostbyname4_r(
	36	const char *name,
	37	struct gaih_addrtuple **pat,
	38	char *buffer, size_t buflen,
	39	int errnop, int h_errnop,
	40	int32_t *ttlp) {
	41
8041b5ba	42	struct gaih_addrtuple r_tuple, r_tuple_prev = NULL;
e80af1bd	43	_cleanup_free_ struct local_address *addresses = NULL;
5502f0d9 LP	44	_cleanup_free_ char *hn = NULL;
5502f0d9 LP	45	const char *canonical = NULL;
a1077c84	46	int n_addresses = 0;
e8a7a315	47	uint32_t local_address_ipv4;
e80af1bd	48	struct local_address *a;
5502f0d9 LP	49	size_t l, idx, ms;
5502f0d9 LP	50	char *r_name;
e80af1bd	51	unsigned n;
4e8c8252	52
0c5eb056 LP	53	BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
0c5eb056 LP	54
5502f0d9 LP	55	assert(name);
	56	assert(pat);
	57	assert(buffer);
	58	assert(errnop);
	59	assert(h_errnop);
	60
	61	if (is_localhost(name)) {
e8a7a315 LP	62	/* We respond to 'localhost', so that /etc/hosts
e8a7a315 LP	63	* is optional */
4e8c8252	64
e8a7a315	65	canonical = "localhost";
8e38570e	66	local_address_ipv4 = htobe32(INADDR_LOOPBACK);
e9140aff	67
46a5e0e7	68	} else if (is_gateway_hostname(name)) {
e9140aff	69
1d050e1e	70	n_addresses = local_gateways(NULL, 0, AF_UNSPEC, &addresses);
e9140aff LP	71	if (n_addresses <= 0) {
	72	*errnop = ENOENT;
	73	*h_errnop = HOST_NOT_FOUND;
	74	return NSS_STATUS_NOTFOUND;
	75	}
	76
5248e7e1	77	canonical = "_gateway";
e9140aff	78
e8a7a315	79	} else {
5502f0d9 LP	80	hn = gethostname_malloc();
	81	if (!hn) {
	82	*errnop = ENOMEM;
e8a7a315	83	*h_errnop = NO_RECOVERY;
5502f0d9	84	return NSS_STATUS_TRYAGAIN;
e8a7a315 LP	85	}
e8a7a315 LP	86
61233823	87	/* We respond to our local host name, our hostname suffixed with a single dot. */
5502f0d9	88	if (!streq(name, hn) && !streq_ptr(startswith(name, hn), ".")) {
e8a7a315 LP	89	*errnop = ENOENT;
	90	*h_errnop = HOST_NOT_FOUND;
	91	return NSS_STATUS_NOTFOUND;
	92	}
	93
1d050e1e	94	n_addresses = local_addresses(NULL, 0, AF_UNSPEC, &addresses);
e80af1bd LP	95	if (n_addresses < 0)
e80af1bd LP	96	n_addresses = 0;
e8a7a315 LP	97
	98	canonical = hn;
	99	local_address_ipv4 = LOCALADDRESS_IPV4;
	100	}
8041b5ba	101
e8a7a315	102	l = strlen(canonical);
5502f0d9	103	ms = ALIGN(l+1) + ALIGN(sizeof(struct gaih_addrtuple)) * (n_addresses > 0 ? n_addresses : 2);
4e8c8252	104	if (buflen < ms) {
cda458a5 LP	105	*errnop = ERANGE;
cda458a5 LP	106	*h_errnop = NETDB_INTERNAL;
4e8c8252 LP	107	return NSS_STATUS_TRYAGAIN;
	108	}
	109
	110	/* First, fill in hostname */
	111	r_name = buffer;
e8a7a315	112	memcpy(r_name, canonical, l+1);
4e8c8252 LP	113	idx = ALIGN(l+1);
4e8c8252 LP	114
68a9c7c4 ZJS	115	assert(n_addresses >= 0);
68a9c7c4 ZJS	116	if (n_addresses == 0) {
8041b5ba LP	117	/* Second, fill in IPv6 tuple */
	118	r_tuple = (struct gaih_addrtuple*) (buffer + idx);
	119	r_tuple->next = r_tuple_prev;
	120	r_tuple->name = r_name;
	121	r_tuple->family = AF_INET6;
	122	memcpy(r_tuple->addr, LOCALADDRESS_IPV6, 16);
a1077c84	123	r_tuple->scopeid = 0;
8041b5ba LP	124
	125	idx += ALIGN(sizeof(struct gaih_addrtuple));
	126	r_tuple_prev = r_tuple;
	127
	128	/* Third, fill in IPv4 tuple */
	129	r_tuple = (struct gaih_addrtuple*) (buffer + idx);
	130	r_tuple->next = r_tuple_prev;
	131	r_tuple->name = r_name;
	132	r_tuple->family = AF_INET;
e8a7a315	133	(uint32_t) r_tuple->addr = local_address_ipv4;
a1077c84	134	r_tuple->scopeid = 0;
8041b5ba LP	135
	136	idx += ALIGN(sizeof(struct gaih_addrtuple));
	137	r_tuple_prev = r_tuple;
	138	}
	139
	140	/* Fourth, fill actual addresses in, but in backwards order */
e80af1bd	141	for (a = addresses + n_addresses - 1, n = 0; (int) n < n_addresses; n++, a--) {
8041b5ba LP	142	r_tuple = (struct gaih_addrtuple*) (buffer + idx);
	143	r_tuple->next = r_tuple_prev;
	144	r_tuple->name = r_name;
	145	r_tuple->family = a->family;
a1077c84	146	r_tuple->scopeid = a->family == AF_INET6 && IN6_IS_ADDR_LINKLOCAL(&a->address.in6) ? a->ifindex : 0;
5502f0d9	147	memcpy(r_tuple->addr, &a->address, 16);
8041b5ba LP	148
	149	idx += ALIGN(sizeof(struct gaih_addrtuple));
	150	r_tuple_prev = r_tuple;
	151	}
4e8c8252 LP	152
	153	/* Verify the size matches */
	154	assert(idx == ms);
	155
d2f1f23a ED	156	/* Nscd expects us to store the first record in *pat. /
	157	if (*pat)
	158	*pat = r_tuple_prev;
	159	else
	160	*pat = r_tuple_prev;
4e8c8252 LP	161
	162	if (ttlp)
	163	*ttlp = 0;
	164
e70df46b LP	165	/* Explicitly reset all error variables */
	166	*errnop = 0;
	167	*h_errnop = NETDB_SUCCESS;
	168	h_errno = 0;
	169
4e8c8252 LP	170	return NSS_STATUS_SUCCESS;
4e8c8252 LP	171	}
6b21f0cf LP	172
6b21f0cf LP	173	static enum nss_status fill_in_hostent(
e8a7a315	174	const char canonical, const char additional,
4e8c8252	175	int af,
e80af1bd	176	struct local_address *addresses, unsigned n_addresses,
e8a7a315	177	uint32_t local_address_ipv4,
4e8c8252 LP	178	struct hostent *result,
	179	char *buffer, size_t buflen,
	180	int errnop, int h_errnop,
	181	int32_t *ttlp,
	182	char **canonp) {
	183
d4c9895d	184	size_t l_canonical, l_additional, idx, ms, alen;
e8a7a315	185	char r_addr, r_name, r_aliases, r_alias = NULL, *r_addr_list;
e80af1bd	186	struct local_address *a;
e8a7a315	187	unsigned n, c;
8041b5ba	188
5502f0d9 LP	189	assert(canonical);
	190	assert(result);
	191	assert(buffer);
	192	assert(errnop);
	193	assert(h_errnop);
	194
9d485985	195	alen = FAMILY_ADDRESS_SIZE(af);
8041b5ba	196
8041b5ba LP	197	for (a = addresses, n = 0, c = 0; n < n_addresses; a++, n++)
	198	if (af == a->family)
	199	c++;
4e8c8252	200
e8a7a315	201	l_canonical = strlen(canonical);
7bf7ce28	202	l_additional = strlen_ptr(additional);
e8a7a315 LP	203	ms = ALIGN(l_canonical+1)+
e8a7a315 LP	204	(additional ? ALIGN(l_additional+1) : 0) +
5502f0d9	205	sizeof(char*) +
e8a7a315	206	(additional ? sizeof(char*) : 0) +
d4c9895d	207	(c > 0 ? c : 1) * ALIGN(alen) +
5502f0d9	208	(c > 0 ? c+1 : 2) * sizeof(char*);
8041b5ba	209
4e8c8252	210	if (buflen < ms) {
cda458a5 LP	211	*errnop = ERANGE;
cda458a5 LP	212	*h_errnop = NETDB_INTERNAL;
4e8c8252 LP	213	return NSS_STATUS_TRYAGAIN;
	214	}
	215
e8a7a315	216	/* First, fill in hostnames */
4e8c8252	217	r_name = buffer;
e8a7a315 LP	218	memcpy(r_name, canonical, l_canonical+1);
e8a7a315 LP	219	idx = ALIGN(l_canonical+1);
4e8c8252	220
e8a7a315 LP	221	if (additional) {
	222	r_alias = buffer + idx;
	223	memcpy(r_alias, additional, l_additional+1);
	224	idx += ALIGN(l_additional+1);
	225	}
	226
	227	/* Second, create aliases array */
4e8c8252	228	r_aliases = buffer + idx;
e8a7a315 LP	229	if (additional) {
	230	((char**) r_aliases)[0] = r_alias;
	231	((char**) r_aliases)[1] = NULL;
	232	idx += 2sizeof(char);
	233	} else {
	234	((char**) r_aliases)[0] = NULL;
	235	idx += sizeof(char*);
	236	}
4e8c8252	237
8041b5ba	238	/* Third, add addresses */
4e8c8252	239	r_addr = buffer + idx;
8041b5ba LP	240	if (c > 0) {
	241	unsigned i = 0;
	242
	243	for (a = addresses, n = 0; n < n_addresses; a++, n++) {
	244	if (af != a->family)
	245	continue;
	246
5502f0d9	247	memcpy(r_addr + i*ALIGN(alen), &a->address, alen);
8041b5ba LP	248	i++;
	249	}
	250
	251	assert(i == c);
	252	idx += c*ALIGN(alen);
	253	} else {
	254	if (af == AF_INET)
e8a7a315	255	(uint32_t) r_addr = local_address_ipv4;
8041b5ba LP	256	else
	257	memcpy(r_addr, LOCALADDRESS_IPV6, 16);
	258
	259	idx += ALIGN(alen);
	260	}
4e8c8252 LP	261
	262	/* Fourth, add address pointer array */
	263	r_addr_list = buffer + idx;
8041b5ba	264	if (c > 0) {
d4c9895d	265	unsigned i;
8041b5ba	266
d4c9895d LP	267	for (i = 0; i < c; i++)
d4c9895d LP	268	((char*) r_addr_list)[i] = r_addr + iALIGN(alen);
8041b5ba	269
d4c9895d LP	270	((char**) r_addr_list)[i] = NULL;
d4c9895d LP	271	idx += (c+1) * sizeof(char*);
8041b5ba LP	272
	273	} else {
	274	((char**) r_addr_list)[0] = r_addr;
	275	((char**) r_addr_list)[1] = NULL;
d4c9895d	276	idx += 2 * sizeof(char*);
8041b5ba	277	}
4e8c8252 LP	278
	279	/* Verify the size matches */
	280	assert(idx == ms);
	281
	282	result->h_name = r_name;
	283	result->h_aliases = (char**) r_aliases;
	284	result->h_addrtype = af;
	285	result->h_length = alen;
	286	result->h_addr_list = (char**) r_addr_list;
	287
	288	if (ttlp)
	289	*ttlp = 0;
	290
	291	if (canonp)
	292	*canonp = r_name;
	293
e70df46b LP	294	/* Explicitly reset all error variables */
	295	*errnop = 0;
	296	*h_errnop = NETDB_SUCCESS;
	297	h_errno = 0;
	298
4e8c8252	299	return NSS_STATUS_SUCCESS;
6b21f0cf LP	300	}
6b21f0cf LP	301
4e8c8252 LP	302	enum nss_status _nss_myhostname_gethostbyname3_r(
	303	const char *name,
	304	int af,
	305	struct hostent *host,
	306	char *buffer, size_t buflen,
	307	int errnop, int h_errnop,
	308	int32_t *ttlp,
	309	char **canonp) {
6b21f0cf	310
e80af1bd	311	_cleanup_free_ struct local_address *addresses = NULL;
e8a7a315	312	const char canonical, additional = NULL;
5502f0d9	313	_cleanup_free_ char *hn = NULL;
e9140aff	314	uint32_t local_address_ipv4 = 0;
e80af1bd	315	int n_addresses = 0;
5502f0d9	316
0c5eb056 LP	317	BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
0c5eb056 LP	318
5502f0d9 LP	319	assert(name);
	320	assert(host);
	321	assert(buffer);
	322	assert(errnop);
	323	assert(h_errnop);
6b21f0cf	324
4e8c8252 LP	325	if (af == AF_UNSPEC)
4e8c8252 LP	326	af = AF_INET;
6b21f0cf	327
ec2ce0c5	328	if (!IN_SET(af, AF_INET, AF_INET6)) {
4e8c8252 LP	329	*errnop = EAFNOSUPPORT;
	330	*h_errnop = NO_DATA;
	331	return NSS_STATUS_UNAVAIL;
	332	}
6b21f0cf	333
5502f0d9	334	if (is_localhost(name)) {
e8a7a315	335	canonical = "localhost";
8e38570e	336	local_address_ipv4 = htobe32(INADDR_LOOPBACK);
e9140aff	337
46a5e0e7	338	} else if (is_gateway_hostname(name)) {
e9140aff	339
1d050e1e	340	n_addresses = local_gateways(NULL, 0, af, &addresses);
e9140aff LP	341	if (n_addresses <= 0) {
	342	*errnop = ENOENT;
	343	*h_errnop = HOST_NOT_FOUND;
	344	return NSS_STATUS_NOTFOUND;
	345	}
	346
5248e7e1	347	canonical = "_gateway";
e9140aff	348
e8a7a315	349	} else {
5502f0d9 LP	350	hn = gethostname_malloc();
	351	if (!hn) {
	352	*errnop = ENOMEM;
e8a7a315	353	*h_errnop = NO_RECOVERY;
5502f0d9	354	return NSS_STATUS_TRYAGAIN;
e8a7a315	355	}
6b21f0cf	356
5502f0d9	357	if (!streq(name, hn) && !streq_ptr(startswith(name, hn), ".")) {
e8a7a315 LP	358	*errnop = ENOENT;
	359	*h_errnop = HOST_NOT_FOUND;
	360	return NSS_STATUS_NOTFOUND;
	361	}
	362
1d050e1e	363	n_addresses = local_addresses(NULL, 0, af, &addresses);
e80af1bd LP	364	if (n_addresses < 0)
e80af1bd LP	365	n_addresses = 0;
e8a7a315 LP	366
	367	canonical = hn;
	368	additional = n_addresses <= 0 && af == AF_INET6 ? "localhost" : NULL;
	369	local_address_ipv4 = LOCALADDRESS_IPV4;
4e8c8252	370	}
6b21f0cf	371
e8a7a315 LP	372	return fill_in_hostent(
	373	canonical, additional,
	374	af,
	375	addresses, n_addresses,
	376	local_address_ipv4,
	377	host,
	378	buffer, buflen,
	379	errnop, h_errnop,
	380	ttlp,
	381	canonp);
4e8c8252	382	}
6b21f0cf	383
4e8c8252 LP	384	enum nss_status _nss_myhostname_gethostbyaddr2_r(
	385	const void* addr, socklen_t len,
	386	int af,
	387	struct hostent *host,
	388	char *buffer, size_t buflen,
	389	int errnop, int h_errnop,
	390	int32_t *ttlp) {
6b21f0cf	391
e8a7a315	392	const char canonical = NULL, additional = NULL;
5502f0d9	393	uint32_t local_address_ipv4 = LOCALADDRESS_IPV4;
e80af1bd	394	_cleanup_free_ struct local_address *addresses = NULL;
5502f0d9	395	_cleanup_free_ char *hn = NULL;
e80af1bd LP	396	int n_addresses = 0;
e80af1bd LP	397	struct local_address *a;
3fdcecc8	398	bool additional_from_hostname = false;
e80af1bd	399	unsigned n;
5502f0d9	400
0c5eb056 LP	401	BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
0c5eb056 LP	402
5502f0d9 LP	403	assert(addr);
	404	assert(host);
	405	assert(buffer);
	406	assert(errnop);
	407	assert(h_errnop);
8041b5ba	408
555bd6e9 LP	409	if (!IN_SET(af, AF_INET, AF_INET6)) {
	410	*errnop = EAFNOSUPPORT;
	411	*h_errnop = NO_DATA;
	412	return NSS_STATUS_UNAVAIL;
	413	}
	414
9d485985	415	if (len != FAMILY_ADDRESS_SIZE(af)) {
8041b5ba LP	416	*errnop = EINVAL;
	417	*h_errnop = NO_RECOVERY;
	418	return NSS_STATUS_UNAVAIL;
	419	}
6b21f0cf	420
4e8c8252	421	if (af == AF_INET) {
8041b5ba LP	422	if (((uint32_t) addr) == LOCALADDRESS_IPV4)
8041b5ba LP	423	goto found;
6b21f0cf	424
8e38570e	425	if (((uint32_t) addr) == htobe32(INADDR_LOOPBACK)) {
e8a7a315	426	canonical = "localhost";
8e38570e	427	local_address_ipv4 = htobe32(INADDR_LOOPBACK);
e8a7a315 LP	428	goto found;
	429	}
	430
555bd6e9 LP	431	} else {
555bd6e9 LP	432	assert(af == AF_INET6);
8041b5ba	433
e8a7a315	434	if (memcmp(addr, LOCALADDRESS_IPV6, 16) == 0) {
3fdcecc8 LP	435	canonical = "localhost";
3fdcecc8 LP	436	additional_from_hostname = true;
8041b5ba	437	goto found;
e8a7a315	438	}
4e8c8252 LP	439	}
4e8c8252 LP	440
1d050e1e	441	n_addresses = local_addresses(NULL, 0, AF_UNSPEC, &addresses);
68a9c7c4 ZJS	442	for (a = addresses, n = 0; (int) n < n_addresses; n++, a++) {
	443	if (af != a->family)
	444	continue;
8041b5ba	445
68a9c7c4 ZJS	446	if (memcmp(addr, &a->address, FAMILY_ADDRESS_SIZE(af)) == 0)
68a9c7c4 ZJS	447	goto found;
e9140aff LP	448	}
e9140aff LP	449
97b11eed	450	addresses = mfree(addresses);
e9140aff	451
1d050e1e	452	n_addresses = local_gateways(NULL, 0, AF_UNSPEC, &addresses);
68a9c7c4 ZJS	453	for (a = addresses, n = 0; (int) n < n_addresses; n++, a++) {
	454	if (af != a->family)
	455	continue;
e9140aff	456
68a9c7c4	457	if (memcmp(addr, &a->address, FAMILY_ADDRESS_SIZE(af)) == 0) {
5248e7e1	458	canonical = "_gateway";
68a9c7c4	459	goto found;
e9140aff	460	}
8041b5ba LP	461	}
	462
	463	*errnop = ENOENT;
	464	*h_errnop = HOST_NOT_FOUND;
8041b5ba LP	465	return NSS_STATUS_NOTFOUND;
	466
	467	found:
82e4c2d6	468	if (!canonical \|\| additional_from_hostname) {
3fdcecc8 LP	469	hn = gethostname_malloc();
	470	if (!hn) {
	471	*errnop = ENOMEM;
	472	*h_errnop = NO_RECOVERY;
	473	return NSS_STATUS_TRYAGAIN;
	474	}
	475
	476	if (!canonical)
	477	canonical = hn;
82e4c2d6	478	else
3fdcecc8 LP	479	additional = hn;
3fdcecc8 LP	480	}
4e8c8252	481
e8a7a315 LP	482	return fill_in_hostent(
	483	canonical, additional,
	484	af,
	485	addresses, n_addresses,
	486	local_address_ipv4,
	487	host,
	488	buffer, buflen,
	489	errnop, h_errnop,
	490	ttlp,
	491	NULL);
4e8c8252	492	}
6b21f0cf	493
c9fdc26e LP	494	NSS_GETHOSTBYNAME_FALLBACKS(myhostname);
c9fdc26e LP	495	NSS_GETHOSTBYADDR_FALLBACKS(myhostname);