1 /* SPDX-License-Identifier: LGPL-2.1+ */
9 #include "alloc-util.h"
10 #include "errno-util.h"
11 #include "hostname-util.h"
12 #include "local-addresses.h"
15 #include "signal-util.h"
16 #include "string-util.h"
18 /* We use 127.0.0.2 as IPv4 address. This has the advantage over
19 * 127.0.0.1 that it can be translated back to the local hostname. For
20 * IPv6 we use ::1 which unfortunately will not translate back to the
21 * hostname but instead something like "localhost" or so. */
23 #define LOCALADDRESS_IPV4 (htobe32(0x7F000002))
24 #define LOCALADDRESS_IPV6 &in6addr_loopback
26 NSS_GETHOSTBYNAME_PROTOTYPES(myhostname);
27 NSS_GETHOSTBYADDR_PROTOTYPES(myhostname);
29 enum nss_status _nss_myhostname_gethostbyname4_r(
31 struct gaih_addrtuple **pat,
32 char *buffer, size_t buflen,
33 int *errnop, int *h_errnop,
36 struct gaih_addrtuple *r_tuple, *r_tuple_prev = NULL;
37 _cleanup_free_ struct local_address *addresses = NULL;
38 _cleanup_free_ char *hn = NULL;
39 const char *canonical = NULL;
41 uint32_t local_address_ipv4;
42 struct local_address *a;
48 BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
56 if (is_localhost(name)) {
57 /* We respond to 'localhost', so that /etc/hosts
60 canonical = "localhost";
61 local_address_ipv4 = htobe32(INADDR_LOOPBACK);
63 } else if (is_gateway_hostname(name)) {
65 n_addresses = local_gateways(NULL, 0, AF_UNSPEC, &addresses);
69 canonical = "_gateway";
72 hn = gethostname_malloc();
76 *h_errnop = NO_RECOVERY;
77 return NSS_STATUS_TRYAGAIN;
80 /* We respond to our local host name, our hostname suffixed with a single dot. */
81 if (!streq(name, hn) && !streq_ptr(startswith(name, hn), "."))
84 n_addresses = local_addresses(NULL, 0, AF_UNSPEC, &addresses);
89 local_address_ipv4 = LOCALADDRESS_IPV4;
92 l = strlen(canonical);
93 ms = ALIGN(l+1) + ALIGN(sizeof(struct gaih_addrtuple)) * (n_addresses > 0 ? n_addresses : 2);
97 *h_errnop = NETDB_INTERNAL;
98 return NSS_STATUS_TRYAGAIN;
101 /* First, fill in hostname */
103 memcpy(r_name, canonical, l+1);
106 assert(n_addresses >= 0);
107 if (n_addresses == 0) {
108 /* Second, fill in IPv6 tuple */
109 r_tuple = (struct gaih_addrtuple*) (buffer + idx);
110 r_tuple->next = r_tuple_prev;
111 r_tuple->name = r_name;
112 r_tuple->family = AF_INET6;
113 memcpy(r_tuple->addr, LOCALADDRESS_IPV6, 16);
114 r_tuple->scopeid = 0;
116 idx += ALIGN(sizeof(struct gaih_addrtuple));
117 r_tuple_prev = r_tuple;
119 /* Third, fill in IPv4 tuple */
120 r_tuple = (struct gaih_addrtuple*) (buffer + idx);
121 r_tuple->next = r_tuple_prev;
122 r_tuple->name = r_name;
123 r_tuple->family = AF_INET;
124 *(uint32_t*) r_tuple->addr = local_address_ipv4;
125 r_tuple->scopeid = 0;
127 idx += ALIGN(sizeof(struct gaih_addrtuple));
128 r_tuple_prev = r_tuple;
131 /* Fourth, fill actual addresses in, but in backwards order */
132 for (a = addresses + n_addresses - 1, n = 0; (int) n < n_addresses; n++, a--) {
133 r_tuple = (struct gaih_addrtuple*) (buffer + idx);
134 r_tuple->next = r_tuple_prev;
135 r_tuple->name = r_name;
136 r_tuple->family = a->family;
137 r_tuple->scopeid = a->family == AF_INET6 && IN6_IS_ADDR_LINKLOCAL(&a->address.in6) ? a->ifindex : 0;
138 memcpy(r_tuple->addr, &a->address, 16);
140 idx += ALIGN(sizeof(struct gaih_addrtuple));
141 r_tuple_prev = r_tuple;
144 /* Verify the size matches */
147 /* Nscd expects us to store the first record in **pat. */
149 **pat = *r_tuple_prev;
156 /* Explicitly reset both *h_errnop and h_errno to work around
157 * https://bugzilla.redhat.com/show_bug.cgi?id=1125975 */
158 *h_errnop = NETDB_SUCCESS;
161 return NSS_STATUS_SUCCESS;
164 *h_errnop = HOST_NOT_FOUND;
165 return NSS_STATUS_NOTFOUND;
168 static enum nss_status fill_in_hostent(
169 const char *canonical, const char *additional,
171 struct local_address *addresses, unsigned n_addresses,
172 uint32_t local_address_ipv4,
173 struct hostent *result,
174 char *buffer, size_t buflen,
175 int *errnop, int *h_errnop,
179 size_t l_canonical, l_additional, idx, ms, alen;
180 char *r_addr, *r_name, *r_aliases, *r_alias = NULL, *r_addr_list;
181 struct local_address *a;
192 alen = FAMILY_ADDRESS_SIZE(af);
194 for (a = addresses, n = 0, c = 0; n < n_addresses; a++, n++)
198 l_canonical = strlen(canonical);
199 l_additional = strlen_ptr(additional);
200 ms = ALIGN(l_canonical+1)+
201 (additional ? ALIGN(l_additional+1) : 0) +
203 (additional ? sizeof(char*) : 0) +
204 (c > 0 ? c : 1) * ALIGN(alen) +
205 (c > 0 ? c+1 : 2) * sizeof(char*);
210 *h_errnop = NETDB_INTERNAL;
211 return NSS_STATUS_TRYAGAIN;
214 /* First, fill in hostnames */
216 memcpy(r_name, canonical, l_canonical+1);
217 idx = ALIGN(l_canonical+1);
220 r_alias = buffer + idx;
221 memcpy(r_alias, additional, l_additional+1);
222 idx += ALIGN(l_additional+1);
225 /* Second, create aliases array */
226 r_aliases = buffer + idx;
228 ((char**) r_aliases)[0] = r_alias;
229 ((char**) r_aliases)[1] = NULL;
230 idx += 2*sizeof(char*);
232 ((char**) r_aliases)[0] = NULL;
233 idx += sizeof(char*);
236 /* Third, add addresses */
237 r_addr = buffer + idx;
241 for (a = addresses, n = 0; n < n_addresses; a++, n++) {
245 memcpy(r_addr + i*ALIGN(alen), &a->address, alen);
250 idx += c*ALIGN(alen);
253 *(uint32_t*) r_addr = local_address_ipv4;
255 memcpy(r_addr, LOCALADDRESS_IPV6, 16);
260 /* Fourth, add address pointer array */
261 r_addr_list = buffer + idx;
265 for (i = 0; i < c; i++)
266 ((char**) r_addr_list)[i] = r_addr + i*ALIGN(alen);
268 ((char**) r_addr_list)[i] = NULL;
269 idx += (c+1) * sizeof(char*);
272 ((char**) r_addr_list)[0] = r_addr;
273 ((char**) r_addr_list)[1] = NULL;
274 idx += 2 * sizeof(char*);
277 /* Verify the size matches */
280 result->h_name = r_name;
281 result->h_aliases = (char**) r_aliases;
282 result->h_addrtype = af;
283 result->h_length = alen;
284 result->h_addr_list = (char**) r_addr_list;
292 /* Explicitly reset both *h_errnop and h_errno to work around
293 * https://bugzilla.redhat.com/show_bug.cgi?id=1125975 */
294 *h_errnop = NETDB_SUCCESS;
297 return NSS_STATUS_SUCCESS;
300 enum nss_status _nss_myhostname_gethostbyname3_r(
303 struct hostent *host,
304 char *buffer, size_t buflen,
305 int *errnop, int *h_errnop,
309 _cleanup_free_ struct local_address *addresses = NULL;
310 const char *canonical, *additional = NULL;
311 _cleanup_free_ char *hn = NULL;
312 uint32_t local_address_ipv4 = 0;
316 BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
327 if (!IN_SET(af, AF_INET, AF_INET6)) {
329 *errnop = EAFNOSUPPORT;
331 return NSS_STATUS_UNAVAIL;
334 if (is_localhost(name)) {
335 canonical = "localhost";
336 local_address_ipv4 = htobe32(INADDR_LOOPBACK);
338 } else if (is_gateway_hostname(name)) {
340 n_addresses = local_gateways(NULL, 0, af, &addresses);
341 if (n_addresses <= 0)
344 canonical = "_gateway";
347 hn = gethostname_malloc();
351 *h_errnop = NO_RECOVERY;
352 return NSS_STATUS_TRYAGAIN;
355 if (!streq(name, hn) && !streq_ptr(startswith(name, hn), "."))
358 n_addresses = local_addresses(NULL, 0, af, &addresses);
363 additional = n_addresses <= 0 && af == AF_INET6 ? "localhost" : NULL;
364 local_address_ipv4 = LOCALADDRESS_IPV4;
369 return fill_in_hostent(
370 canonical, additional,
372 addresses, n_addresses,
381 *h_errnop = HOST_NOT_FOUND;
382 return NSS_STATUS_NOTFOUND;
385 enum nss_status _nss_myhostname_gethostbyaddr2_r(
386 const void* addr, socklen_t len,
388 struct hostent *host,
389 char *buffer, size_t buflen,
390 int *errnop, int *h_errnop,
393 const char *canonical = NULL, *additional = NULL;
394 uint32_t local_address_ipv4 = LOCALADDRESS_IPV4;
395 _cleanup_free_ struct local_address *addresses = NULL;
396 _cleanup_free_ char *hn = NULL;
398 struct local_address *a;
399 bool additional_from_hostname = false;
403 BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
411 if (!IN_SET(af, AF_INET, AF_INET6)) {
413 *errnop = EAFNOSUPPORT;
415 return NSS_STATUS_UNAVAIL;
418 if (len != FAMILY_ADDRESS_SIZE(af)) {
421 *h_errnop = NO_RECOVERY;
422 return NSS_STATUS_UNAVAIL;
426 if ((*(uint32_t*) addr) == LOCALADDRESS_IPV4)
429 if ((*(uint32_t*) addr) == htobe32(INADDR_LOOPBACK)) {
430 canonical = "localhost";
431 local_address_ipv4 = htobe32(INADDR_LOOPBACK);
436 assert(af == AF_INET6);
438 if (memcmp(addr, LOCALADDRESS_IPV6, 16) == 0) {
439 canonical = "localhost";
440 additional_from_hostname = true;
445 n_addresses = local_addresses(NULL, 0, AF_UNSPEC, &addresses);
446 for (a = addresses, n = 0; (int) n < n_addresses; n++, a++) {
450 if (memcmp(addr, &a->address, FAMILY_ADDRESS_SIZE(af)) == 0)
454 addresses = mfree(addresses);
456 n_addresses = local_gateways(NULL, 0, AF_UNSPEC, &addresses);
457 for (a = addresses, n = 0; (int) n < n_addresses; n++, a++) {
461 if (memcmp(addr, &a->address, FAMILY_ADDRESS_SIZE(af)) == 0) {
462 canonical = "_gateway";
467 *h_errnop = HOST_NOT_FOUND;
468 return NSS_STATUS_NOTFOUND;
471 if (!canonical || additional_from_hostname) {
472 hn = gethostname_malloc();
476 *h_errnop = NO_RECOVERY;
477 return NSS_STATUS_TRYAGAIN;
487 return fill_in_hostent(
488 canonical, additional,
490 addresses, n_addresses,
499 NSS_GETHOSTBYNAME_FALLBACKS(myhostname);
500 NSS_GETHOSTBYADDR_FALLBACKS(myhostname);