3 * Resolver library with GLib integration
5 * Copyright (C) 2009-2010 Intel Corporation. All rights reserved.
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
32 #include <sys/types.h>
33 #include <sys/socket.h>
35 #include <arpa/inet.h>
36 #include <arpa/nameser.h>
49 struct sockaddr_in sin;
50 struct sockaddr_in6 sin6;
54 struct sockaddr_in sin;
55 struct sockaddr_in6 sin6;
61 struct resolv_lookup {
66 struct sort_result *results;
68 struct resolv_query *ipv4_query;
69 struct resolv_query *ipv6_query;
74 GResolvResultFunc result_func;
85 struct resolv_lookup *lookup;
88 struct resolv_nameserver {
95 GIOChannel *udp_channel;
102 guint next_lookup_id;
103 GQueue *lookup_queue;
107 GList *nameserver_list;
109 struct __res_state res;
111 GResolvDebugFunc debug_func;
115 static void sort_and_return_results(struct resolv_lookup *lookup);
116 static void rfc3484_sort_results(struct resolv_lookup *lookup);
118 static inline void debug(GResolv *resolv, const char *format, ...)
123 if (resolv->debug_func == NULL)
126 va_start(ap, format);
128 if (vsnprintf(str, sizeof(str), format, ap) > 0)
129 resolv->debug_func(str, resolv->debug_data);
134 static void destroy_query(struct resolv_query *query)
136 if (query->timeout > 0)
137 g_source_remove(query->timeout);
142 static void destroy_lookup(struct resolv_lookup *lookup)
144 if (lookup->ipv4_query) {
145 destroy_query(lookup->ipv4_query);
146 g_queue_remove(lookup->resolv->query_queue, lookup->ipv4_query);
148 if (lookup->ipv6_query) {
149 destroy_query(lookup->ipv6_query);
150 g_queue_remove(lookup->resolv->query_queue, lookup->ipv4_query);
152 g_free(lookup->results);
156 static gboolean query_timeout(gpointer user_data)
158 struct resolv_query *query = user_data;
159 struct resolv_lookup *lookup = query->lookup;
160 GResolv *resolv = query->resolv;
164 if (query == lookup->ipv4_query) {
165 lookup->ipv4_status = G_RESOLV_RESULT_STATUS_NO_RESPONSE;
166 lookup->ipv4_query = NULL;
167 } else if (query == lookup->ipv6_query) {
168 lookup->ipv6_status = G_RESOLV_RESULT_STATUS_NO_RESPONSE;
169 lookup->ipv6_query = NULL;
171 if (!lookup->ipv4_query && !lookup->ipv4_query)
172 sort_and_return_results(lookup);
174 destroy_query(query);
175 g_queue_remove(resolv->query_queue, query);
180 static void free_nameserver(struct resolv_nameserver *nameserver)
182 if (nameserver == NULL)
185 if (nameserver->udp_watch > 0)
186 g_source_remove(nameserver->udp_watch);
188 if (nameserver->udp_channel != NULL)
189 g_io_channel_unref(nameserver->udp_channel);
191 g_free(nameserver->address);
195 static void flush_nameservers(GResolv *resolv)
199 for (list = g_list_first(resolv->nameserver_list);
200 list; list = g_list_next(list))
201 free_nameserver(list->data);
203 g_list_free(resolv->nameserver_list);
204 resolv->nameserver_list = NULL;
207 static int send_query(GResolv *resolv, const unsigned char *buf, int len)
211 if (resolv->nameserver_list == NULL)
214 for (list = g_list_first(resolv->nameserver_list);
215 list; list = g_list_next(list)) {
216 struct resolv_nameserver *nameserver = list->data;
219 if (nameserver->udp_channel == NULL)
222 sk = g_io_channel_unix_get_fd(nameserver->udp_channel);
224 sent = send(sk, buf, len, 0);
230 static gint compare_lookup_id(gconstpointer a, gconstpointer b)
232 const struct resolv_lookup *lookup = a;
233 guint id = GPOINTER_TO_UINT(b);
244 static gint compare_query_msgid(gconstpointer a, gconstpointer b)
246 const struct resolv_query *query = a;
247 uint16_t msgid = GPOINTER_TO_UINT(b);
249 if (query->msgid < msgid)
252 if (query->msgid > msgid)
258 static void add_result(struct resolv_lookup *lookup, int family, const void *data)
260 int n = lookup->nr_results++;
261 lookup->results = g_realloc(lookup->results,
262 sizeof(struct sort_result) * (n+1));
264 memset(&lookup->results[n], 0, sizeof(struct sort_result));
266 lookup->results[n].dst.sa.sa_family = family;
267 if (family == AF_INET)
268 memcpy(&lookup->results[n].dst.sin.sin_addr, data, NS_INADDRSZ);
270 memcpy(&lookup->results[n].dst.sin6.sin6_addr, data, NS_IN6ADDRSZ);
273 static void parse_response(struct resolv_nameserver *nameserver,
274 const unsigned char *buf, int len)
276 GResolv *resolv = nameserver->resolv;
277 GResolvResultStatus status;
278 struct resolv_query *query;
279 struct resolv_lookup *lookup;
283 int i, n, rcode, count;
285 debug(resolv, "response from %s", nameserver->address);
287 ns_initparse(buf, len, &msg);
289 rcode = ns_msg_getflag(msg, ns_f_rcode);
290 count = ns_msg_count(msg, ns_s_an);
292 debug(resolv, "msg id: 0x%04x rcode: %d count: %d",
293 ns_msg_id(msg), rcode, count);
297 status = G_RESOLV_RESULT_STATUS_SUCCESS;
300 status = G_RESOLV_RESULT_STATUS_FORMAT_ERROR;
303 status = G_RESOLV_RESULT_STATUS_SERVER_FAILURE;
306 status = G_RESOLV_RESULT_STATUS_NAME_ERROR;
309 status = G_RESOLV_RESULT_STATUS_NOT_IMPLEMENTED;
312 status = G_RESOLV_RESULT_STATUS_REFUSED;
315 status = G_RESOLV_RESULT_STATUS_ERROR;
319 list = g_queue_find_custom(resolv->query_queue,
320 GUINT_TO_POINTER(ns_msg_id(msg)), compare_query_msgid);
325 lookup = query->lookup;
327 if (query == lookup->ipv6_query) {
328 lookup->ipv6_status = status;
329 lookup->ipv6_query = NULL;
330 } else if (query == lookup->ipv4_query) {
331 lookup->ipv4_status = status;
332 lookup->ipv4_query = NULL;
335 for (i = 0, n = 0; i < count; i++) {
336 ns_parserr(&msg, ns_s_an, i, &rr);
338 if (ns_rr_class(rr) != ns_c_in)
341 g_assert(offsetof(struct sockaddr_in, sin_addr) ==
342 offsetof(struct sockaddr_in6, sin6_flowinfo));
344 if (ns_rr_type(rr) == ns_t_a &&
345 ns_rr_rdlen(rr) == NS_INADDRSZ) {
346 add_result(lookup, AF_INET, ns_rr_rdata(rr));
347 } else if (ns_rr_type(rr) == ns_t_aaaa &&
348 ns_rr_rdlen(rr) == NS_IN6ADDRSZ) {
349 add_result(lookup, AF_INET6, ns_rr_rdata(rr));
353 if (!lookup->ipv4_query && !lookup->ipv6_query)
354 sort_and_return_results(lookup);
356 destroy_query(query);
357 g_queue_remove(resolv->query_queue, query);
360 static gboolean received_udp_data(GIOChannel *channel, GIOCondition cond,
363 struct resolv_nameserver *nameserver = user_data;
364 unsigned char buf[4096];
367 if (cond & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
368 nameserver->udp_watch = 0;
372 sk = g_io_channel_unix_get_fd(nameserver->udp_channel);
374 len = recv(sk, buf, sizeof(buf), 0);
378 parse_response(nameserver, buf, len);
383 static int connect_udp_channel(struct resolv_nameserver *nameserver)
385 struct addrinfo hints, *rp;
389 memset(&hints, 0, sizeof(hints));
390 hints.ai_family = AF_UNSPEC;
391 hints.ai_socktype = SOCK_DGRAM;
392 hints.ai_flags = AI_PASSIVE | AI_NUMERICSERV | AI_NUMERICHOST;
394 sprintf(portnr, "%d", nameserver->port);
395 err = getaddrinfo(nameserver->address, portnr, &hints, &rp);
399 /* Do not blindly copy this code elsewhere; it doesn't loop over the
400 results using ->ai_next as it should. That's OK in *this* case
401 because it was a numeric lookup; we *know* there's only one. */
405 sk = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
411 if (connect(sk, rp->ai_addr, rp->ai_addrlen) < 0) {
419 nameserver->udp_channel = g_io_channel_unix_new(sk);
420 if (nameserver->udp_channel == NULL) {
425 g_io_channel_set_close_on_unref(nameserver->udp_channel, TRUE);
427 nameserver->udp_watch = g_io_add_watch(nameserver->udp_channel,
428 G_IO_IN | G_IO_NVAL | G_IO_ERR | G_IO_HUP,
429 received_udp_data, nameserver);
434 GResolv *g_resolv_new(int index)
441 resolv = g_try_new0(GResolv, 1);
445 resolv->ref_count = 1;
447 resolv->next_lookup_id = 1;
449 resolv->query_queue = g_queue_new();
450 if (resolv->query_queue == NULL) {
455 resolv->lookup_queue = g_queue_new();
456 if (resolv->lookup_queue == NULL) {
457 g_queue_free(resolv->query_queue);
462 resolv->index = index;
463 resolv->nameserver_list = NULL;
465 res_ninit(&resolv->res);
470 GResolv *g_resolv_ref(GResolv *resolv)
475 g_atomic_int_inc(&resolv->ref_count);
480 void g_resolv_unref(GResolv *resolv)
482 struct resolv_query *query;
487 if (g_atomic_int_dec_and_test(&resolv->ref_count) == FALSE)
490 while ((query = g_queue_pop_head(resolv->query_queue)))
491 destroy_query(query);
493 g_queue_free(resolv->query_queue);
494 g_queue_free(resolv->lookup_queue);
496 flush_nameservers(resolv);
498 res_nclose(&resolv->res);
503 void g_resolv_set_debug(GResolv *resolv,
504 GResolvDebugFunc func, gpointer user_data)
509 resolv->debug_func = func;
510 resolv->debug_data = user_data;
513 gboolean g_resolv_add_nameserver(GResolv *resolv, const char *address,
514 uint16_t port, unsigned long flags)
516 struct resolv_nameserver *nameserver;
521 nameserver = g_try_new0(struct resolv_nameserver, 1);
522 if (nameserver == NULL)
525 nameserver->address = g_strdup(address);
526 nameserver->port = port;
527 nameserver->flags = flags;
529 if (connect_udp_channel(nameserver) < 0) {
530 free_nameserver(nameserver);
534 nameserver->resolv = resolv;
536 resolv->nameserver_list = g_list_append(resolv->nameserver_list,
539 debug(resolv, "setting nameserver %s", address);
544 void g_resolv_flush_nameservers(GResolv *resolv)
549 flush_nameservers(resolv);
552 static void sort_and_return_results(struct resolv_lookup *lookup)
555 GResolvResultStatus status;
556 char **results = g_try_new0(char *, lookup->nr_results + 1);
562 rfc3484_sort_results(lookup);
564 for (i = 0; i < lookup->nr_results; i++) {
565 if (lookup->results[i].dst.sa.sa_family == AF_INET) {
566 if (!inet_ntop(AF_INET, &lookup->results[i].dst.sin.sin_addr,
569 } else if (lookup->results[i].dst.sa.sa_family == AF_INET6) {
570 if (!inet_ntop(AF_INET6, &lookup->results[i].dst.sin6.sin6_addr,
576 results[n++] = strdup(buf);
580 status = lookup->ipv4_status;
581 if (status == G_RESOLV_RESULT_STATUS_SUCCESS)
582 status = lookup->ipv6_status;
584 lookup->result_func(status, results, lookup->result_data);
587 g_queue_remove(lookup->resolv->lookup_queue, lookup);
588 destroy_lookup(lookup);
591 static gint add_query(struct resolv_lookup *lookup, const char *hostname, int type)
593 struct resolv_query *query = g_try_new0(struct resolv_query, 1);
594 unsigned char buf[4096];
600 len = res_mkquery(ns_o_query, hostname, ns_c_in, type,
601 NULL, 0, NULL, buf, sizeof(buf));
603 query->msgid = buf[0] << 8 | buf[1];
605 if (send_query(lookup->resolv, buf, len) < 0)
608 query->resolv = lookup->resolv;
609 query->lookup = lookup;
611 g_queue_push_tail(lookup->resolv->query_queue, query);
613 query->timeout = g_timeout_add_seconds(5, query_timeout, query);
615 if (type == ns_t_aaaa)
616 lookup->ipv6_query = query;
618 lookup->ipv4_query = query;
623 guint g_resolv_lookup_hostname(GResolv *resolv, const char *hostname,
624 GResolvResultFunc func, gpointer user_data)
626 struct resolv_lookup *lookup;
628 debug(resolv, "lookup hostname %s", hostname);
633 if (resolv->nameserver_list == NULL) {
636 for (i = 0; i < resolv->res.nscount; i++) {
638 int family = resolv->res.nsaddr_list[i].sin_family;
639 void *sa_addr = &resolv->res.nsaddr_list[i].sin_addr;
641 if (family != AF_INET && resolv->res._u._ext.nsaddrs[i]) {
643 sa_addr = &resolv->res._u._ext.nsaddrs[i]->sin6_addr;
645 if (family != AF_INET && family != AF_INET6)
648 if (inet_ntop(family, sa_addr, buf, sizeof(buf)))
649 g_resolv_add_nameserver(resolv, buf, 53, 0);
652 if (resolv->nameserver_list == NULL)
653 g_resolv_add_nameserver(resolv, "127.0.0.1", 53, 0);
656 lookup = g_try_new0(struct resolv_lookup, 1);
660 lookup->resolv = resolv;
661 lookup->result_func = func;
662 lookup->result_data = user_data;
663 lookup->id = resolv->next_lookup_id++;
665 if (add_query(lookup, hostname, ns_t_a)) {
669 if (add_query(lookup, hostname, ns_t_aaaa)) {
670 destroy_query(lookup->ipv4_query);
671 g_queue_remove(resolv->query_queue, lookup->ipv4_query);
676 g_queue_push_tail(resolv->lookup_queue, lookup);
680 gboolean g_resolv_cancel_lookup(GResolv *resolv, guint id)
684 list = g_queue_find_custom(resolv->lookup_queue,
685 GUINT_TO_POINTER(id), compare_lookup_id);
690 destroy_lookup(list->data);
691 g_queue_remove(resolv->query_queue, list->data);
696 static void find_srcaddr(struct sort_result *res)
699 socklen_t sl = sizeof(res->src);
701 fd = socket(res->dst.sa.sa_family, SOCK_DGRAM, IPPROTO_IP);
705 if (connect(fd, &res->dst.sa, sizeof(res->dst))) {
709 if (getsockname(fd, &res->src.sa, &sl)) {
713 res->reachable = TRUE;
719 unsigned char addr[NS_IN6ADDRSZ];
724 static const struct gai_table gai_labels[] = {
726 .addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
727 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 },
731 .addr = { 0x20, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
732 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
736 .addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
737 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
741 .addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
742 0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00 },
746 /* Variations from RFC 3484, matching glibc behaviour */
747 .addr = { 0xfe, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
748 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
752 .addr = { 0xfc, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
753 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
757 .addr = { 0x20, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
758 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
763 .addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
764 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
770 static const struct gai_table gai_precedences[] = {
772 .addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
773 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 },
777 .addr = { 0x20, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
778 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
782 .addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
783 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
787 .addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
788 0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00 },
792 .addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
793 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
799 static unsigned char v4mapped[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
800 0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00 };
802 static gboolean mask_compare(const unsigned char *one, const unsigned char *two, int mask)
805 if (memcmp(one, two, mask / 8))
811 if (mask && ((*one ^ *two) >> (8-mask)))
817 static int match_gai_table(struct sockaddr *sa, const struct gai_table *tbl)
819 struct sockaddr_in *sin = (void *)sa;
820 struct sockaddr_in6 *sin6 = (void *)sa;
823 if (sa->sa_family == AF_INET) {
825 memcpy(v4mapped+12, &sin->sin_addr, NS_INADDRSZ);
827 addr = &sin6->sin6_addr;
830 if (mask_compare(addr, tbl->addr, tbl->mask))
836 #define DQUAD(_a,_b,_c,_d) ( ((_a)<<24) | ((_b)<<16) | ((_c)<<8) | (_d) )
837 #define V4MATCH(addr, a,b,c,d, m) ( ((addr) ^ DQUAD(a,b,c,d)) >> (32 - (m)) )
839 #define RFC3484_SCOPE_LINK 2
840 #define RFC3484_SCOPE_SITE 5
841 #define RFC3484_SCOPE_GLOBAL 14
843 static int addr_scope(struct sockaddr *sa)
845 if (sa->sa_family == AF_INET) {
846 struct sockaddr_in *sin = (void *)sa;
847 guint32 addr = ntohl(sin->sin_addr.s_addr);
849 if (V4MATCH(addr, 169,254,0,0, 16) ||
850 V4MATCH(addr, 127,0,0,0, 8))
851 return RFC3484_SCOPE_LINK;
854 if (V4MATCH(addr, 10,0,0,0, 8) ||
855 V4MATCH(addr, 172,16,0,0, 12) ||
856 V4MATCH(addr, 192,168,0,0, 16))
857 return RFC3484_SCOPE_SITE;
860 return RFC3484_SCOPE_GLOBAL;
862 struct sockaddr_in6 *sin6 = (void *)sa;
864 /* Multicast addresses have a 4-bit scope field */
865 if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
866 return sin6->sin6_addr.s6_addr[1] & 0xf;
868 if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr) ||
869 IN6_IS_ADDR_LOOPBACK(&sin6->sin6_addr))
870 return RFC3484_SCOPE_LINK;
872 if (IN6_IS_ADDR_SITELOCAL(&sin6->sin6_addr))
873 return RFC3484_SCOPE_SITE;
875 return RFC3484_SCOPE_GLOBAL;
879 static int rfc3484_compare(const void *__one, const void *__two)
881 const struct sort_result *one = __one;
882 const struct sort_result *two = __two;
884 /* Rule 1: Avoid unusable destinations */
885 if (one->reachable && !two->reachable)
887 else if (two->reachable && !one->reachable)
890 /* Rule 2: Prefer matching scope */
891 if (one->dst_scope == one->src_scope &&
892 two->dst_scope != two->src_scope)
894 else if (two->dst_scope == two->src_scope &&
895 one->dst_scope != one->src_scope)
898 /* Rule 3: Avoid deprecated addresses */
900 /* Rule 4: Prefer home addresses */
902 /* Rule 5: Prefer matching label */
903 if (one->dst_label == one->src_label &&
904 two->dst_label != two->src_label)
906 else if (two->dst_label == two->src_label &&
907 one->dst_label != one->src_label)
910 /* Rule 6: Prefer higher precedence */
911 if (one->precedence > two->precedence)
913 else if (two->precedence > one->precedence)
916 /* Rule 7: Prefer native transport */
918 /* Rule 8: Prefer smaller scope */
919 if (one->dst_scope != two->dst_scope)
920 return one->dst_scope - two->dst_scope;
922 /* Rule 9: Use longest matching prefix */
924 /* Rule 10: Otherwise, leave the order unchanged */
931 static void rfc3484_sort_results(struct resolv_lookup *lookup)
935 for (i = 0; i < lookup->nr_results; i++) {
936 struct sort_result *res = &lookup->results[i];
938 res->precedence = match_gai_table(&res->dst.sa, gai_precedences);
939 res->dst_label = match_gai_table(&res->dst.sa, gai_labels);
940 res->src_label = match_gai_table(&res->src.sa, gai_labels);
941 res->dst_scope = addr_scope(&res->dst.sa);
942 res->src_scope = addr_scope(&res->src.sa);
945 qsort(lookup->results, lookup->nr_results, sizeof(struct sort_result),