[mirror_frr.git] / lib / resolver.c

/* C-Ares integration to Quagga mainloop
 * Copyright (c) 2014-2015 Timo Teräs
 *
 * This file is free software: you may copy, redistribute and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <ares.h>
#include <ares_version.h>

#include "typesafe.h"
#include "jhash.h"
#include "thread.h"
#include "lib_errors.h"
#include "resolver.h"
#include "command.h"
#include "xref.h"
#include "vrf.h"

XREF_SETUP();

struct resolver_state {
	ares_channel channel;
	struct thread_master *master;
	struct thread *timeout;
};

static struct resolver_state state;
static bool resolver_debug;

/* a FD doesn't necessarily map 1:1 to a request;  we could be talking to
 * multiple caches simultaneously, to see which responds fastest.
 * Theoretically we could also be using the same fd for multiple lookups,
 * but the c-ares API guarantees an n:1 mapping for fd => channel.
 *
 * Either way c-ares makes that decision and we just need to deal with
 * whatever FDs it gives us.
 */

DEFINE_MTYPE_STATIC(LIB, ARES_FD, "c-ares (DNS) file descriptor information");
PREDECL_HASH(resolver_fds);

struct resolver_fd {
	struct resolver_fds_item itm;

	int fd;
	struct resolver_state *state;
	struct thread *t_read, *t_write;
};

static int resolver_fd_cmp(const struct resolver_fd *a,
			   const struct resolver_fd *b)
{
	return numcmp(a->fd, b->fd);
}

static uint32_t resolver_fd_hash(const struct resolver_fd *item)
{
	return jhash_1word(item->fd, 0xacd04c9e);
}

DECLARE_HASH(resolver_fds, struct resolver_fd, itm, resolver_fd_cmp,
	     resolver_fd_hash);

static struct resolver_fds_head resfds[1] = {INIT_HASH(resfds[0])};

static struct resolver_fd *resolver_fd_get(int fd,
					   struct resolver_state *newstate)
{
	struct resolver_fd ref = {.fd = fd}, *res;

	res = resolver_fds_find(resfds, &ref);
	if (!res && newstate) {
		res = XCALLOC(MTYPE_ARES_FD, sizeof(*res));
		res->fd = fd;
		res->state = newstate;
		resolver_fds_add(resfds, res);

		if (resolver_debug)
			zlog_debug("c-ares registered FD %d", fd);
	}
	return res;
}

static void resolver_fd_drop_maybe(struct resolver_fd *resfd)
{
	if (resfd->t_read || resfd->t_write)
		return;

	if (resolver_debug)
		zlog_debug("c-ares unregistered FD %d", resfd->fd);

	resolver_fds_del(resfds, resfd);
	XFREE(MTYPE_ARES_FD, resfd);
}

/* end of FD housekeeping */

static void resolver_update_timeouts(struct resolver_state *r);

static void resolver_cb_timeout(struct thread *t)
{
	struct resolver_state *r = THREAD_ARG(t);

	ares_process(r->channel, NULL, NULL);
	resolver_update_timeouts(r);
}

static void resolver_cb_socket_readable(struct thread *t)
{
	struct resolver_fd *resfd = THREAD_ARG(t);
	struct resolver_state *r = resfd->state;

	thread_add_read(r->master, resolver_cb_socket_readable, resfd,
			resfd->fd, &resfd->t_read);
	/* ^ ordering important:
	 * ares_process_fd may transitively call THREAD_OFF(resfd->t_read)
	 * combined with resolver_fd_drop_maybe, so resfd may be free'd after!
	 */
	ares_process_fd(r->channel, resfd->fd, ARES_SOCKET_BAD);
	resolver_update_timeouts(r);
}

static void resolver_cb_socket_writable(struct thread *t)
{
	struct resolver_fd *resfd = THREAD_ARG(t);
	struct resolver_state *r = resfd->state;

	thread_add_write(r->master, resolver_cb_socket_writable, resfd,
			 resfd->fd, &resfd->t_write);
	/* ^ ordering important:
	 * ares_process_fd may transitively call THREAD_OFF(resfd->t_write)
	 * combined with resolver_fd_drop_maybe, so resfd may be free'd after!
	 */
	ares_process_fd(r->channel, ARES_SOCKET_BAD, resfd->fd);
	resolver_update_timeouts(r);
}

static void resolver_update_timeouts(struct resolver_state *r)
{
	struct timeval *tv, tvbuf;

	THREAD_OFF(r->timeout);
	tv = ares_timeout(r->channel, NULL, &tvbuf);
	if (tv) {
		unsigned int timeoutms = tv->tv_sec * 1000 + tv->tv_usec / 1000;

		thread_add_timer_msec(r->master, resolver_cb_timeout, r,
				      timeoutms, &r->timeout);
	}
}

static void ares_socket_cb(void *data, ares_socket_t fd, int readable,
			   int writable)
{
	struct resolver_state *r = (struct resolver_state *)data;
	struct resolver_fd *resfd;

	resfd = resolver_fd_get(fd, (readable || writable) ? r : NULL);
	if (!resfd)
		return;

	assert(resfd->state == r);

	if (!readable)
		THREAD_OFF(resfd->t_read);
	else if (!resfd->t_read)
		thread_add_read(r->master, resolver_cb_socket_readable, resfd,
				fd, &resfd->t_read);

	if (!writable)
		THREAD_OFF(resfd->t_write);
	else if (!resfd->t_write)
		thread_add_write(r->master, resolver_cb_socket_writable, resfd,
				 fd, &resfd->t_write);

	resolver_fd_drop_maybe(resfd);
}


static void ares_address_cb(void *arg, int status, int timeouts,
			    struct hostent *he)
{
	struct resolver_query *query = (struct resolver_query *)arg;
	union sockunion addr[16];
	void (*callback)(struct resolver_query *, const char *, int,
			 union sockunion *);
	size_t i;

	callback = query->callback;
	query->callback = NULL;

	if (status != ARES_SUCCESS) {
		if (resolver_debug)
			zlog_debug("[%p] Resolving failed (%s)",
				   query, ares_strerror(status));

		callback(query, ares_strerror(status), -1, NULL);
		return;
	}

	for (i = 0; i < array_size(addr) && he->h_addr_list[i] != NULL; i++) {
		memset(&addr[i], 0, sizeof(addr[i]));
		addr[i].sa.sa_family = he->h_addrtype;
		switch (he->h_addrtype) {
		case AF_INET:
			memcpy(&addr[i].sin.sin_addr,
			       (uint8_t *)he->h_addr_list[i], he->h_length);
			break;
		case AF_INET6:
			memcpy(&addr[i].sin6.sin6_addr,
			       (uint8_t *)he->h_addr_list[i], he->h_length);
			break;
		}
	}

	if (resolver_debug)
		zlog_debug("[%p] Resolved with %d results", query, (int)i);

	callback(query, NULL, i, &addr[0]);
}

static void resolver_cb_literal(struct thread *t)
{
	struct resolver_query *query = THREAD_ARG(t);
	void (*callback)(struct resolver_query *, const char *, int,
			 union sockunion *);

	callback = query->callback;
	query->callback = NULL;

	callback(query, ARES_SUCCESS, 1, &query->literal_addr);
}

void resolver_resolve(struct resolver_query *query, int af, vrf_id_t vrf_id,
		      const char *hostname,
		      void (*callback)(struct resolver_query *, const char *,
				       int, union sockunion *))
{
	int ret;

	if (query->callback != NULL) {
		flog_err(
			EC_LIB_RESOLVER,
			"Trying to resolve '%s', but previous query was not finished yet",
			hostname);
		return;
	}

	query->callback = callback;
	query->literal_cb = NULL;

	ret = str2sockunion(hostname, &query->literal_addr);
	if (ret == 0) {
		if (resolver_debug)
			zlog_debug("[%p] Resolving '%s' (IP literal)",
				   query, hostname);

		/* for consistency with proper name lookup, don't call the
		 * callback immediately; defer to thread loop
		 */
		thread_add_timer_msec(state.master, resolver_cb_literal,
				      query, 0, &query->literal_cb);
		return;
	}

	if (resolver_debug)
		zlog_debug("[%p] Resolving '%s'", query, hostname);

	ret = vrf_switch_to_netns(vrf_id);
	if (ret < 0) {
		flog_err_sys(EC_LIB_SOCKET, "%s: Can't switch to VRF %u (%s)",
			     __func__, vrf_id, safe_strerror(errno));
		return;
	}
	ares_gethostbyname(state.channel, hostname, af, ares_address_cb, query);
	ret = vrf_switchback_to_initial();
	if (ret < 0)
		flog_err_sys(EC_LIB_SOCKET,
			     "%s: Can't switchback from VRF %u (%s)", __func__,
			     vrf_id, safe_strerror(errno));
	resolver_update_timeouts(&state);
}

DEFUN(debug_resolver,
      debug_resolver_cmd,
      "[no] debug resolver",
      NO_STR
      DEBUG_STR
      "Debug DNS resolver actions\n")
{
	resolver_debug = (argc == 2);
	return CMD_SUCCESS;
}

static int resolver_config_write_debug(struct vty *vty);
static struct cmd_node resolver_debug_node = {
	.name = "resolver debug",
	.node = RESOLVER_DEBUG_NODE,
	.prompt = "",
	.config_write = resolver_config_write_debug,
};

static int resolver_config_write_debug(struct vty *vty)
{
	if (resolver_debug)
		vty_out(vty, "debug resolver\n");
	return 1;
}


void resolver_init(struct thread_master *tm)
{
	struct ares_options ares_opts;

	state.master = tm;

	ares_opts = (struct ares_options){
		.sock_state_cb = &ares_socket_cb,
		.sock_state_cb_data = &state,
		.timeout = 2,
		.tries = 3,
	};

	ares_init_options(&state.channel, &ares_opts,
			  ARES_OPT_SOCK_STATE_CB | ARES_OPT_TIMEOUT
				  | ARES_OPT_TRIES);

	install_node(&resolver_debug_node);
	install_element(CONFIG_NODE, &debug_resolver_cmd);
	install_element(ENABLE_NODE, &debug_resolver_cmd);
}
Commit	Line	Data
2fb975da TT	1	/* C-Ares integration to Quagga mainloop
	2	* Copyright (c) 2014-2015 Timo Teräs
	3	*
	4	* This file is free software: you may copy, redistribute and/or modify
	5	* it under the terms of the GNU General Public License as published by
	6	* the Free Software Foundation, either version 2 of the License, or
	7	* (at your option) any later version.
	8	*/
	9
b45ac5f5 DL	10	#ifdef HAVE_CONFIG_H
	11	#include "config.h"
	12	#endif
	13
2fb975da TT	14	#include <ares.h>
	15	#include <ares_version.h>
	16
faf079ff DL	17	#include "typesafe.h"
faf079ff DL	18	#include "jhash.h"
2fb975da	19	#include "thread.h"
aed07011	20	#include "lib_errors.h"
fe9e7b71 DL	21	#include "resolver.h"
fe9e7b71 DL	22	#include "command.h"
b2fa8c0f	23	#include "xref.h"
c742573b	24	#include "vrf.h"
b2fa8c0f	25
80413c20	26	XREF_SETUP();
2fb975da TT	27
	28	struct resolver_state {
	29	ares_channel channel;
fe9e7b71	30	struct thread_master *master;
2fb975da	31	struct thread *timeout;
2fb975da TT	32	};
	33
	34	static struct resolver_state state;
fe9e7b71	35	static bool resolver_debug;
2fb975da	36
faf079ff DL	37	/* a FD doesn't necessarily map 1:1 to a request; we could be talking to
	38	* multiple caches simultaneously, to see which responds fastest.
	39	* Theoretically we could also be using the same fd for multiple lookups,
	40	* but the c-ares API guarantees an n:1 mapping for fd => channel.
	41	*
	42	* Either way c-ares makes that decision and we just need to deal with
	43	* whatever FDs it gives us.
	44	*/
	45
	46	DEFINE_MTYPE_STATIC(LIB, ARES_FD, "c-ares (DNS) file descriptor information");
	47	PREDECL_HASH(resolver_fds);
	48
	49	struct resolver_fd {
	50	struct resolver_fds_item itm;
	51
	52	int fd;
	53	struct resolver_state *state;
	54	struct thread t_read, t_write;
	55	};
	56
	57	static int resolver_fd_cmp(const struct resolver_fd *a,
	58	const struct resolver_fd *b)
	59	{
	60	return numcmp(a->fd, b->fd);
	61	}
	62
	63	static uint32_t resolver_fd_hash(const struct resolver_fd *item)
	64	{
	65	return jhash_1word(item->fd, 0xacd04c9e);
	66	}
	67
	68	DECLARE_HASH(resolver_fds, struct resolver_fd, itm, resolver_fd_cmp,
	69	resolver_fd_hash);
	70
	71	static struct resolver_fds_head resfds[1] = {INIT_HASH(resfds[0])};
	72
	73	static struct resolver_fd *resolver_fd_get(int fd,
	74	struct resolver_state *newstate)
	75	{
	76	struct resolver_fd ref = {.fd = fd}, *res;
	77
	78	res = resolver_fds_find(resfds, &ref);
	79	if (!res && newstate) {
	80	res = XCALLOC(MTYPE_ARES_FD, sizeof(*res));
	81	res->fd = fd;
	82	res->state = newstate;
	83	resolver_fds_add(resfds, res);
	84
	85	if (resolver_debug)
	86	zlog_debug("c-ares registered FD %d", fd);
	87	}
	88	return res;
	89	}
	90
	91	static void resolver_fd_drop_maybe(struct resolver_fd *resfd)
	92	{
	93	if (resfd->t_read \|\| resfd->t_write)
	94	return;
	95
	96	if (resolver_debug)
	97	zlog_debug("c-ares unregistered FD %d", resfd->fd);
	98
	99	resolver_fds_del(resfds, resfd);
	100	XFREE(MTYPE_ARES_FD, resfd);
101	}
102
103	/* end of FD housekeeping */
2fb975da TT	104
	105	static void resolver_update_timeouts(struct resolver_state *r);
	106
cc9f21da	107	static void resolver_cb_timeout(struct thread *t)
2fb975da TT	108	{
	109	struct resolver_state *r = THREAD_ARG(t);
	110
2fb975da	111	ares_process(r->channel, NULL, NULL);
2fb975da	112	resolver_update_timeouts(r);
2fb975da TT	113	}
2fb975da TT	114
cc9f21da	115	static void resolver_cb_socket_readable(struct thread *t)
2fb975da	116	{
faf079ff DL	117	struct resolver_fd *resfd = THREAD_ARG(t);
	118	struct resolver_state *r = resfd->state;
	119
	120	thread_add_read(r->master, resolver_cb_socket_readable, resfd,
	121	resfd->fd, &resfd->t_read);
	122	/* ^ ordering important:
	123	* ares_process_fd may transitively call THREAD_OFF(resfd->t_read)
	124	* combined with resolver_fd_drop_maybe, so resfd may be free'd after!
	125	*/
	126	ares_process_fd(r->channel, resfd->fd, ARES_SOCKET_BAD);
2fb975da	127	resolver_update_timeouts(r);
2fb975da TT	128	}
2fb975da TT	129
cc9f21da	130	static void resolver_cb_socket_writable(struct thread *t)
2fb975da	131	{
faf079ff DL	132	struct resolver_fd *resfd = THREAD_ARG(t);
	133	struct resolver_state *r = resfd->state;
	134
	135	thread_add_write(r->master, resolver_cb_socket_writable, resfd,
	136	resfd->fd, &resfd->t_write);
	137	/* ^ ordering important:
	138	* ares_process_fd may transitively call THREAD_OFF(resfd->t_write)
	139	* combined with resolver_fd_drop_maybe, so resfd may be free'd after!
	140	*/
	141	ares_process_fd(r->channel, ARES_SOCKET_BAD, resfd->fd);
2fb975da	142	resolver_update_timeouts(r);
2fb975da TT	143	}
	144
	145	static void resolver_update_timeouts(struct resolver_state *r)
	146	{
	147	struct timeval *tv, tvbuf;
	148
2fb975da TT	149	THREAD_OFF(r->timeout);
	150	tv = ares_timeout(r->channel, NULL, &tvbuf);
	151	if (tv) {
	152	unsigned int timeoutms = tv->tv_sec * 1000 + tv->tv_usec / 1000;
faf079ff	153
fe9e7b71 DL	154	thread_add_timer_msec(r->master, resolver_cb_timeout, r,
fe9e7b71 DL	155	timeoutms, &r->timeout);
2fb975da TT	156	}
	157	}
	158
996c9314 LB	159	static void ares_socket_cb(void *data, ares_socket_t fd, int readable,
996c9314 LB	160	int writable)
2fb975da	161	{
996c9314	162	struct resolver_state r = (struct resolver_state )data;
faf079ff	163	struct resolver_fd *resfd;
2fb975da	164
faf079ff DL	165	resfd = resolver_fd_get(fd, (readable \|\| writable) ? r : NULL);
	166	if (!resfd)
	167	return;
	168
	169	assert(resfd->state == r);
	170
	171	if (!readable)
	172	THREAD_OFF(resfd->t_read);
	173	else if (!resfd->t_read)
	174	thread_add_read(r->master, resolver_cb_socket_readable, resfd,
	175	fd, &resfd->t_read);
	176
	177	if (!writable)
	178	THREAD_OFF(resfd->t_write);
	179	else if (!resfd->t_write)
	180	thread_add_write(r->master, resolver_cb_socket_writable, resfd,
	181	fd, &resfd->t_write);
	182
	183	resolver_fd_drop_maybe(resfd);
2fb975da TT	184	}
2fb975da TT	185
2fb975da	186
996c9314 LB	187	static void ares_address_cb(void *arg, int status, int timeouts,
996c9314 LB	188	struct hostent *he)
2fb975da	189	{
996c9314	190	struct resolver_query query = (struct resolver_query )arg;
2fb975da	191	union sockunion addr[16];
3286ca07 DL	192	void (callback)(struct resolver_query , const char *, int,
3286ca07 DL	193	union sockunion *);
2fb975da TT	194	size_t i;
2fb975da TT	195
50cdb6cf DL	196	callback = query->callback;
	197	query->callback = NULL;
	198
2fb975da	199	if (status != ARES_SUCCESS) {
fe9e7b71	200	if (resolver_debug)
3286ca07 DL	201	zlog_debug("[%p] Resolving failed (%s)",
3286ca07 DL	202	query, ares_strerror(status));
fe9e7b71	203
3286ca07	204	callback(query, ares_strerror(status), -1, NULL);
2fb975da TT	205	return;
	206	}
	207
7e3a1ec7	208	for (i = 0; i < array_size(addr) && he->h_addr_list[i] != NULL; i++) {
2fb975da TT	209	memset(&addr[i], 0, sizeof(addr[i]));
	210	addr[i].sa.sa_family = he->h_addrtype;
	211	switch (he->h_addrtype) {
	212	case AF_INET:
996c9314 LB	213	memcpy(&addr[i].sin.sin_addr,
996c9314 LB	214	(uint8_t *)he->h_addr_list[i], he->h_length);
2fb975da TT	215	break;
2fb975da TT	216	case AF_INET6:
996c9314 LB	217	memcpy(&addr[i].sin6.sin6_addr,
996c9314 LB	218	(uint8_t *)he->h_addr_list[i], he->h_length);
2fb975da TT	219	break;
	220	}
	221	}
	222
fe9e7b71 DL	223	if (resolver_debug)
	224	zlog_debug("[%p] Resolved with %d results", query, (int)i);
	225
3286ca07	226	callback(query, NULL, i, &addr[0]);
2fb975da TT	227	}
2fb975da TT	228
cc9f21da	229	static void resolver_cb_literal(struct thread *t)
125dc952 DL	230	{
125dc952 DL	231	struct resolver_query *query = THREAD_ARG(t);
3286ca07 DL	232	void (callback)(struct resolver_query , const char *, int,
3286ca07 DL	233	union sockunion *);
125dc952 DL	234
	235	callback = query->callback;
	236	query->callback = NULL;
	237
3286ca07	238	callback(query, ARES_SUCCESS, 1, &query->literal_addr);
125dc952 DL	239	}
125dc952 DL	240
c742573b	241	void resolver_resolve(struct resolver_query *query, int af, vrf_id_t vrf_id,
996c9314	242	const char *hostname,
3286ca07 DL	243	void (callback)(struct resolver_query , const char *,
3286ca07 DL	244	int, union sockunion *))
2fb975da	245	{
125dc952 DL	246	int ret;
125dc952 DL	247
2fb975da	248	if (query->callback != NULL) {
1c50c1c0	249	flog_err(
fe9e7b71	250	EC_LIB_RESOLVER,
1c50c1c0 QY	251	"Trying to resolve '%s', but previous query was not finished yet",
1c50c1c0 QY	252	hostname);
2fb975da TT	253	return;
	254	}
	255
125dc952 DL	256	query->callback = callback;
	257	query->literal_cb = NULL;
	258
	259	ret = str2sockunion(hostname, &query->literal_addr);
	260	if (ret == 0) {
	261	if (resolver_debug)
	262	zlog_debug("[%p] Resolving '%s' (IP literal)",
	263	query, hostname);
	264
	265	/* for consistency with proper name lookup, don't call the
	266	* callback immediately; defer to thread loop
	267	*/
	268	thread_add_timer_msec(state.master, resolver_cb_literal,
	269	query, 0, &query->literal_cb);
	270	return;
	271	}
	272
fe9e7b71 DL	273	if (resolver_debug)
fe9e7b71 DL	274	zlog_debug("[%p] Resolving '%s'", query, hostname);
2fb975da	275
c742573b PG	276	ret = vrf_switch_to_netns(vrf_id);
	277	if (ret < 0) {
	278	flog_err_sys(EC_LIB_SOCKET, "%s: Can't switch to VRF %u (%s)",
	279	__func__, vrf_id, safe_strerror(errno));
	280	return;
	281	}
2fb975da	282	ares_gethostbyname(state.channel, hostname, af, ares_address_cb, query);
c742573b PG	283	ret = vrf_switchback_to_initial();
	284	if (ret < 0)
	285	flog_err_sys(EC_LIB_SOCKET,
	286	"%s: Can't switchback from VRF %u (%s)", __func__,
	287	vrf_id, safe_strerror(errno));
2fb975da TT	288	resolver_update_timeouts(&state);
2fb975da TT	289	}
fe9e7b71 DL	290
	291	DEFUN(debug_resolver,
	292	debug_resolver_cmd,
	293	"[no] debug resolver",
	294	NO_STR
	295	DEBUG_STR
	296	"Debug DNS resolver actions\n")
	297	{
	298	resolver_debug = (argc == 2);
	299	return CMD_SUCCESS;
	300	}
	301
612c2c15	302	static int resolver_config_write_debug(struct vty *vty);
62b346ee	303	static struct cmd_node resolver_debug_node = {
f4b8291f	304	.name = "resolver debug",
62b346ee DL	305	.node = RESOLVER_DEBUG_NODE,
62b346ee DL	306	.prompt = "",
612c2c15	307	.config_write = resolver_config_write_debug,
62b346ee	308	};
fe9e7b71 DL	309
	310	static int resolver_config_write_debug(struct vty *vty)
	311	{
	312	if (resolver_debug)
	313	vty_out(vty, "debug resolver\n");
	314	return 1;
	315	}
	316
	317
	318	void resolver_init(struct thread_master *tm)
	319	{
	320	struct ares_options ares_opts;
	321
	322	state.master = tm;
fe9e7b71 DL	323
	324	ares_opts = (struct ares_options){
	325	.sock_state_cb = &ares_socket_cb,
	326	.sock_state_cb_data = &state,
	327	.timeout = 2,
	328	.tries = 3,
	329	};
	330
	331	ares_init_options(&state.channel, &ares_opts,
	332	ARES_OPT_SOCK_STATE_CB \| ARES_OPT_TIMEOUT
	333	\| ARES_OPT_TRIES);
	334
612c2c15	335	install_node(&resolver_debug_node);
fe9e7b71 DL	336	install_element(CONFIG_NODE, &debug_resolver_cmd);
	337	install_element(ENABLE_NODE, &debug_resolver_cmd);
	338	}