[people/ms/dma.git] / dns.c

/*
 * Copyright (c) 2008-2014, Simon Schubert <2@0x2c.org>.
 * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
 *
 * This code is derived from software contributed to The DragonFly Project
 * by Simon Schubert <2@0x2c.org>.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name of The DragonFly Project nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific, prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <errno.h>
#include <netdb.h>
#include <resolv.h>
#include <string.h>
#include <stdlib.h>

#include "dma.h"

static int
sort_pref(const void *a, const void *b)
{
	const struct mx_hostentry *ha = a, *hb = b;
	int v;

	/* sort increasing by preference primarily */
	v = ha->pref - hb->pref;
	if (v != 0)
		return (v);

	/* sort PF_INET6 before PF_INET */
	v = - (ha->ai.ai_family - hb->ai.ai_family);
	return (v);
}

static int
add_host(int pref, const char *host, int port, struct mx_hostentry **he, size_t *ps)
{
	struct addrinfo hints, *res, *res0 = NULL;
	char servname[10];
	struct mx_hostentry *p;
	const int count_inc = 10;
	int err;

	memset(&hints, 0, sizeof(hints));
	hints.ai_family = PF_UNSPEC;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_protocol = IPPROTO_TCP;

	snprintf(servname, sizeof(servname), "%d", port);
	err = getaddrinfo(host, servname, &hints, &res0);
	if (err)
		return (err == EAI_AGAIN ? 1 : -1);

	for (res = res0; res != NULL; res = res->ai_next) {
		if (*ps + 1 >= roundup(*ps, count_inc)) {
			size_t newsz = roundup(*ps + 2, count_inc);
			*he = reallocf(*he, newsz * sizeof(**he));
			if (*he == NULL)
				goto out;
		}

		p = &(*he)[*ps];
		strlcpy(p->host, host, sizeof(p->host));
		p->pref = pref;
		p->ai = *res;
		p->ai.ai_addr = NULL;
		bcopy(res->ai_addr, &p->sa, p->ai.ai_addrlen);

		getnameinfo((struct sockaddr *)&p->sa, p->ai.ai_addrlen,
			    p->addr, sizeof(p->addr),
			    NULL, 0, NI_NUMERICHOST);

		(*ps)++;
	}
	freeaddrinfo(res0);

	return (0);

out:
	if (res0 != NULL)
		freeaddrinfo(res0);
	return (1);
}

int
dns_get_mx_list(const char *host, int port, struct mx_hostentry **he, int no_mx)
{
	char outname[MAXDNAME];
	ns_msg msg;
	ns_rr rr;
	const char *searchhost;
	const unsigned char *cp;
	unsigned char *ans;
	struct mx_hostentry *hosts = NULL;
	size_t nhosts = 0;
	size_t anssz;
	int pref;
	int cname_recurse;
	int have_mx = 0;
	int err;
	int i;

	res_init();
	searchhost = host;
	cname_recurse = 0;

	anssz = 65536;
	ans = malloc(anssz);
	if (ans == NULL)
		return (1);

	if (no_mx)
		goto out;

repeat:
	err = res_search(searchhost, ns_c_in, ns_t_mx, ans, anssz);
	if (err < 0) {
		switch (h_errno) {
		case NO_DATA:
			/*
			 * Host exists, but no MX (or CNAME) entry.
			 * Not an error, use host name instead.
			 */
			goto out;
		case TRY_AGAIN:
			/* transient error */
			goto transerr;
		case NO_RECOVERY:
		case HOST_NOT_FOUND:
		default:
			errno = ENOENT;
			goto err;
		}
	}

	if (!ns_initparse(ans, anssz, &msg))
		goto transerr;

	switch (ns_msg_getflag(msg, ns_f_rcode)) {
	case ns_r_noerror:
		break;
	case ns_r_nxdomain:
		goto err;
	default:
		goto transerr;
	}

	for (i = 0; i < ns_msg_count(msg, ns_s_an); i++) {
		if (ns_parserr(&msg, ns_s_an, i, &rr))
			goto transerr;

		cp = ns_rr_rdata(rr);

		switch (ns_rr_type(rr)) {
		case ns_t_mx:
			have_mx = 1;
			pref = ns_get16(cp);
			cp += 2;
			err = ns_name_uncompress(ns_msg_base(msg), ns_msg_end(msg),
						 cp, outname, sizeof(outname));
			if (err < 0)
				goto transerr;

			err = add_host(pref, outname, port, &hosts, &nhosts);
			if (err == -1)
				goto err;
			break;

		case ns_t_cname:
			err = ns_name_uncompress(ns_msg_base(msg), ns_msg_end(msg),
						 cp, outname, sizeof(outname));
			if (err < 0)
				goto transerr;

			/* Prevent a CNAME loop */
			if (cname_recurse++ > 10)
				goto err;

			searchhost = outname;
			goto repeat;

		default:
			break;
		}
	}

out:
	err = 0;
	if (0) {
transerr:
		if (nhosts == 0)
			err = 1;
	}
	if (0) {
err:
		err = -1;
	}

	free(ans);

	if (err == 0) {
		if (!have_mx) {
			/*
			 * If we didn't find any MX, use the hostname instead.
			 */
			err = add_host(0, host, port, &hosts, &nhosts);
		} else if (nhosts == 0) {
			/*
			 * We did get MX, but couldn't resolve any of them
			 * due to transient errors.
			 */
			err = 1;
		}
	}

	if (nhosts > 0) {
		qsort(hosts, nhosts, sizeof(*hosts), sort_pref);
		/* terminate list */
		*hosts[nhosts].host = 0;
	} else {
		if (hosts != NULL)
			free(hosts);
		hosts = NULL;
	}

	*he = hosts;
	return (err);

	free(ans);
	if (hosts != NULL)
		free(hosts);
	return (err);
}

#if defined(TESTING)
int
main(int argc, char **argv)
{
	struct mx_hostentry *he, *p;
	int err;

	err = dns_get_mx_list(argv[1], 53, &he, 0);
	if (err)
		return (err);

	for (p = he; *p->host != 0; p++) {
		printf("%d\t%s\t%s\n", p->pref, p->host, p->addr);
	}

	return (0);
}
#endif
Commit	Line	Data
8cbdbd34	1	/*
e458e5f0	2	* Copyright (c) 2008-2014, Simon Schubert <2@0x2c.org>.
8cbdbd34 SS	3	* Copyright (c) 2008 The DragonFly Project. All rights reserved.
	4	*
	5	* This code is derived from software contributed to The DragonFly Project
e458e5f0	6	* by Simon Schubert <2@0x2c.org>.
8cbdbd34 SS	7	*
	8	* Redistribution and use in source and binary forms, with or without
	9	* modification, are permitted provided that the following conditions
	10	* are met:
	11	*
	12	* 1. Redistributions of source code must retain the above copyright
	13	* notice, this list of conditions and the following disclaimer.
	14	* 2. Redistributions in binary form must reproduce the above copyright
	15	* notice, this list of conditions and the following disclaimer in
	16	* the documentation and/or other materials provided with the
	17	* distribution.
	18	* 3. Neither the name of The DragonFly Project nor the names of its
	19	* contributors may be used to endorse or promote products derived
	20	* from this software without specific, prior written permission.
	21	*
	22	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	23	* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	24	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
	25	* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
	26	* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
	27	* INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
	28	* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	29	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
	30	* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
	31	* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
	32	* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	33	* SUCH DAMAGE.
	34	*/
	35
	36	#include <sys/types.h>
	37	#include <netinet/in.h>
	38	#include <arpa/inet.h>
	39	#include <arpa/nameser.h>
	40	#include <errno.h>
	41	#include <netdb.h>
	42	#include <resolv.h>
	43	#include <string.h>
	44	#include <stdlib.h>
	45
	46	#include "dma.h"
	47
	48	static int
	49	sort_pref(const void a, const void b)
	50	{
	51	const struct mx_hostentry ha = a, hb = b;
	52	int v;
	53
	54	/* sort increasing by preference primarily */
	55	v = ha->pref - hb->pref;
	56	if (v != 0)
	57	return (v);
	58
	59	/* sort PF_INET6 before PF_INET */
	60	v = - (ha->ai.ai_family - hb->ai.ai_family);
	61	return (v);
	62	}
	63
	64	static int
	65	add_host(int pref, const char host, int port, struct mx_hostentry he, size_t ps)
	66	{
	67	struct addrinfo hints, res, res0 = NULL;
	68	char servname[10];
	69	struct mx_hostentry *p;
8cbdbd34 SS	70	const int count_inc = 10;
	71	int err;
	72
8cbdbd34 SS	73	memset(&hints, 0, sizeof(hints));
	74	hints.ai_family = PF_UNSPEC;
	75	hints.ai_socktype = SOCK_STREAM;
	76	hints.ai_protocol = IPPROTO_TCP;
	77
	78	snprintf(servname, sizeof(servname), "%d", port);
	79	err = getaddrinfo(host, servname, &hints, &res0);
	80	if (err)
4b26e6a7	81	return (err == EAI_AGAIN ? 1 : -1);
8cbdbd34 SS	82
	83	for (res = res0; res != NULL; res = res->ai_next) {
	84	if (ps + 1 >= roundup(ps, count_inc)) {
	85	size_t newsz = roundup(*ps + 2, count_inc);
	86	he = reallocf(he, newsz * sizeof(**he));
	87	if (*he == NULL)
	88	goto out;
	89	}
	90
	91	p = &(he)[ps];
	92	strlcpy(p->host, host, sizeof(p->host));
	93	p->pref = pref;
	94	p->ai = *res;
	95	p->ai.ai_addr = NULL;
	96	bcopy(res->ai_addr, &p->sa, p->ai.ai_addrlen);
	97
32d3ec65	98	getnameinfo((struct sockaddr *)&p->sa, p->ai.ai_addrlen,
8cbdbd34 SS	99	p->addr, sizeof(p->addr),
	100	NULL, 0, NI_NUMERICHOST);
	101
	102	(*ps)++;
	103	}
	104	freeaddrinfo(res0);
	105
06dd5b89	106	return (0);
8cbdbd34 SS	107
	108	out:
	109	if (res0 != NULL)
	110	freeaddrinfo(res0);
4b26e6a7	111	return (1);
8cbdbd34 SS	112	}
	113
	114	int
	115	dns_get_mx_list(const char host, int port, struct mx_hostentry *he, int no_mx)
	116	{
	117	char outname[MAXDNAME];
	118	ns_msg msg;
	119	ns_rr rr;
	120	const char *searchhost;
9b921550 SS	121	const unsigned char *cp;
9b921550 SS	122	unsigned char *ans;
8cbdbd34 SS	123	struct mx_hostentry *hosts = NULL;
	124	size_t nhosts = 0;
	125	size_t anssz;
	126	int pref;
	127	int cname_recurse;
4b26e6a7	128	int have_mx = 0;
8cbdbd34 SS	129	int err;
	130	int i;
	131
	132	res_init();
	133	searchhost = host;
	134	cname_recurse = 0;
	135
	136	anssz = 65536;
	137	ans = malloc(anssz);
	138	if (ans == NULL)
	139	return (1);
	140
	141	if (no_mx)
	142	goto out;
	143
	144	repeat:
	145	err = res_search(searchhost, ns_c_in, ns_t_mx, ans, anssz);
	146	if (err < 0) {
	147	switch (h_errno) {
	148	case NO_DATA:
	149	/*
	150	* Host exists, but no MX (or CNAME) entry.
	151	* Not an error, use host name instead.
	152	*/
	153	goto out;
	154	case TRY_AGAIN:
	155	/* transient error */
	156	goto transerr;
	157	case NO_RECOVERY:
	158	case HOST_NOT_FOUND:
	159	default:
	160	errno = ENOENT;
	161	goto err;
	162	}
	163	}
	164
	165	if (!ns_initparse(ans, anssz, &msg))
	166	goto transerr;
	167
	168	switch (ns_msg_getflag(msg, ns_f_rcode)) {
	169	case ns_r_noerror:
	170	break;
	171	case ns_r_nxdomain:
	172	goto err;
	173	default:
	174	goto transerr;
	175	}
	176
	177	for (i = 0; i < ns_msg_count(msg, ns_s_an); i++) {
	178	if (ns_parserr(&msg, ns_s_an, i, &rr))
	179	goto transerr;
	180
9b921550	181	cp = ns_rr_rdata(rr);
8cbdbd34 SS	182
	183	switch (ns_rr_type(rr)) {
	184	case ns_t_mx:
4b26e6a7	185	have_mx = 1;
8cbdbd34 SS	186	pref = ns_get16(cp);
	187	cp += 2;
	188	err = ns_name_uncompress(ns_msg_base(msg), ns_msg_end(msg),
	189	cp, outname, sizeof(outname));
	190	if (err < 0)
	191	goto transerr;
	192
4b26e6a7 SS	193	err = add_host(pref, outname, port, &hosts, &nhosts);
	194	if (err == -1)
	195	goto err;
8cbdbd34 SS	196	break;
	197
	198	case ns_t_cname:
	199	err = ns_name_uncompress(ns_msg_base(msg), ns_msg_end(msg),
	200	cp, outname, sizeof(outname));
	201	if (err < 0)
	202	goto transerr;
	203
	204	/* Prevent a CNAME loop */
	205	if (cname_recurse++ > 10)
	206	goto err;
	207
	208	searchhost = outname;
	209	goto repeat;
	210
	211	default:
	212	break;
	213	}
	214	}
	215
	216	out:
	217	err = 0;
	218	if (0) {
	219	transerr:
	220	if (nhosts == 0)
	221	err = 1;
	222	}
	223	if (0) {
	224	err:
	225	err = -1;
	226	}
	227
	228	free(ans);
	229
4b26e6a7 SS	230	if (err == 0) {
	231	if (!have_mx) {
	232	/*
	233	* If we didn't find any MX, use the hostname instead.
	234	*/
	235	err = add_host(0, host, port, &hosts, &nhosts);
	236	} else if (nhosts == 0) {
	237	/*
	238	* We did get MX, but couldn't resolve any of them
	239	* due to transient errors.
	240	*/
	241	err = 1;
	242	}
8cbdbd34 SS	243	}
	244
	245	if (nhosts > 0) {
4b26e6a7	246	qsort(hosts, nhosts, sizeof(*hosts), sort_pref);
8cbdbd34 SS	247	/* terminate list */
	248	*hosts[nhosts].host = 0;
	249	} else {
	250	if (hosts != NULL)
	251	free(hosts);
	252	hosts = NULL;
	253	}
	254
	255	*he = hosts;
	256	return (err);
	257
	258	free(ans);
	259	if (hosts != NULL)
	260	free(hosts);
	261	return (err);
	262	}
	263
	264	#if defined(TESTING)
	265	int
	266	main(int argc, char **argv)
	267	{
	268	struct mx_hostentry he, p;
	269	int err;
	270
	271	err = dns_get_mx_list(argv[1], 53, &he, 0);
	272	if (err)
	273	return (err);
	274
	275	for (p = he; *p->host != 0; p++) {
	276	printf("%d\t%s\t%s\n", p->pref, p->host, p->addr);
	277	}
	278
	279	return (0);
	280	}
	281	#endif