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

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