[thirdparty/openssh-portable.git] / dns.c

/* $OpenBSD: dns.c,v 1.44 2023/03/10 04:06:21 dtucker Exp $ */

/*
 * Copyright (c) 2003 Wesley Griffin. All rights reserved.
 * Copyright (c) 2003 Jakob Schlyter. All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 "includes.h"

#include <sys/types.h>
#include <sys/socket.h>

#include <netdb.h>
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include "xmalloc.h"
#include "sshkey.h"
#include "ssherr.h"
#include "dns.h"
#include "log.h"
#include "digest.h"

static const char * const errset_text[] = {
	"success",		/* 0 ERRSET_SUCCESS */
	"out of memory",	/* 1 ERRSET_NOMEMORY */
	"general failure",	/* 2 ERRSET_FAIL */
	"invalid parameter",	/* 3 ERRSET_INVAL */
	"name does not exist",	/* 4 ERRSET_NONAME */
	"data does not exist",	/* 5 ERRSET_NODATA */
};

static const char *
dns_result_totext(unsigned int res)
{
	switch (res) {
	case ERRSET_SUCCESS:
		return errset_text[ERRSET_SUCCESS];
	case ERRSET_NOMEMORY:
		return errset_text[ERRSET_NOMEMORY];
	case ERRSET_FAIL:
		return errset_text[ERRSET_FAIL];
	case ERRSET_INVAL:
		return errset_text[ERRSET_INVAL];
	case ERRSET_NONAME:
		return errset_text[ERRSET_NONAME];
	case ERRSET_NODATA:
		return errset_text[ERRSET_NODATA];
	default:
		return "unknown error";
	}
}

/*
 * Read SSHFP parameters from key buffer.
 * Caller must free digest which is allocated by sshkey_fingerprint_raw().
 */
static int
dns_read_key(u_int8_t *algorithm, u_int8_t *digest_type,
    u_char **digest, size_t *digest_len, struct sshkey *key)
{
	int r, success = 0;
	int fp_alg = -1;

	switch (key->type) {
	case KEY_RSA:
		*algorithm = SSHFP_KEY_RSA;
		break;
	case KEY_DSA:
		*algorithm = SSHFP_KEY_DSA;
		break;
	case KEY_ECDSA:
		*algorithm = SSHFP_KEY_ECDSA;
		break;
	case KEY_ED25519:
		*algorithm = SSHFP_KEY_ED25519;
		break;
	case KEY_XMSS:
		*algorithm = SSHFP_KEY_XMSS;
		break;
	default:
		*algorithm = SSHFP_KEY_RESERVED; /* 0 */
	}

	switch (*digest_type) {
	case SSHFP_HASH_SHA1:
		fp_alg = SSH_DIGEST_SHA1;
		break;
	case SSHFP_HASH_SHA256:
		fp_alg = SSH_DIGEST_SHA256;
		break;
	default:
		*digest_type = SSHFP_HASH_RESERVED; /* 0 */
	}

	if (*algorithm && *digest_type) {
		if ((r = sshkey_fingerprint_raw(key, fp_alg, digest,
		    digest_len)) != 0)
			fatal_fr(r, "sshkey_fingerprint_raw");
		success = 1;
	} else {
		*digest = NULL;
		*digest_len = 0;
	}

	return success;
}

/*
 * Read SSHFP parameters from rdata buffer.
 */
static int
dns_read_rdata(u_int8_t *algorithm, u_int8_t *digest_type,
    u_char **digest, size_t *digest_len, u_char *rdata, int rdata_len)
{
	int success = 0;

	*algorithm = SSHFP_KEY_RESERVED;
	*digest_type = SSHFP_HASH_RESERVED;

	if (rdata_len >= 2) {
		*algorithm = rdata[0];
		*digest_type = rdata[1];
		*digest_len = rdata_len - 2;

		if (*digest_len > 0) {
			*digest = xmalloc(*digest_len);
			memcpy(*digest, rdata + 2, *digest_len);
		} else {
			*digest = (u_char *)xstrdup("");
		}

		success = 1;
	}

	return success;
}

/*
 * Check if hostname is numerical.
 * Returns -1 if hostname is numeric, 0 otherwise
 */
static int
is_numeric_hostname(const char *hostname)
{
	struct addrinfo hints, *ai;

	/*
	 * We shouldn't ever get a null host but if we do then log an error
	 * and return -1 which stops DNS key fingerprint processing.
	 */
	if (hostname == NULL) {
		error("is_numeric_hostname called with NULL hostname");
		return -1;
	}

	memset(&hints, 0, sizeof(hints));
	hints.ai_socktype = SOCK_DGRAM;
	hints.ai_flags = AI_NUMERICHOST;

	if (getaddrinfo(hostname, NULL, &hints, &ai) == 0) {
		freeaddrinfo(ai);
		return -1;
	}

	return 0;
}

/*
 * Verify the given hostname, address and host key using DNS.
 * Returns 0 if lookup succeeds, -1 otherwise
 */
int
verify_host_key_dns(const char *hostname, struct sockaddr *address,
    struct sshkey *hostkey, int *flags)
{
	u_int counter;
	int result;
	struct rrsetinfo *fingerprints = NULL;

	u_int8_t hostkey_algorithm;
	u_char *hostkey_digest;
	size_t hostkey_digest_len;

	u_int8_t dnskey_algorithm;
	u_int8_t dnskey_digest_type;
	u_char *dnskey_digest;
	size_t dnskey_digest_len;

	*flags = 0;

	debug3("verify_host_key_dns");
	if (hostkey == NULL)
		fatal("No key to look up!");

	if (is_numeric_hostname(hostname)) {
		debug("skipped DNS lookup for numerical hostname");
		return -1;
	}

	result = getrrsetbyname(hostname, DNS_RDATACLASS_IN,
	    DNS_RDATATYPE_SSHFP, 0, &fingerprints);
	if (result) {
		verbose("DNS lookup error: %s", dns_result_totext(result));
		return -1;
	}

	if (fingerprints->rri_flags & RRSET_VALIDATED) {
		*flags |= DNS_VERIFY_SECURE;
		debug("found %d secure fingerprints in DNS",
		    fingerprints->rri_nrdatas);
	} else {
		debug("found %d insecure fingerprints in DNS",
		    fingerprints->rri_nrdatas);
	}

	if (fingerprints->rri_nrdatas)
		*flags |= DNS_VERIFY_FOUND;

	for (counter = 0; counter < fingerprints->rri_nrdatas; counter++) {
		/*
		 * Extract the key from the answer. Ignore any badly
		 * formatted fingerprints.
		 */
		if (!dns_read_rdata(&dnskey_algorithm, &dnskey_digest_type,
		    &dnskey_digest, &dnskey_digest_len,
		    fingerprints->rri_rdatas[counter].rdi_data,
		    fingerprints->rri_rdatas[counter].rdi_length)) {
			verbose("Error parsing fingerprint from DNS.");
			continue;
		}
		debug3_f("checking SSHFP type %d fptype %d", dnskey_algorithm,
		    dnskey_digest_type);

		/* Calculate host key fingerprint. */
		if (!dns_read_key(&hostkey_algorithm, &dnskey_digest_type,
		    &hostkey_digest, &hostkey_digest_len, hostkey)) {
			error("Error calculating key fingerprint.");
			free(dnskey_digest);
			freerrset(fingerprints);
			return -1;
		}

		/* Check if the current key is the same as the given key */
		if (hostkey_algorithm == dnskey_algorithm &&
		    hostkey_digest_len == dnskey_digest_len) {
			if (timingsafe_bcmp(hostkey_digest, dnskey_digest,
			    hostkey_digest_len) == 0) {
				debug_f("matched SSHFP type %d fptype %d",
				    dnskey_algorithm, dnskey_digest_type);
				*flags |= DNS_VERIFY_MATCH;
			} else {
				debug_f("failed SSHFP type %d fptype %d",
				    dnskey_algorithm, dnskey_digest_type);
				*flags |= DNS_VERIFY_FAILED;
			}
		}
		free(dnskey_digest);
		free(hostkey_digest); /* from sshkey_fingerprint_raw() */
	}

	freerrset(fingerprints);

	/* If any fingerprint failed to validate, return failure. */
	if (*flags & DNS_VERIFY_FAILED)
		*flags &= ~DNS_VERIFY_MATCH;

	if (*flags & DNS_VERIFY_FOUND)
		if (*flags & DNS_VERIFY_MATCH)
			debug("matching host key fingerprint found in DNS");
		else
			debug("mismatching host key fingerprint found in DNS");
	else
		debug("no host key fingerprint found in DNS");

	return 0;
}

/*
 * Export the fingerprint of a key as a DNS resource record
 */
int
export_dns_rr(const char *hostname, struct sshkey *key, FILE *f, int generic,
    int alg)
{
	u_int8_t rdata_pubkey_algorithm = 0;
	u_int8_t rdata_digest_type = SSHFP_HASH_RESERVED;
	u_int8_t dtype;
	u_char *rdata_digest;
	size_t i, rdata_digest_len;
	int success = 0;

	for (dtype = SSHFP_HASH_SHA1; dtype < SSHFP_HASH_MAX; dtype++) {
		if (alg != -1 && dtype != alg)
			continue;
		rdata_digest_type = dtype;
		if (dns_read_key(&rdata_pubkey_algorithm, &rdata_digest_type,
		    &rdata_digest, &rdata_digest_len, key)) {
			if (generic) {
				fprintf(f, "%s IN TYPE%d \\# %zu %02x %02x ",
				    hostname, DNS_RDATATYPE_SSHFP,
				    2 + rdata_digest_len,
				    rdata_pubkey_algorithm, rdata_digest_type);
			} else {
				fprintf(f, "%s IN SSHFP %d %d ", hostname,
				    rdata_pubkey_algorithm, rdata_digest_type);
			}
			for (i = 0; i < rdata_digest_len; i++)
				fprintf(f, "%02x", rdata_digest[i]);
			fprintf(f, "\n");
			free(rdata_digest); /* from sshkey_fingerprint_raw() */
			success = 1;
		}
	}

	/* No SSHFP record was generated at all */
	if (success == 0) {
		error_f("unsupported algorithm and/or digest_type");
	}

	return success;
}
Commit	Line	Data
89b8df51	1	/* $OpenBSD: dns.c,v 1.44 2023/03/10 04:06:21 dtucker Exp $ */
37876e91 DM	2
	3	/*
	4	* Copyright (c) 2003 Wesley Griffin. All rights reserved.
	5	* Copyright (c) 2003 Jakob Schlyter. All rights reserved.
	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	* 1. Redistributions of source code must retain the above copyright
	11	* notice, this list of conditions and the following disclaimer.
	12	* 2. Redistributions in binary form must reproduce the above copyright
	13	* notice, this list of conditions and the following disclaimer in the
	14	* documentation and/or other materials provided with the distribution.
	15	*
	16	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	17	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	18	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	19	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	20	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	21	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	22	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	23	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	24	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	25	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	26	*/
	27
37876e91 DM	28	#include "includes.h"
37876e91 DM	29
e3b60b52 DM	30	#include <sys/types.h>
	31	#include <sys/socket.h>
	32
b8fe89c4	33	#include <netdb.h>
ded319cc	34	#include <stdarg.h>
a7a73ee3	35	#include <stdio.h>
e3476ed0	36	#include <string.h>
8668706d	37	#include <stdlib.h>
37876e91 DM	38
37876e91 DM	39	#include "xmalloc.h"
1129dcfc	40	#include "sshkey.h"
1129dcfc	41	#include "ssherr.h"
37876e91 DM	42	#include "dns.h"
37876e91 DM	43	#include "log.h"
56d1c83c	44	#include "digest.h"
37876e91	45
541667fe	46	static const char * const errset_text[] = {
37876e91 DM	47	"success", /* 0 ERRSET_SUCCESS */
	48	"out of memory", /* 1 ERRSET_NOMEMORY */
	49	"general failure", /* 2 ERRSET_FAIL */
	50	"invalid parameter", /* 3 ERRSET_INVAL */
	51	"name does not exist", /* 4 ERRSET_NONAME */
	52	"data does not exist", /* 5 ERRSET_NODATA */
	53	};
	54
	55	static const char *
3f9fdc71	56	dns_result_totext(unsigned int res)
37876e91	57	{
3f9fdc71	58	switch (res) {
37876e91 DM	59	case ERRSET_SUCCESS:
	60	return errset_text[ERRSET_SUCCESS];
	61	case ERRSET_NOMEMORY:
	62	return errset_text[ERRSET_NOMEMORY];
	63	case ERRSET_FAIL:
	64	return errset_text[ERRSET_FAIL];
	65	case ERRSET_INVAL:
	66	return errset_text[ERRSET_INVAL];
	67	case ERRSET_NONAME:
	68	return errset_text[ERRSET_NONAME];
	69	case ERRSET_NODATA:
	70	return errset_text[ERRSET_NODATA];
	71	default:
	72	return "unknown error";
	73	}
	74	}
37876e91 DM	75
	76	/*
	77	* Read SSHFP parameters from key buffer.
b75a80fa	78	* Caller must free digest which is allocated by sshkey_fingerprint_raw().
37876e91 DM	79	*/
	80	static int
	81	dns_read_key(u_int8_t algorithm, u_int8_t digest_type,
1129dcfc	82	u_char *digest, size_t digest_len, struct sshkey *key)
37876e91	83	{
1129dcfc	84	int r, success = 0;
56d1c83c	85	int fp_alg = -1;
37876e91 DM	86
	87	switch (key->type) {
	88	case KEY_RSA:
	89	*algorithm = SSHFP_KEY_RSA;
	90	break;
	91	case KEY_DSA:
	92	*algorithm = SSHFP_KEY_DSA;
3bde12ae DM	93	break;
	94	case KEY_ECDSA:
	95	*algorithm = SSHFP_KEY_ECDSA;
37876e91	96	break;
16cd3928 DM	97	case KEY_ED25519:
16cd3928 DM	98	*algorithm = SSHFP_KEY_ED25519;
16cd3928	99	break;
1b11ea7c	100	case KEY_XMSS:
1b11ea7c	101	*algorithm = SSHFP_KEY_XMSS;
1b11ea7c	102	break;
37876e91	103	default:
65712490	104	algorithm = SSHFP_KEY_RESERVED; / 0 */
3bde12ae DM	105	}
	106
	107	switch (*digest_type) {
	108	case SSHFP_HASH_SHA1:
56d1c83c	109	fp_alg = SSH_DIGEST_SHA1;
3bde12ae DM	110	break;
3bde12ae DM	111	case SSHFP_HASH_SHA256:
56d1c83c	112	fp_alg = SSH_DIGEST_SHA256;
3bde12ae DM	113	break;
	114	default:
	115	digest_type = SSHFP_HASH_RESERVED; / 0 */
37876e91 DM	116	}
37876e91 DM	117
3bde12ae	118	if (algorithm && digest_type) {
1129dcfc	119	if ((r = sshkey_fingerprint_raw(key, fp_alg, digest,
1129dcfc	120	digest_len)) != 0)
816036f1	121	fatal_fr(r, "sshkey_fingerprint_raw");
37876e91 DM	122	success = 1;
37876e91 DM	123	} else {
37876e91 DM	124	*digest = NULL;
37876e91 DM	125	*digest_len = 0;
37876e91 DM	126	}
	127
	128	return success;
	129	}
	130
	131	/*
	132	* Read SSHFP parameters from rdata buffer.
	133	*/
	134	static int
	135	dns_read_rdata(u_int8_t algorithm, u_int8_t digest_type,
1129dcfc	136	u_char *digest, size_t digest_len, u_char *rdata, int rdata_len)
37876e91 DM	137	{
	138	int success = 0;
	139
	140	*algorithm = SSHFP_KEY_RESERVED;
	141	*digest_type = SSHFP_HASH_RESERVED;
	142
	143	if (rdata_len >= 2) {
	144	*algorithm = rdata[0];
	145	*digest_type = rdata[1];
	146	*digest_len = rdata_len - 2;
	147
	148	if (*digest_len > 0) {
ce445b0e	149	digest = xmalloc(digest_len);
37876e91 DM	150	memcpy(digest, rdata + 2, digest_len);
37876e91 DM	151	} else {
5996294a	152	digest = (u_char )xstrdup("");
37876e91 DM	153	}
	154
	155	success = 1;
	156	}
	157
	158	return success;
	159	}
	160
a31c929f DM	161	/*
	162	* Check if hostname is numerical.
	163	* Returns -1 if hostname is numeric, 0 otherwise
	164	*/
	165	static int
	166	is_numeric_hostname(const char *hostname)
	167	{
	168	struct addrinfo hints, *ai;
	169
30ac73bc DT	170	/*
	171	* We shouldn't ever get a null host but if we do then log an error
	172	* and return -1 which stops DNS key fingerprint processing.
	173	*/
	174	if (hostname == NULL) {
	175	error("is_numeric_hostname called with NULL hostname");
	176	return -1;
	177	}
	178
a31c929f DM	179	memset(&hints, 0, sizeof(hints));
	180	hints.ai_socktype = SOCK_DGRAM;
	181	hints.ai_flags = AI_NUMERICHOST;
	182
30ac73bc	183	if (getaddrinfo(hostname, NULL, &hints, &ai) == 0) {
a31c929f DM	184	freeaddrinfo(ai);
	185	return -1;
	186	}
	187
	188	return 0;
	189	}
37876e91 DM	190
	191	/*
	192	* Verify the given hostname, address and host key using DNS.
a8e06cef	193	* Returns 0 if lookup succeeds, -1 otherwise
37876e91 DM	194	*/
	195	int
	196	verify_host_key_dns(const char hostname, struct sockaddr address,
1129dcfc	197	struct sshkey hostkey, int flags)
37876e91	198	{
eccb9de7	199	u_int counter;
37876e91 DM	200	int result;
37876e91 DM	201	struct rrsetinfo *fingerprints = NULL;
37876e91 DM	202
37876e91 DM	203	u_int8_t hostkey_algorithm;
37876e91	204	u_char *hostkey_digest;
1129dcfc	205	size_t hostkey_digest_len;
37876e91 DM	206
	207	u_int8_t dnskey_algorithm;
	208	u_int8_t dnskey_digest_type;
	209	u_char *dnskey_digest;
1129dcfc	210	size_t dnskey_digest_len;
37876e91	211
150b5574	212	*flags = 0;
37876e91	213
319550a5	214	debug3("verify_host_key_dns");
37876e91 DM	215	if (hostkey == NULL)
	216	fatal("No key to look up!");
	217
a31c929f DM	218	if (is_numeric_hostname(hostname)) {
	219	debug("skipped DNS lookup for numerical hostname");
	220	return -1;
	221	}
	222
37876e91 DM	223	result = getrrsetbyname(hostname, DNS_RDATACLASS_IN,
	224	DNS_RDATATYPE_SSHFP, 0, &fingerprints);
	225	if (result) {
	226	verbose("DNS lookup error: %s", dns_result_totext(result));
150b5574	227	return -1;
37876e91 DM	228	}
37876e91 DM	229
150b5574 DM	230	if (fingerprints->rri_flags & RRSET_VALIDATED) {
	231	*flags \|= DNS_VERIFY_SECURE;
	232	debug("found %d secure fingerprints in DNS",
	233	fingerprints->rri_nrdatas);
	234	} else {
	235	debug("found %d insecure fingerprints in DNS",
	236	fingerprints->rri_nrdatas);
37876e91	237	}
37876e91	238
150b5574 DM	239	if (fingerprints->rri_nrdatas)
	240	*flags \|= DNS_VERIFY_FOUND;
	241
80163907	242	for (counter = 0; counter < fingerprints->rri_nrdatas; counter++) {
37876e91 DM	243	/*
	244	* Extract the key from the answer. Ignore any badly
	245	* formatted fingerprints.
	246	*/
	247	if (!dns_read_rdata(&dnskey_algorithm, &dnskey_digest_type,
	248	&dnskey_digest, &dnskey_digest_len,
	249	fingerprints->rri_rdatas[counter].rdi_data,
	250	fingerprints->rri_rdatas[counter].rdi_length)) {
	251	verbose("Error parsing fingerprint from DNS.");
	252	continue;
	253	}
b75a80fa	254	debug3_f("checking SSHFP type %d fptype %d", dnskey_algorithm,
	255	dnskey_digest_type);
	256
	257	/* Calculate host key fingerprint. */
	258	if (!dns_read_key(&hostkey_algorithm, &dnskey_digest_type,
	259	&hostkey_digest, &hostkey_digest_len, hostkey)) {
	260	error("Error calculating key fingerprint.");
89b8df51	261	free(dnskey_digest);
b75a80fa	262	freerrset(fingerprints);
b75a80fa	263	return -1;
3bde12ae DM	264	}
3bde12ae DM	265
37876e91 DM	266	/* Check if the current key is the same as the given key */
37876e91 DM	267	if (hostkey_algorithm == dnskey_algorithm &&
b75a80fa	268	hostkey_digest_len == dnskey_digest_len) {
	269	if (timingsafe_bcmp(hostkey_digest, dnskey_digest,
	270	hostkey_digest_len) == 0) {
	271	debug_f("matched SSHFP type %d fptype %d",
	272	dnskey_algorithm, dnskey_digest_type);
150b5574	273	*flags \|= DNS_VERIFY_MATCH;
b75a80fa	274	} else {
	275	debug_f("failed SSHFP type %d fptype %d",
	276	dnskey_algorithm, dnskey_digest_type);
	277	*flags \|= DNS_VERIFY_FAILED;
	278	}
37876e91	279	}
a627d42e	280	free(dnskey_digest);
b75a80fa	281	free(hostkey_digest); /* from sshkey_fingerprint_raw() */
37876e91 DM	282	}
37876e91 DM	283
aea59a0d	284	freerrset(fingerprints);
aea59a0d	285
b75a80fa	286	/* If any fingerprint failed to validate, return failure. */
	287	if (*flags & DNS_VERIFY_FAILED)
	288	*flags &= ~DNS_VERIFY_MATCH;
	289
aea59a0d	290	if (*flags & DNS_VERIFY_FOUND)
150b5574 DM	291	if (*flags & DNS_VERIFY_MATCH)
	292	debug("matching host key fingerprint found in DNS");
	293	else
	294	debug("mismatching host key fingerprint found in DNS");
aea59a0d	295	else
150b5574	296	debug("no host key fingerprint found in DNS");
37876e91	297
150b5574	298	return 0;
37876e91 DM	299	}
37876e91 DM	300
37876e91 DM	301	/*
	302	* Export the fingerprint of a key as a DNS resource record
	303	*/
	304	int
d651f5c9	305	export_dns_rr(const char hostname, struct sshkey key, FILE *f, int generic,
d651f5c9	306	int alg)
37876e91 DM	307	{
37876e91 DM	308	u_int8_t rdata_pubkey_algorithm = 0;
3bde12ae DM	309	u_int8_t rdata_digest_type = SSHFP_HASH_RESERVED;
3bde12ae DM	310	u_int8_t dtype;
37876e91	311	u_char *rdata_digest;
1129dcfc	312	size_t i, rdata_digest_len;
37876e91 DM	313	int success = 0;
37876e91 DM	314
3bde12ae	315	for (dtype = SSHFP_HASH_SHA1; dtype < SSHFP_HASH_MAX; dtype++) {
d651f5c9	316	if (alg != -1 && dtype != alg)
d651f5c9	317	continue;
3bde12ae DM	318	rdata_digest_type = dtype;
	319	if (dns_read_key(&rdata_pubkey_algorithm, &rdata_digest_type,
	320	&rdata_digest, &rdata_digest_len, key)) {
	321	if (generic) {
1129dcfc	322	fprintf(f, "%s IN TYPE%d \\# %zu %02x %02x ",
3bde12ae DM	323	hostname, DNS_RDATATYPE_SSHFP,
	324	2 + rdata_digest_len,
	325	rdata_pubkey_algorithm, rdata_digest_type);
	326	} else {
	327	fprintf(f, "%s IN SSHFP %d %d ", hostname,
	328	rdata_pubkey_algorithm, rdata_digest_type);
	329	}
	330	for (i = 0; i < rdata_digest_len; i++)
	331	fprintf(f, "%02x", rdata_digest[i]);
	332	fprintf(f, "\n");
9ce86c92	333	free(rdata_digest); /* from sshkey_fingerprint_raw() */
3bde12ae DM	334	success = 1;
	335	}
	336	}
37876e91	337
3bde12ae DM	338	/* No SSHFP record was generated at all */
3bde12ae DM	339	if (success == 0) {
816036f1	340	error_f("unsupported algorithm and/or digest_type");
37876e91 DM	341	}
	342
	343	return success;
	344	}