291 lines
7.6 KiB
C
291 lines
7.6 KiB
C
/* $OpenBSD: dnssec.c,v 1.28 2021/10/09 18:43:50 deraadt Exp $ */
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/*
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* Copyright (c) 2001 Håkan Olsson. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/types.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <stdlib.h>
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#include <openssl/rsa.h>
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#ifdef LWRES
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#include <lwres/netdb.h>
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#include <dns/keyvalues.h>
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#else
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#include <netdb.h>
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#endif
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#include "dnssec.h"
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#include "exchange.h"
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#include "ipsec_num.h"
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#include "libcrypto.h"
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#include "log.h"
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#include "message.h"
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#include "transport.h"
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#include "util.h"
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#ifndef DNS_UFQDN_SEPARATOR
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#define DNS_UFQDN_SEPARATOR "._ipsec."
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#endif
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/* adapted from <dns/rdatastruct.h> / RFC 2535 */
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struct dns_rdata_key {
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u_int16_t flags;
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u_int8_t protocol;
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u_int8_t algorithm;
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u_int16_t datalen;
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unsigned char *data;
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};
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void *
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dns_get_key(int type, struct message *msg, int *keylen)
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{
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struct exchange *exchange = msg->exchange;
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struct rrsetinfo *rr;
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struct dns_rdata_key key_rr;
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char name[HOST_NAME_MAX+1];
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in_addr_t ip4;
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u_int8_t algorithm, *id, *umark;
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size_t id_len;
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int ret, i;
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switch (type) {
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case IKE_AUTH_RSA_SIG:
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algorithm = DNS_KEYALG_RSA;
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break;
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case IKE_AUTH_RSA_ENC:
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case IKE_AUTH_RSA_ENC_REV:
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/* XXX Not yet. */
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/* algorithm = DNS_KEYALG_RSA; */
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return 0;
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case IKE_AUTH_DSS:
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/* XXX Not yet. */
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/* algorithm = DNS_KEYALG_DSS; */
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return 0;
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case IKE_AUTH_PRE_SHARED:
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default:
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return 0;
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}
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id = exchange->initiator ? exchange->id_r : exchange->id_i;
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id_len = exchange->initiator ? exchange->id_r_len : exchange->id_i_len;
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bzero(name, sizeof name);
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if (!id || id_len == 0) {
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log_print("dns_get_key: ID is missing");
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return 0;
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}
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/* Exchanges (and SAs) don't carry the ID in ISAKMP form */
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id -= ISAKMP_GEN_SZ;
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id_len += ISAKMP_GEN_SZ - ISAKMP_ID_DATA_OFF;
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switch (GET_ISAKMP_ID_TYPE(id)) {
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case IPSEC_ID_IPV4_ADDR:
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/* We want to lookup a KEY RR in the reverse zone. */
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if (id_len < sizeof ip4)
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return 0;
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memcpy(&ip4, id + ISAKMP_ID_DATA_OFF, sizeof ip4);
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snprintf(name, sizeof name, "%d.%d.%d.%d.in-addr.arpa.", ip4
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>> 24, (ip4 >> 16) & 0xFF, (ip4 >> 8) & 0xFF, ip4 & 0xFF);
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break;
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case IPSEC_ID_IPV6_ADDR:
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/* XXX Not yet. */
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return 0;
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break;
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case IPSEC_ID_FQDN:
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if ((id_len + 1) >= sizeof name)
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return 0;
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/* ID is not NULL-terminated. Add trailing dot and NULL. */
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memcpy(name, id + ISAKMP_ID_DATA_OFF, id_len);
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*(name + id_len) = '.';
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*(name + id_len + 1) = '\0';
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break;
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case IPSEC_ID_USER_FQDN:
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/*
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* Some special handling here. We want to convert the ID
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* 'user@host.domain' string into 'user._ipsec.host.domain.'.
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*/
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if ((id_len + sizeof(DNS_UFQDN_SEPARATOR)) >= sizeof name)
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return 0;
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/* Look for the '@' separator. */
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for (umark = id + ISAKMP_ID_DATA_OFF; (umark - id) < id_len;
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umark++)
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if (*umark == '@')
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break;
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if (*umark != '@') {
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LOG_DBG((LOG_MISC, 50, "dns_get_key: bad UFQDN ID"));
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return 0;
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}
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*umark++ = '\0';
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/* id is now terminated. 'umark', however, is not. */
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snprintf(name, sizeof name, "%s%s", id + ISAKMP_ID_DATA_OFF,
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DNS_UFQDN_SEPARATOR);
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memcpy(name + strlen(name), umark, id_len - strlen(id) - 1);
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*(name + id_len + sizeof(DNS_UFQDN_SEPARATOR) - 2) = '.';
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*(name + id_len + sizeof(DNS_UFQDN_SEPARATOR) - 1) = '\0';
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break;
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default:
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return 0;
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}
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LOG_DBG((LOG_MISC, 50, "dns_get_key: trying KEY RR for %s", name));
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ret = getrrsetbyname(name, C_IN, T_KEY, 0, &rr);
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if (ret) {
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LOG_DBG((LOG_MISC, 30, "dns_get_key: no DNS responses "
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"(error %d)", ret));
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return 0;
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}
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LOG_DBG((LOG_MISC, 80,
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"dns_get_key: rrset class %d type %d ttl %d nrdatas %d nrsigs %d",
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rr->rri_rdclass, rr->rri_rdtype, rr->rri_ttl, rr->rri_nrdatas,
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rr->rri_nsigs));
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/* We don't accept unvalidated data. */
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if (!(rr->rri_flags & RRSET_VALIDATED)) {
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LOG_DBG((LOG_MISC, 10, "dns_get_key: "
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"got unvalidated response"));
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freerrset(rr);
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return 0;
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}
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/* Sanity. */
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if (rr->rri_nrdatas == 0 || rr->rri_rdtype != T_KEY) {
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LOG_DBG((LOG_MISC, 30, "dns_get_key: no KEY RRs received"));
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freerrset(rr);
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return 0;
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}
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bzero(&key_rr, sizeof key_rr);
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/*
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* Find a key with the wanted algorithm, if any.
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* XXX If there are several keys present, we currently only find the
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* first.
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*/
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for (i = 0; i < rr->rri_nrdatas && key_rr.datalen == 0; i++) {
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key_rr.flags = ntohs((u_int16_t) * rr->rri_rdatas[i].rdi_data);
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key_rr.protocol = *(rr->rri_rdatas[i].rdi_data + 2);
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key_rr.algorithm = *(rr->rri_rdatas[i].rdi_data + 3);
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if (key_rr.protocol != DNS_KEYPROTO_IPSEC) {
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LOG_DBG((LOG_MISC, 50, "dns_get_key: ignored "
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"non-IPsec key"));
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continue;
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}
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if (key_rr.algorithm != algorithm) {
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LOG_DBG((LOG_MISC, 50, "dns_get_key: ignored "
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"key with other alg"));
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continue;
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}
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key_rr.datalen = rr->rri_rdatas[i].rdi_length - 4;
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if (key_rr.datalen <= 0) {
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LOG_DBG((LOG_MISC, 50, "dns_get_key: "
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"ignored bad key"));
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key_rr.datalen = 0;
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continue;
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}
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/* This key seems to fit our requirements... */
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key_rr.data = malloc(key_rr.datalen);
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if (!key_rr.data) {
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log_error("dns_get_key: malloc (%d) failed",
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key_rr.datalen);
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freerrset(rr);
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return 0;
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}
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memcpy(key_rr.data, rr->rri_rdatas[i].rdi_data + 4,
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key_rr.datalen);
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*keylen = key_rr.datalen;
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}
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freerrset(rr);
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if (key_rr.datalen)
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return key_rr.data;
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return 0;
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}
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int
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dns_RSA_dns_to_x509(u_int8_t *key, int keylen, RSA **rsa_key)
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{
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RSA *rsa;
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int key_offset;
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u_int8_t e_len;
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if (!key || keylen <= 0) {
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log_print("dns_RSA_dns_to_x509: invalid public key");
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return -1;
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}
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rsa = RSA_new();
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if (rsa == NULL) {
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log_error("dns_RSA_dns_to_x509: "
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"failed to allocate new RSA struct");
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return -1;
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}
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e_len = *key;
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key_offset = 1;
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if (e_len == 0) {
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if (keylen < 3) {
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log_print("dns_RSA_dns_to_x509: invalid public key");
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RSA_free(rsa);
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return -1;
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}
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e_len = *(key + key_offset++) << 8;
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e_len += *(key + key_offset++);
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}
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if (e_len > (keylen - key_offset)) {
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log_print("dns_RSA_dns_to_x509: invalid public key");
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RSA_free(rsa);
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return -1;
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}
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rsa->e = BN_bin2bn(key + key_offset, e_len, NULL);
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key_offset += e_len;
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/* XXX if (keylen <= key_offset) -> "invalid public key" ? */
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rsa->n = BN_bin2bn(key + key_offset, keylen - key_offset, NULL);
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*rsa_key = rsa;
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LOG_DBG((LOG_MISC, 30, "dns_RSA_dns_to_x509: got %d bits RSA key",
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BN_num_bits(rsa->n)));
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return 0;
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}
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#if notyet
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int
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dns_RSA_x509_to_dns(RSA *rsa_key, u_int8_t *key, int *keylen)
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{
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return 0;
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}
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#endif
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