a3db237b8f
Specifically, it appears as if the NSEC next domain name should be in the original casing rather than canonical form, when validating.
262 lines
10 KiB
C
262 lines
10 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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#pragma once
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/***
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This file is part of systemd.
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Copyright 2014 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <netinet/ip.h>
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#include <netinet/udp.h>
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#include "hashmap.h"
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#include "in-addr-util.h"
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#include "macro.h"
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#include "sparse-endian.h"
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typedef struct DnsPacketHeader DnsPacketHeader;
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typedef struct DnsPacket DnsPacket;
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#include "resolved-def.h"
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#include "resolved-dns-answer.h"
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#include "resolved-dns-question.h"
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#include "resolved-dns-rr.h"
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typedef enum DnsProtocol {
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DNS_PROTOCOL_DNS,
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DNS_PROTOCOL_MDNS,
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DNS_PROTOCOL_LLMNR,
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_DNS_PROTOCOL_MAX,
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_DNS_PROTOCOL_INVALID = -1
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} DnsProtocol;
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struct DnsPacketHeader {
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uint16_t id;
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be16_t flags;
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be16_t qdcount;
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be16_t ancount;
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be16_t nscount;
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be16_t arcount;
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};
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#define DNS_PACKET_HEADER_SIZE sizeof(DnsPacketHeader)
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#define UDP_PACKET_HEADER_SIZE (sizeof(struct iphdr) + sizeof(struct udphdr))
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/* The various DNS protocols deviate in how large a packet can grow,
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but the TCP transport has a 16bit size field, hence that appears to
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be the absolute maximum. */
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#define DNS_PACKET_SIZE_MAX 0xFFFF
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/* RFC 1035 say 512 is the maximum, for classic unicast DNS */
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#define DNS_PACKET_UNICAST_SIZE_MAX 512
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/* With EDNS0 we can use larger packets, default to 4096, which is what is commonly used */
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#define DNS_PACKET_UNICAST_SIZE_LARGE_MAX 4096
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#define DNS_PACKET_SIZE_START 512
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struct DnsPacket {
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int n_ref;
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DnsProtocol protocol;
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size_t size, allocated, rindex;
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void *_data; /* don't access directly, use DNS_PACKET_DATA()! */
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Hashmap *names; /* For name compression */
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/* Parsed data */
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DnsQuestion *question;
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DnsAnswer *answer;
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DnsResourceRecord *opt;
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/* Packet reception metadata */
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int ifindex;
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int family, ipproto;
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union in_addr_union sender, destination;
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uint16_t sender_port, destination_port;
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uint32_t ttl;
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/* For support of truncated packets */
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DnsPacket *more;
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bool on_stack:1;
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bool extracted:1;
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bool refuse_compression:1;
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bool canonical_form:1;
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};
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static inline uint8_t* DNS_PACKET_DATA(DnsPacket *p) {
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if (_unlikely_(!p))
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return NULL;
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if (p->_data)
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return p->_data;
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return ((uint8_t*) p) + ALIGN(sizeof(DnsPacket));
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}
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#define DNS_PACKET_HEADER(p) ((DnsPacketHeader*) DNS_PACKET_DATA(p))
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#define DNS_PACKET_ID(p) DNS_PACKET_HEADER(p)->id
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#define DNS_PACKET_QR(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 15) & 1)
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#define DNS_PACKET_OPCODE(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 11) & 15)
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#define DNS_PACKET_AA(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 10) & 1)
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#define DNS_PACKET_TC(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 9) & 1)
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#define DNS_PACKET_RD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 8) & 1)
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#define DNS_PACKET_RA(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 7) & 1)
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#define DNS_PACKET_AD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 5) & 1)
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#define DNS_PACKET_CD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 4) & 1)
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#define DNS_PACKET_RCODE(p) (be16toh(DNS_PACKET_HEADER(p)->flags) & 15)
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/* LLMNR defines some bits differently */
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#define DNS_PACKET_LLMNR_C(p) DNS_PACKET_AA(p)
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#define DNS_PACKET_LLMNR_T(p) DNS_PACKET_RD(p)
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#define DNS_PACKET_QDCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->qdcount)
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#define DNS_PACKET_ANCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->ancount)
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#define DNS_PACKET_NSCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->nscount)
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#define DNS_PACKET_ARCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->arcount)
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#define DNS_PACKET_MAKE_FLAGS(qr, opcode, aa, tc, rd, ra, ad, cd, rcode) \
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(((uint16_t) !!(qr) << 15) | \
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((uint16_t) ((opcode) & 15) << 11) | \
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((uint16_t) !!(aa) << 10) | /* on LLMNR: c */ \
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((uint16_t) !!(tc) << 9) | \
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((uint16_t) !!(rd) << 8) | /* on LLMNR: t */ \
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((uint16_t) !!(ra) << 7) | \
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((uint16_t) !!(ad) << 5) | \
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((uint16_t) !!(cd) << 4) | \
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((uint16_t) ((rcode) & 15)))
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static inline unsigned DNS_PACKET_RRCOUNT(DnsPacket *p) {
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return
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(unsigned) DNS_PACKET_ANCOUNT(p) +
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(unsigned) DNS_PACKET_NSCOUNT(p) +
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(unsigned) DNS_PACKET_ARCOUNT(p);
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}
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int dns_packet_new(DnsPacket **p, DnsProtocol protocol, size_t mtu);
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int dns_packet_new_query(DnsPacket **p, DnsProtocol protocol, size_t mtu, bool dnssec_checking_disabled);
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void dns_packet_set_flags(DnsPacket *p, bool dnssec_checking_disabled, bool truncated);
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DnsPacket *dns_packet_ref(DnsPacket *p);
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DnsPacket *dns_packet_unref(DnsPacket *p);
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DEFINE_TRIVIAL_CLEANUP_FUNC(DnsPacket*, dns_packet_unref);
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int dns_packet_validate(DnsPacket *p);
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int dns_packet_validate_reply(DnsPacket *p);
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int dns_packet_validate_query(DnsPacket *p);
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int dns_packet_is_reply_for(DnsPacket *p, const DnsResourceKey *key);
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int dns_packet_append_blob(DnsPacket *p, const void *d, size_t sz, size_t *start);
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int dns_packet_append_uint8(DnsPacket *p, uint8_t v, size_t *start);
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int dns_packet_append_uint16(DnsPacket *p, uint16_t v, size_t *start);
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int dns_packet_append_uint32(DnsPacket *p, uint32_t v, size_t *start);
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int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start);
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int dns_packet_append_raw_string(DnsPacket *p, const void *s, size_t size, size_t *start);
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int dns_packet_append_label(DnsPacket *p, const char *s, size_t l, bool canonical_candidate, size_t *start);
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int dns_packet_append_name(DnsPacket *p, const char *name, bool allow_compression, bool canonical_candidate, size_t *start);
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int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *key, size_t *start);
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int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start, size_t *rdata_start);
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int dns_packet_append_opt_rr(DnsPacket *p, uint16_t max_udp_size, bool edns0_do, size_t *start);
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void dns_packet_truncate(DnsPacket *p, size_t sz);
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int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start);
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int dns_packet_read_blob(DnsPacket *p, void *d, size_t sz, size_t *start);
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int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start);
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int dns_packet_read_uint16(DnsPacket *p, uint16_t *ret, size_t *start);
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int dns_packet_read_uint32(DnsPacket *p, uint32_t *ret, size_t *start);
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int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start);
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int dns_packet_read_raw_string(DnsPacket *p, const void **ret, size_t *size, size_t *start);
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int dns_packet_read_name(DnsPacket *p, char **ret, bool allow_compression, size_t *start);
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int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, size_t *start);
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int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start);
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void dns_packet_rewind(DnsPacket *p, size_t idx);
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int dns_packet_skip_question(DnsPacket *p);
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int dns_packet_extract(DnsPacket *p);
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static inline bool DNS_PACKET_SHALL_CACHE(DnsPacket *p) {
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/* Never cache data originating from localhost, under the
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* assumption, that it's coming from a locally DNS forwarder
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* or server, that is caching on its own. */
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return in_addr_is_localhost(p->family, &p->sender) == 0;
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}
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enum {
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DNS_RCODE_SUCCESS = 0,
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DNS_RCODE_FORMERR = 1,
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DNS_RCODE_SERVFAIL = 2,
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DNS_RCODE_NXDOMAIN = 3,
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DNS_RCODE_NOTIMP = 4,
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DNS_RCODE_REFUSED = 5,
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DNS_RCODE_YXDOMAIN = 6,
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DNS_RCODE_YXRRSET = 7,
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DNS_RCODE_NXRRSET = 8,
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DNS_RCODE_NOTAUTH = 9,
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DNS_RCODE_NOTZONE = 10,
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DNS_RCODE_BADVERS = 16,
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DNS_RCODE_BADSIG = 16, /* duplicate value! */
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DNS_RCODE_BADKEY = 17,
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DNS_RCODE_BADTIME = 18,
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DNS_RCODE_BADMODE = 19,
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DNS_RCODE_BADNAME = 20,
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DNS_RCODE_BADALG = 21,
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DNS_RCODE_BADTRUNC = 22,
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_DNS_RCODE_MAX_DEFINED
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};
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const char* dns_rcode_to_string(int i) _const_;
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int dns_rcode_from_string(const char *s) _pure_;
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const char* dns_protocol_to_string(DnsProtocol p) _const_;
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DnsProtocol dns_protocol_from_string(const char *s) _pure_;
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#define LLMNR_MULTICAST_IPV4_ADDRESS ((struct in_addr) { .s_addr = htobe32(224U << 24 | 252U) })
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#define LLMNR_MULTICAST_IPV6_ADDRESS ((struct in6_addr) { .s6_addr = { 0xFF, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x03 } })
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#define MDNS_MULTICAST_IPV4_ADDRESS ((struct in_addr) { .s_addr = htobe32(224U << 24 | 251U) })
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#define MDNS_MULTICAST_IPV6_ADDRESS ((struct in6_addr) { .s6_addr = { 0xFF, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0xfb } })
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static inline uint64_t SD_RESOLVED_FLAGS_MAKE(DnsProtocol protocol, int family, bool authenticated) {
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uint64_t f;
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/* Converts a protocol + family into a flags field as used in queries and responses */
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f = authenticated ? SD_RESOLVED_AUTHENTICATED : 0;
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switch (protocol) {
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case DNS_PROTOCOL_DNS:
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return f|SD_RESOLVED_DNS;
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case DNS_PROTOCOL_LLMNR:
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return f|(family == AF_INET6 ? SD_RESOLVED_LLMNR_IPV6 : SD_RESOLVED_LLMNR_IPV4);
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case DNS_PROTOCOL_MDNS:
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return family == AF_INET6 ? SD_RESOLVED_MDNS_IPV6 : SD_RESOLVED_MDNS_IPV4;
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default:
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break;
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}
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return 0;
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}
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