/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ #pragma once /*** This file is part of systemd. Copyright 2014 Lennart Poettering systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see . ***/ typedef struct DnsPacketHeader DnsPacketHeader; typedef struct DnsPacket DnsPacket; #include #include "macro.h" #include "sparse-endian.h" #include "hashmap.h" #include "resolved-dns-rr.h" #include "resolved-dns-question.h" #include "resolved-dns-answer.h" typedef enum DnsProtocol { DNS_PROTOCOL_DNS, DNS_PROTOCOL_MDNS, DNS_PROTOCOL_LLMNR, _DNS_PROTOCOL_MAX, _DNS_PROTOCOL_INVALID = -1 } DnsProtocol; struct DnsPacketHeader { uint16_t id; be16_t flags; be16_t qdcount; be16_t ancount; be16_t nscount; be16_t arcount; }; #define DNS_PACKET_HEADER_SIZE sizeof(DnsPacketHeader) /* The various DNS protocols deviate in how large a packet can grow, but the TCP transport has a 16bit size field, hence that appears to be the absolute maximum. */ #define DNS_PACKET_SIZE_MAX 0xFFFF /* RFC 1035 say 512 is the maximum, for classic unicast DNS */ #define DNS_PACKET_UNICAST_SIZE_MAX 512 #define DNS_PACKET_SIZE_START 512 struct DnsPacket { int n_ref; DnsProtocol protocol; size_t size, allocated, rindex; void *_data; /* don't access directly, use DNS_PACKET_DATA()! */ Hashmap *names; /* For name compression */ /* Parsed data */ DnsQuestion *question; DnsAnswer *answer; /* Packet reception meta data */ int ifindex; int family; union in_addr_union sender, destination; uint32_t ttl; }; static inline uint8_t* DNS_PACKET_DATA(DnsPacket *p) { if (_unlikely_(!p)) return NULL; if (p->_data) return p->_data; return ((uint8_t*) p) + ALIGN(sizeof(DnsPacket)); } #define DNS_PACKET_HEADER(p) ((DnsPacketHeader*) DNS_PACKET_DATA(p)) #define DNS_PACKET_ID(p) DNS_PACKET_HEADER(p)->id #define DNS_PACKET_QR(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 15) & 1) #define DNS_PACKET_OPCODE(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 11) & 15) #define DNS_PACKET_RCODE(p) (be16toh(DNS_PACKET_HEADER(p)->flags) & 15) #define DNS_PACKET_TC(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 9) & 1) #define DNS_PACKET_QDCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->qdcount) #define DNS_PACKET_ANCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->ancount) #define DNS_PACKET_NSCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->nscount) #define DNS_PACKET_ARCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->arcount) #define DNS_PACKET_MAKE_FLAGS(qr, opcode, aa, tc, rd, ra, ad, cd, rcode) \ (((uint16_t) !!qr << 15) | \ ((uint16_t) (opcode & 15) << 11) | \ ((uint16_t) !!aa << 10) | \ ((uint16_t) !!tc << 9) | \ ((uint16_t) !!rd << 8) | \ ((uint16_t) !!ra << 7) | \ ((uint16_t) !!ad << 5) | \ ((uint16_t) !!cd << 4) | \ ((uint16_t) (rcode & 15))) static inline unsigned DNS_PACKET_RRCOUNT(DnsPacket *p) { return (unsigned) DNS_PACKET_ANCOUNT(p) + (unsigned) DNS_PACKET_NSCOUNT(p) + (unsigned) DNS_PACKET_ARCOUNT(p); } int dns_packet_new(DnsPacket **p, DnsProtocol protocol, size_t mtu); int dns_packet_new_query(DnsPacket **p, DnsProtocol protocol, size_t mtu); DnsPacket *dns_packet_ref(DnsPacket *p); DnsPacket *dns_packet_unref(DnsPacket *p); DEFINE_TRIVIAL_CLEANUP_FUNC(DnsPacket*, dns_packet_unref); int dns_packet_validate(DnsPacket *p); int dns_packet_validate_reply(DnsPacket *p); int dns_packet_append_uint8(DnsPacket *p, uint8_t v, size_t *start); int dns_packet_append_uint16(DnsPacket *p, uint16_t v, size_t *start); int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start); int dns_packet_append_label(DnsPacket *p, const char *s, size_t l, size_t *start); int dns_packet_append_name(DnsPacket *p, const char *name, size_t *start); int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *k, size_t *start); int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start); int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start); int dns_packet_read_uint16(DnsPacket *p, uint16_t *ret, size_t *start); int dns_packet_read_uint32(DnsPacket *p, uint32_t *ret, size_t *start); int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start); int dns_packet_read_name(DnsPacket *p, char **ret, size_t *start); int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, size_t *start); int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start); void dns_packet_rewind(DnsPacket *p, size_t idx); int dns_packet_skip_question(DnsPacket *p); int dns_packet_extract(DnsPacket *p); enum { DNS_RCODE_SUCCESS = 0, DNS_RCODE_FORMERR = 1, DNS_RCODE_SERVFAIL = 2, DNS_RCODE_NXDOMAIN = 3, DNS_RCODE_NOTIMP = 4, DNS_RCODE_REFUSED = 5, DNS_RCODE_YXDOMAIN = 6, DNS_RCODE_YXRRSET = 7, DNS_RCODE_NXRRSET = 8, DNS_RCODE_NOTAUTH = 9, DNS_RCODE_NOTZONE = 10, DNS_RCODE_BADVERS = 16, DNS_RCODE_BADSIG = 16, /* duplicate value! */ DNS_RCODE_BADKEY = 17, DNS_RCODE_BADTIME = 18, DNS_RCODE_BADMODE = 19, DNS_RCODE_BADNAME = 20, DNS_RCODE_BADALG = 21, DNS_RCODE_BADTRUNC = 22, _DNS_RCODE_MAX_DEFINED }; const char* dns_rcode_to_string(int i) _const_; int dns_rcode_from_string(const char *s) _pure_; const char* dns_protocol_to_string(DnsProtocol p) _const_; DnsProtocol dns_protocol_from_string(const char *s) _pure_; #define LLMNR_MULTICAST_IPV4_ADDRESS ((struct in_addr) { .s_addr = htobe32(224U << 24 | 252U) }) #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 } })