| #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 <http://www.gnu.org/licenses/>. |
| ***/ |
| |
| #include <netinet/ip.h> |
| #include <netinet/udp.h> |
| |
| #include "hashmap.h" |
| #include "in-addr-util.h" |
| #include "macro.h" |
| #include "sparse-endian.h" |
| |
| typedef struct DnsPacketHeader DnsPacketHeader; |
| typedef struct DnsPacket DnsPacket; |
| |
| #include "resolved-def.h" |
| #include "resolved-dns-answer.h" |
| #include "resolved-dns-question.h" |
| #include "resolved-dns-rr.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) |
| #define UDP_PACKET_HEADER_SIZE (sizeof(struct iphdr) + sizeof(struct udphdr)) |
| |
| /* 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 |
| |
| /* With EDNS0 we can use larger packets, default to 4096, which is what is commonly used */ |
| #define DNS_PACKET_UNICAST_SIZE_LARGE_MAX 4096 |
| |
| #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 */ |
| size_t opt_start, opt_size; |
| |
| /* Parsed data */ |
| DnsQuestion *question; |
| DnsAnswer *answer; |
| DnsResourceRecord *opt; |
| |
| /* Packet reception metadata */ |
| int ifindex; |
| int family, ipproto; |
| union in_addr_union sender, destination; |
| uint16_t sender_port, destination_port; |
| uint32_t ttl; |
| |
| /* For support of truncated packets */ |
| DnsPacket *more; |
| |
| bool on_stack:1; |
| bool extracted:1; |
| bool refuse_compression:1; |
| bool canonical_form:1; |
| }; |
| |
| 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_AA(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 10) & 1) |
| #define DNS_PACKET_TC(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 9) & 1) |
| #define DNS_PACKET_RD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 8) & 1) |
| #define DNS_PACKET_RA(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 7) & 1) |
| #define DNS_PACKET_AD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 5) & 1) |
| #define DNS_PACKET_CD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 4) & 1) |
| |
| #define DNS_PACKET_FLAG_TC (UINT16_C(1) << 9) |
| |
| static inline uint16_t DNS_PACKET_RCODE(DnsPacket *p) { |
| uint16_t rcode; |
| |
| if (p->opt) |
| rcode = (uint16_t) (p->opt->ttl >> 24); |
| else |
| rcode = 0; |
| |
| return rcode | (be16toh(DNS_PACKET_HEADER(p)->flags) & 0xF); |
| } |
| |
| static inline uint16_t DNS_PACKET_PAYLOAD_SIZE_MAX(DnsPacket *p) { |
| |
| /* Returns the advertised maximum datagram size for replies, or the DNS default if there's nothing defined. */ |
| |
| if (p->opt) |
| return MAX(DNS_PACKET_UNICAST_SIZE_MAX, p->opt->key->class); |
| |
| return DNS_PACKET_UNICAST_SIZE_MAX; |
| } |
| |
| static inline bool DNS_PACKET_DO(DnsPacket *p) { |
| if (!p->opt) |
| return false; |
| |
| return !!(p->opt->ttl & (1U << 15)); |
| } |
| |
| static inline bool DNS_PACKET_VERSION_SUPPORTED(DnsPacket *p) { |
| /* Returns true if this packet is in a version we support. Which means either non-EDNS or EDNS(0), but not EDNS |
| * of any newer versions */ |
| |
| if (!p->opt) |
| return true; |
| |
| return DNS_RESOURCE_RECORD_OPT_VERSION_SUPPORTED(p->opt); |
| } |
| |
| /* LLMNR defines some bits differently */ |
| #define DNS_PACKET_LLMNR_C(p) DNS_PACKET_AA(p) |
| #define DNS_PACKET_LLMNR_T(p) DNS_PACKET_RD(p) |
| |
| #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) | /* on LLMNR: c */ \ |
| ((uint16_t) !!(tc) << 9) | \ |
| ((uint16_t) !!(rd) << 8) | /* on LLMNR: t */ \ |
| ((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, bool dnssec_checking_disabled); |
| |
| void dns_packet_set_flags(DnsPacket *p, bool dnssec_checking_disabled, bool truncated); |
| |
| 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_validate_query(DnsPacket *p); |
| |
| int dns_packet_is_reply_for(DnsPacket *p, const DnsResourceKey *key); |
| |
| int dns_packet_append_blob(DnsPacket *p, const void *d, size_t sz, size_t *start); |
| 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_uint32(DnsPacket *p, uint32_t v, size_t *start); |
| int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start); |
| int dns_packet_append_raw_string(DnsPacket *p, const void *s, size_t size, size_t *start); |
| int dns_packet_append_label(DnsPacket *p, const char *s, size_t l, bool canonical_candidate, size_t *start); |
| int dns_packet_append_name(DnsPacket *p, const char *name, bool allow_compression, bool canonical_candidate, size_t *start); |
| int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *key, const DnsAnswerFlags flags, size_t *start); |
| int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, const DnsAnswerFlags flags, size_t *start, size_t *rdata_start); |
| int dns_packet_append_opt(DnsPacket *p, uint16_t max_udp_size, bool edns0_do, int rcode, size_t *start); |
| int dns_packet_append_question(DnsPacket *p, DnsQuestion *q); |
| int dns_packet_append_answer(DnsPacket *p, DnsAnswer *a); |
| |
| void dns_packet_truncate(DnsPacket *p, size_t sz); |
| int dns_packet_truncate_opt(DnsPacket *p); |
| |
| int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start); |
| int dns_packet_read_blob(DnsPacket *p, void *d, size_t sz, 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_raw_string(DnsPacket *p, const void **ret, size_t *size, size_t *start); |
| int dns_packet_read_name(DnsPacket *p, char **ret, bool allow_compression, size_t *start); |
| int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, bool *ret_cache_flush, size_t *start); |
| int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, bool *ret_cache_flush, 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); |
| |
| static inline bool DNS_PACKET_SHALL_CACHE(DnsPacket *p) { |
| /* Never cache data originating from localhost, under the |
| * assumption, that it's coming from a locally DNS forwarder |
| * or server, that is caching on its own. */ |
| |
| return in_addr_is_localhost(p->family, &p->sender) == 0; |
| } |
| |
| /* https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-6 */ |
| 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_BADCOOKIE = 23, |
| _DNS_RCODE_MAX_DEFINED, |
| _DNS_RCODE_MAX = 4095 /* 4 bit rcode in the header plus 8 bit rcode in OPT, makes 12 bit */ |
| }; |
| |
| 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 } }) |
| |
| #define MDNS_MULTICAST_IPV4_ADDRESS ((struct in_addr) { .s_addr = htobe32(224U << 24 | 251U) }) |
| #define MDNS_MULTICAST_IPV6_ADDRESS ((struct in6_addr) { .s6_addr = { 0xFF, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xfb } }) |
| |
| static inline uint64_t SD_RESOLVED_FLAGS_MAKE(DnsProtocol protocol, int family, bool authenticated) { |
| uint64_t f; |
| |
| /* Converts a protocol + family into a flags field as used in queries and responses */ |
| |
| f = authenticated ? SD_RESOLVED_AUTHENTICATED : 0; |
| |
| switch (protocol) { |
| case DNS_PROTOCOL_DNS: |
| return f|SD_RESOLVED_DNS; |
| |
| case DNS_PROTOCOL_LLMNR: |
| return f|(family == AF_INET6 ? SD_RESOLVED_LLMNR_IPV6 : SD_RESOLVED_LLMNR_IPV4); |
| |
| case DNS_PROTOCOL_MDNS: |
| return f|(family == AF_INET6 ? SD_RESOLVED_MDNS_IPV6 : SD_RESOLVED_MDNS_IPV4); |
| |
| default: |
| return f; |
| } |
| } |