diff options
Diffstat (limited to 'src/grp-resolve/libbasic-dns/resolved-dns-packet.h')
| -rw-r--r-- | src/grp-resolve/libbasic-dns/resolved-dns-packet.h | 270 |
1 files changed, 270 insertions, 0 deletions
diff --git a/src/grp-resolve/libbasic-dns/resolved-dns-packet.h b/src/grp-resolve/libbasic-dns/resolved-dns-packet.h new file mode 100644 index 0000000000..416335d0a2 --- /dev/null +++ b/src/grp-resolve/libbasic-dns/resolved-dns-packet.h @@ -0,0 +1,270 @@ +#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) + +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) & 15); +} + +/* 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, size_t *start); +int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start, size_t *rdata_start); +int dns_packet_append_opt(DnsPacket *p, uint16_t max_udp_size, bool edns0_do, size_t *start); + +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_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 } }) + +#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; + } +} |