/* * Copyright (c) 2016 Intel Corporation * * SPDX-License-Identifier: Apache-2.0 */ #ifndef _DNS_PACK_H_ #define _DNS_PACK_H_ #include #include #include #include #include /* See RFC 1035, 4.1.1 Header section format * DNS Message Header is always 12 bytes */ #define DNS_MSG_HEADER_SIZE 12 /* This is the label's length octet, see 4.1.2. Question section format */ #define DNS_LABEL_LEN_SIZE 1 #define DNS_POINTER_SIZE 2 #define DNS_LABEL_MIN_SIZE 1 #define DNS_LABEL_MAX_SIZE 63 #define DNS_NAME_MAX_SIZE 255 #define DNS_ANSWER_MIN_SIZE 12 #define DNS_COMMON_UINT_SIZE 2 #define DNS_HEADER_ID_LEN 2 #define DNS_HEADER_FLAGS_LEN 2 #define DNS_QTYPE_LEN 2 #define DNS_QCLASS_LEN 2 #define DNS_QDCOUNT_LEN 2 #define DNS_ANCOUNT_LEN 2 #define DNS_NSCOUNT_LEN 2 #define DNS_ARCOUNT_LEN 2 #define DNS_TTL_LEN 4 #define DNS_RDLENGTH_LEN 2 #define NS_CMPRSFLGS 0xc0 /* DNS name compression */ /* RFC 1035 '4.1.1. Header section format' defines the following flags: * QR, Opcode, AA, TC, RD, RA, Z and RCODE. * This implementation only uses RD (Recursion Desired). */ #define DNS_RECURSION 1 /* These two defines represent the 3rd and 4th bytes of the DNS msg header. * See RFC 1035, 4.1.1. Header section format. */ #define DNS_FLAGS1 DNS_RECURSION /* QR, Opcode, AA, and TC = 0 */ #define DNS_FLAGS2 0 /* RA, Z and RCODE = 0 */ /** * DNS message structure for DNS responses * * Structure that points to the buffer containing the DNS message. It also * contains some decodified message's properties that can not be recovered * easily: * - cname_offset * - query_offset * - answer_offset: * + response_type: It indicates the response's content type. It could be * an IP address, a CNAME with IP (two answers), a CNAME with no IP * address. See enum dns_response_type for more details. * + response_position: this is an offset. It holds the starting byte of * the field containing the desired info. For example an IPv4 address. * + response_length: this is an offset. It holds the response's length. */ struct dns_msg_t { uint8_t *msg; int response_type; uint16_t response_position; uint16_t response_length; uint16_t query_offset; uint16_t answer_offset; uint16_t msg_size; }; #define DNS_MSG_INIT(b, s) {.msg = b, .msg_size = s, \ .response_type = -EINVAL} enum dns_rr_type { DNS_RR_TYPE_INVALID = 0, DNS_RR_TYPE_A = 1, /* IPv4 */ DNS_RR_TYPE_CNAME = 5, /* CNAME */ DNS_RR_TYPE_PTR = 12, /* PTR */ DNS_RR_TYPE_TXT = 16, /* TXT */ DNS_RR_TYPE_AAAA = 28, /* IPv6 */ DNS_RR_TYPE_SRV = 33, /* SRV */ DNS_RR_TYPE_ANY = 0xff, /* ANY (all records) */ }; enum dns_response_type { DNS_RESPONSE_INVALID = -EINVAL, DNS_RESPONSE_IP, DNS_RESPONSE_CNAME_WITH_IP, DNS_RESPONSE_CNAME_NO_IP }; enum dns_class { DNS_CLASS_INVALID = 0, DNS_CLASS_IN, DNS_CLASS_FLUSH = BIT(15) }; enum dns_msg_type { DNS_QUERY = 0, DNS_RESPONSE }; enum dns_header_rcode { DNS_HEADER_NOERROR = 0, DNS_HEADER_FORMATERROR, DNS_HEADER_SERVERFAILURE, DNS_HEADER_NAMEERROR, DNS_HEADER_NOTIMPLEMENTED, DNS_HEADER_REFUSED }; struct dns_header { /** Transaction ID */ uint16_t id; /** * | Name | Bit Position | Width | Description | * |------|--------------|-------|-------------| * | RCODE | 0 | 4 | Response / Error code | * | CD | 4 | 1 | | * | AD | 5 | 1 | Authenticated Data. 0 := Unacceptable, 1 := Acceptable | * | Z | 6 | 1 | Reserved (WZ/RAZ) | * | RA | 7 | 1 | Recursion Available. 0 := Unavailable, 1 := Available | * | RD | 8 | 1 | Recursion Desired. 0 := No Recursion, 1 := Recursion | * | TC | 9 | 1 | 0 := Not Truncated, 1 := Truncated | * | AA | 10 | 1 | Answer Authenticated / Answer Authoritative. 0 := Not Authenticated, 1 := Authenticated| * | Opcode | 11 | 4 | See @ref dns_opcode | * | QR | 15 | 1 | 0 := Query, 1 := Response | */ uint16_t flags; /** Query count */ uint16_t qdcount; /** Answer count */ uint16_t ancount; /** Authority count */ uint16_t nscount; /** Additional information count */ uint16_t arcount; /** Flexible array member for records */ uint8_t data[]; } __packed; struct dns_query { uint16_t type; uint16_t class_; } __packed; struct dns_rr { uint16_t type; uint16_t class_; uint32_t ttl; uint16_t rdlength; uint8_t rdata[]; } __packed; struct dns_srv_rdata { uint16_t priority; uint16_t weight; uint16_t port; } __packed; struct dns_a_rdata { uint32_t address; } __packed; struct dns_aaaa_rdata { uint8_t address[16]; } __packed; /** It returns the ID field in the DNS msg header */ static inline int dns_header_id(uint8_t *header) { return htons(UNALIGNED_GET((uint16_t *)(header))); } /* inline unpack routines are used to unpack data from network * order to cpu. Similar routines without the unpack prefix are * used for cpu to network order. */ static inline int dns_unpack_header_id(uint8_t *header) { return ntohs(UNALIGNED_GET((uint16_t *)(header))); } /** It returns the QR field in the DNS msg header */ static inline int dns_header_qr(uint8_t *header) { return ((*(header + 2)) & 0x80) ? 1 : 0; } /** It returns the OPCODE field in the DNS msg header */ static inline int dns_header_opcode(uint8_t *header) { return ((*(header + 2)) & 0x70) >> 1; } /** It returns the AA field in the DNS msg header */ static inline int dns_header_aa(uint8_t *header) { return ((*(header + 2)) & 0x04) ? 1 : 0; } /** It returns the TC field in the DNS msg header */ static inline int dns_header_tc(uint8_t *header) { return ((*(header + 2)) & 0x02) ? 1 : 0; } /** It returns the RD field in the DNS msg header */ static inline int dns_header_rd(uint8_t *header) { return ((*(header + 2)) & 0x01) ? 1 : 0; } /** It returns the RA field in the DNS msg header */ static inline int dns_header_ra(uint8_t *header) { return ((*(header + 3)) & 0x80) >> 7; } /** It returns the Z field in the DNS msg header */ static inline int dns_header_z(uint8_t *header) { return ((*(header + 3)) & 0x70) >> 4; } /** It returns the RCODE field in the DNS msg header */ static inline int dns_header_rcode(uint8_t *header) { return ((*(header + 3)) & 0x0F); } /** It returns the QDCOUNT field in the DNS msg header */ static inline int dns_header_qdcount(uint8_t *header) { return htons(UNALIGNED_GET((uint16_t *)(header + 4))); } static inline int dns_unpack_header_qdcount(uint8_t *header) { return ntohs(UNALIGNED_GET((uint16_t *)(header + 4))); } /** It returns the ANCOUNT field in the DNS msg header */ static inline int dns_header_ancount(uint8_t *header) { return htons(UNALIGNED_GET((uint16_t *)(header + 6))); } static inline int dns_unpack_header_ancount(uint8_t *header) { return ntohs(UNALIGNED_GET((uint16_t *)(header + 6))); } /** It returns the NSCOUNT field in the DNS msg header */ static inline int dns_header_nscount(uint8_t *header) { return htons(UNALIGNED_GET((uint16_t *)(header + 8))); } /** It returns the ARCOUNT field in the DNS msg header */ static inline int dns_header_arcount(uint8_t *header) { return htons(UNALIGNED_GET((uint16_t *)(header + 10))); } static inline int dns_query_qtype(uint8_t *question) { return htons(UNALIGNED_GET((uint16_t *)(question + 0))); } static inline int dns_unpack_query_qtype(const uint8_t *question) { return ntohs(UNALIGNED_GET((uint16_t *)(question + 0))); } static inline int dns_query_qclass(uint8_t *question) { return htons(UNALIGNED_GET((uint16_t *)(question + 2))); } static inline int dns_unpack_query_qclass(const uint8_t *question) { return ntohs(UNALIGNED_GET((uint16_t *)(question + 2))); } static inline int dns_answer_type(uint16_t dname_size, uint8_t *answer) { /* 4.1.3. Resource record format */ return ntohs(UNALIGNED_GET((uint16_t *)(answer + dname_size + 0))); } static inline int dns_answer_class(uint16_t dname_size, uint8_t *answer) { /* 4.1.3. Resource record format */ return ntohs(UNALIGNED_GET((uint16_t *)(answer + dname_size + 2))); } static inline int dns_answer_ttl(uint16_t dname_size, uint8_t *answer) { return ntohl(UNALIGNED_GET((uint32_t *)(answer + dname_size + 4))); } static inline int dns_answer_rdlength(uint16_t dname_size, uint8_t *answer) { return ntohs(UNALIGNED_GET((uint16_t *)(answer + dname_size + 8))); } /** * @brief Packs a QNAME * * @param len Bytes used by this function * @param buf Buffer * @param sizeof Buffer's size * @param domain_name Something like www.example.com * @retval 0 on success * @retval -ENOMEM if there is no enough space to store the resultant QNAME * @retval -EINVAL if an invalid parameter was passed as an argument */ int dns_msg_pack_qname(uint16_t *len, uint8_t *buf, uint16_t size, const char *domain_name); /** * @brief Unpacks an answer message * * @param dns_msg Structure * @param dname_ptr An index to the previous CNAME. For example for the * first answer, ptr must be 0x0c, the DNAME at the question. * @param ttl TTL answer parameter. * @param type Answer type parameter. * @retval 0 on success * @retval -ENOMEM on error */ int dns_unpack_answer(struct dns_msg_t *dns_msg, int dname_ptr, uint32_t *ttl, enum dns_rr_type *type); /** * @brief Unpacks the header's response. * * @param msg Structure containing the response. * @param src_id Transaction id, it must match the id used in the query * datagram sent to the DNS server. * @retval 0 on success * @retval -ENOMEM if the buffer in msg has no enough space to store the header. * The header is always 12 bytes length. * @retval -EINVAL if the src_id does not match the header's id, or if the * header's QR value is not DNS_RESPONSE or if the header's OPCODE * value is not DNS_QUERY, or if the header's Z value is not 0 or if * the question counter is not 1 or the answer counter is less than 1. * @retval RFC 1035 RCODEs (> 0) 1 Format error, 2 Server failure, 3 Name Error, * 4 Not Implemented and 5 Refused. */ int dns_unpack_response_header(struct dns_msg_t *msg, int src_id); /** * @brief Packs the query message * * @param buf Buffer that will contain the resultant query * @param len Number of bytes used to encode the query * @param size Buffer size * @param qname Domain name represented as a sequence of labels. * See RFC 1035, 4.1.2. Question section format. * @param qname_len Number of octets in qname. * @param id Transaction Identifier * @param qtype Query type: AA, AAAA. See enum dns_rr_type * @retval 0 on success * @retval On error, a negative value is returned. * See: dns_msg_pack_query_header and dns_msg_pack_qname. */ int dns_msg_pack_query(uint8_t *buf, uint16_t *len, uint16_t size, uint8_t *qname, uint16_t qname_len, uint16_t id, enum dns_rr_type qtype); /** * @brief Unpacks the response's query. * * @details RFC 1035 states that the response's query comes after the first * 12 bytes i.e., after the message's header. This function computes * the answer_offset field. * * @param dns_msg Structure containing the message. * @retval 0 on success * @retval -ENOMEM if the null label is not found after traversing the buffer * or if QCLASS and QTYPE are not found. * @retval -EINVAL if QTYPE is not "A" (IPv4) or "AAAA" (IPv6) or if QCLASS * is not "IN". */ int dns_unpack_response_query(struct dns_msg_t *dns_msg); /** * @brief Copies the qname from dns_msg to buf * * @details This routine implements the algorithm described in RFC 1035, 4.1.4. * Message compression to copy the qname (perhaps containing pointers * with offset) to the linear buffer buf. Pointers are removed and * only the "true" labels are copied. * * @param buf Output buffer * @param len Output buffer's length * @param size Output buffer's size * @param dns_msg Structure containing the message * @param pos QNAME's position in dns_msg->msg * @retval 0 on success * @retval -EINVAL if an invalid parameter was passed as an argument * @retval -ENOMEM if the label's size is corrupted */ int dns_copy_qname(uint8_t *buf, uint16_t *len, uint16_t size, struct dns_msg_t *dns_msg, uint16_t pos); /** * @brief Unpacks the mDNS query. This is special version for multicast DNS * as it skips checks to various fields as described in RFC 6762 * chapter 18. * * @param msg Structure containing the response. * @param src_id Transaction id, this is returned to the caller. * @retval 0 on success, <0 if error * @retval -ENOMEM if the buffer in msg has no enough space to store the header. * The header is always 12 bytes length. * @retval -EINVAL if the src_id does not match the header's id, or if the * header's QR value is not DNS_RESPONSE or if the header's OPCODE * value is not DNS_QUERY, or if the header's Z value is not 0 or if * the question counter is not 1 or the answer counter is less than 1. * @retval RFC 1035 RCODEs (> 0) 1 Format error, 2 Server failure, 3 Name Error, * 4 Not Implemented and 5 Refused. */ int mdns_unpack_query_header(struct dns_msg_t *msg, uint16_t *src_id); static inline int llmnr_unpack_query_header(struct dns_msg_t *msg, uint16_t *src_id) { return mdns_unpack_query_header(msg, src_id); } /** * @brief Unpacks the query. * * @param dns_msg Structure containing the message. * @param buf Result buf * @param qtype Query type is returned to caller * @param qclass Query class is returned to caller * @retval 0 on success * @retval -ENOMEM if the null label is not found after traversing the buffer * or if QCLASS and QTYPE are not found. * @retval -EINVAL if QTYPE is not "A" (IPv4) or "AAAA" (IPv6) or if QCLASS * is not "IN". */ int dns_unpack_query(struct dns_msg_t *dns_msg, struct net_buf *buf, enum dns_rr_type *qtype, enum dns_class *qclass); /** * @brief Map query type number to a string. * * @param qtype Query type * * @return Printable query type name. */ const char *dns_qtype_to_str(enum dns_rr_type qtype); #endif