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Diffstat (limited to 'src/libknot/packet/pkt.h')
| -rw-r--r-- | src/libknot/packet/pkt.h | 419 |
1 files changed, 419 insertions, 0 deletions
diff --git a/src/libknot/packet/pkt.h b/src/libknot/packet/pkt.h new file mode 100644 index 0000000..383f55e --- /dev/null +++ b/src/libknot/packet/pkt.h @@ -0,0 +1,419 @@ +/* Copyright (C) 2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz> + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + This program 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 General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <https://www.gnu.org/licenses/>. + */ + +/*! + * \file + * + * \brief Structure for holding DNS packet data and metadata. + * + * \addtogroup pkt + * @{ + */ + +#pragma once + +#include <assert.h> +#include <stdint.h> + +#include "libknot/consts.h" +#include "libknot/dname.h" +#include "libknot/mm_ctx.h" +#include "libknot/rrset.h" +#include "libknot/rrtype/opt.h" +#include "libknot/packet/wire.h" +#include "libknot/packet/compr.h" +#include "libknot/wire.h" + +/* Number of packet sections (ANSWER, AUTHORITY, ADDITIONAL). */ +#define KNOT_PKT_SECTIONS 3 + +/*! + * \brief Packet flags. + */ +enum { + KNOT_PF_NULL = 0 << 0, /*!< No flags. */ + KNOT_PF_FREE = 1 << 1, /*!< Free with packet. */ + KNOT_PF_NOTRUNC = 1 << 2, /*!< Don't truncate. */ + KNOT_PF_CHECKDUP = 1 << 3, /*!< Check for duplicates. */ + KNOT_PF_KEEPWIRE = 1 << 4, /*!< Keep wireformat untouched when parsing. */ + KNOT_PF_NOCANON = 1 << 5, /*!< Don't canonicalize rrsets during parsing. */ + KNOT_PF_ORIGTTL = 1 << 6, /*!< Write RRSIGs with their original TTL. */ + KNOT_PF_SOAMINTTL = 1 << 7, /*!< Write SOA with its minimum-ttl as TTL. */ + KNOT_PF_BUFENOUGH = 1 << 8, /*!< The output buffer is big enough for the output. */ +}; + +typedef struct knot_pkt knot_pkt_t; + +/*! + * \brief Packet section. + * Points to RRSet and RRSet info arrays in the packet. + * This structure is required for random access to packet sections. + */ +typedef struct { + knot_pkt_t *pkt; /*!< Owner. */ + uint16_t pos; /*!< Position in the rr/rrinfo fields in packet. */ + uint16_t count; /*!< Number of RRSets in this section. */ +} knot_pktsection_t; + +/*! + * \brief Structure representing a DNS packet. + */ +struct knot_pkt { + uint8_t *wire; /*!< Wire format of the packet. */ + size_t size; /*!< Current wire size of the packet. */ + size_t max_size; /*!< Maximum allowed size of the packet. */ + size_t parsed; /*!< Parsed size. */ + uint16_t reserved; /*!< Reserved space. */ + uint16_t qname_size; /*!< QNAME size. */ + uint16_t rrset_count; /*!< Packet RRSet count. */ + uint16_t flags; /*!< Packet flags. */ + + knot_rrset_t *opt_rr; /*!< OPT RR included in the packet. */ + knot_rrset_t *tsig_rr; /*!< TSIG RR stored in the packet. */ + + /*! EDNS option positions in the wire (if parsed from wire). */ + knot_edns_options_t *edns_opts; + + /*! TSIG RR position in the wire (if parsed from wire). */ + struct { + uint8_t *pos; + size_t len; + } tsig_wire; + + /* Packet sections. */ + knot_section_t current; + knot_pktsection_t sections[KNOT_PKT_SECTIONS]; + + /* Packet RRSet (meta)data. */ + size_t rrset_allocd; + knot_rrinfo_t *rr_info; + knot_rrset_t *rr; + + knot_mm_t mm; /*!< Memory allocation context. */ + + knot_compr_t compr; /*!< Compression context. */ + + /*! Lowercased QNAME. MUST BE LAST ITEM! */ + knot_dname_storage_t lower_qname; +}; + +/*! + * \brief Create new packet over existing memory, or allocate new from memory context. + * + * \note Packet is allocated from given memory context. + * + * \param wire If NULL, memory of 'len' size shall be allocated. + * Otherwise pointer is used for the wire format of the packet. + * \param len Wire format length. + * \param mm Memory context (NULL for default). + * \return New packet or NULL. + */ +knot_pkt_t *knot_pkt_new(void *wire, uint16_t len, knot_mm_t *mm); + +/*! + * \brief Copy packet. + * + * \note Current implementation is not very efficient, as it re-parses the wire. + * + * \param dst Target packet. + * \param src Source packet. + * + * \return new packet or NULL + */ +int knot_pkt_copy(knot_pkt_t *dst, const knot_pkt_t *src); + +/*! + * \brief Initialized response from query packet. + * + * \note Question is not checked, it is expected to be checked already. + * + * \param pkt Given packet. + * \param query Query. + * \return KNOT_EOK, KNOT_EINVAL, KNOT_ESPACE + */ +int knot_pkt_init_response(knot_pkt_t *pkt, const knot_pkt_t *query); + +/*! \brief Reinitialize packet for another use. */ +void knot_pkt_clear(knot_pkt_t *pkt); + +/*! \brief Begone you foul creature of the underworld. */ +void knot_pkt_free(knot_pkt_t *pkt); + +/*! + * \brief Reserve an arbitrary amount of space in the packet. + * + * \return KNOT_EOK + * \return KNOT_ERANGE if size can't be reserved + */ +int knot_pkt_reserve(knot_pkt_t *pkt, uint16_t size); + +/*! + * \brief Reclaim reserved size. + * + * \return KNOT_EOK + * \return KNOT_ERANGE if size can't be reclaimed + */ +int knot_pkt_reclaim(knot_pkt_t *pkt, uint16_t size); + +/* + * Packet QUESTION accessors. + */ +static inline uint16_t knot_pkt_question_size(const knot_pkt_t *pkt) +{ + if (pkt == NULL || pkt->qname_size == 0) { + return 0; + } + + return pkt->qname_size + 2 * sizeof(uint16_t); +} + +static inline const knot_dname_t *knot_pkt_qname(const knot_pkt_t *pkt) +{ + if (pkt == NULL || pkt->qname_size == 0) { + return NULL; + } + + return pkt->lower_qname; +} + +static inline const knot_dname_t *knot_pkt_wire_qname(const knot_pkt_t *pkt) +{ + if (pkt == NULL || pkt->qname_size == 0) { + return NULL; + } + + return pkt->wire + KNOT_WIRE_HEADER_SIZE; +} + +static inline uint16_t knot_pkt_qtype(const knot_pkt_t *pkt) +{ + if (pkt == NULL || pkt->qname_size == 0) { + return 0; + } + + unsigned off = KNOT_WIRE_HEADER_SIZE + pkt->qname_size; + return knot_wire_read_u16(pkt->wire + off); +} + +static inline uint16_t knot_pkt_qclass(const knot_pkt_t *pkt) +{ + if (pkt == NULL || pkt->qname_size == 0) { + return 0; + } + + unsigned off = KNOT_WIRE_HEADER_SIZE + pkt->qname_size + sizeof(uint16_t); + return knot_wire_read_u16(pkt->wire + off); +} + +/* + * Packet writing API. + */ + +/*! + * \brief Begin reading/writing packet section. + * + * \note You must proceed in the natural order (ANSWER, AUTHORITY, ADDITIONAL). + * + * \param pkt + * \param section_id + * \return KNOT_EOK or KNOT_EINVAL + */ +int knot_pkt_begin(knot_pkt_t *pkt, knot_section_t section_id); + +/*! + * \brief Put QUESTION in the packet. + * + * \note Since we support QD=1 only, QUESTION is a special type of packet section. + * \note Must not be used after putting RRsets into the packet. + * + * \param pkt + * \param qname + * \param qclass + * \param qtype + * \return KNOT_EOK or various errors + */ +int knot_pkt_put_question(knot_pkt_t *pkt, const knot_dname_t *qname, + uint16_t qclass, uint16_t qtype); + +/*! + * \brief Put RRSet into packet. + * + * \note See compr.h for description on how compression hints work. + * \note Available flags: PF_FREE, KNOT_PF_CHECKDUP, KNOT_PF_NOTRUNC + * + * \param pkt + * \param compr_hint Compression hint, see enum knot_compr_hint or absolute + * position. + * \param rr Given RRSet. + * \param rotate Rotate the RRSet order by this count. + * \param flags RRSet flags (set PF_FREE if you want RRSet to be freed + * with the packet). + * + * \return KNOT_EOK, KNOT_ESPACE, various errors + */ +int knot_pkt_put_rotate(knot_pkt_t *pkt, uint16_t compr_hint, const knot_rrset_t *rr, + uint16_t rotate, uint16_t flags); + +/*! \brief Same as knot_pkt_put_rotate but without rrset rotation. */ +static inline int knot_pkt_put(knot_pkt_t *pkt, uint16_t compr_hint, + const knot_rrset_t *rr, uint16_t flags) +{ + return knot_pkt_put_rotate(pkt, compr_hint, rr, 0, flags); +} + +/*! \brief Get description of the given packet section. */ +static inline const knot_pktsection_t *knot_pkt_section(const knot_pkt_t *pkt, + knot_section_t section_id) +{ + assert(pkt); + return &pkt->sections[section_id]; +} + +/*! \brief Get RRSet from the packet section. */ +static inline const knot_rrset_t *knot_pkt_rr(const knot_pktsection_t *section, + uint16_t i) +{ + assert(section); + return section->pkt->rr + section->pos + i; +} + +/*! \brief Get RRSet offset in the packet wire. */ +static inline uint16_t knot_pkt_rr_offset(const knot_pktsection_t *section, + uint16_t i) +{ + assert(section); + return section->pkt->rr_info[section->pos + i].pos; +} + +/* + * Packet parsing API. + */ + +/*! + * \brief Parse both packet question and payload. + * + * Parses both QUESTION and all packet sections, + * includes semantic checks over specific RRs (TSIG, OPT). + * + * \note If KNOT_PF_KEEPWIRE is set, TSIG RR is not stripped from the wire + * and is processed as any other RR. + * + * \param pkt Given packet. + * \param flags Parsing flags (allowed KNOT_PF_KEEPWIRE) + * + * \retval KNOT_EOK if success. + * \retval KNOT_ETRAIL if success but with some trailing data. + * \retval KNOT_EMALF and other errors. + */ +int knot_pkt_parse(knot_pkt_t *pkt, unsigned flags); + +/*! + * \brief Parse packet header and a QUESTION section. + */ +int knot_pkt_parse_question(knot_pkt_t *pkt); + +/*! + * \brief Get packet extended RCODE. + * + * Extended RCODE is created by considering TSIG RCODE, EDNS RCODE and + * DNS Header RCODE. (See RFC 6895, Section 2.3). + * + * \param pkt Packet to get the response code from. + * + * \return Whole extended RCODE (0 if pkt == NULL). + */ +uint16_t knot_pkt_ext_rcode(const knot_pkt_t *pkt); + +/*! + * \brief Get packet extended RCODE name. + * + * The packet parameter is important as the name depends on TSIG. + * + * \param pkt Packet to get the response code from. + * + * \return RCODE name (or empty string if not known). + */ +const char *knot_pkt_ext_rcode_name(const knot_pkt_t *pkt); + +/*! + * \brief Checks if there is an OPT RR in the packet. + */ +static inline bool knot_pkt_has_edns(const knot_pkt_t *pkt) +{ + assert(pkt); + return pkt->opt_rr != NULL; +} + +/*! + * \brief Checks if TSIG is present. + */ +static inline bool knot_pkt_has_tsig(const knot_pkt_t *pkt) +{ + assert(pkt); + return pkt->tsig_rr != NULL; +} + +/*! + * \brief Checks if DO bit is set in the packet's OPT RR. + */ +static inline bool knot_pkt_has_dnssec(const knot_pkt_t *pkt) +{ + assert(pkt); + return knot_pkt_has_edns(pkt) && knot_edns_do(pkt->opt_rr); +} + +/*! + * \brief Get specific EDNS option from a parsed packet. + */ +static inline uint8_t *knot_pkt_edns_option(const knot_pkt_t *pkt, uint16_t code) +{ + assert(pkt); + if (pkt->edns_opts != NULL && code <= KNOT_EDNS_MAX_OPTION_CODE) { + return pkt->edns_opts->ptr[code]; + } else { + return NULL; + } +} + +/*! + * \brief Computes a reasonable Padding data length for a given packet and opt RR. + * + * \param pkt DNS Packet prepared and otherwise ready to go, no OPT yet added. + * \param opt_rr OPT RR, not yet including padding. + * + * \return Required padding length or -1 if padding not required. + */ +static inline int knot_pkt_default_padding_size(const knot_pkt_t *pkt, + const knot_rrset_t *opt_rr) +{ + if (knot_wire_get_qr(pkt->wire)) { + return knot_edns_alignment_size(pkt->size + pkt->reserved, + knot_rrset_size(opt_rr), + KNOT_EDNS_ALIGNMENT_RESPONSE_DEFAULT); + } else { + return knot_edns_alignment_size(pkt->size + pkt->reserved, + knot_rrset_size(opt_rr), + KNOT_EDNS_ALIGNMENT_QUERY_DEFAULT); + } +} + +static inline size_t knot_pkt_size(const knot_pkt_t *pkt) +{ + assert(pkt); + return pkt->size + (knot_pkt_has_tsig(pkt) ? pkt->tsig_wire.len : 0); +} + +/*! @} */ |