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/*!
* \file response.h
*
* \author Lubos Slovak <lubos.slovak@nic.cz>
*
* \brief API for response manipulation.
*
* \addtogroup libknot
* @{
*/
/* Copyright (C) 2011 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 <http://www.gnu.org/licenses/>.
*/
#ifndef _KNOT_RESPONSE_H_
#define _KNOT_RESPONSE_H_
#include <stdint.h>
#include <string.h>
#include "libknot/packet/packet.h"
#include "libknot/dname.h"
#include "libknot/rrset.h"
#include "libknot/edns.h"
/*!
* \brief Holds information about compressed domain name.
*
* Used only to pass information between functions.
*
* \todo This description should be revised and clarified.
*/
struct knot_compr_owner {
/*!
* \brief Place where the name is stored in the wire format of the
* packet.
*/
uint8_t *wire;
uint8_t size; /*!< Size of the domain name in bytes. */
/*! \brief Position of the name relative to the start of the packet. */
size_t pos;
};
typedef struct knot_compr_owner knot_compr_owner_t;
/*!
* \brief Holds information about compressed domain names in packet.
*
* Used only to pass information between functions.
*
* \todo This description should be revised and clarified.
*/
struct knot_compr {
knot_compr_ptr_t *table; /*!< Compression table. */
uint8_t *wire;
size_t wire_pos; /*!< Current position in the wire format. */
knot_compr_owner_t owner; /*!< Information about the current name. */
};
typedef struct knot_compr knot_compr_t;
struct compression_param {
uint8_t *wire;
size_t wire_pos;
knot_compr_ptr_t *compressed_dnames;
};
typedef struct compression_param compression_param_t;
/*!
* \brief Default maximum DNS response size
*
* This size must be supported by all servers and clients.
*/
static const short KNOT_MAX_RESPONSE_SIZE = 512;
/*----------------------------------------------------------------------------*/
int knot_response_init(knot_packet_t *response);
/*!
* \brief Initializes response from the given query.
*
* Copies the header, Changes QR bit to 1, copies the Question section and
* stores pointer to the query packet structure in the response packet
* structure.
*
* \warning Never free the query packet structure after calling this function,
* it will be freed when the response structure is freed.
*
* \param response Packet structure representing the response.
* \param query Packet structure representing the query.
*
* \retval KNOT_EOK
*/
int knot_response_init_from_query(knot_packet_t *response, knot_packet_t *query);
/*!
* \brief Clears the response structure for reuse.
*
* After call to this function, the response will be in the same state as if
* knot_response_new() was called. The maximum wire size is retained.
*
* \param response Response structure to clear.
*
* \todo Replace the use of this function with something else maybe?
*/
void knot_response_clear(knot_packet_t *resp);
/*!
* \brief Sets the OPT RR of the response.
*
* This function also allocates space for the wireformat of the response, if
* the payload in the OPT RR is larger than the current maximum size of the
* response and copies the current wireformat over to the new space.
*
* \note The contents of the OPT RR are copied.
*
* \note It is expected that resp.max_size is already set to correct value as
* it is impossible to distinguish TCP scenario in this function.
*
* \param resp Response to set the OPT RR to.
* \param opt_rr OPT RR to set.
*
* \retval KNOT_EOK
* \retval KNOT_EINVAL
* \retval KNOT_ENOMEM
*
* \todo Needs test.
*/
int knot_response_add_opt(knot_packet_t *resp,
const knot_opt_rr_t *opt_rr,
int add_nsid);
/*!
* \brief Adds a RRSet to the Answer section of the response.
*
* \param response Response to add the RRSet into.
* \param rrset RRSet to be added.
* \param tc Set to <> 0 if omitting this RRSet should result in the TC bit set.
* Otherwise set to 0.
* \param check_duplicates Set to <> 0 if the RRSet should not be added to the
* response in case it is already there.
*
* \retval KNOT_EOK if successful, or the RRSet was already in the answer.
* \retval KNOT_ENOMEM
* \retval KNOT_ESPACE
*/
int knot_response_add_rrset_answer(knot_packet_t *response,
knot_rrset_t *rrset, uint32_t flags);
/*!
* \brief Adds a RRSet to the Authority section of the response.
*
* \param response Response to add the RRSet into.
* \param rrset RRSet to be added.
* \param tc Set to <> 0 if omitting this RRSet should result in the TC bit set.
* Otherwise set to 0.
* \param check_duplicates Set to <> 0 if the RRSet should not be added to the
* response in case it is already there.
*
* \retval KNOT_EOK if successful, or the RRSet was already in the answer.
* \retval KNOT_ENOMEM
* \retval KNOT_ESPACE
*/
int knot_response_add_rrset_authority(knot_packet_t *response,
knot_rrset_t *rrset, uint32_t flags);
/*!
* \brief Adds a RRSet to the Additional section of the response.
*
* \param response Response to add the RRSet into.
* \param rrset RRSet to be added.
* \param tc Set to <> 0 if omitting this RRSet should result in the TC bit set.
* Otherwise set to 0.
* \param check_duplicates Set to <> 0 if the RRSet should not be added to the
* response in case it is already there.
*
* \retval KNOT_EOK if successful, or the RRSet was already in the answer.
* \retval KNOT_ENOMEM
* \retval KNOT_ESPACE
*/
int knot_response_add_rrset_additional(knot_packet_t *response,
knot_rrset_t *rrset, uint32_t flags);
/*!
* \brief Sets the RCODE of the response.
*
* \param response Response to set the RCODE in.
* \param rcode RCODE to set.
*/
void knot_response_set_rcode(knot_packet_t *response, short rcode);
/*!
* \brief Sets the AA bit of the response to 1.
*
* \param response Response in which the AA bit should be set.
*/
void knot_response_set_aa(knot_packet_t *response);
/*!
* \brief Sets the TC bit of the response to 1.
*
* \param response Response in which the TC bit should be set.
*/
void knot_response_set_tc(knot_packet_t *response);
/*!
* \brief Adds NSID option to the response.
*
* \param response Response to add the NSID option into.
* \param data NSID data.
* \param length Size of NSID data in bytes.
*
* \retval KNOT_EOK
* \retval KNOT_ENOMEM
*/
int knot_response_add_nsid(knot_packet_t *response, const uint8_t *data,
uint16_t length);
int knot_response_add_wildcard_node(knot_packet_t *response,
const knot_node_t *node,
const knot_dname_t *sname);
/*----------------------------------------------------------------------------*/
/*!
* \brief Tries to compress domain name and creates its wire format.
*
* \param dname Domain name to convert and compress.
* \param compr Compression table holding information about offsets of domain
* names in the packet.
* \param dst Place where to put the wire format of the name.
* \param max Maximum available size of the place for the wire format.
*
* \return Size of the domain name's wire format or KNOT_ESPACE if it did not
* fit into the provided space.
*/
int knot_response_compress_dname(const knot_dname_t *dname,
knot_compr_t *compr, uint8_t *dst, size_t max);
#endif /* _KNOT_response_H_ */
/*! @} */
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