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/* Copyright (C) 2014-2017 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/>.
*/
#pragma once
#include "lib/defines.h"
#include "lib/utils.h"
#ifdef NOVERBOSELOG
#define QRVERBOSE(query, cls, ...)
#else
/** Print a debug message related to resolution.
* \param _query associated kr_query, may be NULL
* \param _cls identifying string, typically of length exactly four (padded)
* \param ... printf-compatible list of parameters
*/
#define QRVERBOSE(_query, _cls, ...) do { \
const struct kr_query *_qry = (_query); \
if (kr_log_trace_enabled(_qry)) { \
kr_log_trace(_qry, (_cls), __VA_ARGS__); \
} else if (VERBOSE_STATUS) { \
kr_log_qverbose_impl(_qry, (_cls), __VA_ARGS__); \
} \
} while (false)
#endif
/** Layer processing states. Only one value at a time (but see TODO).
*
* Each state represents the state machine transition,
* and determines readiness for the next action.
* See struct kr_layer_api for the actions.
*
* TODO: the cookie module sometimes sets (_FAIL | _DONE) on purpose (!)
*/
enum kr_layer_state {
KR_STATE_CONSUME = 1 << 0, /*!< Consume data. */
KR_STATE_PRODUCE = 1 << 1, /*!< Produce data. */
KR_STATE_DONE = 1 << 2, /*!< Finished successfully. */
KR_STATE_FAIL = 1 << 3, /*!< Error. */
KR_STATE_YIELD = 1 << 4, /*!< Paused, waiting for a sub-query. */
};
/* Forward declarations. */
struct kr_layer_api;
/** Packet processing context. */
typedef struct kr_layer {
int state; /*!< The current state; bitmap of enum kr_layer_state. */
struct kr_request *req; /*!< The corresponding request. */
const struct kr_layer_api *api;
} kr_layer_t;
/** Packet processing module API. All functions return the new kr_layer_state. */
struct kr_layer_api {
/** Start of processing the DNS request. */
int (*begin)(kr_layer_t *ctx);
int (*reset)(kr_layer_t *ctx);
/** Paired to begin, called both on successes and failures. */
int (*finish)(kr_layer_t *ctx);
/** Processing an answer from upstream or the answer to the request. */
int (*consume)(kr_layer_t *ctx, knot_pkt_t *pkt);
/** Produce either an answer to the request or a query for upstream (or fail). */
int (*produce)(kr_layer_t *ctx, knot_pkt_t *pkt);
/** Finalises the outbound query packet with the knowledge of the IP addresses.
* The checkout layer doesn't persist the state, so canceled subrequests
* don't affect the resolution or rest of the processing. */
int (*checkout)(kr_layer_t *ctx, knot_pkt_t *packet, struct sockaddr *dst, int type);
/** Finalises the answer.
* Last chance to affect what will get into the answer, including EDNS.*/
int (*answer_finalize)(kr_layer_t *ctx);
/** The module can store anything in here. */
void *data;
/** Internal to ./daemon/ffimodule.c. */
int cb_slots[];
};
typedef struct kr_layer_api kr_layer_api_t;
/** Pickled layer state (api, input, state). */
struct kr_layer_pickle {
struct kr_layer_pickle *next;
const struct kr_layer_api *api;
knot_pkt_t *pkt;
unsigned state;
};
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