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/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz>
* SPDX-License-Identifier: GPL-3.0-or-later
*/
#pragma once
#include "kresconfig.h"
#include "lib/defines.h"
#include "lib/utils.h"
/** 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. */
/*! Finished successfully or a special case: in CONSUME phase this can
* be used (by iterator) to do a transition to PRODUCE phase again,
* in which case the packet wasn't accepted for some reason. */
KR_STATE_DONE = 1 << 2,
KR_STATE_FAIL = 1 << 3, /*!< Error. */
KR_STATE_YIELD = 1 << 4, /*!< Paused, waiting for a sub-query. */
};
/** Check that a kr_layer_state makes sense. We're not very strict ATM. */
static inline bool kr_state_consistent(enum kr_layer_state s)
{
#ifdef __clang__
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wtautological-constant-out-of-range-compare"
#pragma clang diagnostic ignored "-Wtautological-unsigned-enum-zero-compare"
#endif
return s >= 0 && s < (1 << 5);
#ifdef __clang__
#pragma clang diagnostic pop
#endif
}
/* 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;
knot_pkt_t *pkt; /*!< In glue for lua kr_layer_api it's used to pass the parameter. */
struct sockaddr *dst; /*!< In glue for checkout layer it's used to pass the parameter. */
bool is_stream; /*!< In glue for checkout layer it's used to pass the parameter. */
} kr_layer_t;
/** Packet processing module API. All functions return the new kr_layer_state.
*
* Lua modules are allowed to return nil/nothing, meaning the state shall not change.
*/
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);
/** Process an answer from upstream or from cache.
* Lua API: call is omitted iff (state & KR_STATE_FAIL). */
int (*consume)(kr_layer_t *ctx, knot_pkt_t *pkt);
/** Produce either an answer to the request or a query for upstream (or fail).
* Lua API: call is omitted iff (state & KR_STATE_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.
* Lua API: call is omitted iff (state & KR_STATE_FAIL). */
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.
* Not called if the packet is being dropped. */
int (*answer_finalize)(kr_layer_t *ctx);
/** The C 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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