1 files changed, 194 insertions, 0 deletions
diff --git a/lib/cache/api.h b/lib/cache/api.h
new file mode 100644
index 0000000..0abe920
--- /dev/null
+++ b/lib/cache/api.h
@@ -0,0 +1,194 @@
+/*  Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <libknot/consts.h>
+#include <libknot/rrset.h>
+#include <sys/time.h>
+#include "lib/cache/cdb_api.h"
+#include "lib/defines.h"
+#include "contrib/ucw/config.h" /*uint*/
+
+#include "lib/module.h"
+/* Prototypes for the 'cache' module implementation. */
+int cache_peek(kr_layer_t *ctx, knot_pkt_t *pkt);
+int cache_stash(kr_layer_t *ctx, knot_pkt_t *pkt);
+
+
+/**
+ * Cache structure, keeps API, instance and metadata.
+ */
+struct kr_cache
+{
+	kr_cdb_pt db;                 /**< Storage instance */
+	const struct kr_cdb_api *api; /**< Storage engine */
+	struct kr_cdb_stats stats;
+	uint32_t ttl_min, ttl_max; /**< TTL limits; enforced primarily in iterator actually. */
+
+	/* A pair of stamps for detection of real-time shifts during runtime. */
+	struct timeval checkpoint_walltime; /**< Wall time on the last check-point. */
+	uint64_t checkpoint_monotime; /**< Monotonic milliseconds on the last check-point. */
+
+	uv_timer_t *health_timer; /**< Timer used for kr_cache_check_health() */
+};
+// https://datatracker.ietf.org/doc/html/rfc2181#section-8
+#define TTL_MAX_MAX ((1u << 31) - 1)
+
+/**
+ * Open/create cache with provided storage options.
+ * @param cache cache structure to be initialized
+ * @param api   storage engine API
+ * @param opts  storage-specific options (may be NULL for default)
+ * @param mm    memory context.
+ * @return 0 or an error code
+ */
+KR_EXPORT
+int kr_cache_open(struct kr_cache *cache, const struct kr_cdb_api *api, struct kr_cdb_opts *opts, knot_mm_t *mm);
+
+/**
+ * Path to cache file to remove on critical out-of-space error. (do NOT modify it)
+ */
+KR_EXPORT extern
+const char *kr_cache_emergency_file_to_remove;
+
+/**
+ * Close persistent cache.
+ * @note This doesn't clear the data, just closes the connection to the database.
+ * @param cache structure
+ */
+KR_EXPORT
+void kr_cache_close(struct kr_cache *cache);
+
+/** Run after a row of operations to release transaction/lock if needed. */
+KR_EXPORT
+int kr_cache_commit(struct kr_cache *cache);
+
+/**
+ * Return true if cache is open and enabled.
+ */
+static inline bool kr_cache_is_open(struct kr_cache *cache)
+{
+	return cache->db != NULL;
+}
+
+/** (Re)set the time pair to the current values. */
+static inline void kr_cache_make_checkpoint(struct kr_cache *cache)
+{
+	cache->checkpoint_monotime = kr_now();
+	gettimeofday(&cache->checkpoint_walltime, NULL);
+}
+
+/**
+ * Insert RRSet into cache, replacing any existing data.
+ * @param cache cache structure
+ * @param rr inserted RRSet
+ * @param rrsig RRSIG for inserted RRSet (optional)
+ * @param rank rank of the data
+ * @param timestamp current time (as-if; if the RR are older, their timestamp is appropriate)
+ * @param ins_nsec_p update NSEC* parameters if applicable
+ * @return 0 or an errcode
+ */
+KR_EXPORT
+int kr_cache_insert_rr(struct kr_cache *cache,
+			const knot_rrset_t *rr, const knot_rrset_t *rrsig,
+			uint8_t rank, uint32_t timestamp, bool ins_nsec_p);
+
+/**
+ * Clear all items from the cache.
+ * @param cache cache structure
+ * @return if nonzero is returned, there's a big problem - you probably want to abort(),
+ * 	perhaps except for kr_error(EAGAIN) which probably indicates transient errors.
+ */
+KR_EXPORT
+int kr_cache_clear(struct kr_cache *cache);
+
+
+/* ** This interface is temporary. ** */
+
+struct kr_cache_p {
+	uint32_t time;	/**< The time of inception. */
+	uint32_t ttl;	/**< TTL at inception moment.  Assuming it fits into int32_t ATM. */
+	uint8_t  rank;	/**< See enum kr_rank */
+	struct {
+		/* internal: pointer to eh struct */
+		void *raw_data, *raw_bound;
+	};
+};
+KR_EXPORT
+int kr_cache_peek_exact(struct kr_cache *cache, const knot_dname_t *name, uint16_t type,
+			struct kr_cache_p *peek);
+/* Parameters (qry, name, type) are used for timestamp and stale-serving decisions. */
+KR_EXPORT
+int32_t kr_cache_ttl(const struct kr_cache_p *peek, const struct kr_query *qry,
+		     const knot_dname_t *name, uint16_t type);
+
+KR_EXPORT
+int kr_cache_materialize(knot_rdataset_t *dst, const struct kr_cache_p *ref,
+			 knot_mm_t *pool);
+
+
+/**
+ * Remove an entry from cache.
+ * @param cache cache structure
+ * @param name dname
+ * @param type rr type
+ * @return number of deleted records, or negative error code
+ * @note only "exact hits" are considered ATM, and
+ * 	some other information may be removed alongside.
+ */
+KR_EXPORT
+int kr_cache_remove(struct kr_cache *cache, const knot_dname_t *name, uint16_t type);
+
+/**
+ * Get keys matching a dname lf prefix
+ * @param cache cache structure
+ * @param name dname
+ * @param exact_name whether to only consider exact name matches
+ * @param keyval matched key-value pairs
+ * @param maxcount limit on the number of returned key-value pairs
+ * @return result count or an errcode
+ * @note the cache keys are matched by prefix, i.e. it very much depends
+ * 	on their structure; CACHE_KEY_DEF.
+ */
+KR_EXPORT
+int kr_cache_match(struct kr_cache *cache, const knot_dname_t *name,
+		   bool exact_name, knot_db_val_t keyval[][2], int maxcount);
+
+/**
+ * Remove a subtree in cache.  It's like _match but removing them instead of returning.
+ * @return number of deleted entries or an errcode
+ */
+KR_EXPORT
+int kr_cache_remove_subtree(struct kr_cache *cache, const knot_dname_t *name,
+			    bool exact_name, int maxcount);
+
+/**
+ * Find the closest cached zone apex for a name (in cache).
+ * @param is_DS start searching one name higher
+ * @return the number of labels to remove from the name, or negative error code
+ * @note timestamp is found by a syscall, and stale-serving is not considered
+ */
+KR_EXPORT
+int kr_cache_closest_apex(struct kr_cache *cache, const knot_dname_t *name, bool is_DS,
+			  knot_dname_t **apex);
+
+/**
+ * Unpack dname and type from db key
+ * @param key db key representation
+ * @param buf output buffer of domain name in dname format
+ * @param type output for type
+ * @return length of dname or an errcode
+ * @note only "exact hits" are considered ATM, moreover xNAME records
+ * 	are "hidden" as NS. (see comments in struct entry_h)
+ */
+KR_EXPORT
+int kr_unpack_cache_key(knot_db_val_t key, knot_dname_t *buf, uint16_t *type);
+
+/** Periodic kr_cdb_api::check_health().
+ * @param interval in milliseconds.  0 for one-time check, -1 to stop the checks.
+ * @return see check_health() for one-time check; otherwise normal kr_error() code. */
+KR_EXPORT
+int kr_cache_check_health(struct kr_cache *cache, int interval);
+