1 files changed, 107 insertions, 0 deletions
diff --git a/lib/layer.h b/lib/layer.h
new file mode 100644
index 0000000..0909cb7
--- /dev/null
+++ b/lib/layer.h
@@ -0,0 +1,107 @@
+/*  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;
+};
+