/*
 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
 *
 * SPDX-License-Identifier: MPL-2.0
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, you can obtain one at https://mozilla.org/MPL/2.0/.
 *
 * See the COPYRIGHT file distributed with this work for additional
 * information regarding copyright ownership.
 */

#include <assert.h>
#include <err.h>
#include <stdbool.h>
#include <stdint.h>

#include <isc/random.h>
#include <isc/refcount.h>
#include <isc/rwlock.h>
#include <isc/urcu.h>
#include <isc/util.h>

#include <dns/qp.h>
#include <dns/types.h>

#include "fuzz.h"
#include "qp_p.h"

#include <tests/qp.h>

bool debug = false;

#if 0
#define TRACE(...) warnx(__VA_ARGS__)
#else
#define TRACE(...)
#endif

#if 0
#define ASSERT(p)                                               \
	do {                                                    \
		warnx("%s:%d: %s (%s)", __func__, __LINE__, #p, \
		      (p) ? "OK" : "FAIL");                     \
		ok = ok && (p);                                 \
	} while (0)
#else
#define ASSERT(p) assert(p)
#endif

static struct {
	uint32_t refcount;
	bool exists;
	uint8_t len;
	dns_qpkey_t key;
	dns_qpkey_t ascii;
} item[256 * 256 / 4];

static void
fuzz_attach(void *ctx, void *pval, uint32_t ival) {
	assert(ctx == NULL);
	assert(pval == &item[ival]);
	item[ival].refcount++;
}

static void
fuzz_detach(void *ctx, void *pval, uint32_t ival) {
	assert(ctx == NULL);
	assert(pval == &item[ival]);
	item[ival].refcount--;
}

static size_t
fuzz_makekey(dns_qpkey_t key, void *ctx, void *pval, uint32_t ival) {
	assert(ctx == NULL);
	assert(pval == &item[ival]);
	memmove(key, item[ival].key, item[ival].len);
	return item[ival].len;
}

static void
fuzz_triename(void *ctx, char *buf, size_t size) {
	assert(ctx == NULL);
	strlcpy(buf, "fuzz", size);
}

const dns_qpmethods_t fuzz_methods = {
	fuzz_attach,
	fuzz_detach,
	fuzz_makekey,
	fuzz_triename,
};

static uint8_t
random_byte(void) {
	return isc_random_uniform(SHIFT_OFFSET - SHIFT_NOBYTE) + SHIFT_NOBYTE;
}

int
LLVMFuzzerInitialize(int *argc, char ***argv) {
	UNUSED(argc);
	UNUSED(argv);

	for (size_t i = 0; i < ARRAY_SIZE(item); i++) {
		size_t len = isc_random_uniform(100) + 16;
		item[i].len = len + 1;
		item[i].key[0] = 0;
		for (size_t off = 1; off < len; off++) {
			item[i].key[off] = random_byte();
		}
		memmove(item[i].ascii, item[i].key, item[i].len);
		qp_test_keytoascii(item[i].ascii, item[i].len);
	}

	return 0;
}

int
LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
	isc_result_t result;

	TRACE("------------------------------------------------");

	isc_mem_t *mctx = NULL;
	isc_mem_create("fuzz", &mctx);
	isc_mem_setdestroycheck(mctx, true);

	dns_qp_t *qp = NULL;
	dns_qp_create(mctx, &fuzz_methods, NULL, &qp);

	/* avoid overrun */
	size = size & ~1;

	size_t count = 0;

	for (size_t in = 0; in < size; in += 2) {
		size_t what = data[in] + data[in + 1] * 256;
		size_t i = (what / 4) % (count * 2 + 2);
		bool exists = item[i].exists;
		uint32_t refcount = item[i].refcount;
		bool ok = true;
		if (what & 2) {
			void *pval = NULL;
			uint32_t ival = ~0U;
			result = dns_qp_getkey(qp, item[i].key, item[i].len,
					       &pval, &ival);
			TRACE("count %zu get %s %zu >%s<", count,
			      isc_result_toid(result), i, item[i].ascii);
			if (result == ISC_R_SUCCESS) {
				ASSERT(pval == &item[i]);
				ASSERT(ival == i);
				ASSERT(item[i].refcount == 1);
				ASSERT(item[i].exists == true);
			} else if (result == ISC_R_NOTFOUND) {
				ASSERT(pval == NULL);
				ASSERT(ival == ~0U);
				ASSERT(item[i].refcount == 0);
				ASSERT(item[i].exists == false);
			} else {
				UNREACHABLE();
			}
		} else if (what & 1) {
			result = dns_qp_insert(qp, &item[i], i);
			TRACE("count %zu ins %s %zu >%s<", count,
			      isc_result_toid(result), i, item[i].ascii);
			if (result == ISC_R_SUCCESS) {
				item[i].exists = true;
				ASSERT(exists == false);
				ASSERT(refcount == 0);
				ASSERT(item[i].refcount == 1);
				count += 1;
				ASSERT(qp->leaf_count == count);
			} else if (result == ISC_R_EXISTS) {
				ASSERT(exists == true);
				ASSERT(refcount == 1);
				ASSERT(item[i].refcount == 1);
				ASSERT(qp->leaf_count == count);
			} else {
				UNREACHABLE();
			}
		} else {
			result = dns_qp_deletekey(qp, item[i].key, item[i].len,
						  NULL, NULL);
			TRACE("count %zu del %s %zu >%s<", count,
			      isc_result_toid(result), i, item[i].ascii);
			if (result == ISC_R_SUCCESS) {
				item[i].exists = false;
				ASSERT(exists == true);
				ASSERT(refcount == 1);
				ASSERT(item[i].refcount == 0);
				count -= 1;
				ASSERT(qp->leaf_count == count);
			} else if (result == ISC_R_NOTFOUND) {
				ASSERT(exists == false);
				ASSERT(refcount == 0);
				ASSERT(item[i].refcount == 0);
				ASSERT(qp->leaf_count == count);
			} else {
				UNREACHABLE();
			}
		}
		if (!ok) {
			qp_test_dumpqp(qp);
			qp_test_dumptrie(qp);
		}
		assert(ok);
	}

	for (size_t i = 0; i < ARRAY_SIZE(item); i++) {
		assert(item[i].exists == (item[i].refcount != 0));
	}

	dns_qp_destroy(&qp);
	isc_mem_detach(&mctx);
	isc_mem_checkdestroyed(stderr);

	for (size_t i = 0; i < ARRAY_SIZE(item); i++) {
		item[i].exists = false;
		assert(item[i].refcount == 0);
	}

	return 0;
}
