1 files changed, 573 insertions, 0 deletions
diff --git a/lib/isc/ht.c b/lib/isc/ht.c
new file mode 100644
index 0000000..eaf2b3c
--- /dev/null
+++ b/lib/isc/ht.c
@@ -0,0 +1,573 @@
+/*
+ * 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 <inttypes.h>
+#include <string.h>
+
+#include <isc/hash.h>
+#include <isc/ht.h>
+#include <isc/magic.h>
+#include <isc/mem.h>
+#include <isc/result.h>
+#include <isc/types.h>
+#include <isc/util.h>
+
+typedef struct isc_ht_node isc_ht_node_t;
+
+#define ISC_HT_MAGIC	 ISC_MAGIC('H', 'T', 'a', 'b')
+#define ISC_HT_VALID(ht) ISC_MAGIC_VALID(ht, ISC_HT_MAGIC)
+
+#define HT_NO_BITS    0
+#define HT_MIN_BITS   1
+#define HT_MAX_BITS   32
+#define HT_OVERCOMMIT 3
+
+#define HT_NEXTTABLE(idx)      ((idx == 0) ? 1 : 0)
+#define TRY_NEXTTABLE(idx, ht) (idx == ht->hindex && rehashing_in_progress(ht))
+
+#define GOLDEN_RATIO_32 0x61C88647
+
+#define HASHSIZE(bits) (UINT64_C(1) << (bits))
+
+struct isc_ht_node {
+	void *value;
+	isc_ht_node_t *next;
+	uint32_t hashval;
+	size_t keysize;
+	unsigned char key[];
+};
+
+struct isc_ht {
+	unsigned int magic;
+	isc_mem_t *mctx;
+	size_t count;
+	bool case_sensitive;
+	size_t size[2];
+	uint8_t hashbits[2];
+	isc_ht_node_t **table[2];
+	uint8_t hindex;
+	uint32_t hiter; /* rehashing iterator */
+};
+
+struct isc_ht_iter {
+	isc_ht_t *ht;
+	size_t i;
+	uint8_t hindex;
+	isc_ht_node_t *cur;
+};
+
+static isc_ht_node_t *
+isc__ht_find(const isc_ht_t *ht, const unsigned char *key,
+	     const uint32_t keysize, const uint32_t hashval, const uint8_t idx);
+static void
+isc__ht_add(isc_ht_t *ht, const unsigned char *key, const uint32_t keysize,
+	    const uint32_t hashval, const uint8_t idx, void *value);
+static isc_result_t
+isc__ht_delete(isc_ht_t *ht, const unsigned char *key, const uint32_t keysize,
+	       const uint32_t hashval, const uint8_t idx);
+
+static uint32_t
+rehash_bits(isc_ht_t *ht, size_t newcount);
+
+static void
+hashtable_new(isc_ht_t *ht, const uint8_t idx, const uint8_t bits);
+static void
+hashtable_free(isc_ht_t *ht, const uint8_t idx);
+static void
+hashtable_rehash(isc_ht_t *ht, uint32_t newbits);
+static void
+hashtable_rehash_one(isc_ht_t *ht);
+static void
+maybe_rehash(isc_ht_t *ht, size_t newcount);
+
+static isc_result_t
+isc__ht_iter_next(isc_ht_iter_t *it);
+
+static bool
+isc__ht_node_match(isc_ht_node_t *node, const uint32_t hashval,
+		   const uint8_t *key, uint32_t keysize) {
+	return (node->hashval == hashval && node->keysize == keysize &&
+		memcmp(node->key, key, keysize) == 0);
+}
+
+static uint32_t
+hash_32(uint32_t val, unsigned int bits) {
+	REQUIRE(bits <= HT_MAX_BITS);
+	/* High bits are more random. */
+	return (val * GOLDEN_RATIO_32 >> (32 - bits));
+}
+
+static bool
+rehashing_in_progress(const isc_ht_t *ht) {
+	return (ht->table[HT_NEXTTABLE(ht->hindex)] != NULL);
+}
+
+static bool
+hashtable_is_overcommited(isc_ht_t *ht) {
+	return (ht->count >= (ht->size[ht->hindex] * HT_OVERCOMMIT));
+}
+
+static uint32_t
+rehash_bits(isc_ht_t *ht, size_t newcount) {
+	uint32_t newbits = ht->hashbits[ht->hindex];
+
+	while (newcount >= HASHSIZE(newbits) && newbits <= HT_MAX_BITS) {
+		newbits += 1;
+	}
+
+	return (newbits);
+}
+
+/*
+ * Rebuild the hashtable to reduce the load factor
+ */
+static void
+hashtable_rehash(isc_ht_t *ht, uint32_t newbits) {
+	uint8_t oldindex = ht->hindex;
+	uint32_t oldbits = ht->hashbits[oldindex];
+	uint8_t newindex = HT_NEXTTABLE(oldindex);
+
+	REQUIRE(ht->hashbits[oldindex] >= HT_MIN_BITS);
+	REQUIRE(ht->hashbits[oldindex] <= HT_MAX_BITS);
+	REQUIRE(ht->table[oldindex] != NULL);
+
+	REQUIRE(newbits <= HT_MAX_BITS);
+	REQUIRE(ht->hashbits[newindex] == HT_NO_BITS);
+	REQUIRE(ht->table[newindex] == NULL);
+
+	REQUIRE(newbits > oldbits);
+
+	hashtable_new(ht, newindex, newbits);
+
+	ht->hindex = newindex;
+
+	hashtable_rehash_one(ht);
+}
+
+static void
+hashtable_rehash_one(isc_ht_t *ht) {
+	isc_ht_node_t **newtable = ht->table[ht->hindex];
+	uint32_t oldsize = ht->size[HT_NEXTTABLE(ht->hindex)];
+	isc_ht_node_t **oldtable = ht->table[HT_NEXTTABLE(ht->hindex)];
+	isc_ht_node_t *node = NULL;
+	isc_ht_node_t *nextnode;
+
+	/* Find first non-empty node */
+	while (ht->hiter < oldsize && oldtable[ht->hiter] == NULL) {
+		ht->hiter++;
+	}
+
+	/* Rehashing complete */
+	if (ht->hiter == oldsize) {
+		hashtable_free(ht, HT_NEXTTABLE(ht->hindex));
+		ht->hiter = 0;
+		return;
+	}
+
+	/* Move the first non-empty node from old hashtable to new hashtable */
+	for (node = oldtable[ht->hiter]; node != NULL; node = nextnode) {
+		uint32_t hash = hash_32(node->hashval,
+					ht->hashbits[ht->hindex]);
+		nextnode = node->next;
+		node->next = newtable[hash];
+		newtable[hash] = node;
+	}
+
+	oldtable[ht->hiter] = NULL;
+
+	ht->hiter++;
+}
+
+static void
+maybe_rehash(isc_ht_t *ht, size_t newcount) {
+	uint32_t newbits = rehash_bits(ht, newcount);
+
+	if (ht->hashbits[ht->hindex] < newbits && newbits <= HT_MAX_BITS) {
+		hashtable_rehash(ht, newbits);
+	}
+}
+
+static void
+hashtable_new(isc_ht_t *ht, const uint8_t idx, const uint8_t bits) {
+	size_t size;
+	REQUIRE(ht->hashbits[idx] == HT_NO_BITS);
+	REQUIRE(ht->table[idx] == NULL);
+	REQUIRE(bits >= HT_MIN_BITS);
+	REQUIRE(bits <= HT_MAX_BITS);
+
+	ht->hashbits[idx] = bits;
+	ht->size[idx] = HASHSIZE(ht->hashbits[idx]);
+
+	size = ht->size[idx] * sizeof(isc_ht_node_t *);
+
+	ht->table[idx] = isc_mem_get(ht->mctx, size);
+	memset(ht->table[idx], 0, size);
+}
+
+static void
+hashtable_free(isc_ht_t *ht, const uint8_t idx) {
+	size_t size = ht->size[idx] * sizeof(isc_ht_node_t *);
+
+	for (size_t i = 0; i < ht->size[idx]; i++) {
+		isc_ht_node_t *node = ht->table[idx][i];
+		while (node != NULL) {
+			isc_ht_node_t *next = node->next;
+			ht->count--;
+			isc_mem_put(ht->mctx, node,
+				    sizeof(*node) + node->keysize);
+			node = next;
+		}
+	}
+
+	isc_mem_put(ht->mctx, ht->table[idx], size);
+	ht->hashbits[idx] = HT_NO_BITS;
+	ht->table[idx] = NULL;
+}
+
+void
+isc_ht_init(isc_ht_t **htp, isc_mem_t *mctx, uint8_t bits,
+	    unsigned int options) {
+	isc_ht_t *ht = NULL;
+	bool case_sensitive = ((options & ISC_HT_CASE_INSENSITIVE) == 0);
+
+	REQUIRE(htp != NULL && *htp == NULL);
+	REQUIRE(mctx != NULL);
+	REQUIRE(bits >= 1 && bits <= HT_MAX_BITS);
+
+	ht = isc_mem_get(mctx, sizeof(*ht));
+	*ht = (isc_ht_t){
+		.case_sensitive = case_sensitive,
+	};
+
+	isc_mem_attach(mctx, &ht->mctx);
+
+	hashtable_new(ht, 0, bits);
+
+	ht->magic = ISC_HT_MAGIC;
+
+	*htp = ht;
+}
+
+void
+isc_ht_destroy(isc_ht_t **htp) {
+	isc_ht_t *ht;
+
+	REQUIRE(htp != NULL);
+	REQUIRE(ISC_HT_VALID(*htp));
+
+	ht = *htp;
+	*htp = NULL;
+	ht->magic = 0;
+
+	for (size_t i = 0; i <= 1; i++) {
+		if (ht->table[i] != NULL) {
+			hashtable_free(ht, i);
+		}
+	}
+
+	INSIST(ht->count == 0);
+
+	isc_mem_putanddetach(&ht->mctx, ht, sizeof(*ht));
+}
+
+static void
+isc__ht_add(isc_ht_t *ht, const unsigned char *key, const uint32_t keysize,
+	    const uint32_t hashval, const uint8_t idx, void *value) {
+	isc_ht_node_t *node;
+	uint32_t hash;
+
+	hash = hash_32(hashval, ht->hashbits[idx]);
+
+	node = isc_mem_get(ht->mctx, sizeof(*node) + keysize);
+	*node = (isc_ht_node_t){
+		.keysize = keysize,
+		.hashval = hashval,
+		.next = ht->table[idx][hash],
+		.value = value,
+	};
+
+	memmove(node->key, key, keysize);
+
+	ht->count++;
+	ht->table[idx][hash] = node;
+}
+
+isc_result_t
+isc_ht_add(isc_ht_t *ht, const unsigned char *key, const uint32_t keysize,
+	   void *value) {
+	uint32_t hashval;
+
+	REQUIRE(ISC_HT_VALID(ht));
+	REQUIRE(key != NULL && keysize > 0);
+
+	if (rehashing_in_progress(ht)) {
+		/* Rehash in progress */
+		hashtable_rehash_one(ht);
+	} else if (hashtable_is_overcommited(ht)) {
+		/* Rehash requested */
+		maybe_rehash(ht, ht->count);
+	}
+
+	hashval = isc_hash32(key, keysize, ht->case_sensitive);
+
+	if (isc__ht_find(ht, key, keysize, hashval, ht->hindex) != NULL) {
+		return (ISC_R_EXISTS);
+	}
+
+	isc__ht_add(ht, key, keysize, hashval, ht->hindex, value);
+
+	return (ISC_R_SUCCESS);
+}
+
+static isc_ht_node_t *
+isc__ht_find(const isc_ht_t *ht, const unsigned char *key,
+	     const uint32_t keysize, const uint32_t hashval,
+	     const uint8_t idx) {
+	uint32_t hash;
+	uint8_t findex = idx;
+
+nexttable:
+	hash = hash_32(hashval, ht->hashbits[findex]);
+	for (isc_ht_node_t *node = ht->table[findex][hash]; node != NULL;
+	     node = node->next)
+	{
+		if (isc__ht_node_match(node, hashval, key, keysize)) {
+			return (node);
+		}
+	}
+	if (TRY_NEXTTABLE(findex, ht)) {
+		/*
+		 * Rehashing in progress, check the other table
+		 */
+		findex = HT_NEXTTABLE(findex);
+		goto nexttable;
+	}
+
+	return (NULL);
+}
+
+isc_result_t
+isc_ht_find(const isc_ht_t *ht, const unsigned char *key,
+	    const uint32_t keysize, void **valuep) {
+	uint32_t hashval;
+	isc_ht_node_t *node;
+
+	REQUIRE(ISC_HT_VALID(ht));
+	REQUIRE(key != NULL && keysize > 0);
+	REQUIRE(valuep == NULL || *valuep == NULL);
+
+	hashval = isc_hash32(key, keysize, ht->case_sensitive);
+
+	node = isc__ht_find(ht, key, keysize, hashval, ht->hindex);
+	if (node == NULL) {
+		return (ISC_R_NOTFOUND);
+	}
+
+	if (valuep != NULL) {
+		*valuep = node->value;
+	}
+	return (ISC_R_SUCCESS);
+}
+
+static isc_result_t
+isc__ht_delete(isc_ht_t *ht, const unsigned char *key, const uint32_t keysize,
+	       const uint32_t hashval, const uint8_t idx) {
+	isc_ht_node_t *prev = NULL;
+	uint32_t hash;
+
+	hash = hash_32(hashval, ht->hashbits[idx]);
+
+	for (isc_ht_node_t *node = ht->table[idx][hash]; node != NULL;
+	     prev = node, node = node->next)
+	{
+		if (isc__ht_node_match(node, hashval, key, keysize)) {
+			if (prev == NULL) {
+				ht->table[idx][hash] = node->next;
+			} else {
+				prev->next = node->next;
+			}
+			isc_mem_put(ht->mctx, node,
+				    sizeof(*node) + node->keysize);
+			ht->count--;
+
+			return (ISC_R_SUCCESS);
+		}
+	}
+
+	return (ISC_R_NOTFOUND);
+}
+
+isc_result_t
+isc_ht_delete(isc_ht_t *ht, const unsigned char *key, const uint32_t keysize) {
+	uint32_t hashval;
+	uint8_t hindex;
+	isc_result_t result;
+
+	REQUIRE(ISC_HT_VALID(ht));
+	REQUIRE(key != NULL && keysize > 0);
+
+	if (rehashing_in_progress(ht)) {
+		/* Rehash in progress */
+		hashtable_rehash_one(ht);
+	}
+
+	hindex = ht->hindex;
+	hashval = isc_hash32(key, keysize, ht->case_sensitive);
+nexttable:
+	result = isc__ht_delete(ht, key, keysize, hashval, hindex);
+
+	if (result == ISC_R_NOTFOUND && TRY_NEXTTABLE(hindex, ht)) {
+		/*
+		 * Rehashing in progress, check the other table
+		 */
+		hindex = HT_NEXTTABLE(hindex);
+		goto nexttable;
+	}
+
+	return (result);
+}
+
+void
+isc_ht_iter_create(isc_ht_t *ht, isc_ht_iter_t **itp) {
+	isc_ht_iter_t *it;
+
+	REQUIRE(ISC_HT_VALID(ht));
+	REQUIRE(itp != NULL && *itp == NULL);
+
+	it = isc_mem_get(ht->mctx, sizeof(isc_ht_iter_t));
+	*it = (isc_ht_iter_t){
+		.ht = ht,
+		.hindex = ht->hindex,
+	};
+
+	*itp = it;
+}
+
+void
+isc_ht_iter_destroy(isc_ht_iter_t **itp) {
+	isc_ht_iter_t *it;
+	isc_ht_t *ht;
+
+	REQUIRE(itp != NULL && *itp != NULL);
+
+	it = *itp;
+	*itp = NULL;
+	ht = it->ht;
+	isc_mem_put(ht->mctx, it, sizeof(*it));
+}
+
+isc_result_t
+isc_ht_iter_first(isc_ht_iter_t *it) {
+	isc_ht_t *ht;
+
+	REQUIRE(it != NULL);
+
+	ht = it->ht;
+
+	it->hindex = ht->hindex;
+	it->i = 0;
+
+	return (isc__ht_iter_next(it));
+}
+
+static isc_result_t
+isc__ht_iter_next(isc_ht_iter_t *it) {
+	isc_ht_t *ht = it->ht;
+
+	while (it->i < ht->size[it->hindex] &&
+	       ht->table[it->hindex][it->i] == NULL)
+	{
+		it->i++;
+	}
+
+	if (it->i < ht->size[it->hindex]) {
+		it->cur = ht->table[it->hindex][it->i];
+
+		return (ISC_R_SUCCESS);
+	}
+
+	if (TRY_NEXTTABLE(it->hindex, ht)) {
+		it->hindex = HT_NEXTTABLE(it->hindex);
+		it->i = 0;
+		return (isc__ht_iter_next(it));
+	}
+
+	return (ISC_R_NOMORE);
+}
+
+isc_result_t
+isc_ht_iter_next(isc_ht_iter_t *it) {
+	REQUIRE(it != NULL);
+	REQUIRE(it->cur != NULL);
+
+	it->cur = it->cur->next;
+
+	if (it->cur != NULL) {
+		return (ISC_R_SUCCESS);
+	}
+
+	it->i++;
+
+	return (isc__ht_iter_next(it));
+}
+
+isc_result_t
+isc_ht_iter_delcurrent_next(isc_ht_iter_t *it) {
+	isc_result_t result = ISC_R_SUCCESS;
+	isc_ht_node_t *dnode = NULL;
+	uint8_t dindex;
+	isc_ht_t *ht;
+	isc_result_t dresult;
+
+	REQUIRE(it != NULL);
+	REQUIRE(it->cur != NULL);
+
+	ht = it->ht;
+	dnode = it->cur;
+	dindex = it->hindex;
+
+	result = isc_ht_iter_next(it);
+
+	dresult = isc__ht_delete(ht, dnode->key, dnode->keysize, dnode->hashval,
+				 dindex);
+	INSIST(dresult == ISC_R_SUCCESS);
+
+	return (result);
+}
+
+void
+isc_ht_iter_current(isc_ht_iter_t *it, void **valuep) {
+	REQUIRE(it != NULL);
+	REQUIRE(it->cur != NULL);
+	REQUIRE(valuep != NULL && *valuep == NULL);
+
+	*valuep = it->cur->value;
+}
+
+void
+isc_ht_iter_currentkey(isc_ht_iter_t *it, unsigned char **key,
+		       size_t *keysize) {
+	REQUIRE(it != NULL);
+	REQUIRE(it->cur != NULL);
+	REQUIRE(key != NULL && *key == NULL);
+
+	*key = it->cur->key;
+	*keysize = it->cur->keysize;
+}
+
+size_t
+isc_ht_count(const isc_ht_t *ht) {
+	REQUIRE(ISC_HT_VALID(ht));
+
+	return (ht->count);
+}