diff --git a/imap/http_dav.c b/imap/http_dav.c
index 91bbc28b6b..a6fa5c8345 100644
--- a/imap/http_dav.c
+++ b/imap/http_dav.c
@@ -5494,7 +5494,7 @@ EXPORTED int meth_propfind(struct transaction_t *txn, void *params)
xmlDocPtr indoc = NULL, outdoc = NULL;
xmlNodePtr root, cur = NULL, props = NULL;
xmlNsPtr ns[NUM_NAMESPACE];
- struct hash_table ns_table = { 0, NULL, NULL };
+ struct hash_table ns_table = HASH_TABLE_INITIALIZER;
struct propfind_ctx fctx;
struct propfind_entry_list *elist = NULL;
@@ -7900,7 +7900,7 @@ int meth_report(struct transaction_t *txn, void *params)
xmlNodePtr inroot = NULL, outroot = NULL, cur, prop = NULL, props = NULL;
const struct report_type_t *report = NULL;
xmlNsPtr ns[NUM_NAMESPACE];
- struct hash_table ns_table = { 0, NULL, NULL };
+ struct hash_table ns_table = HASH_TABLE_INITIALIZER;
struct propfind_ctx fctx;
struct propfind_entry_list *elist = NULL;
diff --git a/lib/hash.c b/lib/hash.c
index 9703142c3b..84f2e80d28 100644
--- a/lib/hash.c
+++ b/lib/hash.c
@@ -43,10 +43,11 @@ EXPORTED hash_table *construct_hash_table(hash_table *table, size_t size, int us
assert(table);
assert(size);
- table->size = size;
+ table->size = size;
+ table->seed = rand(); /* might be zero, that's okay */
/* Allocate the table -- different for using memory pools and not */
- if(use_mpool) {
+ if (use_mpool) {
/* Allocate an initial memory pool for 32 byte keys + the hash table
* + the buckets themselves */
table->pool =
@@ -72,7 +73,7 @@ EXPORTED hash_table *construct_hash_table(hash_table *table, size_t size, int us
EXPORTED void *hash_insert(const char *key, void *data, hash_table *table)
{
- unsigned val = strhash(key) % table->size;
+ unsigned val = strhash_seeded(table->seed, key) % table->size;
bucket *ptr, *newptr;
bucket **prev;
@@ -153,9 +154,14 @@ EXPORTED void *hash_insert(const char *key, void *data, hash_table *table)
EXPORTED void *hash_lookup(const char *key, hash_table *table)
{
- unsigned val = strhash(key) % table->size;
+ unsigned val;
bucket *ptr;
+ if (!table->size)
+ return NULL;
+
+ val = strhash_seeded(table->seed, key) % table->size;
+
if (!(table->table)[val])
return NULL;
@@ -178,8 +184,7 @@ EXPORTED void *hash_lookup(const char *key, hash_table *table)
* since it will leak memory until you get rid of the entire hash table */
EXPORTED void *hash_del(const char *key, hash_table *table)
{
- unsigned val = strhash(key) % table->size;
- void *data;
+ unsigned val = strhash_seeded(table->seed, key) % table->size;
bucket *ptr, *last = NULL;
if (!(table->table)[val])
@@ -200,15 +205,10 @@ EXPORTED void *hash_del(const char *key, hash_table *table)
int cmpresult = strcmp(key, ptr->key);
if (!cmpresult)
{
+ void *data = ptr->data;
if (last != NULL )
{
- data = ptr -> data;
last -> next = ptr -> next;
- if(!table->pool) {
- free(ptr->key);
- free(ptr);
- }
- return data;
}
/*
@@ -221,15 +221,15 @@ EXPORTED void *hash_del(const char *key, hash_table *table)
else
{
- data = ptr->data;
(table->table)[val] = ptr->next;
- if(!table->pool) {
- free(ptr->key);
- free(ptr);
- }
- return data;
}
- } else if (cmpresult < 0) {
+ if(!table->pool) {
+ free(ptr->key);
+ free(ptr);
+ }
+ return data;
+ }
+ if (cmpresult < 0) {
/* its not here! */
return NULL;
}
diff --git a/lib/hash.h b/lib/hash.h
index 8051ac1760..cfa7da1ffa 100644
--- a/lib/hash.h
+++ b/lib/hash.h
@@ -3,10 +3,11 @@
#define HASH__H
#include <stddef.h> /* For size_t */
+#include <stdint.h>
#include "mpool.h"
#include "strarray.h"
-#define HASH_TABLE_INITIALIZER {0, NULL, NULL}
+#define HASH_TABLE_INITIALIZER {0, 0, NULL, NULL}
/*
** A hash table consists of an array of these buckets. Each bucket
@@ -32,6 +33,7 @@ typedef struct bucket {
typedef struct hash_table {
size_t size;
+ uint32_t seed;
bucket **table;
struct mpool *pool;
} hash_table;
diff --git a/lib/strhash.c b/lib/strhash.c
index d7c1741d2a..1b3251db73 100644
--- a/lib/strhash.c
+++ b/lib/strhash.c
@@ -42,17 +42,32 @@
#include "config.h"
-EXPORTED unsigned strhash(const char *string)
+#include "lib/strhash.h"
+
+/* The well-known djb2 algorithm (e.g. http://www.cse.yorku.ca/~oz/hash.html),
+ * with the addition of an optional seed to limit predictability.
+ *
+ * XXX return type 'unsigned' for back-compat to previous version, but
+ * XXX ought to be 'uint32_t'
+ */
+EXPORTED unsigned strhash_seeded_djb2(uint32_t seed, const char *string)
{
- unsigned ret_val = 0;
- int i;
+ const unsigned char *ustr = (const unsigned char *) string;
+ unsigned hash = 5381;
+ int c;
- while (*string)
- {
- i = (int) *string;
- ret_val ^= i;
- ret_val <<= 1;
- string ++;
- }
- return ret_val;
+ if (seed) {
+ /* treat the bytes of the seed as a prefix to the string */
+ unsigned i;
+ for (i = 0; i < sizeof seed; i++) {
+ c = seed & 0xff;
+ hash = ((hash << 5) + hash) ^ c;
+ seed >>= 8;
+ }
+ }
+
+ while ((c = *ustr++))
+ hash = ((hash << 5) + hash) ^ c;
+
+ return hash;
}
diff --git a/lib/strhash.h b/lib/strhash.h
index 34533fdffa..27339bb288 100644
--- a/lib/strhash.h
+++ b/lib/strhash.h
@@ -41,7 +41,11 @@
*/
#ifndef _STRHASH_H_
+#include <stdint.h>
-unsigned strhash(const char *string);
+unsigned strhash_seeded_djb2(uint32_t seed, const char *string);
+
+#define strhash(in) strhash_seeded_djb2((0), (in))
+#define strhash_seeded(sd, in) strhash_seeded_djb2((sd), (in))
#endif /* _STRHASH_H_ */