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siphash: Replace current hash algorithm by SipHash

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This commit is contained in:
Sebastian Pipping 2017-06-10 22:18:24 +02:00
parent c0f7c250e3
commit 3fcef5021a
1 changed files with 43 additions and 19 deletions
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62
expat/lib/xmlparse.c
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@ -33,6 +33,7 @@
#include "ascii.h"
#include "expat.h"
#include "siphash.h"
#ifdef XML_UNICODE
#define XML_ENCODE_MAX XML_UTF16_ENCODE_MAX
@ -111,17 +112,11 @@ typedef struct {
const XML_Memory_Handling_Suite *mem;
} HASH_TABLE;
/* Basic character hash algorithm, taken from Python's string hash:
h = h * 1000003 ^ character, the constant being a prime number.
static size_t
keylen(KEY s);
*/
#ifdef XML_UNICODE
#define CHAR_HASH(h, c) \
(((h) * 0xF4243) ^ (unsigned short)(c))
#else
#define CHAR_HASH(h, c) \
(((h) * 0xF4243) ^ (unsigned char)(c))
#endif
static void
copy_salt_to_sipkey(XML_Parser parser, struct sipkey * key);
/* For probing (after a collision) we need a step size relative prime
to the hash table size, which is a power of 2. We use double-hashing,
@ -3245,7 +3240,13 @@ storeAtts(XML_Parser parser, const ENCODING *enc,
if (s[-1] == 2) { /* prefixed */
ATTRIBUTE_ID *id;
const BINDING *b;
unsigned long uriHash = get_hash_secret_salt(parser);
unsigned long uriHash;
struct siphash sip_state;
struct sipkey sip_key;
copy_salt_to_sipkey(parser, &sip_key);
sip24_init(&sip_state, &sip_key);
((XML_Char *)s)[-1] = 0; /* clear flag */
id = (ATTRIBUTE_ID *)lookup(parser, &dtd->attributeIds, s, 0);
if (!id || !id->prefix)
@ -3254,22 +3255,26 @@ storeAtts(XML_Parser parser, const ENCODING *enc,
if (!b)
return XML_ERROR_UNBOUND_PREFIX;
/* as we expand the name we also calculate its hash value */
for (j = 0; j < b->uriLen; j++) {
const XML_Char c = b->uri[j];
if (!poolAppendChar(&tempPool, c))
return XML_ERROR_NO_MEMORY;
uriHash = CHAR_HASH(uriHash, c);
}
sip24_update(&sip_state, b->uri, b->uriLen * sizeof(XML_Char));
while (*s++ != XML_T(ASCII_COLON))
;
sip24_update(&sip_state, s, keylen(s) * sizeof(XML_Char));
do { /* copies null terminator */
const XML_Char c = *s;
if (!poolAppendChar(&tempPool, *s))
return XML_ERROR_NO_MEMORY;
uriHash = CHAR_HASH(uriHash, c);
} while (*s++);
uriHash = (unsigned long)sip24_final(&sip_state);
{ /* Check hash table for duplicate of expanded name (uriName).
Derived from code in lookup(parser, HASH_TABLE *table, ...).
*/
@ -6302,13 +6307,32 @@ keyeq(KEY s1, KEY s2)
return XML_FALSE;
}
static size_t
keylen(KEY s)
{
size_t len = 0;
for (; *s; s++, len++);
return len;
}
static void
copy_salt_to_sipkey(XML_Parser parser, struct sipkey * key)
{
key->k[0] = 0;
key->k[1] = get_hash_secret_salt(parser);
}
static unsigned long FASTCALL
hash(XML_Parser parser, KEY s)
{
unsigned long h = get_hash_secret_salt(parser);
while (*s)
h = CHAR_HASH(h, *s++);
return h;
struct siphash state;
struct sipkey key;
(void)sip_tobin;
(void)sip24_valid;
copy_salt_to_sipkey(parser, &key);
sip24_init(&state, &key);
sip24_update(&state, s, keylen(s) * sizeof(XML_Char));
return (unsigned long)sip24_final(&state);
}
static NAMED *