static char *url_component_separators = "";
static uns url_min_repeat_count = 0x7fffffff;
static uns url_max_repeat_length = 0;
+static uns url_max_occurences = ~0U;
static struct cf_section url_config = {
CF_ITEMS {
CF_STRING("ComponentSeparators", &url_component_separators),
CF_UNS("MinRepeatCount", &url_min_repeat_count),
CF_UNS("MaxRepeatLength", &url_max_repeat_length),
+ CF_UNS("MaxOccurences", &url_max_occurences),
CF_END
}
};
struct component {
const byte *start;
int length;
+ uns count;
u32 hash;
};
url_has_repeated_component(const byte *url)
{
struct component *comp;
- uns comps, comp_len, rep_prefix;
+ uns comps, comp_len, rep_prefix, hash_size, *hash, *next;
const byte *c;
- uns i;
+ uns i, j, k;
for (comps=0, c=url; c; comps++)
{
if (c)
c++;
}
- if (comps < url_min_repeat_count)
+ if (comps < url_min_repeat_count && comps <= url_max_occurences)
return 0;
- comp = alloca(comps * sizeof(struct component));
+ comp = alloca(comps * sizeof(*comp));
for (i=0, c=url; c; i++)
{
comp[i].start = c;
ASSERT(i == comps);
for (i=0; i<comps; i++)
comp[i].hash = hashf(comp[i].start, comp[i].length);
+ if (comps > url_max_occurences)
+ {
+ hash_size = next_table_prime(comps);
+ hash = alloca(hash_size * sizeof(*hash));
+ next = alloca(comps * sizeof(*next));
+ memset(hash, 255, hash_size * sizeof(*hash));
+ for (i=0; i<comps; i++)
+ {
+ j = comp[i].hash % hash_size;
+ for (k = hash[j]; ~k && (comp[i].hash != comp[k].hash || comp[i].length != comp[k].length ||
+ memcmp(comp[k].start, comp[i].start, comp[i].length)); k = next[k]);
+ if (!~k)
+ {
+ next[i] = hash[j];
+ hash[j] = i;
+ comp[i].count = 1;
+ }
+ else
+ {
+ if (comp[k].count++ >= url_max_occurences)
+ return 1;
+ }
+ }
+ }
for (comp_len = 1; comp_len <= url_max_repeat_length && comp_len <= comps; comp_len++)
for (rep_prefix = 0; rep_prefix <= comps - comp_len; rep_prefix++)
if (repeat_count(comp + rep_prefix, comps - rep_prefix, comp_len) >= url_min_repeat_count)