Library: Improved the detector of cycled URLs (Bug #6188).

diff --git a/lib/url.c b/lib/url.c
index 8f1a435bb241fa2c4592f5f6d93e545baa10d2ef..3a3d8c21368b8bc3adabb533b7c4f910426aa0d8 100644 (file)
--- a/lib/url.c
+++ b/lib/url.c
@@ -32,6 +32,7 @@ static uns url_ignore_underflow;
 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 {
@@ -40,6 +41,7 @@ static struct cf_section url_config = {
     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
   }
 };
@@ -667,6 +669,7 @@ int main(int argc, char **argv)
 struct component {
        const byte *start;
        int length;
+       uns count;
        u32 hash;
 };
 
@@ -703,10 +706,10 @@ repeat_count(struct component *comp, uns count, uns len)
 int
 url_has_repeated_component(const byte *url)
 {
-       struct component *comp;
+       struct component *comp, **hash;
        uns comps, comp_len, rep_prefix;
        const byte *c;
-       uns i;
+       uns i, j;
 
        for (comps=0, c=url; c; comps++)
        {
@@ -714,9 +717,9 @@ url_has_repeated_component(const byte *url)
                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;
@@ -732,6 +735,24 @@ url_has_repeated_component(const byte *url)
        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 = alloca(comps * sizeof(*hash));
+               bzero(hash, comps * sizeof(*hash));
+               for (i=0; i<comps; i++)
+               {
+                       j = comp[i].hash % comps;
+                       while (hash[j] && memcmp(hash[j]->start, comp[i].start, comp[i].length))
+                               j = (j + 1) % comps;
+                       if (!hash[j])
+                       {
+                               hash[j] = &comp[i];
+                               comp[i].count = 1;
+                       }
+                       else if (hash[j]->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)