65 lines
1.7 KiB
C++
65 lines
1.7 KiB
C++
/*
|
|
* Authored by Alex Hultman, 2018-2019.
|
|
* Intellectual property of third-party.
|
|
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
#ifndef UWS_BLOOMFILTER_H
|
|
#define UWS_BLOOMFILTER_H
|
|
|
|
/* This filter has a decently low amount of false positives for the
|
|
* standard and non-standard common request headers */
|
|
|
|
#include <string_view>
|
|
#include <bitset>
|
|
|
|
namespace uWS {
|
|
|
|
struct BloomFilter {
|
|
private:
|
|
std::bitset<512> filter;
|
|
|
|
unsigned int hash1(std::string_view key) {
|
|
return ((size_t)key[key.length() - 1] - (key.length() << 3)) & 511;
|
|
}
|
|
|
|
unsigned int hash2(std::string_view key) {
|
|
return (((size_t)key[0] + (key.length() << 4)) & 511);
|
|
}
|
|
|
|
unsigned int hash3(std::string_view key) {
|
|
return ((unsigned int)key[key.length() - 2] - 97 - (key.length() << 5)) & 511;
|
|
}
|
|
|
|
public:
|
|
bool mightHave(std::string_view key) {
|
|
return filter.test(hash1(key)) && filter.test(hash2(key)) && (key.length() < 2 || filter.test(hash3(key)));
|
|
}
|
|
|
|
void add(std::string_view key) {
|
|
filter.set(hash1(key));
|
|
filter.set(hash2(key));
|
|
if (key.length() >= 2) {
|
|
filter.set(hash3(key));
|
|
}
|
|
}
|
|
|
|
void reset() {
|
|
filter.reset();
|
|
}
|
|
};
|
|
|
|
}
|
|
|
|
#endif // UWS_BLOOMFILTER_H
|