bneradt commented on code in PR #11424: URL: https://github.com/apache/trafficserver/pull/11424#discussion_r1631459587
########## plugins/ja3_fingerprint/ja3_utils.cc: ########## @@ -0,0 +1,102 @@ +/** @ja3_utils.cc + Plugin JA3 Fingerprint calculates JA3 signatures for incoming SSL traffic. + @section license License + Licensed to the Apache Software Foundation (ASF) under one + or more contributor license agreements. See the NOTICE file + distributed with this work for additional information + regarding copyright ownership. The ASF licenses this file + to you 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. + */ + +#include <algorithm> +#include <cstdint> +#include <string> +#include <unordered_set> + +namespace ja3 +{ + +// GREASE table as in ja3 +static std::unordered_set<std::uint16_t> const GREASE_table = {0x0a0a, 0x1a1a, 0x2a2a, 0x3a3a, 0x4a4a, 0x5a5a, 0x6a6a, 0x7a7a, + 0x8a8a, 0x9a9a, 0xaaaa, 0xbaba, 0xcaca, 0xdada, 0xeaea, 0xfafa}; + +static constexpr std::uint16_t +from_big_endian(unsigned char lowbyte, unsigned char highbyte) +{ + return (static_cast<std::uint16_t>(lowbyte) << 8) + highbyte; +} + +static bool +ja3_should_ignore(std::uint16_t n) +{ + return GREASE_table.find(n) != GREASE_table.end(); +} + +std::string +encode_word_buffer(unsigned char const *buf, int const len) +{ + std::string result; + if (len > 0) { + // Benchmarks show that reserving space in the string here would cause + // a 40% increase in runtime for a buffer with 10 elements... so we + // don't do it. + result.append(std::to_string(buf[0])); + std::for_each(buf + 1, buf + len, [&result](unsigned char i) { + result.push_back('-'); + result.append(std::to_string(i)); + }); + } + return result; +} + +std::string +encode_dword_buffer(unsigned char const *buf, int const len) +{ + std::string result; + auto it{buf}; + while (it < buf + len && ja3_should_ignore(from_big_endian(it[0], it[1]))) { + it += 2; + } + if (it < buf + len) { Review Comment: ```cpp if (it < (buf + len)) { ``` There's at least one other place like this. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
