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106 lines
3.5 KiB
C++
106 lines
3.5 KiB
C++
#include <Functions/checkHyperscanRegexp.h>
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#include <Common/Exception.h>
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#include <charconv>
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namespace DB
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{
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namespace ErrorCodes
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{
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extern const int BAD_ARGUMENTS;
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}
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void checkHyperscanRegexp(const std::vector<std::string_view> & regexps, size_t max_hyperscan_regexp_length, size_t max_hyperscan_regexp_total_length)
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{
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if (max_hyperscan_regexp_length > 0 || max_hyperscan_regexp_total_length > 0)
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{
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size_t total_regexp_length = 0;
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for (const auto & regexp : regexps)
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{
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if (max_hyperscan_regexp_length > 0 && regexp.size() > max_hyperscan_regexp_length)
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throw Exception(ErrorCodes::BAD_ARGUMENTS, "Regexp length too large ({} > {})", regexp.size(), max_hyperscan_regexp_length);
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total_regexp_length += regexp.size();
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}
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if (max_hyperscan_regexp_total_length > 0 && total_regexp_length > max_hyperscan_regexp_total_length)
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throw Exception(ErrorCodes::BAD_ARGUMENTS, "Total regexp lengths too large ({} > {})",
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total_regexp_length, max_hyperscan_regexp_total_length);
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}
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}
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namespace
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{
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bool isLargerThanFifty(std::string_view str)
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{
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int number;
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auto [_, ec] = std::from_chars(str.begin(), str.end(), number);
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if (ec != std::errc())
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return false;
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return number > 50;
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}
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}
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/// Check for sub-patterns of the form x{n} or x{n,} can be expensive. Ignore spaces before/after n and m.
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bool SlowWithHyperscanChecker::isSlowOneRepeat(std::string_view regexp)
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{
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std::string_view haystack(regexp.data(), regexp.size());
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std::string_view matches[2];
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size_t start_pos = 0;
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while (start_pos < haystack.size())
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{
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if (searcher_one_repeat.Match(haystack, start_pos, haystack.size(), re2::RE2::Anchor::UNANCHORED, matches, 2))
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{
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const auto & match = matches[0];
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start_pos = (matches[0].data() - haystack.data()) + match.size(); // new start pos = prefix before match + match length
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const auto & submatch = matches[1];
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if (isLargerThanFifty({submatch.data(), submatch.size()}))
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return true;
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}
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else
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break;
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}
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return false;
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}
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/// Check if sub-patterns of the form x{n,m} can be expensive. Ignore spaces before/after n and m.
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bool SlowWithHyperscanChecker::isSlowTwoRepeats(std::string_view regexp)
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{
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std::string_view haystack(regexp.data(), regexp.size());
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std::string_view matches[3];
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size_t start_pos = 0;
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while (start_pos < haystack.size())
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{
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if (searcher_two_repeats.Match(haystack, start_pos, haystack.size(), re2::RE2::Anchor::UNANCHORED, matches, 3))
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{
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const auto & match = matches[0];
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start_pos = (matches[0].data() - haystack.data()) + match.size(); // new start pos = prefix before match + match length
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const auto & submatch1 = matches[1];
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const auto & submatch2 = matches[2];
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if (isLargerThanFifty({submatch1.data(), submatch1.size()})
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|| isLargerThanFifty({submatch2.data(), submatch2.size()}))
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return true;
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}
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else
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break;
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}
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return false;
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}
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SlowWithHyperscanChecker::SlowWithHyperscanChecker()
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: searcher_one_repeat(R"(\{\s*([\d]+)\s*,?\s*})")
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, searcher_two_repeats(R"(\{\s*([\d]+)\s*,\s*([\d]+)\s*\})")
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{}
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bool SlowWithHyperscanChecker::isSlow(std::string_view regexp)
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{
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if (isSlowOneRepeat(regexp))
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return true;
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if (isSlowTwoRepeats(regexp))
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return true;
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return false;
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}
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}
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