Avoid HashDoS attacks via random per-session hash initial state #1433
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This patch randomizes the hash parameters for HTTP request and response classes per session. This avoids HashDoS attacks while not causing tremendous performance overhead.
Other approaches we considered includes
mapinstead ofunordered_mapunordered_map<map<string, string>>But all methods above causes more performance loss then this. We will be making a new release very soon after this PR being merged in order for our users to avoid the vulnerability.
Also, this introduces an API break as the return type of
parameters()is no longerstd::unordered_map<std::string, std::string>(). However in our survey (of the projects that the maintainers run). That API is rarely used and can be easily updated by usingautoor updating the return type.We'd like to attribute @itrofimow for discovering the issue