httputil: Fix quadratic performance of repeated header lines #3553
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Prompt customizations (notably the PYTHONSTARTUP file used by vscode's terminal integration) can interfere with tests that run interactive interpreters in a subprocess. Run those interpreters in isolated mode to avoid this problem.)
Previouisly, when many header lines with the same name were found in an HTTP request or response, repeated string concatenation would result in quadratic performance. This change does the concatenation lazily (with a cache) so that repeated headers can be processed efficiently. Security: The previous behavior allowed a denial of service attack via a maliciously crafted HTTP message, but only if the max_header_size was increased from its default of 64kB.
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Previouisly, when many header lines with the same name were found
in an HTTP request or response, repeated string concatenation would
result in quadratic performance. This change does the concatenation
lazily (with a cache) so that repeated headers can be processed
efficiently.
Security: The previous behavior allowed a denial of service attack
via a maliciously crafted HTTP message, but only if the
max_header_size was increased from its default of 64kB.