decline invalid permessage-deflate offers rather than fail handshake#1019
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sahvx655-wq wants to merge 1 commit into
Open
decline invalid permessage-deflate offers rather than fail handshake#1019sahvx655-wq wants to merge 1 commit into
sahvx655-wq wants to merge 1 commit into
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A WebSocket client that offers permessage-deflate with an invalid window size, for example
Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits=16, makesPerMessageDeflate.build()throw. An out-of-range value raisesIllegalArgumentExceptionand a non-numeric or value-lessserver_max_window_bitsraisesNumberFormatException; nothing on the server handshake path catches either, so the exception unwinds throughUpgradeUtil.doUpgrade()andWsFilterand the upgrade is aborted with a 500. I traced it from the build stack, which surfaces at theInteger.parseInt/range check inbuild(), and since permessage-deflate is a default-installed extension every endpoint is reachable.RFC 7692 section 5.1 requires the server to decline an offer that carries an invalid parameter, meaning the handshake should complete without that extension rather than fail.
build()already returnsnullwhen it cannot agree terms, so wrapping the parameter loop and routing an invalid parameter down that existing decline path keeps the change in the one method that owns extension negotiation, with the validation and its messages untouched. The added test exercises the three trigger values and fails on the current tree.