Require ALPN when forcing HTTP/2 over TLS#631
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arturobernalg merged 1 commit intoapache:masterfrom Feb 22, 2026
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When endpoint policy is FORCE_HTTP_2, require strict ALPN negotiation on TLS sessions and fail if 'h2' is not negotiated (missing/empty/other protocol). RFC 9113 §3.2, §3.3: HTTP/2 over TLS MUST use protocol negotiation in TLS (ALPN).
ok2c
approved these changes
Feb 21, 2026
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This PR fixes a conformance issue in the FORCE_HTTP_2 negotiation path: when running over TLS, the client could proceed with strictALPNHandshake=false and send the HTTP/2 preface even if ALPN was missing/empty (or not h2). For HTTPS, HTTP/2 startup must be explicitly negotiated via ALPN; otherwise the connection should fail fast.
RFC 9113 3.2 (Starting HTTP/2 for “https” URIs)
“A client that makes a request to an "https" URI uses TLS [TLS13] with the ALPN extension [TLS-ALPN].”
RFC 9113 3.3 (Starting HTTP/2 with Prior Knowledge)
“This only affects the establishment of HTTP/2 connections over cleartext TCP; HTTP/2 connections over TLS MUST use protocol negotiation in TLS [TLS-ALPN].”