Fix ECH rejection to verify the outer cert against the public_name#407
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bindreams wants to merge 3 commits into
Open
Fix ECH rejection to verify the outer cert against the public_name#407bindreams wants to merge 3 commits into
bindreams wants to merge 3 commits into
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On an ECH rejection,
verifyServerCertificateincorrectly verifies the presented outer certificate against the inner name (c.config.ServerName), instead of the ClientHelloOuter'spublic_name(c.serverName). These two names almost always differ, and in that case the verification fails and the handshake aborts with aCertificateVerificationErrorbefore the*ECHRejectionErrorcarryingretry_configsis ever surfaced.As a consequence of this bug, ECH retry recovery can never complete against a real rejecting server. The client always errors out verifying the outer cert against the inner name, so a caller cannot both send ECH and recover from an ECH-config rotation (e.g. Cloudflare's ~hourly key rotation).
This PR fixes the bug by correctly verifying against
c.serverNameinstead ofc.config.ServerName.See also: https://github.com/golang/go/blob/go1.26.1/src/crypto/tls/handshake_client.go#L1118-L1146