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proposal: crypto/tls: Export list of Supported TLS Client Extensions #36337
The clientHelloMsg unmarshal function (in handshake_messages.go) currently exports client information such as supported cipher suites and curves but does not export a list of supported extensions in the form of a uint16 slice. Client extension information is already parsed so this would be a simple mod. Modification of the ClientHelloInfo struct (common.go) and the clientHelloInfo functions (handshake_server.go) would also be required to export this info in the GetConfigForClient callback.
A use case for this would be to allow for TLS server client fingerprinting on the server side using JA3 (https://engineering.salesforce.com/tls-fingerprinting-with-ja3-and-ja3s-247362855967).