IHttpSysRequestPropertyFeature.TryGetTlsClientHello Method
Definition
Important
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Reads the TLS client hello from HTTP.SYS
public bool TryGetTlsClientHello(Span<byte> tlsClientHelloBytesDestination, out int bytesReturned);abstract member TryGetTlsClientHello : Span<byte> * int -> boolPublic Function TryGetTlsClientHello (tlsClientHelloBytesDestination As Span(Of Byte), ByRef bytesReturned As Integer) As BooleanParameters
Where the raw bytes of the TLS Client Hello message are written.
- bytesReturned
- Int32
Returns the number of bytes written to tlsClientHelloBytesDestination.
Or can return the size of the buffer needed if tlsClientHelloBytesDestination wasn't large enough.
Returns
True, if fetching TLS client hello was successful, false if tlsClientHelloBytesDestination size is not large enough.
If unsuccessful for other reason throws an exception.
Exceptions
Any HttpSys error except for ERROR_INSUFFICIENT_BUFFER or ERROR_MORE_DATA.
If HttpSys does not support querying the TLS Client Hello.
Remarks
Works only if HTTP_SERVICE_CONFIG_SSL_FLAG_ENABLE_CACHE_CLIENT_HELLO flag is set on http.sys service configuration. See https://learn.microsoft.com/windows/win32/api/http/nf-http-httpsetserviceconfiguration and https://learn.microsoft.com/windows/win32/api/http/ne-http-http_service_config_id
If you don't want to guess the required tlsClientHelloBytesDestination size before first invocation, you should first call with tlsClientHelloBytesDestination set to empty size, so that you can retrieve the required buffer size from bytesReturned, then allocate that amount of memory and retry the query.