Function is_supported_version

mitmproxy/net/tls.py:75–90

(version: Version)

@cache
def is_supported_version(version: Version):
    client_ctx = SSL.Context(SSL.TLS_CLIENT_METHOD)
    # Without SECLEVEL, recent OpenSSL versions forbid old TLS versions.
    # https://github.com/pyca/cryptography/issues/9523
    client_ctx.set_cipher_list(b"@SECLEVEL=0:ALL")
    client_ctx.set_min_proto_version(version.value)
    client_ctx.set_max_proto_version(version.value)
    client_conn = SSL.Connection(client_ctx)
    client_conn.set_connect_state()

    try:
        client_conn.recv(4096)
    except SSL.WantReadError:
        return True
    except SSL.Error:
        return False


EC_CURVES: dict[str, EllipticCurve] = {}