Flight3: respect curves configuration

Reuse logic from Flight1 to ensure correct behaviour.

Signed-off-by: Vladislav Yarmak <[email protected]>

flight3handler.go

@@ -248,10 +248,19 @@ func flight3Generate(_ flightConn, state *State, _ *handshakeCache, cfg *handsha
 			RenegotiatedConnection: 0,
 		},
 	}
-	if state.namedCurve != 0 {
+
+	var setEllipticCurveCryptographyClientHelloExtensions bool
+	for _, c := range cfg.localCipherSuites {
+		if c.ECC() {
+			setEllipticCurveCryptographyClientHelloExtensions = true
+			break
+		}
+	}
+
+	if setEllipticCurveCryptographyClientHelloExtensions {
 		extensions = append(extensions, []extension.Extension{
 			&extension.SupportedEllipticCurves{
-				EllipticCurves: []elliptic.Curve{elliptic.X25519, elliptic.P256, elliptic.P384},
+				EllipticCurves: cfg.ellipticCurves,
 			},
 			&extension.SupportedPointFormats{
 				PointFormats: []elliptic.CurvePointFormat{elliptic.CurvePointFormatUncompressed},