From a3526e62c383183a1ba5572a3af40912431121fc Mon Sep 17 00:00:00 2001
From: Thomas Pornin <pornin@bolet.org>
Date: Sat, 19 May 2018 01:54:26 +0200
Subject: [PATCH] Added test for a server choosing a TLS-1.2 cipher suite with
 a pre-1.2 protocol version (client should reject it).

---
 SSLTLS/SSLServer.cs | 20 ++++++++++++++++++++
 conf/bearssl.json   | 11 +++++++++++
 2 files changed, 31 insertions(+)

diff --git a/SSLTLS/SSLServer.cs b/SSLTLS/SSLServer.cs
index 6f39135..71c97d0 100644
--- a/SSLTLS/SSLServer.cs
+++ b/SSLTLS/SSLServer.cs
@@ -453,6 +453,18 @@ public class SSLServer : SSLEngine {
 		 * resumption).
 		 */
 		Version = Math.Min(ClientVersionMax, VersionMax);
+		string forcedVersion = GetQuirkString("forceVersion");
+		if (forcedVersion != null) {
+			switch (forcedVersion) {
+			case "TLS10": Version = SSL.TLS10; break;
+			case "TLS11": Version = SSL.TLS11; break;
+			case "TLS12": Version = SSL.TLS12; break;
+			default:
+				throw new Exception(string.Format(
+					"Unknown forced version: '{0}'", 
+					forcedVersion));
+			}
+		}
 
 		/*
 		 * Recompute list of acceptable cipher suites. We keep
@@ -471,6 +483,11 @@ public class SSLServer : SSLEngine {
 		CommonCipherSuites = new List<int>();
 		List<int> commonSuitesResume = new List<int>();
 		bool canTLS12 = Version >= SSL.TLS12;
+		bool mustTLS12 = false;
+		if (GetQuirkBool("forceTls12CipherSuite")) {
+			canTLS12 = true;
+			mustTLS12 = true;
+		}
 		bool canSignRSA;
 		bool canSignECDSA;
 		if (Version >= SSL.TLS12) {
@@ -499,6 +516,9 @@ public class SSLServer : SSLEngine {
 			if (!canTLS12 && SSL.IsTLS12(cs)) {
 				continue;
 			}
+			if (mustTLS12 && !SSL.IsTLS12(cs)) {
+				continue;
+			}
 			commonSuitesResume.Add(cs);
 			if (!canECDHE && SSL.IsECDHE(cs)) {
 				continue;
diff --git a/conf/bearssl.json b/conf/bearssl.json
index d46f349..97f213a 100644
--- a/conf/bearssl.json
+++ b/conf/bearssl.json
@@ -245,6 +245,17 @@
       "comment" : "Peer should forget session. Peer should close and reconnect.",
       "reconnect" : "peer",
       "forget" : "peer"
+    },
+    {
+      "name" : "tls12SuiteWithOlder",
+      "comment" : "Server selects a TLS-1.2 specific cipher suite with TLS-1.1; the client should refuse.",
+      "clientOnly" : "true",
+      "expectedExitCode" : 1,
+      "expectedFailure" : "Unexpected transport closure",
+      "quirks" : {
+        "forceVersion" : "TLS11",
+        "forceTls12CipherSuite" : "true"
+      }
     }
   ]
 }
-- 
2.17.1