Fix the display of MACs when AEAD is selected

This is mostly a cosmetic issue, but it is annoying me in ConnectBot.

Author: kruton

src/main/java/com/trilead/ssh2/transport/KexManager.java

@@ -277,10 +277,22 @@ private NegotiatedParameters mergeKexParameters(KexParameters client, KexParamet
 			log.log(20, "enc_algo_client_to_server=" + np.enc_algo_client_to_server);
 			log.log(20, "enc_algo_server_to_client=" + np.enc_algo_server_to_client);
 
-			np.mac_algo_client_to_server = getFirstMatch(client.mac_algorithms_client_to_server,
-					server.mac_algorithms_client_to_server);
-			np.mac_algo_server_to_client = getFirstMatch(client.mac_algorithms_server_to_client,
-					server.mac_algorithms_server_to_client);
+			boolean c2s_is_aead = BlockCipherFactory.isAead(np.enc_algo_client_to_server);
+			boolean s2c_is_aead = BlockCipherFactory.isAead(np.enc_algo_server_to_client);
+
+			if (c2s_is_aead) {
+				np.mac_algo_client_to_server = null;
+			} else {
+				np.mac_algo_client_to_server = getFirstMatch(client.mac_algorithms_client_to_server,
+						server.mac_algorithms_client_to_server);
+			}
+
+			if (s2c_is_aead) {
+				np.mac_algo_server_to_client = null;
+			} else {
+				np.mac_algo_server_to_client = getFirstMatch(client.mac_algorithms_server_to_client,
+						server.mac_algorithms_server_to_client);
+			}
 
 			log.log(20, "mac_algo_client_to_server=" + np.mac_algo_client_to_server);
 			log.log(20, "mac_algo_server_to_client=" + np.mac_algo_server_to_client);

src/test/java/com/trilead/ssh2/AsyncSSHCompatibilityTest.java

@@ -201,6 +201,9 @@ public void canConnectWithCipherAes256Gcm() throws Exception {
 	}
 
 	private void setMac(Connection c, String mac) {
+		// This is needed because AEAD selection would result in null MAC.
+		setCiphers(c, "aes128-ctr");
+
 		c.setClient2ServerMACs(new String[] { mac });
 		c.setServer2ClientMACs(new String[] { mac });
 	}

src/test/java/com/trilead/ssh2/DropbearCompatibilityTest.java

@@ -249,6 +249,9 @@ public void canConnectWithCipherChacha20Poly1305() throws Exception {
 	}
 
 	private void setMac(Connection c, String mac) {
+		// This is needed because AEAD selection would result in null MAC.
+		setCiphers(c, "aes128-ctr");
+
 		c.setClient2ServerMACs(new String[] { mac });
 		c.setServer2ClientMACs(new String[] { mac });
 	}

src/test/java/com/trilead/ssh2/OpenSSHCompatibilityTest.java

@@ -80,7 +80,7 @@ private ConnectionInfo connectToServerWithOptions(@NotNull String options) throw
 
 	private void assertCanConnectToServerThatHasKeyType(@NotNull String keyPath, String keyType) throws IOException {
 		ConnectionInfo info = connectToServerWithOptions("-h " + keyPath);
-		assertThat(keyType, is(info.serverHostKeyAlgorithm));
+		assertThat(info.serverHostKeyAlgorithm, is(keyType));
 	}
 
 	private void canConnectWithPubkey(String keyFilename) throws Exception {
@@ -159,7 +159,7 @@ public void connectToEd25519Host() throws Exception {
 
 	private void assertCanConnectToServerWithKex(@NotNull String kexType) throws IOException {
 		ConnectionInfo info = connectToServerWithOptions("-oKexAlgorithms=" + kexType);
-		assertThat(kexType, is(info.keyExchangeAlgorithm));
+		assertThat(info.keyExchangeAlgorithm, is(kexType));
 	}
 
 	@Test
@@ -230,8 +230,8 @@ public void canConnectWithKexMlKem768X25519() throws Exception {
 
 	private void assertCanConnectToServerWithCipher(@NotNull String ciphers) throws IOException {
 		ConnectionInfo info = connectToServerWithOptions("-oCiphers=" + ciphers);
-		assertThat(ciphers, is(info.clientToServerCryptoAlgorithm));
-		assertThat(ciphers, is(info.serverToClientCryptoAlgorithm));
+		assertThat(info.clientToServerCryptoAlgorithm, is(ciphers));
+		assertThat(info.serverToClientCryptoAlgorithm, is(ciphers));
 	}
 
 	@Test
@@ -275,9 +275,9 @@ public void canConnectWithCipherChaCha20Poly1305() throws Exception {
 	}
 
 	private void assertCanConnectToServerWithMac(@NotNull String macs) throws IOException {
-		ConnectionInfo info = connectToServerWithOptions("-oMACs=" + macs);
-		assertThat(macs, is(info.clientToServerMACAlgorithm));
-		assertThat(macs, is(info.serverToClientMACAlgorithm));
+		ConnectionInfo info = connectToServerWithOptions("-oCiphers=aes128-ctr -oMACs=" + macs);
+		assertThat(info.clientToServerMACAlgorithm, is(macs));
+		assertThat(info.serverToClientMACAlgorithm, is(macs));
 	}
 
 	@Test
@@ -324,15 +324,15 @@ public void canConnectWithCompression() throws Exception {
 				}
 
 				ConnectionInfo info = c.getConnectionInfo();
-				assertThat("zlib@openssh.com", is(info.clientToServerCompressionAlgorithm));
-				assertThat("zlib@openssh.com", is(info.serverToClientCompressionAlgorithm));
+				assertThat(info.clientToServerCompressionAlgorithm, is("zlib@openssh.com"));
+				assertThat(info.serverToClientCompressionAlgorithm, is("zlib@openssh.com"));
 			}
 		}
 	}
 
 	private void canConnectWithHostKeyAlgorithm(String keyPath, String hostKeyAlgorithm) throws Exception {
 		ConnectionInfo info = connectToServerWithOptions("-h " + keyPath + " -oHostKeyAlgorithms=" + hostKeyAlgorithm);
-		assertThat(hostKeyAlgorithm, is(info.serverHostKeyAlgorithm));
+		assertThat(info.serverHostKeyAlgorithm, is(hostKeyAlgorithm));
 	}
 
 	@Test