nts: make server and client AEAD algorithms configurable

Add ntsaeads directive to specify a list of AEAD algorithms enabled for
NTS. The list is shared between the server and client. For the client it
also specifies the order of priority. The default is "30 15", matching
the previously hardcoded preference of AES-128-GCM-SIV (30) over
AES-SIV-CMAC-256 (15).

test/simulation/139-nts

@@ -313,4 +313,31 @@ check_sync && test_fail
 check_file_messages "	3	1	.*	123	" 0 0 log.packets || test_fail
 check_file_messages "	3	2	.*	123	" 0 0 log.packets || test_fail
 
+for server_aead in "" "15" "30"; do
+	for client_aead in "" "15" "30"; do
+		server_conf="
+		ntsaeads $server_aead
+		ntsserverkey tmp/server1.key
+		ntsservercert tmp/server1.crt
+		ntsprocesses 0"
+		client_conf="
+		nosystemcert
+		ntsaeads $client_aead
+		ntstrustedcerts tmp/server1.crt
+		ntstrustedcerts tmp/server2.crt"
+		client_server_conf=""
+
+		run_test || test_fail
+		check_chronyd_exit || test_fail
+		if [ -n "$server_aead" ] && [ "$server_aead" == "$client_aead" ] &&
+		    ( [ "$server_aead" != "30" ] || check_config_h '.*_SIV_GCM 1' ); then
+			check_source_selection || test_fail
+			check_sync || test_fail
+		else
+			check_source_selection && test_fail
+			check_sync && test_fail
+		fi
+	done
+done
+
 test_pass