API: Better free range finding algorithm

api/views.py

@@ -8,6 +8,9 @@ from whoisdb.models import ASBlock, ASNumber, InetNum
 from domains.models import Domain, ReverseZone
 from dnmgmt.settings import TLD_NAMESERVERS
 
+import ipaddress
+
+
 @login_required
 def asblockFreeAS(request):
 
@@ -91,12 +94,28 @@ def freeSubnet(request):
 			raise ValidationError("PrefixLen is not a number")
 
 		usableNet = None
-		# FIXME: use first biggest usable netblock... 
+		# FIXME: use first biggest usable netblock...
 		#biggestNet = parentRange.inetnum_set.order_by("-address")
 		#if biggestNet
-		#	candidateNet = 
+		#	candidateNet =
 		#	and (biggestNet.getNetwork().broadcast_address.:
 
+		# try using next network in range
+		# ordering does not work, as order_by sorts alphabetically
+		# ==> the set is short, we can iterate through all. no sense in unpacking the SQL magic
+		#biggestNets = parentRange.inetnum_set.order_by("-address")
+		biggestNet = None
+		for ipRange in parentRange.inetnum_set.all():
+			if not biggestNet or ipRange.getNetwork() > biggestNet:
+				biggestNet = ipRange.getNetwork()
+
+		if biggestNet:
+			candidateNet = ipaddress.ip_network("%s/%s" % (biggestNet.broadcast_address + 1, biggestNet.prefixlen))
+			print("biggest net", biggestNet, "candidate", candidateNet)
+			if candidateNet.network_address in parentRange.getNetwork():
+				usableNet = candidateNet
+
+		# check if there are still networks left in range
 		if not usableNet:
 			# search for free network
 			nets = list(parentRange.getNetwork().subnets())