Merge pull request #422 from gthiemonge/fix_mgmt_subnet_cidrs

Allow custom-sized CIDR for the management subnets

pkg/octavia/network_parameters.go

@@ -55,33 +55,31 @@ func getConfigFromNAD(
 func GetRangeFromCIDR(
 	cidr netip.Prefix,
 ) (start netip.Addr, end netip.Addr) {
-	// For IPv6, a /64 is expected, if the CIDR is aaaa:bbbb:cccc:dddd::/64,
-	// the range is aaaa:bbbb:cccc:dddd::5 - aaaa:bbbb:cccc:dddd:ffff:ffff:ffff:fffe
-	// For IPv4, a /16 is expected, if the CIDR is a.b.0.0/16
-	// the range is a.b.0.5 - a.b.255.254
-	// IPs from from 1 to 5 are reserved for later user
-	addr := cidr.Addr()
-	if addr.Is6() {
-		addrBytes := addr.As16()
-		for i := 8; i < 15; i++ {
-			addrBytes[i] = 0
-		}
-		addrBytes[15] = 5
-		start = netip.AddrFrom16(addrBytes)
-		for i := 8; i < 15; i++ {
-			addrBytes[i] = 0xff
-		}
-		addrBytes[15] = 0xfe
-		end = netip.AddrFrom16(addrBytes)
-	} else {
-		addrBytes := addr.As4()
-		addrBytes[2] = 0
-		addrBytes[3] = 5
-		start = netip.AddrFrom4(addrBytes)
-		addrBytes[2] = 0xff
-		addrBytes[3] = 0xfe
-		end = netip.AddrFrom4(addrBytes)
+	// start is the 5th address of the Cidr
+	start = cidr.Masked().Addr()
+	for i := 0; i < 5; i++ {
+		start = start.Next()
+	}
+
+	bits := cidr.Bits()
+	if start.Is4() {
+		// Padding for ipv4 addresses in a [16]bytes table
+		bits += 96
+	}
+	// convert it to a [16]bytes table, set the remaining bits to 1
+	addrBytes := start.As16()
+	for b := bits; b < 128; b++ {
+		addrBytes[b/8] |= 1 << uint(7-(b%8))
 	}
+	// convert the table to an ip address to get the last IP
+	// in case of IPv4, the address should be unmapped
+	last := netip.AddrFrom16(addrBytes)
+	if start.Is4() {
+		last = last.Unmap()
+	}
+	// end is the 2nd last
+	end = last.Prev()
+
 	return
 }
 

tests/functional/octavia_controller_test.go

@@ -663,7 +663,7 @@ var _ = Describe("Octavia controller", func() {
 
 			spec["lbMgmtNetwork"].(map[string]interface{})["availabilityZoneCIDRs"] = map[string]string{
 				"az1": "172.34.0.0/16",
-				"az2": "172.44.0.0/16",
+				"az2": "172.44.8.0/21",
 			}
 			spec["lbMgmtNetwork"].(map[string]interface{})["createDefaultLbMgmtNetwork"] = false
 			DeferCleanup(th.DeleteInstance, CreateOctavia(octaviaName, spec))
@@ -763,6 +763,16 @@ var _ = Describe("Octavia controller", func() {
 					CIDR:        nadConfig.IPAM.CIDR.String(),
 				},
 			}
+			expectedAllocationPools := map[string]subnets.AllocationPool{
+				subnetNameAZ1: {
+					Start: "172.34.0.5",
+					End:   "172.34.255.254",
+				},
+				subnetNameAZ2: {
+					Start: "172.44.8.5",
+					End:   "172.44.15.254",
+				},
+			}
 
 			resultSubnets := map[string]subnets.Subnet{}
 			for _, subnet := range apiFixtures.Neutron.Subnets {
@@ -777,6 +787,10 @@ var _ = Describe("Octavia controller", func() {
 				Expect(subnet.NetworkID).To(Equal(expectedSubnet.NetworkID))
 				Expect(subnet.CIDR).To(Equal(expectedSubnet.CIDR))
 				Expect(subnet.HostRoutes).To(Equal(expectedSubnet.HostRoutes))
+				if expectedAllocationPool, ok := expectedAllocationPools[name]; ok {
+					Expect(subnet.AllocationPools[0].Start).To(Equal(expectedAllocationPool.Start))
+					Expect(subnet.AllocationPools[0].End).To(Equal(expectedAllocationPool.End))
+				}
 			}
 
 			// Routers