ipam/host-local: support multiple IP ranges

This change allows the host-local allocator to allocate multiple IPs.
This is intended to enable dual-stack, but is not limited to only two
subnets or separate address families.

plugins/ipam/host-local/backend/allocator/range.go

@@ -0,0 +1,159 @@
+// Copyright 2017 CNI authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package allocator
+
+import (
+	"fmt"
+	"net"
+
+	"github.com/containernetworking/cni/pkg/types"
+	"github.com/containernetworking/plugins/pkg/ip"
+)
+
+// Canonicalize takes a given range and ensures that all information is consistent,
+// filling out Start, End, and Gateway with sane values if missing
+func (r *Range) Canonicalize() error {
+	if err := canonicalizeIP(&r.Subnet.IP); err != nil {
+		return err
+	}
+
+	// Can't create an allocator for a network with no addresses, eg
+	// a /32 or /31
+	ones, masklen := r.Subnet.Mask.Size()
+	if ones > masklen-2 {
+		return fmt.Errorf("Network %s too small to allocate from", (*net.IPNet)(&r.Subnet).String())
+	}
+
+	if len(r.Subnet.IP) != len(r.Subnet.Mask) {
+		return fmt.Errorf("IPNet IP and Mask version mismatch")
+	}
+
+	// If the gateway is nil, claim .1
+	if r.Gateway == nil {
+		r.Gateway = ip.NextIP(r.Subnet.IP)
+	} else {
+		if err := canonicalizeIP(&r.Gateway); err != nil {
+			return err
+		}
+		subnet := (net.IPNet)(r.Subnet)
+		if !subnet.Contains(r.Gateway) {
+			return fmt.Errorf("gateway %s not in network %s", r.Gateway.String(), subnet.String())
+		}
+	}
+
+	// RangeStart: If specified, make sure it's sane (inside the subnet),
+	// otherwise use the first free IP (i.e. .1) - this will conflict with the
+	// gateway but we skip it in the iterator
+	if r.RangeStart != nil {
+		if err := canonicalizeIP(&r.RangeStart); err != nil {
+			return err
+		}
+
+		if err := r.IPInRange(r.RangeStart); err != nil {
+			return err
+		}
+	} else {
+		r.RangeStart = ip.NextIP(r.Subnet.IP)
+	}
+
+	// RangeEnd: If specified, verify sanity. Otherwise, add a sensible default
+	// (e.g. for a /24: .254 if IPv4, ::255 if IPv6)
+	if r.RangeEnd != nil {
+		if err := canonicalizeIP(&r.RangeEnd); err != nil {
+			return err
+		}
+
+		if err := r.IPInRange(r.RangeEnd); err != nil {
+			return err
+		}
+	} else {
+		r.RangeEnd = lastIP(r.Subnet)
+	}
+
+	return nil
+}
+
+// IsValidIP checks if a given ip is a valid, allocatable address in a given Range
+func (r *Range) IPInRange(addr net.IP) error {
+	if err := canonicalizeIP(&addr); err != nil {
+		return err
+	}
+
+	subnet := (net.IPNet)(r.Subnet)
+
+	if len(addr) != len(r.Subnet.IP) {
+		return fmt.Errorf("IP %s is not the same protocol as subnet %s",
+			addr, subnet.String())
+	}
+
+	if !subnet.Contains(addr) {
+		return fmt.Errorf("%s not in network %s", addr, subnet.String())
+	}
+
+	// We ignore nils here so we can use this function as we initialize the range.
+	if r.RangeStart != nil {
+		if ip.Cmp(addr, r.RangeStart) < 0 {
+			return fmt.Errorf("%s is in network %s but before start %s",
+				addr, (*net.IPNet)(&r.Subnet).String(), r.RangeStart)
+		}
+	}
+
+	if r.RangeEnd != nil {
+		if ip.Cmp(addr, r.RangeEnd) > 0 {
+			return fmt.Errorf("%s is in network %s but after end %s",
+				addr, (*net.IPNet)(&r.Subnet).String(), r.RangeEnd)
+		}
+	}
+
+	return nil
+}
+
+// Overlaps returns true if there is any overlap between ranges
+func (r *Range) Overlaps(r1 *Range) bool {
+	// different familes
+	if len(r.RangeStart) != len(r1.RangeStart) {
+		return false
+	}
+
+	return r.IPInRange(r1.RangeStart) == nil ||
+		r.IPInRange(r1.RangeEnd) == nil ||
+		r1.IPInRange(r.RangeStart) == nil ||
+		r1.IPInRange(r.RangeEnd) == nil
+}
+
+// canonicalizeIP makes sure a provided ip is in standard form
+func canonicalizeIP(ip *net.IP) error {
+	if ip.To4() != nil {
+		*ip = ip.To4()
+		return nil
+	} else if ip.To16() != nil {
+		*ip = ip.To16()
+		return nil
+	}
+	return fmt.Errorf("IP %s not v4 nor v6", *ip)
+}
+
+// Determine the last IP of a subnet, excluding the broadcast if IPv4
+func lastIP(subnet types.IPNet) net.IP {
+	var end net.IP
+	for i := 0; i < len(subnet.IP); i++ {
+		end = append(end, subnet.IP[i]|^subnet.Mask[i])
+	}
+	if subnet.IP.To4() != nil {
+		end[3]--
+	}
+
+	return end
+}