Move address range helpers into address package

This means that users don't drag in a dependency on aws-sdk.

net/address/helpers.go

@@ -0,0 +1,42 @@
+package address
+
+// Merge merges adjacent range entries.
+// The given slice has to be sorted in increasing order.
+func Merge(r []Range) []Range {
+	var merged []Range
+
+	for i := range r {
+		if prev := len(merged) - 1; prev >= 0 && merged[prev].End == r[i].Start {
+			merged[prev].End = r[i].End
+		} else {
+			merged = append(merged, r[i])
+		}
+	}
+
+	return merged
+}
+
+// RemoveCommon filters out CIDR ranges which are contained in both a and b slices.
+// Both slices have to be sorted in increasing order.
+func RemoveCommon(a, b []CIDR) (newA, newB []CIDR) {
+	i, j := 0, 0
+
+	for i < len(a) && j < len(b) {
+		switch {
+		case a[i].Start() < b[j].Start() || a[i].End() < b[j].End():
+			newA = append(newA, a[i])
+			i++
+		case a[i].Start() > b[j].Start() || a[i].End() > b[j].End():
+			newB = append(newB, b[j])
+			j++
+		default:
+			i++
+			j++
+		}
+
+	}
+	newA = append(newA, a[i:]...)
+	newB = append(newB, b[j:]...)
+
+	return
+}

net/address/helpers_test.go

@@ -0,0 +1,43 @@
+package address
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+var (
+	r0to127     = cidr2("10.0.0.0", "10.0.0.127")
+	r128to255   = cidr2("10.0.0.128", "10.0.0.255")
+	r0to255     = cidr2("10.0.0.0", "10.0.0.255")
+	r1dot0to255 = cidr2("10.0.1.0", "10.0.1.255")
+	r2dot0to255 = cidr2("10.0.2.0", "10.0.2.255")
+)
+
+func TestRemoveCommon(t *testing.T) {
+	a := []CIDR{r0to127, r1dot0to255}
+	b := []CIDR{r1dot0to255, r2dot0to255}
+	newA, newB := RemoveCommon(a, b)
+	require.Equal(t, []CIDR{r0to127}, newA)
+	require.Equal(t, []CIDR{r2dot0to255}, newB)
+}
+
+func TestMerge(t *testing.T) {
+	ranges := []Range{
+		r0to127.Range(),
+		r128to255.Range(),
+		r2dot0to255.Range(),
+	}
+	require.Equal(t, []Range{r0to255.Range(), r2dot0to255.Range()}, Merge(ranges))
+}
+
+// Helper
+
+// [start; end]
+func cidr2(start, end string) CIDR {
+	c := Range{Start: ip(start), End: ip(end) + 1}.CIDRs()
+	if len(c) != 1 {
+		panic("invalid cidr")
+	}
+	return c[0]
+}

net/bridge.go

@@ -15,7 +15,6 @@ import (
 	"github.com/weaveworks/weave/common"
 	"github.com/weaveworks/weave/common/chains"
 	"github.com/weaveworks/weave/common/odp"
-	"github.com/weaveworks/weave/ipam/tracker"
 	"github.com/weaveworks/weave/net/address"
 	"github.com/weaveworks/weave/net/ipset"
 )
@@ -606,9 +605,9 @@ func (t *NoMasqLocalTracker) HandleUpdate(prevRanges, currRanges []address.Range
 		return nil
 	}
 
-	prev, curr := tracker.RemoveCommon(
-		address.NewCIDRs(tracker.Merge(prevRanges)),
-		address.NewCIDRs(tracker.Merge(currRanges)))
+	prev, curr := address.RemoveCommon(
+		address.NewCIDRs(address.Merge(prevRanges)),
+		address.NewCIDRs(address.Merge(currRanges)))
 
 	for _, cidr := range curr {
 		if err := t.ips.AddEntry(t.owner, NoMasqLocalIpset, cidr.String(), ""); err != nil {