resources: net: Add net resource

This patch adds a net resource for managing nework interfaces, based
around netlink.

resources/util.go

@@ -270,3 +270,27 @@ func GetGID(group string) (int, error) {
 
 	return -1, errwrap.Wrapf(err, "group lookup error (%s)", group)
 }
+
+// StrSortedSliceCompare takes two lists of strings and returns whether or not
+// they are equivalent. It will return nil if both sets contain the same
+// elements, regardless of order, and an error if they do not.
+func StrSortedSliceCompare(a, b []string) error {
+	if len(a) != len(b) {
+		return fmt.Errorf("slices have different lengths: %d vs %d", len(a), len(b))
+	}
+
+	// make a copy of each to sort, so we don't reorder the inputs
+	x := make([]string, len(a))
+	y := make([]string, len(b))
+	copy(x, a)
+	copy(y, b)
+
+	sort.Strings(x)
+	sort.Strings(y)
+	for i := range x {
+		if x[i] != y[i] {
+			return fmt.Errorf("values do not match: %s vs %s", x[i], y[i])
+		}
+	}
+	return nil
+}