Remove the word middleware (#1067)

* Rename middleware to plugin

first pass; mostly used 'sed', few spots where I manually changed
text.

This still builds a coredns binary.

* fmt error

* Rename AddMiddleware to AddPlugin

* Readd AddMiddleware to remain backwards compat

plugin/reverse/setup.go

@@ -0,0 +1,147 @@
+package reverse
+
+import (
+	"net"
+	"regexp"
+	"sort"
+	"strconv"
+	"strings"
+
+	"github.com/coredns/coredns/core/dnsserver"
+	"github.com/coredns/coredns/plugin"
+
+	"github.com/mholt/caddy"
+)
+
+func init() {
+	caddy.RegisterPlugin("reverse", caddy.Plugin{
+		ServerType: "dns",
+		Action:     setupReverse,
+	})
+}
+
+func setupReverse(c *caddy.Controller) error {
+	networks, fallThrough, err := reverseParse(c)
+	if err != nil {
+		return plugin.Error("reverse", err)
+	}
+
+	dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {
+		return Reverse{Next: next, Networks: networks, Fallthrough: fallThrough}
+	})
+
+	return nil
+}
+
+func reverseParse(c *caddy.Controller) (nets networks, fall bool, err error) {
+	zones := make([]string, len(c.ServerBlockKeys))
+	wildcard := false
+
+	// We copy from the serverblock, these contains Hosts.
+	for i, str := range c.ServerBlockKeys {
+		zones[i] = plugin.Host(str).Normalize()
+	}
+
+	for c.Next() {
+		var cidrs []*net.IPNet
+
+		// parse all networks
+		for _, cidr := range c.RemainingArgs() {
+			if cidr == "{" {
+				break
+			}
+			_, ipnet, err := net.ParseCIDR(cidr)
+			if err != nil {
+				return nil, false, c.Errf("network needs to be CIDR formatted: %q\n", cidr)
+			}
+			cidrs = append(cidrs, ipnet)
+		}
+		if len(cidrs) == 0 {
+			return nil, false, c.ArgErr()
+		}
+
+		// set defaults
+		var (
+			template = "ip-" + templateNameIP + ".{zone[1]}"
+			ttl      = 60
+		)
+		for c.NextBlock() {
+			switch c.Val() {
+			case "hostname":
+				if !c.NextArg() {
+					return nil, false, c.ArgErr()
+				}
+				template = c.Val()
+
+			case "ttl":
+				if !c.NextArg() {
+					return nil, false, c.ArgErr()
+				}
+				ttl, err = strconv.Atoi(c.Val())
+				if err != nil {
+					return nil, false, err
+				}
+
+			case "wildcard":
+				wildcard = true
+
+			case "fallthrough":
+				fall = true
+
+			default:
+				return nil, false, c.ArgErr()
+			}
+		}
+
+		// prepare template
+		// replace {zone[index]} by the listen zone/domain of this config block
+		for i, zone := range zones {
+			// TODO: we should be smarter about actually replacing this. This works, but silently allows "zone[-1]"
+			// for instance.
+			template = strings.Replace(template, "{zone["+strconv.Itoa(i+1)+"]}", zone, 1)
+		}
+		if !strings.HasSuffix(template, ".") {
+			template += "."
+		}
+
+		// extract zone from template
+		templateZone := strings.SplitAfterN(template, ".", 2)
+		if len(templateZone) != 2 || templateZone[1] == "" {
+			return nil, false, c.Errf("cannot find domain in template '%v'", template)
+		}
+
+		// Create for each configured network in this stanza
+		for _, ipnet := range cidrs {
+			// precompile regex for hostname to ip matching
+			regexIP := regexMatchV4
+			if ipnet.IP.To4() == nil {
+				regexIP = regexMatchV6
+			}
+			prefix := "^"
+			if wildcard {
+				prefix += ".*"
+			}
+			regex, err := regexp.Compile(
+				prefix + strings.Replace( // inject ip regex into template
+					regexp.QuoteMeta(template), // escape dots
+					regexp.QuoteMeta(templateNameIP),
+					regexIP,
+					1) + "$")
+			if err != nil {
+				return nil, false, err
+			}
+
+			nets = append(nets, network{
+				IPnet:        ipnet,
+				Zone:         templateZone[1],
+				Template:     template,
+				RegexMatchIP: regex,
+				TTL:          uint32(ttl),
+			})
+		}
+	}
+
+	// sort by cidr
+	sort.Sort(nets)
+	return nets, fall, nil
+}