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/erratic/setup.go

@@ -0,0 +1,117 @@
+package erratic
+
+import (
+	"fmt"
+	"strconv"
+	"time"
+
+	"github.com/coredns/coredns/core/dnsserver"
+	"github.com/coredns/coredns/plugin"
+
+	"github.com/mholt/caddy"
+)
+
+func init() {
+	caddy.RegisterPlugin("erratic", caddy.Plugin{
+		ServerType: "dns",
+		Action:     setupErratic,
+	})
+}
+
+func setupErratic(c *caddy.Controller) error {
+	e, err := parseErratic(c)
+	if err != nil {
+		return plugin.Error("erratic", err)
+	}
+
+	dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {
+		return e
+	})
+
+	return nil
+}
+
+func parseErratic(c *caddy.Controller) (*Erratic, error) {
+	e := &Erratic{drop: 2}
+	drop := false // true if we've seen the drop keyword
+
+	for c.Next() { // 'erratic'
+		for c.NextBlock() {
+			switch c.Val() {
+			case "drop":
+				args := c.RemainingArgs()
+				if len(args) > 1 {
+					return nil, c.ArgErr()
+				}
+
+				if len(args) == 0 {
+					continue
+				}
+
+				amount, err := strconv.ParseInt(args[0], 10, 32)
+				if err != nil {
+					return nil, err
+				}
+				if amount < 0 {
+					return nil, fmt.Errorf("illegal amount value given %q", args[0])
+				}
+				e.drop = uint64(amount)
+				drop = true
+			case "delay":
+				args := c.RemainingArgs()
+				if len(args) > 2 {
+					return nil, c.ArgErr()
+				}
+
+				// Defaults.
+				e.delay = 2
+				e.duration = 100 * time.Millisecond
+				if len(args) == 0 {
+					continue
+				}
+
+				amount, err := strconv.ParseInt(args[0], 10, 32)
+				if err != nil {
+					return nil, err
+				}
+				if amount < 0 {
+					return nil, fmt.Errorf("illegal amount value given %q", args[0])
+				}
+				e.delay = uint64(amount)
+
+				if len(args) > 1 {
+					duration, err := time.ParseDuration(args[1])
+					if err != nil {
+						return nil, err
+					}
+					e.duration = duration
+				}
+			case "truncate":
+				args := c.RemainingArgs()
+				if len(args) > 1 {
+					return nil, c.ArgErr()
+				}
+
+				if len(args) == 0 {
+					continue
+				}
+
+				amount, err := strconv.ParseInt(args[0], 10, 32)
+				if err != nil {
+					return nil, err
+				}
+				if amount < 0 {
+					return nil, fmt.Errorf("illegal amount value given %q", args[0])
+				}
+				e.truncate = uint64(amount)
+			default:
+				return nil, c.Errf("unknown property '%s'", c.Val())
+			}
+		}
+	}
+	if (e.delay > 0 || e.truncate > 0) && !drop { // delay is set, but we've haven't seen a drop keyword, remove default drop stuff
+		e.drop = 0
+	}
+
+	return e, nil
+}