plugin/dnstap: Fix behavior when multiple dnstap plugins specified (#5773)

* fix multiple dnstap plugins behavior

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

plugin/dnstap/setup.go

@@ -15,89 +15,104 @@ var log = clog.NewWithPlugin("dnstap")
 
 func init() { plugin.Register("dnstap", setup) }
 
-func parseConfig(c *caddy.Controller) (Dnstap, error) {
-	c.Next() // directive name
-	d := Dnstap{}
-	endpoint := ""
+func parseConfig(c *caddy.Controller) ([]*Dnstap, error) {
+	dnstaps := []*Dnstap{}
 
-	args := c.RemainingArgs()
+	for c.Next() { // directive name
+		d := Dnstap{}
+		endpoint := ""
 
-	if len(args) == 0 {
-		return d, c.ArgErr()
-	}
+		args := c.RemainingArgs()
 
-	endpoint = args[0]
-
-	if strings.HasPrefix(endpoint, "tcp://") {
-		// remote network endpoint
-		endpointURL, err := url.Parse(endpoint)
-		if err != nil {
-			return d, c.ArgErr()
+		if len(args) == 0 {
+			return nil, c.ArgErr()
 		}
-		dio := newIO("tcp", endpointURL.Host)
-		d = Dnstap{io: dio}
-	} else {
-		endpoint = strings.TrimPrefix(endpoint, "unix://")
-		dio := newIO("unix", endpoint)
-		d = Dnstap{io: dio}
-	}
 
-	d.IncludeRawMessage = len(args) == 2 && args[1] == "full"
+		endpoint = args[0]
 
-	hostname, _ := os.Hostname()
-	d.Identity = []byte(hostname)
-	d.Version = []byte(caddy.AppName + "-" + caddy.AppVersion)
-
-	for c.NextBlock() {
-		switch c.Val() {
-		case "identity":
-			{
-				if !c.NextArg() {
-					return d, c.ArgErr()
-				}
-				d.Identity = []byte(c.Val())
+		if strings.HasPrefix(endpoint, "tcp://") {
+			// remote network endpoint
+			endpointURL, err := url.Parse(endpoint)
+			if err != nil {
+				return nil, c.ArgErr()
 			}
-		case "version":
-			{
-				if !c.NextArg() {
-					return d, c.ArgErr()
+			dio := newIO("tcp", endpointURL.Host)
+			d = Dnstap{io: dio}
+		} else {
+			endpoint = strings.TrimPrefix(endpoint, "unix://")
+			dio := newIO("unix", endpoint)
+			d = Dnstap{io: dio}
+		}
+
+		d.IncludeRawMessage = len(args) == 2 && args[1] == "full"
+
+		hostname, _ := os.Hostname()
+		d.Identity = []byte(hostname)
+		d.Version = []byte(caddy.AppName + "-" + caddy.AppVersion)
+
+		for c.NextBlock() {
+			switch c.Val() {
+			case "identity":
+				{
+					if !c.NextArg() {
+						return nil, c.ArgErr()
+					}
+					d.Identity = []byte(c.Val())
+				}
+			case "version":
+				{
+					if !c.NextArg() {
+						return nil, c.ArgErr()
+					}
+					d.Version = []byte(c.Val())
 				}
-				d.Version = []byte(c.Val())
 			}
 		}
+		dnstaps = append(dnstaps, &d)
 	}
-
-	return d, nil
+	return dnstaps, nil
 }
 
 func setup(c *caddy.Controller) error {
-	dnstap, err := parseConfig(c)
+	dnstaps, err := parseConfig(c)
 	if err != nil {
 		return plugin.Error("dnstap", err)
 	}
 
-	c.OnStartup(func() error {
-		if err := dnstap.io.(*dio).connect(); err != nil {
-			log.Errorf("No connection to dnstap endpoint: %s", err)
-		}
-		return nil
-	})
-
-	c.OnRestart(func() error {
-		dnstap.io.(*dio).close()
-		return nil
-	})
-
-	c.OnFinalShutdown(func() error {
-		dnstap.io.(*dio).close()
-		return nil
-	})
-
-	dnsserver.GetConfig(c).AddPlugin(
-		func(next plugin.Handler) plugin.Handler {
-			dnstap.Next = next
-			return dnstap
+	for i := range dnstaps {
+		dnstap := dnstaps[i]
+		c.OnStartup(func() error {
+			if err := dnstap.io.(*dio).connect(); err != nil {
+				log.Errorf("No connection to dnstap endpoint: %s", err)
+			}
+			return nil
 		})
 
+		c.OnRestart(func() error {
+			dnstap.io.(*dio).close()
+			return nil
+		})
+
+		c.OnFinalShutdown(func() error {
+			dnstap.io.(*dio).close()
+			return nil
+		})
+
+		if i == len(dnstaps)-1 {
+			// last dnstap plugin in block: point next to next plugin
+			dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {
+				dnstap.Next = next
+				return dnstap
+			})
+		} else {
+			// not last dnstap plugin in block: point next to next dnstap
+			nextDnstap := dnstaps[i+1]
+			dnsserver.GetConfig(c).AddPlugin(func(plugin.Handler) plugin.Handler {
+				dnstap.Next = nextDnstap
+				return dnstap
+			})
+		}
+	}
+
 	return nil
 }