Identity and version support for the dnstap plugin (#5555)

* Added identity and version support to dnstap plugin

Signed-off-by: Daniel Jolly <code@danieljolly.com>

* Added missing commas

Signed-off-by: Daniel Jolly <code@danieljolly.com>

* Moved byte slice conversions to setup rather than handler.
Fixed indentation issue.

Signed-off-by: Daniel Jolly <code@danieljolly.com>

* Improved setup config parsing and added tests to detect various configurations

Signed-off-by: Daniel Jolly <code@danieljolly.com>

Signed-off-by: Daniel Jolly <code@danieljolly.com>
Co-authored-by: Daniel Jolly <code@danieljolly.com>

4 files changed, 67 insertions, 10 deletions

diff --git a/plugin/dnstap/README.md b/plugin/dnstap/README.md
index 029a93907..8e5615772 100644
--- a/plugin/dnstap/README.md
+++ b/plugin/dnstap/README.md
@@ -15,11 +15,16 @@ Every message is sent to the socket as soon as it comes in, the *dnstap* plugin
 ## Syntax
 
 ~~~ txt
-dnstap SOCKET [full]
+dnstap SOCKET [full] {
+  [identity IDENTITY]
+  [version VERSION]
+}
 ~~~
 
 * **SOCKET** is the socket (path) supplied to the dnstap command line tool.
 * `full` to include the wire-format DNS message.
+* **IDENTITY** to override the identity of the server. Defaults to the hostname.
+* **VERSION** to override the version field. Defaults to the CoreDNS version.
 
 ## Examples
 
@@ -47,6 +52,15 @@ Log to a remote endpoint by FQDN.
 dnstap tcp://example.com:6000 full
 ~~~
 
+Log to a socket, overriding the default identity and version.
+
+~~~ txt
+dnstap /tmp/dnstap.sock {
+  identity my-dns-server1
+  version MyDNSServer-1.2.3
+}
+~~~
+
 ## Command Line Tool
 
 Dnstap has a command line tool that can be used to inspect the logging. The tool can be found
diff --git a/plugin/dnstap/handler.go b/plugin/dnstap/handler.go
index 04d29860e..e8a1fbc4a 100644
--- a/plugin/dnstap/handler.go
+++ b/plugin/dnstap/handler.go
@@ -18,12 +18,14 @@ type Dnstap struct {
 
 	// IncludeRawMessage will include the raw DNS message into the dnstap messages if true.
 	IncludeRawMessage bool
+	Identity []byte
+	Version []byte
 }
 
 // TapMessage sends the message m to the dnstap interface.
 func (h Dnstap) TapMessage(m *tap.Message) {
 	t := tap.Dnstap_MESSAGE
-	h.io.Dnstap(&tap.Dnstap{Type: &t, Message: m})
+	h.io.Dnstap(&tap.Dnstap{Type: &t, Message: m, Identity: h.Identity, Version: h.Version})
 }
 
 func (h Dnstap) tapQuery(w dns.ResponseWriter, query *dns.Msg, queryTime time.Time) {
diff --git a/plugin/dnstap/setup.go b/plugin/dnstap/setup.go
index dfe63f38b..d7d1cdc1b 100644
--- a/plugin/dnstap/setup.go
+++ b/plugin/dnstap/setup.go
@@ -2,6 +2,7 @@ package dnstap
 
 import (
 	"net/url"
+	"os"
 	"strings"
 
 	"github.com/coredns/caddy"
@@ -19,10 +20,14 @@ func parseConfig(c *caddy.Controller) (Dnstap, error) {
 	d := Dnstap{}
 	endpoint := ""
 
-	if !c.Args(&endpoint) {
+	args := c.RemainingArgs()
+
+	if len(args) == 0 {
 		return d, c.ArgErr()
 	}
 
+	endpoint = args[0]
+
 	if strings.HasPrefix(endpoint, "tcp://") {
 		// remote network endpoint
 		endpointURL, err := url.Parse(endpoint)
@@ -37,7 +42,30 @@ func parseConfig(c *caddy.Controller) (Dnstap, error) {
 		d = Dnstap{io: dio}
 	}
 
-	d.IncludeRawMessage = c.NextArg() && c.Val() == "full"
+	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 d, c.ArgErr()
+				}
+				d.Identity = []byte(c.Val())
+			}
+		case "version":
+			{
+				if !c.NextArg() {
+					return d, c.ArgErr()
+				}
+				d.Version = []byte(c.Val())
+			}
+		}
+	}
 
 	return d, nil
 }
diff --git a/plugin/dnstap/setup_test.go b/plugin/dnstap/setup_test.go
index 0c680e813..9d5f20a92 100644
--- a/plugin/dnstap/setup_test.go
+++ b/plugin/dnstap/setup_test.go
@@ -1,25 +1,32 @@
 package dnstap
 
 import (
+	"os"
 	"testing"
 
 	"github.com/coredns/caddy"
 )
 
 func TestConfig(t *testing.T) {
+	hostname, _ := os.Hostname()
 	tests := []struct {
 		in       string
 		endpoint string
 		full     bool
 		proto    string
 		fail     bool
+		identity []byte
+		version  []byte
 	}{
-		{"dnstap dnstap.sock full", "dnstap.sock", true, "unix", false},
-		{"dnstap unix://dnstap.sock", "dnstap.sock", false, "unix", false},
-		{"dnstap tcp://127.0.0.1:6000", "127.0.0.1:6000", false, "tcp", false},
-		{"dnstap tcp://[::1]:6000", "[::1]:6000", false, "tcp", false},
-		{"dnstap tcp://example.com:6000", "example.com:6000", false, "tcp", false},
-		{"dnstap", "fail", false, "tcp", true},
+		{"dnstap dnstap.sock full", "dnstap.sock", true, "unix", false, []byte(hostname), []byte("-")},
+		{"dnstap unix://dnstap.sock", "dnstap.sock", false, "unix", false, []byte(hostname), []byte("-")},
+		{"dnstap tcp://127.0.0.1:6000", "127.0.0.1:6000", false, "tcp", false, []byte(hostname), []byte("-")},
+		{"dnstap tcp://[::1]:6000", "[::1]:6000", false, "tcp", false, []byte(hostname), []byte("-")},
+		{"dnstap tcp://example.com:6000", "example.com:6000", false, "tcp", false, []byte(hostname), []byte("-")},
+		{"dnstap", "fail", false, "tcp", true, []byte(hostname), []byte("-")},
+		{"dnstap dnstap.sock full {\nidentity NAME\nversion VER\n}\n", "dnstap.sock", true, "unix", false, []byte("NAME"), []byte("VER")},
+		{"dnstap dnstap.sock {\nidentity NAME\nversion VER\n}\n", "dnstap.sock", false, "unix", false, []byte("NAME"), []byte("VER")},
+		{"dnstap {\nidentity NAME\nversion VER\n}\n", "fail", false, "tcp", true, []byte("NAME"), []byte("VER")},
 	}
 	for i, tc := range tests {
 		c := caddy.NewTestController("dns", tc.in)
@@ -43,5 +50,11 @@ func TestConfig(t *testing.T) {
 		if x := tap.IncludeRawMessage; x != tc.full {
 			t.Errorf("Test %d: expected IncludeRawMessage %t, got %t", i, tc.full, x)
 		}
+		if x := string(tap.Identity); x != string(tc.identity) {
+			t.Errorf("Test %d: expected identity %s, got %s", i, tc.identity, x)
+		}
+		if x := string(tap.Version); x != string(tc.version) {
+			t.Errorf("Test %d: expected version %s, got %s", i, tc.version, x)
+		}
 	}
 }