parse config

README.md

@@ -0,0 +1,25 @@
+A plugin to override A and AAAA records with a custom value. 
+I made this to override the public IP address of my server with its VPN IP address.
+
+There is probably a better way to do this, but I couldn't find it.
+
+# Usage
+
+Add this to your `plugin.cfg`:
+```
+    override:git.kapelle.org/niklas/coredns-override
+```
+
+In your `Corefile`:
+```
+. {
+    override {
+        12.34.56.78 10.0.0.1
+        98.76.54.32 10.0.0.2
+    }
+
+    forward . 1.1.1.1
+}
+```
+
+

ResponseWrapper.go

@@ -3,12 +3,9 @@ package override
 import (
 	"net"
 
-	clog "github.com/coredns/coredns/plugin/pkg/log"
 	"github.com/miekg/dns"
 )
 
-var log = clog.NewWithPlugin("overide")
-
 type Rule struct {
 	Search   net.IP
 	Override net.IP
@@ -22,23 +19,31 @@ type ResponseWrapper struct {
 func (r *ResponseWrapper) WriteMsg(res *dns.Msg) error {
 	for _, r := range r.Rules {
 		for _, rr := range res.Answer {
-			if rr.Header().Rrtype == dns.TypeA {
+			overideRR(r, rr)
-				a := rr.(*dns.A)
+		}
-				if a.A.Equal(r.Search) {
+
-					a.A = r.Override
+		for _, rr := range res.Extra {
-				}
+			overideRR(r, rr)
-			} else if rr.Header().Rrtype == dns.TypeAAAA {
-				a := rr.(*dns.AAAA)
-				if a.AAAA.Equal(r.Search) {
-					a.AAAA = r.Override
-				}
-			}
 		}
 	}
 
 	return r.ResponseWriter.WriteMsg(res)
 }
 
+func overideRR(r Rule, rr dns.RR) {
+	if rr.Header().Rrtype == dns.TypeA {
+		a := rr.(*dns.A)
+		if a.A.Equal(r.Search) {
+			a.A = r.Override
+		}
+	} else if rr.Header().Rrtype == dns.TypeAAAA {
+		a := rr.(*dns.AAAA)
+		if a.AAAA.Equal(r.Search) {
+			a.AAAA = r.Override
+		}
+	}
+}
+
 func (r *ResponseWrapper) Write(buf []byte) (int, error) {
 	log.Warning("ResponseWrapper called with Write: not ensuring overide")
 	return r.ResponseWriter.Write(buf)

setup.go

@@ -6,8 +6,11 @@ import (
 	"github.com/coredns/caddy"
 	"github.com/coredns/coredns/core/dnsserver"
 	"github.com/coredns/coredns/plugin"
+	clog "github.com/coredns/coredns/plugin/pkg/log"
 )
 
+var log = clog.NewWithPlugin("overide")
+
 func init() {
 	plugin.Register("override", setup)
 }
@@ -31,10 +34,25 @@ func setup(c *caddy.Controller) error {
 func parseRules(c *caddy.Controller) ([]Rule, error) {
 	var rules []Rule
 
-	rules = append(rules, Rule{
+	for c.Next() {
-		Search:   net.ParseIP("45.9.63.244"),
+		for c.NextBlock() {
-		Override: net.ParseIP("10.0.0.1"),
+			searchIP := net.ParseIP(c.Val())
-	})
+			if searchIP == nil {
+				return nil, c.Errf("invalid search IP: %s", c.Val())
+			}
+
+			if !c.NextArg() {
+				return nil, c.ArgErr()
+			}
+
+			overrideIP := net.ParseIP(c.Val())
+			if overrideIP == nil {
+				return nil, c.Errf("invalid override IP: %s", c.Val())
+			}
+
+			rules = append(rules, Rule{Search: searchIP, Override: overrideIP})
+		}
+	}
 
 	return rules, nil
 }