dnsseed: serve results

README.md

@@ -2,4 +2,22 @@
 
 This is a CoreDNS plugin that scrapes addresses of peers from a Zcash network. It's intended as a safer and more scalable replacement for the [zcash-seeder](https://github.com/zcash/zcash-seeder) project.
 
-It uses [btcsuite](https://github.com/btcsuite) for networking and [crawshaw/sqlite](https://crawshaw.io/blog/go-and-sqlite) for storing peer data.
+It's written in Go and uses [btcsuite](https://github.com/btcsuite) for low-level networking.
+
+### Build instructions
+
+TODO
+
+### CoreDNS configuration
+
+A sample Corefile that configures `mainnet.seeder.yolo.money` and `testnet.seeder.yolo.money` using two local Zcash nodes:
+
+```
+mainnet.seeder.yolo.money {
+    dnsseed yolo.money mainnet 127.0.0.1:8233
+}
+
+testnet.seeder.yolo.money {
+    dnsseed yolo.money testnet 127.0.0.1:18233
+}
+```

dnsseed/dnsseed.go

@@ -39,32 +39,22 @@ func (zs ZcashSeeder) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns
 	a := new(dns.Msg)
 	a.SetReply(r)
 	a.Authoritative = true
-
-	a.Extra = make([]dns.RR, 0, len(peerIPs))
+	a.Answer = make([]dns.RR, 0, 25)
 
 	for i := 0; i < len(peerIPs); i++ {
 		var rr dns.RR
 
-		ip := peerIPs[i]
-
-		switch state.QType() {
-		case dns.TypeA:
+		if peerIPs[i].To4() == nil {
+			rr = new(dns.AAAA)
+			rr.(*dns.AAAA).Hdr = dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeAAAA, Ttl: 3600, Class: state.QClass()}
+			rr.(*dns.AAAA).AAAA = peerIPs[i]
+		} else {
 			rr = new(dns.A)
-			rr.(*dns.A).Hdr = dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeA, Class: state.QClass()}
-			rr.(*dns.A).A = ip.To4()
-		case dns.TypeAAAA:
-			if ip.To4() != nil {
-				rr = new(dns.AAAA)
-				rr.(*dns.AAAA).Hdr = dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeAAAA, Class: state.QClass()}
-				rr.(*dns.AAAA).AAAA = ip
-			}
-		default:
-			return dns.RcodeNotImplemented, nil
+			rr.(*dns.A).Hdr = dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeA, Ttl: 3600, Class: state.QClass()}
+			rr.(*dns.A).A = peerIPs[i]
 		}
 
-		// TODO: why don't we offer SRV records? Zcash has a configurable port.
-
-		a.Extra = append(a.Extra, rr)
+		a.Answer = append(a.Answer, rr)
 	}
 
 	w.WriteMsg(a)

dnsseed/setup.go

@@ -1,6 +1,7 @@
 package dnsseed
 
 import (
+	"fmt"
 	"net"
 	"time"
 
@@ -23,11 +24,11 @@ func init() { plugin.Register("dnsseed", setup) }
 // setup is the function that gets called when the config parser see the token "dnsseed". Setup is responsible
 // for parsing any extra options the example plugin may have. The first token this function sees is "dnsseed".
 func setup(c *caddy.Controller) error {
-	var zoneArg, networkArg, hostArg string
+	var rootArg, networkArg, hostArg string
 
 	c.Next() // Ignore "dnsseed" and give us the next token.
 
-	if !c.Args(&zoneArg, &networkArg, &hostArg) {
+	if !c.Args(&rootArg, &networkArg, &hostArg) {
 		return plugin.Error("dnsseed", c.ArgErr())
 	}
 
@@ -41,6 +42,9 @@ func setup(c *caddy.Controller) error {
 		return plugin.Error("dnsseed", c.Errf("Config error: expected {mainnet, testnet}, got %s", networkArg))
 	}
 
+	// Automatically configure the responsive zone by network
+	zone := fmt.Sprintf("%s.seeder.%s.", networkArg, rootArg)
+
 	address, port, err := net.SplitHostPort(hostArg)
 	if err != nil {
 		return plugin.Error("dnsseed", c.Errf("Config error: expected 'host:port', got %s", hostArg))
@@ -81,7 +85,7 @@ func setup(c *caddy.Controller) error {
 	dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {
 		return ZcashSeeder{
 			Next:   next,
-			Zones:  []string{zoneArg},
+			Zones:  []string{zone},
 			seeder: seeder,
 		}
 	})

dnsseed/setup_test.go

@@ -9,7 +9,7 @@ import (
 
 // TestSetup tests the various things that should be parsed by setup.
 func TestSetup(t *testing.T) {
-	c := caddy.NewTestController("dns", "dnsseed mainnet.seeder.yolo.money mainnet 127.0.0.1:8233")
+	c := caddy.NewTestController("dns", "dnsseed yolo.money mainnet 127.0.0.1:8233")
 	if err := setup(c); err != nil {
 		if strings.Contains(err.Error(), "connection refused") {
 			// No local peer running