From e80846998ce8b420068177f27ed917869232e1c4 Mon Sep 17 00:00:00 2001
From: Matt Joiner <anacrolix@gmail.com>
Date: Tue, 13 Dec 2016 14:45:40 +1100
Subject: [PATCH] dht: Reply with Method Unknown error to unknown query methods
 received

---
 dht/krpc/error.go |  5 +++++
 dht/server.go     | 21 +++++++++++++++++----
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/dht/krpc/error.go b/dht/krpc/error.go
index fddd0f48..d4b248a7 100644
--- a/dht/krpc/error.go
+++ b/dht/krpc/error.go
@@ -6,6 +6,11 @@ import (
 	"github.com/anacrolix/torrent/bencode"
 )
 
+var ErrorMethodUnknown = KRPCError{
+	Code: 204,
+	Msg:  "Method Unknown",
+}
+
 // Represented as a string or list in bencode.
 type KRPCError struct {
 	Code int
diff --git a/dht/server.go b/dht/server.go
index 7e910979..14042c6e 100644
--- a/dht/server.go
+++ b/dht/server.go
@@ -333,11 +333,24 @@ func (s *Server) handleQuery(source Addr, m krpc.Msg) {
 			}
 			go h(ih, p)
 		}
-	case "vote":
-		// TODO(anacrolix): Or reject, I don't think I want this.
 	default:
-		log.Printf("%s: not handling received query: q=%s", s, m.Q)
-		return
+		s.sendError(source, m.T, krpc.ErrorMethodUnknown)
+	}
+}
+
+func (s *Server) sendError(addr Addr, t string, e krpc.KRPCError) {
+	m := krpc.Msg{
+		T: t,
+		Y: "e",
+		E: &e,
+	}
+	b, err := bencode.Marshal(m)
+	if err != nil {
+		panic(err)
+	}
+	err = s.writeToNode(b, addr)
+	if err != nil {
+		log.Printf("error replying to %s: %s", addr, err)
 	}
 }
 
-- 
2.48.1