dns

commit 6b8f8a165e7b32c133ee48fc2233f91692db5d91
parent 1c3a28b4e3d5fcd9374467eac2287607a1a8e669
Author: Oliver Lowe <o@olowe.co>
Date:   Sat, 20 Nov 2021 12:31:22 +1100

cmd/dohproxy: only ever read max dns message size

Even if content-length header is omitted.
While here remove unused constants.

Diffstat:
M
cmd/dohproxy/dohproxy.go
 | 
15
++++++---------

1 file changed, 6 insertions(+), 9 deletions(-)
diff --git a/cmd/dohproxy/dohproxy.go b/cmd/dohproxy/dohproxy.go
@@ -13,10 +13,6 @@ import (
 	"git.sr.ht/~otl/dns"
 )
 
-// https://quad9.net
-const quad9 string = "9.9.9.9:domain"
-const cloudflare string = "1.1.1.1:domain"
-
 func dnsHandler(w http.ResponseWriter, req *http.Request) {
 	if v, ok := req.Header["Content-Type"]; ok {
 		for _, s := range v {
@@ -54,10 +50,12 @@ func dnsHandler(w http.ResponseWriter, req *http.Request) {
 		return
 	}
 
-	buf := make([]byte, 512)
+	buf := make([]byte, dns.MaxMsgSize)
+	var n int
+	var err error
 	switch req.Method {
 	case http.MethodPost:
-		_, err := req.Body.Read(buf)
+		n, err = req.Body.Read(buf)
 		if err != nil && err != io.EOF {
 			http.Error(w, err.Error(), http.StatusInternalServerError)
 			return
@@ -70,13 +68,12 @@ func dnsHandler(w http.ResponseWriter, req *http.Request) {
 	}
 
 	var msg dnsmessage.Message
-	if err := msg.Unpack(buf); err != nil {
+	if err := msg.Unpack(buf[:n]); err != nil {
 		log.Println("unpack query:", err)
 		http.Error(w, "unpack query: "+err.Error(), http.StatusInternalServerError)
 	}
 
 	var resolved dnsmessage.Message
-	var err error
 	if conf.usetls {
 		resolved, err = dns.ExchangeTLS(msg, conf.forwardaddr)
 	} else {
@@ -89,7 +86,7 @@ func dnsHandler(w http.ResponseWriter, req *http.Request) {
 	}
 	packed, err := resolved.Pack()
 	if err != nil {
-		log.Println("pack resolved query:", err.Error)
+		log.Println("pack resolved query:", err.Error())
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}