From 244af0e631fedc0356eefd7f1bb7541ee773a44e Mon Sep 17 00:00:00 2001
From: Star Brilliant <m13253@hotmail.com>
Date: Fri, 24 Nov 2017 22:04:36 +0800
Subject: [PATCH] Add option -no-ecs

---
 doh-client/client.go | 7 ++++++-
 doh-client/main.go   | 3 ++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/doh-client/client.go b/doh-client/client.go
index 09e3c3e..f9873c3 100644
--- a/doh-client/client.go
+++ b/doh-client/client.go
@@ -39,16 +39,18 @@ type Client struct {
 	upstream		string
 	bootstrap		string
 	timeout			uint
+	noECS			bool
 	udpServer		*dns.Server
 	tcpServer		*dns.Server
 	httpClient		*http.Client
 }
 
-func NewClient(addr, upstream, bootstrap string, timeout uint) (c *Client, err error) {
+func NewClient(addr, upstream, bootstrap string, timeout uint, noECS bool) (c *Client, err error) {
 	c = &Client {
 		addr: addr,
 		upstream: upstream,
 		timeout: timeout,
+		noECS: noECS,
 	}
 	c.udpServer = &dns.Server {
 		Addr: addr,
@@ -224,6 +226,9 @@ var (
 
 func (c *Client) findClientIP(w dns.ResponseWriter, r *dns.Msg) (ednsClientAddress net.IP, ednsClientNetmask uint8) {
 	ednsClientNetmask = 255
+	if c.noECS {
+		return net.IPv4(0, 0, 0, 0), 0
+	}
 	if opt := r.IsEdns0(); opt != nil {
 		for _, option := range opt.Option {
 			if option.Option() == dns.EDNS0SUBNET {
diff --git a/doh-client/main.go b/doh-client/main.go
index 1242572..ef3c157 100644
--- a/doh-client/main.go
+++ b/doh-client/main.go
@@ -28,9 +28,10 @@ func main() {
 	upstream := flag.String("upstream", "https://dns.google.com/resolve", "HTTP path for upstream resolver")
 	bootstrap := flag.String("bootstrap", "", "The bootstrap DNS server to resolve the address of the upstream resolver")
 	timeout := flag.Uint("timeout", 10, "Timeout for upstream request")
+	noECS := flag.Bool("no-ecs", false, "Disable EDNS0-Client-Subnet, do not send client's IP address")
 	flag.Parse()
 
-	client, err := NewClient(*addr, *upstream, *bootstrap, *timeout)
+	client, err := NewClient(*addr, *upstream, *bootstrap, *timeout, *noECS)
 	if err != nil { log.Fatalln(err) }
 	_ = client.Start()
 }