Require URLs for DOH addresses (#684)

* Require URLs for DOH addresses

* Move time.Now directly above http.Client.Do in DoH

* Remove https scheme check from DOH

Although the draft RFC explicitly requires that the scheme be https,
this was deemed undesirable, so remove it.

client.go

@@ -12,7 +12,6 @@ import (
 	"io/ioutil"
 	"net"
 	"net/http"
-	"net/url"
 	"strings"
 	"time"
 )
@@ -216,17 +215,7 @@ func (c *Client) exchangeDOH(ctx context.Context, m *Msg, a string) (r *Msg, rtt
 		return nil, 0, err
 	}
 
-	// TODO(tmthrgd): Allow the path to be customised?
+	req, err := http.NewRequest(http.MethodPost, a, bytes.NewReader(p))
-	u := &url.URL{
-		Scheme: "https",
-		Host:   a,
-		Path:   "/.well-known/dns-query",
-	}
-	if u.Port() == "443" {
-		u.Host = u.Hostname()
-	}
-
-	req, err := http.NewRequest(http.MethodPost, u.String(), bytes.NewReader(p))
 	if err != nil {
 		return nil, 0, err
 	}
@@ -234,8 +223,6 @@ func (c *Client) exchangeDOH(ctx context.Context, m *Msg, a string) (r *Msg, rtt
 	req.Header.Set("Content-Type", dohMimeType)
 	req.Header.Set("Accept", dohMimeType)
 
-	t := time.Now()
-
 	hc := http.DefaultClient
 	if c.HTTPClient != nil {
 		hc = c.HTTPClient
@@ -245,6 +232,8 @@ func (c *Client) exchangeDOH(ctx context.Context, m *Msg, a string) (r *Msg, rtt
 		req = req.WithContext(ctx)
 	}
 
+	t := time.Now()
+
 	resp, err := hc.Do(req)
 	if err != nil {
 		return nil, 0, err

client_test.go

@@ -590,7 +590,7 @@ func TestConcurrentExchanges(t *testing.T) {
 }
 
 func TestDoHExchange(t *testing.T) {
-	const addrstr = "dns.cloudflare.com:443"
+	const addrstr = "https://dns.cloudflare.com/dns-query"
 
 	m := new(Msg)
 	m.SetQuestion("miek.nl.", TypeSOA)