Update deps

vendor/github.com/miekg/dns/client.go

@@ -7,8 +7,12 @@ import (
 	"context"
 	"crypto/tls"
 	"encoding/binary"
+	"fmt"
 	"io"
+	"io/ioutil"
 	"net"
+	"net/http"
+	"net/url"
 	"strings"
 	"time"
 )
@@ -16,6 +20,8 @@ import (
 const dnsTimeout time.Duration = 2 * time.Second
 const tcpIdleTimeout time.Duration = 8 * time.Second
 
+const dohMimeType = "application/dns-udpwireformat"
+
 // A Conn represents a connection to a DNS server.
 type Conn struct {
 	net.Conn                         // a net.Conn holding the connection
@@ -37,6 +43,7 @@ type Client struct {
 	DialTimeout    time.Duration     // net.DialTimeout, defaults to 2 seconds, or net.Dialer.Timeout if expiring earlier - overridden by Timeout when that value is non-zero
 	ReadTimeout    time.Duration     // net.Conn.SetReadTimeout value for connections, defaults to 2 seconds - overridden by Timeout when that value is non-zero
 	WriteTimeout   time.Duration     // net.Conn.SetWriteTimeout value for connections, defaults to 2 seconds - overridden by Timeout when that value is non-zero
+	HTTPClient     *http.Client      // The http.Client to use for DNS-over-HTTPS
 	TsigSecret     map[string]string // secret(s) for Tsig map[<zonename>]<base64 secret>, zonename must be in canonical form (lowercase, fqdn, see RFC 4034 Section 6.2)
 	SingleInflight bool              // if true suppress multiple outstanding queries for the same Qname, Qtype and Qclass
 	group          singleflight
@@ -134,6 +141,11 @@ func (c *Client) Dial(address string) (conn *Conn, err error) {
 // attribute appropriately
 func (c *Client) Exchange(m *Msg, address string) (r *Msg, rtt time.Duration, err error) {
 	if !c.SingleInflight {
+		if c.Net == "https" {
+			// TODO(tmthrgd): pipe timeouts into exchangeDOH
+			return c.exchangeDOH(context.TODO(), m, address)
+		}
+
 		return c.exchange(m, address)
 	}
 
@@ -146,6 +158,11 @@ func (c *Client) Exchange(m *Msg, address string) (r *Msg, rtt time.Duration, er
 		cl = cl1
 	}
 	r, rtt, err, shared := c.group.Do(m.Question[0].Name+t+cl, func() (*Msg, time.Duration, error) {
+		if c.Net == "https" {
+			// TODO(tmthrgd): pipe timeouts into exchangeDOH
+			return c.exchangeDOH(context.TODO(), m, address)
+		}
+
 		return c.exchange(m, address)
 	})
 	if r != nil && shared {
@@ -191,6 +208,77 @@ func (c *Client) exchange(m *Msg, a string) (r *Msg, rtt time.Duration, err erro
 	return r, rtt, err
 }
 
+func (c *Client) exchangeDOH(ctx context.Context, m *Msg, a string) (r *Msg, rtt time.Duration, err error) {
+	p, err := m.Pack()
+	if err != nil {
+		return nil, 0, err
+	}
+
+	// TODO(tmthrgd): Allow the path to be customised?
+	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
+	}
+
+	req.Header.Set("Content-Type", dohMimeType)
+	req.Header.Set("Accept", dohMimeType)
+
+	t := time.Now()
+
+	hc := http.DefaultClient
+	if c.HTTPClient != nil {
+		hc = c.HTTPClient
+	}
+
+	if ctx != context.Background() && ctx != context.TODO() {
+		req = req.WithContext(ctx)
+	}
+
+	resp, err := hc.Do(req)
+	if err != nil {
+		return nil, 0, err
+	}
+	defer closeHTTPBody(resp.Body)
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, 0, fmt.Errorf("dns: server returned HTTP %d error: %q", resp.StatusCode, resp.Status)
+	}
+
+	if ct := resp.Header.Get("Content-Type"); ct != dohMimeType {
+		return nil, 0, fmt.Errorf("dns: unexpected Content-Type %q; expected %q", ct, dohMimeType)
+	}
+
+	p, err = ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, 0, err
+	}
+
+	rtt = time.Since(t)
+
+	r = new(Msg)
+	if err := r.Unpack(p); err != nil {
+		return r, 0, err
+	}
+
+	// TODO: TSIG? Is it even supported over DoH?
+
+	return r, rtt, nil
+}
+
+func closeHTTPBody(r io.ReadCloser) error {
+	io.Copy(ioutil.Discard, io.LimitReader(r, 8<<20))
+	return r.Close()
+}
+
 // ReadMsg reads a message from the connection co.
 // If the received message contains a TSIG record the transaction signature
 // is verified. This method always tries to return the message, however if an
@@ -490,6 +578,10 @@ func DialTimeoutWithTLS(network, address string, tlsConfig *tls.Config, timeout
 // context, if present. If there is both a context deadline and a configured
 // timeout on the client, the earliest of the two takes effect.
 func (c *Client) ExchangeContext(ctx context.Context, m *Msg, a string) (r *Msg, rtt time.Duration, err error) {
+	if !c.SingleInflight && c.Net == "https" {
+		return c.exchangeDOH(ctx, m, a)
+	}
+
 	var timeout time.Duration
 	if deadline, ok := ctx.Deadline(); !ok {
 		timeout = 0
@@ -498,6 +590,7 @@ func (c *Client) ExchangeContext(ctx context.Context, m *Msg, a string) (r *Msg,
 	}
 	// not passing the context to the underlying calls, as the API does not support
 	// context. For timeouts you should set up Client.Dialer and call Client.Exchange.
+	// TODO(tmthrgd): this is a race condition
 	c.Dialer = &net.Dialer{Timeout: timeout}
 	return c.Exchange(m, a)
 }