feat(dns): add support for DNS-over-HTTPS and update version

2026-06-06 11:12:05 +08:00
parent 26f3af3fdd
commit a2b9062f2c
6 changed files with 198 additions and 4 deletions
--- a/pkg/util/net/doh.go
+++ b/pkg/util/net/doh.go
@@ -0,0 +1,181 @@
+// Copyright 2026 The Lolia Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package net
+
+import (
+	"bytes"
+	"context"
+	"encoding/binary"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"sync"
+	"time"
+)
+
+const (
+	dohMimeType        = "application/dns-message"
+	dohMaxResponseSize = 65535
+	dohRequestTimeout  = 10 * time.Second
+)
+
+// SetDefaultDNSOverHTTPS replaces net.DefaultResolver with one that sends
+// DNS queries to the given DNS-over-HTTPS (RFC 8484) endpoint,
+// e.g. "https://1.1.1.1/dns-query" or "https://dns.google/dns-query".
+func SetDefaultDNSOverHTTPS(dohURL string) {
+	client := &http.Client{
+		Timeout: dohRequestTimeout,
+		Transport: &http.Transport{
+			Proxy: http.ProxyFromEnvironment,
+			DialContext: (&net.Dialer{
+				Timeout: dohRequestTimeout,
+				// Use a fresh resolver to look up the DoH server hostname itself,
+				// avoiding infinite recursion through net.DefaultResolver.
+				Resolver: &net.Resolver{},
+			}).DialContext,
+			MaxIdleConns:        10,
+			IdleConnTimeout:     90 * time.Second,
+			TLSHandshakeTimeout: 10 * time.Second,
+			ForceAttemptHTTP2:   true,
+		},
+	}
+	net.DefaultResolver = &net.Resolver{
+		PreferGo: true,
+		Dial: func(ctx context.Context, network, _ string) (net.Conn, error) {
+			return &dohConn{
+				ctx:     ctx,
+				client:  client,
+				url:     dohURL,
+				network: network,
+			}, nil
+		},
+	}
+}
+
+// dohConn adapts the DNS wire-format messages exchanged by net.Resolver
+// into DNS-over-HTTPS requests. Since dohConn does not implement
+// net.PacketConn, the resolver always uses stream (TCP-style) framing with a
+// 2-byte big-endian length prefix, regardless of the dialed network. The
+// resolver writes a query and then reads the response from the same
+// connection; the HTTP round trip happens synchronously inside Write.
+type dohConn struct {
+	ctx     context.Context
+	client  *http.Client
+	url     string
+	network string
+
+	mu       sync.Mutex
+	deadline time.Time
+	reqBuf   bytes.Buffer // unprocessed request bytes
+	respBuf  bytes.Buffer // response stream with 2-byte length prefixes
+}
+
+func (c *dohConn) Write(b []byte) (int, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	c.reqBuf.Write(b)
+	for {
+		data := c.reqBuf.Bytes()
+		if len(data) < 2 {
+			break
+		}
+		msgLen := int(binary.BigEndian.Uint16(data))
+		if len(data) < 2+msgLen {
+			break
+		}
+		msg := make([]byte, msgLen)
+		copy(msg, data[2:2+msgLen])
+		c.reqBuf.Next(2 + msgLen)
+
+		resp, err := c.roundTrip(msg)
+		if err != nil {
+			return 0, err
+		}
+		var lenBuf [2]byte
+		binary.BigEndian.PutUint16(lenBuf[:], uint16(len(resp)))
+		c.respBuf.Write(lenBuf[:])
+		c.respBuf.Write(resp)
+	}
+	return len(b), nil
+}
+
+func (c *dohConn) Read(b []byte) (int, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.respBuf.Len() == 0 {
+		return 0, io.EOF
+	}
+	return c.respBuf.Read(b)
+}
+
+func (c *dohConn) roundTrip(query []byte) ([]byte, error) {
+	ctx := c.ctx
+	if !c.deadline.IsZero() {
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithDeadline(ctx, c.deadline)
+		defer cancel()
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.url, bytes.NewReader(query))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", dohMimeType)
+	req.Header.Set("Accept", dohMimeType)
+
+	resp, err := c.client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("doh server %s returned status %d", c.url, resp.StatusCode)
+	}
+	body, err := io.ReadAll(io.LimitReader(resp.Body, dohMaxResponseSize+1))
+	if err != nil {
+		return nil, err
+	}
+	if len(body) > dohMaxResponseSize {
+		return nil, fmt.Errorf("doh response from %s exceeds %d bytes", c.url, dohMaxResponseSize)
+	}
+	return body, nil
+}
+
+func (c *dohConn) Close() error { return nil }
+
+func (c *dohConn) LocalAddr() net.Addr  { return &dohAddr{network: c.network, addr: "doh-client"} }
+func (c *dohConn) RemoteAddr() net.Addr { return &dohAddr{network: c.network, addr: c.url} }
+
+func (c *dohConn) SetDeadline(t time.Time) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.deadline = t
+	return nil
+}
+
+func (c *dohConn) SetReadDeadline(t time.Time) error  { return c.SetDeadline(t) }
+func (c *dohConn) SetWriteDeadline(t time.Time) error { return c.SetDeadline(t) }
+
+type dohAddr struct {
+	network string
+	addr    string
+}
+
+func (a *dohAddr) Network() string { return a.network }
+func (a *dohAddr) String() string  { return a.addr }