Chore: mix the proxy adapter and interface to dns client

README.md

@@ -76,7 +76,7 @@ mitm:
 ```
 
 ### DNS configuration
-Support resolve ip with a proxy tunnel.
+Support resolve ip with a proxy tunnel or interface.
 
 Support `geosite` with `fallback-filter`.
 
@@ -96,8 +96,8 @@ Use `curl -X POST controllerip:port/cache/fakeip/flush` to flush persistence fak
      - https://doh.pub/dns-query
      - tls://223.5.5.5:853
    fallback:
+     - 'tls://8.8.4.4:853#proxy or interface'
      - 'https://1.0.0.1/dns-query#Proxy'  # append the proxy adapter name to the end of DNS URL with '#' prefix.
-     - 'tls://8.8.4.4:853#Proxy'
    fallback-filter:
      geoip: false
      geosite:

dns/client.go

@@ -54,10 +54,14 @@ func (c *client) ExchangeContext(ctx context.Context, m *D.Msg) (*D.Msg, error)
 	}
 
 	var conn net.Conn
-	if c.proxyAdapter == "" {
-		conn, err = dialer.DialContext(ctx, network, net.JoinHostPort(ip.String(), c.port), options...)
-	} else {
+	if c.proxyAdapter != "" {
 		conn, err = dialContextWithProxyAdapter(ctx, c.proxyAdapter, network, ip, c.port, options...)
+		if err == errProxyNotFound {
+			options = append(options[:0], dialer.WithInterface(c.proxyAdapter), dialer.WithRoutingMark(0))
+			conn, err = dialer.DialContext(ctx, network, net.JoinHostPort(ip.String(), c.port), options...)
+		}
+	} else {
+		conn, err = dialer.DialContext(ctx, network, net.JoinHostPort(ip.String(), c.port), options...)
 	}
 
 	if err != nil {

dns/doh.go

@@ -69,7 +69,9 @@ func (dc *dohClient) doRequest(req *http.Request) (msg *D.Msg, err error) {
 	if err != nil {
 		return nil, err
 	}
-	defer resp.Body.Close()
+	defer func() {
+		_ = resp.Body.Close()
+	}()
 
 	buf, err := io.ReadAll(resp.Body)
 	if err != nil {
@@ -97,11 +99,17 @@ func newDoHClient(url string, r *Resolver, proxyAdapter string) *dohClient {
 					return nil, err
 				}
 
-				if proxyAdapter == "" {
+				if proxyAdapter != "" {
+					var conn net.Conn
+					conn, err = dialContextWithProxyAdapter(ctx, proxyAdapter, "tcp", ip, port)
+					if err == errProxyNotFound {
+						options := []dialer.Option{dialer.WithInterface(proxyAdapter), dialer.WithRoutingMark(0)}
+						conn, err = dialer.DialContext(ctx, "tcp", net.JoinHostPort(ip.String(), port), options...)
+					}
+					return conn, err
+				}
+
 				return dialer.DialContext(ctx, "tcp", net.JoinHostPort(ip.String(), port))
-				} else {
-					return dialContextWithProxyAdapter(ctx, proxyAdapter, "tcp", ip, port)
-				}
 			},
 		},
 	}

dns/util.go

@@ -3,6 +3,7 @@ package dns
 import (
 	"context"
 	"crypto/tls"
+	"errors"
 	"fmt"
 	"net"
 	"net/netip"
@@ -19,6 +20,8 @@ import (
 	D "github.com/miekg/dns"
 )
 
+var errProxyNotFound = errors.New("proxy adapter not found")
+
 func putMsgToCache(c *cache.LruCache[string, *D.Msg], key string, msg *D.Msg) {
 	var ttl uint32
 	switch {
@@ -135,7 +138,7 @@ func (wpc *wrapPacketConn) RemoteAddr() net.Addr {
 func dialContextWithProxyAdapter(ctx context.Context, adapterName string, network string, dstIP netip.Addr, port string, opts ...dialer.Option) (net.Conn, error) {
 	proxy, ok := tunnel.Proxies()[adapterName]
 	if !ok {
-		return nil, fmt.Errorf("proxy adapter [%s] not found", adapterName)
+		return nil, errProxyNotFound
 	}
 
 	networkType := C.TCP