From dba80e614eb6a31b6866e9c0bc5f23bff6c9b40a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E4=B8=96=E7=95=8C?= <i@sekai.icu>
Date: Wed, 29 Jul 2026 13:51:47 +0800
Subject: [PATCH] Fix local DNS transport blocking on canceled queries

---
 experimental/libbox/dns.go | 59 ++++++++++++++++++--------------------
 1 file changed, 28 insertions(+), 31 deletions(-)

diff --git a/experimental/libbox/dns.go b/experimental/libbox/dns.go
index b7b3b0f6..75472188 100644
--- a/experimental/libbox/dns.go
+++ b/experimental/libbox/dns.go
@@ -13,7 +13,6 @@ import (
 	"github.com/sagernet/sing/common"
 	E "github.com/sagernet/sing/common/exceptions"
 	M "github.com/sagernet/sing/common/metadata"
-	"github.com/sagernet/sing/common/task"
 
 	mDNS "github.com/miekg/dns"
 )
@@ -58,24 +57,23 @@ func (p *platformTransport) Exchange(ctx context.Context, message *mDNS.Msg) (*m
 		if err != nil {
 			return nil, err
 		}
-		var responseMessage *mDNS.Msg
-		var group task.Group
-		group.Append0(func(ctx context.Context) error {
-			err = p.iif.Exchange(response, messageBytes)
+		done := make(chan error, 1)
+		go func() {
+			exchangeErr := p.iif.Exchange(response, messageBytes)
+			if exchangeErr == nil {
+				exchangeErr = response.error
+			}
+			done <- exchangeErr
+		}()
+		select {
+		case err = <-done:
 			if err != nil {
-				return err
+				return nil, err
 			}
-			if response.error != nil {
-				return response.error
-			}
-			responseMessage = &response.message
-			return nil
-		})
-		err = group.Run(ctx)
-		if err != nil {
-			return nil, err
+			return &response.message, nil
+		case <-ctx.Done():
+			return nil, ctx.Err()
 		}
-		return responseMessage, nil
 	} else {
 		question := message.Question[0]
 		var network string
@@ -87,24 +85,23 @@ func (p *platformTransport) Exchange(ctx context.Context, message *mDNS.Msg) (*m
 		default:
 			return nil, E.New("only IP queries are supported by current version of Android")
 		}
-		var responseAddrs []netip.Addr
-		var group task.Group
-		group.Append0(func(ctx context.Context) error {
-			err := p.iif.Lookup(response, network, question.Name)
+		done := make(chan error, 1)
+		go func() {
+			lookupErr := p.iif.Lookup(response, network, question.Name)
+			if lookupErr == nil {
+				lookupErr = response.error
+			}
+			done <- lookupErr
+		}()
+		select {
+		case err := <-done:
 			if err != nil {
-				return err
+				return nil, err
 			}
-			if response.error != nil {
-				return response.error
-			}
-			responseAddrs = response.addresses
-			return nil
-		})
-		err := group.Run(ctx)
-		if err != nil {
-			return nil, err
+			return dns.FixedResponse(message.Id, question, response.addresses, C.DefaultDNSTTL), nil
+		case <-ctx.Done():
+			return nil, ctx.Err()
 		}
-		return dns.FixedResponse(message.Id, question, responseAddrs, C.DefaultDNSTTL), nil
 	}
 }