Add dns proxy response ttl control (#3323)

proxy/dns/config.pb.go

@@ -21,10 +21,12 @@ type Config struct {
 	state protoimpl.MessageState `protogen:"open.v1"`
 	// Server is the DNS server address. If specified, this address overrides the
 	// original one.
-	Server        *net.Endpoint `protobuf:"bytes,1,opt,name=server,proto3" json:"server,omitempty"`
-	UserLevel     uint32        `protobuf:"varint,2,opt,name=user_level,json=userLevel,proto3" json:"user_level,omitempty"`
-	unknownFields protoimpl.UnknownFields
-	sizeCache     protoimpl.SizeCache
+	Server              *net.Endpoint `protobuf:"bytes,1,opt,name=server,proto3" json:"server,omitempty"`
+	UserLevel           uint32        `protobuf:"varint,2,opt,name=user_level,json=userLevel,proto3" json:"user_level,omitempty"`
+	OverrideResponseTtl bool          `protobuf:"varint,4,opt,name=override_response_ttl,json=overrideResponseTtl,proto3" json:"override_response_ttl,omitempty"`
+	ResponseTtl         uint32        `protobuf:"varint,3,opt,name=response_ttl,json=responseTtl,proto3" json:"response_ttl,omitempty"`
+	unknownFields       protoimpl.UnknownFields
+	sizeCache           protoimpl.SizeCache
 }
 
 func (x *Config) Reset() {
@@ -71,10 +73,26 @@ func (x *Config) GetUserLevel() uint32 {
 	return 0
 }
 
+func (x *Config) GetOverrideResponseTtl() bool {
+	if x != nil {
+		return x.OverrideResponseTtl
+	}
+	return false
+}
+
+func (x *Config) GetResponseTtl() uint32 {
+	if x != nil {
+		return x.ResponseTtl
+	}
+	return 0
+}
+
 type SimplifiedConfig struct {
-	state         protoimpl.MessageState `protogen:"open.v1"`
-	unknownFields protoimpl.UnknownFields
-	sizeCache     protoimpl.SizeCache
+	state               protoimpl.MessageState `protogen:"open.v1"`
+	OverrideResponseTtl bool                   `protobuf:"varint,4,opt,name=override_response_ttl,json=overrideResponseTtl,proto3" json:"override_response_ttl,omitempty"`
+	ResponseTtl         uint32                 `protobuf:"varint,3,opt,name=response_ttl,json=responseTtl,proto3" json:"response_ttl,omitempty"`
+	unknownFields       protoimpl.UnknownFields
+	sizeCache           protoimpl.SizeCache
 }
 
 func (x *SimplifiedConfig) Reset() {
@@ -107,6 +125,20 @@ func (*SimplifiedConfig) Descriptor() ([]byte, []int) {
 	return file_proxy_dns_config_proto_rawDescGZIP(), []int{1}
 }
 
+func (x *SimplifiedConfig) GetOverrideResponseTtl() bool {
+	if x != nil {
+		return x.OverrideResponseTtl
+	}
+	return false
+}
+
+func (x *SimplifiedConfig) GetResponseTtl() uint32 {
+	if x != nil {
+		return x.ResponseTtl
+	}
+	return 0
+}
+
 var File_proxy_dns_config_proto protoreflect.FileDescriptor
 
 var file_proxy_dns_config_proto_rawDesc = string([]byte{
@@ -116,22 +148,33 @@ var file_proxy_dns_config_proto_rawDesc = string([]byte{
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 })
 
 var (

proxy/dns/config.proto

@@ -14,9 +14,15 @@ message Config {
   // original one.
   v2ray.core.common.net.Endpoint server = 1;
   uint32 user_level = 2;
+
+  bool override_response_ttl = 4;
+  uint32 response_ttl = 3;
 }
 
 message SimplifiedConfig {
   option (v2ray.core.common.protoext.message_opt).type = "outbound";
   option (v2ray.core.common.protoext.message_opt).short_name = "dns";
+
+  bool override_response_ttl = 4;
+  uint32 response_ttl = 3;
 }

proxy/dns/dns.go

@@ -38,6 +38,8 @@ func init() {
 		simplifiedServer := config.(*SimplifiedConfig)
 		_ = simplifiedServer
 		fullConfig := &Config{}
+		fullConfig.OverrideResponseTtl = simplifiedServer.OverrideResponseTtl
+		fullConfig.ResponseTtl = simplifiedServer.ResponseTtl
 		return common.CreateObject(ctx, fullConfig)
 	}))
 }
@@ -53,6 +55,8 @@ type Handler struct {
 	ownLinkVerifier ownLinkVerifier
 	server          net.Destination
 	timeout         time.Duration
+
+	config *Config
 }
 
 func (h *Handler) Init(config *Config, dnsClient dns.Client, policyManager policy.Manager) error {
@@ -82,6 +86,8 @@ func (h *Handler) Init(config *Config, dnsClient dns.Client, policyManager polic
 	if config.Server != nil {
 		h.server = config.Server.AsDestination()
 	}
+
+	h.config = config
 	return nil
 }
 
@@ -239,6 +245,9 @@ func (h *Handler) handleIPQuery(id uint16, qType dnsmessage.Type, domain string,
 	var err error
 
 	var ttl uint32 = 600
+	if h.config.OverrideResponseTtl {
+		ttl = h.config.ResponseTtl
+	}
 
 	switch qType {
 	case dnsmessage.TypeA: