refactor: DNS

option/dns_record.go

@@ -0,0 +1,161 @@
+package option
+
+import (
+	"encoding/base64"
+
+	"github.com/sagernet/sing/common"
+	"github.com/sagernet/sing/common/buf"
+	E "github.com/sagernet/sing/common/exceptions"
+	"github.com/sagernet/sing/common/json"
+	"github.com/sagernet/sing/common/json/badoption"
+	M "github.com/sagernet/sing/common/metadata"
+
+	"github.com/miekg/dns"
+)
+
+type PredefinedDNSServerOptions struct {
+	Responses []DNSResponseOptions `json:"responses,omitempty"`
+}
+
+type DNSResponseOptions struct {
+	Query     badoption.Listable[string]       `json:"query,omitempty"`
+	QueryType badoption.Listable[DNSQueryType] `json:"query_type,omitempty"`
+
+	RCode  *DNSRCode                            `json:"rcode,omitempty"`
+	Answer badoption.Listable[DNSRecordOptions] `json:"answer,omitempty"`
+	Ns     badoption.Listable[DNSRecordOptions] `json:"ns,omitempty"`
+	Extra  badoption.Listable[DNSRecordOptions] `json:"extra,omitempty"`
+}
+
+type DNSRCode int
+
+func (r DNSRCode) MarshalJSON() ([]byte, error) {
+	rCodeValue, loaded := dns.RcodeToString[int(r)]
+	if loaded {
+		return json.Marshal(rCodeValue)
+	}
+	return json.Marshal(int(r))
+}
+
+func (r *DNSRCode) UnmarshalJSON(bytes []byte) error {
+	var intValue int
+	err := json.Unmarshal(bytes, &intValue)
+	if err == nil {
+		*r = DNSRCode(intValue)
+		return nil
+	}
+	var stringValue string
+	err = json.Unmarshal(bytes, &stringValue)
+	if err != nil {
+		return err
+	}
+	rCodeValue, loaded := dns.StringToRcode[stringValue]
+	if !loaded {
+		return E.New("unknown rcode: " + stringValue)
+	}
+	*r = DNSRCode(rCodeValue)
+	return nil
+}
+
+func (r *DNSRCode) Build() int {
+	if r == nil {
+		return dns.RcodeSuccess
+	}
+	return int(*r)
+}
+
+func (o DNSResponseOptions) Build() ([]dns.Question, *dns.Msg, error) {
+	var questions []dns.Question
+	if len(o.Query) == 0 && len(o.QueryType) == 0 {
+		questions = []dns.Question{{Qclass: dns.ClassINET}}
+	} else if len(o.Query) == 0 {
+		for _, queryType := range o.QueryType {
+			questions = append(questions, dns.Question{
+				Qtype:  uint16(queryType),
+				Qclass: dns.ClassINET,
+			})
+		}
+	} else if len(o.QueryType) == 0 {
+		for _, domain := range o.Query {
+			questions = append(questions, dns.Question{
+				Name:   dns.Fqdn(domain),
+				Qclass: dns.ClassINET,
+			})
+		}
+	} else {
+		for _, queryType := range o.QueryType {
+			for _, domain := range o.Query {
+				questions = append(questions, dns.Question{
+					Name:   dns.Fqdn(domain),
+					Qtype:  uint16(queryType),
+					Qclass: dns.ClassINET,
+				})
+			}
+		}
+	}
+	return questions, &dns.Msg{
+		MsgHdr: dns.MsgHdr{
+			Response:           true,
+			Rcode:              o.RCode.Build(),
+			Authoritative:      true,
+			RecursionDesired:   true,
+			RecursionAvailable: true,
+		},
+		Answer: common.Map(o.Answer, DNSRecordOptions.build),
+		Ns:     common.Map(o.Ns, DNSRecordOptions.build),
+		Extra:  common.Map(o.Extra, DNSRecordOptions.build),
+	}, nil
+}
+
+type DNSRecordOptions struct {
+	dns.RR
+	fromBase64 bool
+}
+
+func (o DNSRecordOptions) MarshalJSON() ([]byte, error) {
+	if o.fromBase64 {
+		buffer := buf.Get(dns.Len(o.RR))
+		defer buf.Put(buffer)
+		offset, err := dns.PackRR(o.RR, buffer, 0, nil, false)
+		if err != nil {
+			return nil, err
+		}
+		return json.Marshal(base64.StdEncoding.EncodeToString(buffer[:offset]))
+	}
+	return json.Marshal(o.RR.String())
+}
+
+func (o *DNSRecordOptions) UnmarshalJSON(data []byte) error {
+	var stringValue string
+	err := json.Unmarshal(data, &stringValue)
+	if err != nil {
+		return err
+	}
+	binary, err := base64.StdEncoding.DecodeString(stringValue)
+	if err == nil {
+		return o.unmarshalBase64(binary)
+	}
+	record, err := dns.NewRR(stringValue)
+	if err != nil {
+		return err
+	}
+	if a, isA := record.(*dns.A); isA {
+		a.A = M.AddrFromIP(a.A).Unmap().AsSlice()
+	}
+	o.RR = record
+	return nil
+}
+
+func (o *DNSRecordOptions) unmarshalBase64(binary []byte) error {
+	record, _, err := dns.UnpackRR(binary, 0)
+	if err != nil {
+		return E.New("parse binary DNS record")
+	}
+	o.RR = record
+	o.fromBase64 = true
+	return nil
+}
+
+func (o DNSRecordOptions) build() dns.RR {
+	return o.RR
+}