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Refactor DNS Name Handling and add static encoding function for DNSResourceRecord #4

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Merged
TochusC merged 1 commit into from
May 8, 2025
Merged

Refactor DNS Name Handling and add static encoding function for DNSResourceRecord #4

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119 changes: 95 additions & 24 deletions dns/dns.go
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Original file line number Diff line number Diff line change
Expand Up @@ -90,7 +90,7 @@ type DNSQuestionSection []DNSQuestion

// DNSQuestion 表示DNS查询的问题记录
type DNSQuestion struct {
Name string
Name DNSName
Type DNSType
Class DNSClass
}
Expand Down Expand Up @@ -122,12 +122,16 @@ type DNSResponseSection []DNSResourceRecord
// DNSResourceRecord 表示 DNS 资源记录。
// 设置RDLen为0时，将根据RData的实际大小进行编码。
type DNSResourceRecord struct {
Name string
Name DNSName
Type DNSType
Class DNSClass
TTL uint32
RDLen uint16
RData DNSRRRDATA

// 静态rdata(设置该值将使得Encode不再实时解码Rdata，而是直接使用该静态值)
IsStatic bool
Static_Rdata []byte
}

// DNSMessage 相关方法定义
Expand Down Expand Up @@ -172,31 +176,31 @@ func (dnsMessage *DNSMessage) Equal(other *DNSMessage) bool {
return false
}
for i, question := range dnsMessage.Question {
if question != other.Question[i] {
if question.Equal(other.Question[i]) != true {
return false
}
}
if len(dnsMessage.Answer) != len(other.Answer) {
return false
}
for i, answer := range dnsMessage.Answer {
if answer != other.Answer[i] {
if answer.Equal(other.Answer[i]) != true {
return false
}
}
if len(dnsMessage.Authority) != len(other.Authority) {
return false
}
for i, authority := range dnsMessage.Authority {
if authority != other.Authority[i] {
if authority.Equal(other.Authority[i]) != true {
return false
}
}
if len(dnsMessage.Additional) != len(other.Additional) {
return false
}
for i, additional := range dnsMessage.Additional {
if additional != other.Additional[i] {
if additional.Equal(other.Additional[i]) != true {
return false
}
}
Expand Down Expand Up @@ -469,19 +473,30 @@ func (dnsHeader *DNSHeader) DecodeFromBuffer(buffer []byte, offset int) (int, er

// Size 返回DNS消息 的 问题部分的大小。
func (dnsQuestion *DNSQuestion) Size() int {
return GetDomainNameWireLen(&dnsQuestion.Name) + 4
return dnsQuestion.Name.Length() + 4
}

// String 以“易读的形式”返回DNS消息 的 问题部分的字符串表示。
func (dnsQuestion *DNSQuestion) String() string {
return fmt.Sprint(
"### DNS Question ###\n",
"Name: ", dnsQuestion.Name, "\n",
"Name: ", dnsQuestion.Name.String(), "\n",
"Type: ", dnsQuestion.Type, "\n",
"Class: ", dnsQuestion.Class,
)
}

func (dnsQuestion *DNSQuestion) Equal(other DNSQuestion) bool {
if !dnsQuestion.Name.Equal(&other.Name) {
return false
}
if dnsQuestion.Type != other.Type {
return false
}
if dnsQuestion.Class != other.Class {
return false
}
return true
}

// Size 返回DNS消息 的 问题部分的大小。
func (section DNSQuestionSection) Size() int {
size := 0
Expand Down Expand Up @@ -509,7 +524,7 @@ func (section DNSQuestionSection) Equal(other DNSQuestionSection) bool {
return false
}
for i, question := range section {
if question != other[i] {
if !question.Equal(other[i]) {
return false
}
}
Expand Down Expand Up @@ -554,7 +569,7 @@ func (section DNSQuestionSection) EncodeToBuffer(buffer []byte) (int, error) {
func (dnsQuestion *DNSQuestion) DecodeFromBuffer(buffer []byte, offset int) (int, error) {
var err error
// 解码域名
dnsQuestion.Name, offset, err = DecodeDomainNameFromBuffer(buffer, offset)
dnsQuestion.Name, offset, err = NewDNSNameFromBuffer(buffer, offset)
if err != nil {
return -1, fmt.Errorf("method DNSQuestion DecodeFromBuffer failed: decode Name failed.\n%s", err)
}
Expand All @@ -568,7 +583,7 @@ func (dnsQuestion *DNSQuestion) DecodeFromBuffer(buffer []byte, offset int) (int
// Encode 将 DNS消息的问题部分 编码到 字节切片 中。
func (dnsQuestion *DNSQuestion) Encode() []byte {
buffer := make([]byte, dnsQuestion.Size())
offset, err := EncodeDomainNameToBuffer(&dnsQuestion.Name, buffer)
offset, err := dnsQuestion.Name.EncodeToBuffer(buffer)
if err != nil {
panic(fmt.Sprintf("method DNSQuestion Encode failed: encode Question name failed\n%s\n", err))
}
Expand All @@ -586,7 +601,7 @@ func (dnsQuestion *DNSQuestion) EncodeToBuffer(buffer []byte) (int, error) {
if len(buffer) < dqSize {
return -1, fmt.Errorf("EncodeToBuffer failed: buffer length %d is less than DNSQuestion size %d", len(buffer), dqSize)
}
_, err := EncodeDomainNameToBuffer(&dnsQuestion.Name, buffer)
_, err := dnsQuestion.Name.EncodeToBuffer(buffer)
if err != nil {
return -1, err
}
Expand Down Expand Up @@ -619,7 +634,7 @@ func (responseSection DNSResponseSection) Equal(other DNSResponseSection) bool {
return false
}
for i, record := range responseSection {
if record != other[i] {
if !record.Equal(other[i]) {
return false
}
}
Expand Down Expand Up @@ -675,18 +690,43 @@ func (responseSection DNSResponseSection) DecodeFromBuffer(buffer []byte, offset
return offset, nil
}

// DNSResourceRecord 相关方法定义

// Size 返回 DNS 资源记录的*准确*大小。
// - RDLength 字段可由用户自行设置一个错误的值。
func (rr *DNSResourceRecord) Size() int {
return GetDomainNameWireLen(&rr.Name) + 10 + rr.RData.Size()
return rr.Name.Length() + 10 + rr.RData.Size()
}

func (rr *DNSResourceRecord) Equal(other DNSResourceRecord) bool {
if !rr.Name.Equal(&other.Name) {
return false
}
if rr.Type != other.Type {
return false
}
if rr.Class != other.Class {
return false
}
if rr.TTL != other.TTL {
return false
}
if rr.RDLen != other.RDLen {
return false
}
if !rr.RData.Equal(other.RData) {
return false
}
// 其他字段相等
return true
}

// String 以*易读的形式*返回 DNS 资源记录的字符串表示。
// - 其返回值为 DNS 资源记录的字符串表示。
func (rr *DNSResourceRecord) String() string {
return fmt.Sprint(
"### DNS Resource Record ###\n",
"Name:", rr.Name, "\n",
"Name:", rr.Name.String(), "\n",
"Type:", rr.Type, "\n",
"Class:", rr.Class, "\n",
"TTL:", rr.TTL, "\n",
Expand All @@ -695,21 +735,53 @@ func (rr *DNSResourceRecord) String() string {
)
}

// EncodeStaticRData 将 DNS 资源记录的 RData 编码为静态数据。
// - 该方法将 RData 的编码结果存储在 Static_Rdata 字段中。
// - 同时将 IsStatic 字段设置为 true 并修改 RDLen 字段。
func (rr *DNSResourceRecord) EncodeStaticRData() {
rr.IsStatic = true
rr.Static_Rdata = rr.RData.Encode()
rr.RDLen = uint16(len(rr.Static_Rdata))
}

// DecodeStaticRData 将 DNS 资源记录的静态数据解码为 RData。
// - 该方法将 Static_Rdata 字段的值解码为 RData。
// - 同时将 IsStatic 字段设置为 false 并修改 RDLen 字段。
// - 该方法在调用时，Static_Rdata 字段必须已经被设置为有效的静态数据。
func (rr *DNSResourceRecord) DecodeStaticRData() {
rr.IsStatic = false

rr.RData = DNSRRRDATAFactory(rr.Type)
rr.RDLen = uint16(len(rr.Static_Rdata))

rr.RData.DecodeFromBuffer(rr.Static_Rdata, 0, int(rr.RDLen))
}

// Encode 方法编码 DNS 资源记录至返回的字节切片中。
// - 其返回值为 编码后的字节切片 。
func (rr *DNSResourceRecord) Encode() []byte {
byteArray := make([]byte, rr.Size())
offset, err := EncodeDomainNameToBuffer(&rr.Name, byteArray)
offset, err := rr.Name.EncodeToBuffer(byteArray)
if err != nil {
panic(fmt.Sprintf("method DNSResourceRecord Encode failed: encode Name failed\n%s\n", err))
}
binary.BigEndian.PutUint16(byteArray[offset:], uint16(rr.Type))
binary.BigEndian.PutUint16(byteArray[offset+2:], uint16(rr.Class))
binary.BigEndian.PutUint32(byteArray[offset+4:], rr.TTL)
rdLen, err := rr.RData.EncodeToBuffer(byteArray[offset+10:])
if err != nil {
panic(fmt.Sprintf("method DNSResourceRecord Encode failed: encode RDATA failed\n%s\n", err))

rdLen := int(rr.RDLen)
if rr.IsStatic {
rdLen = len(rr.Static_Rdata)
copy(byteArray[offset+10:], rr.Static_Rdata)
} else {
var err error
rdLen, err = rr.RData.EncodeToBuffer(byteArray[offset+10:])
if err != nil {
panic(fmt.Sprintf("method DNSResourceRecord Encode failed: encode RDATA failed\n%s\n", err))
}
}

// 如果用户设置了 RDLen，则使用用户设置的值，否则使用编码后的长度。
if rr.RDLen == 0 {
binary.BigEndian.PutUint16(byteArray[offset+8:], uint16(rdLen))
} else {
Expand All @@ -724,7 +796,7 @@ func (rr *DNSResourceRecord) Encode() []byte {
//
// 如果出现错误，返回 -1 和 相应报错。
func (rr *DNSResourceRecord) EncodeToBuffer(buffer []byte) (int, error) {
offset, err := EncodeDomainNameToBuffer(&rr.Name, buffer)
offset, err := rr.Name.EncodeToBuffer(buffer)
if err != nil {
return -1, err
}
Expand Down Expand Up @@ -752,11 +824,10 @@ func (rr *DNSResourceRecord) EncodeToBuffer(buffer []byte) (int, error) {
func (rr *DNSResourceRecord) DecodeFromBuffer(buffer []byte, offset int) (int, error) {
var err error
// 解码域名
name, offset, err := DecodeDomainNameFromBuffer(buffer, offset)
rr.Name, offset, err = NewDNSNameFromBuffer(buffer, offset)
if err != nil {
return -1, err
}
rr.Name = name
// 解码类型
rr.Type = DNSType(binary.BigEndian.Uint16(buffer[offset:]))
// 解码类
Expand Down
4 changes: 2 additions & 2 deletions dns/dns_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -105,7 +105,7 @@ func TestDNSHeaderDecodeFromBuffer(t *testing.T) {

// 待测试的 DNSQuestion 对象。
var testedDNSQuestion = DNSQuestion{
Name: "www.example.com",
Name: *NewDNSName("www.example.com"),
Type: DNSRRTypeA,
Class: DNSClassIN,
}
Expand Down Expand Up @@ -176,7 +176,7 @@ func TestDNSQuestionDecodeFromBuffer(t *testing.T) {
t.Errorf(" function DNSQuestionDecodeFromBuffer() failed:\ngot:%d\nexpected: %d",
offset, len(testedDNSQuestionEncoded))
}
if decodedDNSQuestion != testedDNSQuestion {
if !decodedDNSQuestion.Equal(testedDNSQuestion) {
t.Errorf(" function DNSQuestionDecodeFromBuffer() failed:\ngot:\n%v\nexpected:\n%v",
decodedDNSQuestion, testedDNSQuestion)
}
Expand Down
23 changes: 12 additions & 11 deletions dns/metarr.go
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,7 @@ func IsPseudoRR(rr *DNSResourceRecord) bool {
// NewDNSRROPT creates a new DNS Resource Record OPT
func NewDNSRROPT(udpsize int, ttl int, rdata *DNSRDATAOPT) *DNSResourceRecord {
return &DNSResourceRecord{
Name: ".",
Name: *NewDNSName("."),
Type: 41,
Class: DNSClass(udpsize),
TTL: uint32(ttl),
Expand All @@ -41,16 +41,17 @@ func NewPseudoRR(rr *DNSResourceRecord) PseudoRR {

// DNSRROPT is a DNS Resource Record OPT
// See RFC 6891
// +------------+--------------+------------------------------+
// | Field Name | Field Type | Description |
// +------------+--------------+------------------------------+
// | NAME | domain name | MUST be 0 (root domain) |
// | TYPE | u_int16_t | OPT (41) |
// | CLASS | u_int16_t | requestor’s UDP payload size |
// | TTL | u_int32_t | extended RCODE and flags |
// | RDLEN | u_int16_t | length of all RDATA |
// | RDATA | octet stream | {attribute,value} pairs |
// +------------+--------------+------------------------------+
//
// +------------+--------------+------------------------------+
// | Field Name | Field Type | Description |
// +------------+--------------+------------------------------+
// | NAME | domain name | MUST be 0 (root domain) |
// | TYPE | u_int16_t | OPT (41) |
// | CLASS | u_int16_t | requestor’s UDP payload size |
// | TTL | u_int32_t | extended RCODE and flags |
// | RDLEN | u_int16_t | length of all RDATA |
// | RDATA | octet stream | {attribute,value} pairs |
// +------------+--------------+------------------------------+
type DNSRROPT struct {
rr *DNSResourceRecord
}
Expand Down
2 changes: 1 addition & 1 deletion dns/rdata.go
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Original file line number Diff line number Diff line change
Expand Up @@ -45,7 +45,7 @@ type DNSRRRDATA interface {
//
Equal(DNSRRRDATA) bool

/* TODO: Mais 等到真正需要时再实现吧？
/* TODO:
// Masterlize 方法以*Master File中的ASCII表示*返回对应 资源记录 RDATA 部分的 字符串表示。
// - 其返回值为 RDATA 部分的字符串表示。
Masterlize() string
Expand Down
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