refactor dns record parser
This commit is contained in:
parent
11ddf5aedb
commit
0f716a3c49
@ -4,22 +4,23 @@ import (
|
|||||||
"encoding/binary"
|
"encoding/binary"
|
||||||
"errors"
|
"errors"
|
||||||
"fmt"
|
"fmt"
|
||||||
|
"io"
|
||||||
)
|
)
|
||||||
|
|
||||||
var (
|
var (
|
||||||
ErrInvalidDNSMessageHeader = errors.New("invalid DNS message header")
|
|
||||||
ErrInvalidDNSResourceRecordHeader = errors.New("invalid DNS resource record header")
|
|
||||||
ErrInvalidDNSResourceRecordData = errors.New("invalid DNS resource record data")
|
|
||||||
ErrInvalidDNSAddressResourceData = errors.New("invalid DNS address resource data")
|
ErrInvalidDNSAddressResourceData = errors.New("invalid DNS address resource data")
|
||||||
)
|
)
|
||||||
|
|
||||||
func parseName(response []byte, pos int) (Name, int) {
|
func parseName(response []byte, pos int) (*Name, int, error) {
|
||||||
var nameParts []string
|
var nameParts []string
|
||||||
var jumped bool
|
var jumped bool
|
||||||
var outPos int
|
var outPos int
|
||||||
responseLen := len(response)
|
responseLen := len(response)
|
||||||
|
|
||||||
for {
|
for {
|
||||||
|
if responseLen < pos+1 {
|
||||||
|
return nil, pos, io.EOF
|
||||||
|
}
|
||||||
length := int(response[pos])
|
length := int(response[pos])
|
||||||
pos++
|
pos++
|
||||||
if length == 0 {
|
if length == 0 {
|
||||||
@ -27,6 +28,9 @@ func parseName(response []byte, pos int) (Name, int) {
|
|||||||
}
|
}
|
||||||
|
|
||||||
if length&0xC0 == 0xC0 {
|
if length&0xC0 == 0xC0 {
|
||||||
|
if responseLen < pos+1 {
|
||||||
|
return nil, pos, io.EOF
|
||||||
|
}
|
||||||
if !jumped {
|
if !jumped {
|
||||||
outPos = pos + 1
|
outPos = pos + 1
|
||||||
}
|
}
|
||||||
@ -35,8 +39,8 @@ func parseName(response []byte, pos int) (Name, int) {
|
|||||||
continue
|
continue
|
||||||
}
|
}
|
||||||
|
|
||||||
if pos+length > responseLen {
|
if responseLen < pos+length {
|
||||||
break
|
return nil, pos, io.EOF
|
||||||
}
|
}
|
||||||
|
|
||||||
nameParts = append(nameParts, string(response[pos:pos+length]))
|
nameParts = append(nameParts, string(response[pos:pos+length]))
|
||||||
@ -46,75 +50,82 @@ func parseName(response []byte, pos int) (Name, int) {
|
|||||||
if !jumped {
|
if !jumped {
|
||||||
outPos = pos
|
outPos = pos
|
||||||
}
|
}
|
||||||
return Name{Parts: nameParts}, outPos
|
return &Name{Parts: nameParts}, outPos, nil
|
||||||
}
|
}
|
||||||
|
|
||||||
func parseResourceRecord(response []byte, pos int) (ResourceRecord, int, error) {
|
func parseResourceRecord(response []byte, pos int) (ResourceRecord, int, error) {
|
||||||
responseLen := len(response)
|
responseLen := len(response)
|
||||||
|
|
||||||
var rhname Name
|
rhName, pos, err := parseName(response, pos)
|
||||||
rhname, pos = parseName(response, pos)
|
if err != nil {
|
||||||
|
return nil, pos, fmt.Errorf("error while parsing DNS name: %w", err)
|
||||||
|
}
|
||||||
|
|
||||||
if responseLen < pos+10 {
|
if responseLen < pos+10 {
|
||||||
return nil, pos, ErrInvalidDNSResourceRecordHeader
|
return nil, pos, io.EOF
|
||||||
}
|
}
|
||||||
|
|
||||||
rh := ResourceRecordHeader{
|
rh := ResourceRecordHeader{
|
||||||
Name: rhname,
|
Name: *rhName,
|
||||||
Type: binary.BigEndian.Uint16(response[pos+0 : pos+2]),
|
Type: binary.BigEndian.Uint16(response[pos+0 : pos+2]),
|
||||||
Class: binary.BigEndian.Uint16(response[pos+2 : pos+4]),
|
Class: binary.BigEndian.Uint16(response[pos+2 : pos+4]),
|
||||||
TTL: binary.BigEndian.Uint32(response[pos+4 : pos+8]),
|
TTL: binary.BigEndian.Uint32(response[pos+4 : pos+8]),
|
||||||
}
|
}
|
||||||
rdlength := int(binary.BigEndian.Uint16(response[pos+8 : pos+10]))
|
rdLen := int(binary.BigEndian.Uint16(response[pos+8 : pos+10]))
|
||||||
|
|
||||||
pos += 10
|
pos += 10
|
||||||
|
|
||||||
if pos+rdlength > responseLen {
|
if responseLen < pos+rdLen {
|
||||||
return nil, pos, ErrInvalidDNSResourceRecordData
|
return nil, pos, io.EOF
|
||||||
}
|
}
|
||||||
|
|
||||||
switch rh.Type {
|
switch rh.Type {
|
||||||
case 1:
|
case 1:
|
||||||
if rdlength == 4 {
|
if rdLen != 4 {
|
||||||
|
return nil, pos, ErrInvalidDNSAddressResourceData
|
||||||
|
}
|
||||||
return Address{
|
return Address{
|
||||||
ResourceRecordHeader: rh,
|
ResourceRecordHeader: rh,
|
||||||
Address: response[pos+0 : pos+4],
|
Address: response[pos+0 : pos+4],
|
||||||
}, pos + 4, nil
|
}, pos + 4, nil
|
||||||
} else {
|
|
||||||
return nil, pos, ErrInvalidDNSAddressResourceData
|
|
||||||
}
|
|
||||||
case 2:
|
case 2:
|
||||||
var ns Name
|
var ns *Name
|
||||||
ns, pos = parseName(response, pos)
|
ns, pos, err = parseName(response, pos)
|
||||||
|
if err != nil {
|
||||||
|
return nil, pos, fmt.Errorf("error while parsing DNS resource record: %w", err)
|
||||||
|
}
|
||||||
return NameServer{
|
return NameServer{
|
||||||
ResourceRecordHeader: rh,
|
ResourceRecordHeader: rh,
|
||||||
NSDName: ns,
|
NSDName: *ns,
|
||||||
}, pos, nil
|
}, pos, nil
|
||||||
case 5:
|
case 5:
|
||||||
var cname Name
|
var cname *Name
|
||||||
cname, pos = parseName(response, pos)
|
cname, pos, err = parseName(response, pos)
|
||||||
|
if err != nil {
|
||||||
|
return nil, pos, fmt.Errorf("error while parsing DNS resource record: %w", err)
|
||||||
|
}
|
||||||
return CName{
|
return CName{
|
||||||
ResourceRecordHeader: rh,
|
ResourceRecordHeader: rh,
|
||||||
CName: cname,
|
CName: *cname,
|
||||||
}, pos, nil
|
}, pos, nil
|
||||||
}
|
}
|
||||||
|
|
||||||
return Unknown{
|
return Unknown{
|
||||||
ResourceRecordHeader: rh,
|
ResourceRecordHeader: rh,
|
||||||
Data: response[pos+0 : pos+rdlength],
|
Data: response[pos+0 : pos+rdLen],
|
||||||
}, pos + rdlength, nil
|
}, pos + rdLen, nil
|
||||||
}
|
}
|
||||||
|
|
||||||
func ParseResponse(response []byte) (*Message, error) {
|
func ParseResponse(response []byte) (*Message, error) {
|
||||||
var err error
|
var err error
|
||||||
|
|
||||||
|
msg := new(Message)
|
||||||
|
|
||||||
responseLen := len(response)
|
responseLen := len(response)
|
||||||
if responseLen < 12 {
|
if responseLen < 12 {
|
||||||
return nil, ErrInvalidDNSMessageHeader
|
return msg, io.EOF
|
||||||
}
|
}
|
||||||
|
|
||||||
msg := new(Message)
|
|
||||||
|
|
||||||
msg.ID = binary.BigEndian.Uint16(response[0:2])
|
msg.ID = binary.BigEndian.Uint16(response[0:2])
|
||||||
|
|
||||||
flagsRAW := binary.BigEndian.Uint16(response[2:4])
|
flagsRAW := binary.BigEndian.Uint16(response[2:4])
|
||||||
@ -140,10 +151,16 @@ func ParseResponse(response []byte) (*Message, error) {
|
|||||||
|
|
||||||
msg.QD = make([]Question, qdCount)
|
msg.QD = make([]Question, qdCount)
|
||||||
for i := 0; i < qdCount; i++ {
|
for i := 0; i < qdCount; i++ {
|
||||||
var name Name
|
var name *Name
|
||||||
name, pos = parseName(response, pos)
|
name, pos, err = parseName(response, pos)
|
||||||
|
if err != nil {
|
||||||
|
return msg, fmt.Errorf("error while parsing DNS name: %w", err)
|
||||||
|
}
|
||||||
|
if responseLen < pos+4 {
|
||||||
|
return msg, io.EOF
|
||||||
|
}
|
||||||
msg.QD[i] = Question{
|
msg.QD[i] = Question{
|
||||||
QName: name,
|
QName: *name,
|
||||||
QType: binary.BigEndian.Uint16(response[pos+0 : pos+2]),
|
QType: binary.BigEndian.Uint16(response[pos+0 : pos+2]),
|
||||||
QClass: binary.BigEndian.Uint16(response[pos+2 : pos+4]),
|
QClass: binary.BigEndian.Uint16(response[pos+2 : pos+4]),
|
||||||
}
|
}
|
||||||
@ -154,7 +171,7 @@ func ParseResponse(response []byte) (*Message, error) {
|
|||||||
for i := 0; i < anCount; i++ {
|
for i := 0; i < anCount; i++ {
|
||||||
msg.AN[i], pos, err = parseResourceRecord(response, pos)
|
msg.AN[i], pos, err = parseResourceRecord(response, pos)
|
||||||
if err != nil {
|
if err != nil {
|
||||||
return nil, fmt.Errorf("error while parsing AN record: %w", err)
|
return msg, fmt.Errorf("error while parsing AN record: %w", err)
|
||||||
}
|
}
|
||||||
}
|
}
|
||||||
|
|
||||||
@ -162,7 +179,7 @@ func ParseResponse(response []byte) (*Message, error) {
|
|||||||
for i := 0; i < nsCount; i++ {
|
for i := 0; i < nsCount; i++ {
|
||||||
msg.NS[i], pos, err = parseResourceRecord(response, pos)
|
msg.NS[i], pos, err = parseResourceRecord(response, pos)
|
||||||
if err != nil {
|
if err != nil {
|
||||||
return nil, fmt.Errorf("error while parsing NS record: %w", err)
|
return msg, fmt.Errorf("error while parsing NS record: %w", err)
|
||||||
}
|
}
|
||||||
}
|
}
|
||||||
|
|
||||||
@ -170,7 +187,7 @@ func ParseResponse(response []byte) (*Message, error) {
|
|||||||
for i := 0; i < arCount; i++ {
|
for i := 0; i < arCount; i++ {
|
||||||
msg.AR[i], pos, err = parseResourceRecord(response, pos)
|
msg.AR[i], pos, err = parseResourceRecord(response, pos)
|
||||||
if err != nil {
|
if err != nil {
|
||||||
return nil, fmt.Errorf("error while parsing AR record: %w", err)
|
return msg, fmt.Errorf("error while parsing AR record: %w", err)
|
||||||
}
|
}
|
||||||
}
|
}
|
||||||
|
|
||||||
|
Loading…
x
Reference in New Issue
Block a user