147 lines
2.9 KiB
Go
147 lines
2.9 KiB
Go
package dns
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import (
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"bytes"
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"encoding/binary"
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osm "git.loafle.net/overflow/service_matcher-go"
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)
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type Dns_frame_header struct {
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Transaction_id uint16
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Flags uint16
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Questions uint16
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Answer_rrs uint16
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Authority_rrs uint16
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Additional_rrs uint16
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}
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type Dns_query_section struct {
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Name uint8
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Query_type uint16
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Class_type uint16
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}
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type Dns_authority_section struct {
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Name uint8
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Auth_type uint16
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Class_type uint16
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Time_to_live uint32
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Data_length uint16
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Primary_name_server [20]uint8
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Responsible_authority_mailbox [24]uint8
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Serial_number uint32
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Refresh_interval uint32
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Retry_interval uint32
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Expire_limit uint32
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Minium_ttl uint32
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}
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type DNSMatcher struct {
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osm.Matchers
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}
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func (m *DNSMatcher) Key() string {
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return "DNS"
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}
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func (m *DNSMatcher) Name(matchCtx *osm.MatchCtx) string {
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return "DNS"
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}
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func (m *DNSMatcher) IsPrePacket(matchCtx *osm.MatchCtx) bool {
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return false
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}
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func (m *DNSMatcher) HasResponse(matchCtx *osm.MatchCtx, index int) bool {
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return true
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}
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func (m *DNSMatcher) IsError(matchCtx *osm.MatchCtx, index int, packet *osm.Packet) bool {
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return false
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}
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func (m *DNSMatcher) Match(matchCtx *osm.MatchCtx, index int, packet *osm.Packet) error {
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if packet == nil || !packet.Valid() {
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return osm.NoPacketReceivedError()
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}
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reader := new(bytes.Buffer)
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reader.Write(packet.Buffer)
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h := Dns_frame_header{}
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if err := binary.Read(reader, binary.BigEndian, &h); err != nil {
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return err
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}
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if h.Transaction_id != 0x2a88 {
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return osm.NotMatchedError()
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}
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if h.Flags != 0x8180 && h.Flags != 0x8182 {
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return osm.NotMatchedError()
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}
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if h.Questions != 1 {
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return osm.NotMatchedError()
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}
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if h.Answer_rrs != 0 {
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return osm.NotMatchedError()
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}
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if h.Authority_rrs != 0 && h.Authority_rrs != 1 {
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return osm.NotMatchedError()
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}
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if h.Additional_rrs != 0 && h.Additional_rrs != 1 {
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return osm.NotMatchedError()
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}
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q := Dns_query_section{}
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if err := binary.Read(reader, binary.BigEndian, &q); err != nil {
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return osm.NotMatchedError()
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}
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if q.Name != 0 {
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return osm.NotMatchedError()
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}
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if q.Query_type != 1 {
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return osm.NotMatchedError()
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}
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if q.Class_type != 1 {
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return osm.NotMatchedError()
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}
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return nil
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}
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func (m *DNSMatcher) IsSend(port int) bool {
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if 53 == port {
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return true
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}
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return false
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}
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func NewMatcher() osm.UDPMatcher {
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m := &DNSMatcher{}
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header := Dns_frame_header{
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Transaction_id: 0x2a88,
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Flags: 0x0100,
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Questions: 1,
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Answer_rrs: 0,
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Authority_rrs: 0,
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Additional_rrs: 0,
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}
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query := Dns_query_section{
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Name: 0,
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Query_type: 1,
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Class_type: 1,
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}
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buf := new(bytes.Buffer)
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binary.Write(buf, binary.BigEndian, header)
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binary.Write(buf, binary.BigEndian, query)
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m.AddPacket(osm.NewPacket(buf.Bytes(), buf.Len()))
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return m
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}
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