scratch/dns-server/packet.go (view raw)
| 1 | package main |
| 2 | |
| 3 | import "bytes" |
| 4 | |
| 5 | type Packet struct { |
| 6 | Header Header |
| 7 | Questions []Question |
| 8 | Answers []Record |
| 9 | Authorities []Record |
| 10 | Resources []Record |
| 11 | } |
| 12 | |
| 13 | func ParsePacket(packet []byte) (Packet, error) { |
| 14 | r := bytes.NewReader(packet) |
| 15 | |
| 16 | var err error |
| 17 | var p Packet |
| 18 | |
| 19 | p.Header, err = ReadHeader(r) |
| 20 | if err != nil { |
| 21 | return Packet{}, err |
| 22 | } |
| 23 | |
| 24 | for i := 0; i < int(p.Header.Questions); i++ { |
| 25 | q, err := ReadQuestion(r, packet) |
| 26 | if err != nil { |
| 27 | return Packet{}, err |
| 28 | } |
| 29 | p.Questions = append(p.Questions, q) |
| 30 | } |
| 31 | |
| 32 | for i := 0; i < int(p.Header.Answers); i++ { |
| 33 | a, err := ReadRecord(r, packet) |
| 34 | if err != nil { |
| 35 | return Packet{}, err |
| 36 | } |
| 37 | p.Answers = append(p.Answers, a) |
| 38 | } |
| 39 | |
| 40 | for i := 0; i < int(p.Header.AuthoritativeEntries); i++ { |
| 41 | ae, err := ReadRecord(r, packet) |
| 42 | if err != nil { |
| 43 | return Packet{}, err |
| 44 | } |
| 45 | p.Authorities = append(p.Authorities, ae) |
| 46 | } |
| 47 | |
| 48 | for i := 0; i < int(p.Header.ResourceEntries); i++ { |
| 49 | re, err := ReadRecord(r, packet) |
| 50 | if err != nil { |
| 51 | return Packet{}, err |
| 52 | } |
| 53 | p.Resources = append(p.Resources, re) |
| 54 | } |
| 55 | |
| 56 | return p, nil |
| 57 | } |
| 58 | |
| 59 | func (p *Packet) Write(b *bytes.Buffer) error { |
| 60 | p.Header.Questions = uint16(len(p.Questions)) |
| 61 | p.Header.Answers = uint16(len(p.Answers)) |
| 62 | p.Header.AuthoritativeEntries = uint16(len(p.Authorities)) |
| 63 | p.Header.ResourceEntries = uint16(len(p.Resources)) |
| 64 | _ = p.Header.Write(b) |
| 65 | |
| 66 | for i := range p.Questions { |
| 67 | _ = p.Questions[i].Write(b) |
| 68 | } |
| 69 | |
| 70 | for i := range p.Answers { |
| 71 | _, _ = p.Answers[i].Write(b) |
| 72 | } |
| 73 | |
| 74 | for i := range p.Authorities { |
| 75 | _, _ = p.Authorities[i].Write(b) |
| 76 | } |
| 77 | |
| 78 | for i := range p.Resources { |
| 79 | _, _ = p.Resources[i].Write(b) |
| 80 | } |
| 81 | |
| 82 | return nil |
| 83 | } |