86 lines
1.6 KiB
Go
86 lines
1.6 KiB
Go
package dissector
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import (
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"bytes"
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"encoding/binary"
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"io"
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)
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const (
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ExtServerName uint16 = 0x0000
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)
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type Extension interface {
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Type() uint16
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Bytes() []byte
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}
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func ReadExtension(r io.Reader) (ext Extension, err error) {
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b := make([]byte, 4)
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if _, err = io.ReadFull(r, b); err != nil {
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return
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}
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bb := make([]byte, int(binary.BigEndian.Uint16(b[2:4])))
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if _, err = io.ReadFull(r, bb); err != nil {
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return nil, err
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}
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t := binary.BigEndian.Uint16(b[:2])
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switch t {
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case ExtServerName:
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ext = &ServerNameExtension{
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NameType: bb[2],
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Name: string(bb[5:]),
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}
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default:
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ext = &unknownExtension{
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raw: append(b, bb...),
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}
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}
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return
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}
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type unknownExtension struct {
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raw []byte
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}
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func NewExtension(t uint16, data []byte) Extension {
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ext := &unknownExtension{
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raw: make([]byte, 2+2+len(data)),
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}
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binary.BigEndian.PutUint16(ext.raw[:2], t)
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binary.BigEndian.PutUint16(ext.raw[2:4], uint16(len(data)))
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copy(ext.raw[4:], data)
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return ext
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}
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func (ext *unknownExtension) Type() uint16 {
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return binary.BigEndian.Uint16(ext.raw)
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}
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func (ext *unknownExtension) Bytes() []byte {
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return ext.raw
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}
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type ServerNameExtension struct {
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NameType uint8
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Name string
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}
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func (ext *ServerNameExtension) Type() uint16 {
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return ExtServerName
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}
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func (ext *ServerNameExtension) Bytes() []byte {
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buf := &bytes.Buffer{}
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binary.Write(buf, binary.BigEndian, ExtServerName)
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binary.Write(buf, binary.BigEndian, uint16(2+1+2+len(ext.Name)))
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binary.Write(buf, binary.BigEndian, uint16(1+2+len(ext.Name)))
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buf.WriteByte(ext.NameType)
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binary.Write(buf, binary.BigEndian, uint16(len(ext.Name)))
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buf.WriteString(ext.Name)
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return buf.Bytes()
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}
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