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package inform
import (
"bytes"
"encoding/binary"
"errors"
"io"
)
type Codec struct {
// KeyBag contains a mapping of comma-separated MAC addresses to their AES
// keys
KeyBag map[string]string
}
func (c *Codec) Unmarshal(fp io.Reader) (*InformWrapper, error) {
w := NewInformWrapper()
var magic int32
binary.Read(fp, binary.BigEndian, &magic)
if magic != PROTOCOL_MAGIC {
return nil, errors.New("Invalid magic number")
}
binary.Read(fp, binary.BigEndian, &w.Version)
io.ReadFull(fp, w.MacAddr)
binary.Read(fp, binary.BigEndian, &w.Flags)
iv := make([]byte, 16)
io.ReadFull(fp, iv)
binary.Read(fp, binary.BigEndian, &w.DataVersion)
var dataLen int32
binary.Read(fp, binary.BigEndian, &dataLen)
p := make([]byte, dataLen)
io.ReadFull(fp, p)
key, ok := c.KeyBag[w.FormattedMac()]
if !ok {
return nil, errors.New("No key found")
}
u, err := Decrypt(p, iv, key)
if err != nil {
return nil, err
}
w.Payload = u
return w, nil
}
func (c *Codec) Marshal(msg *InformWrapper) ([]byte, error) {
b := &bytes.Buffer{}
payload := msg.Payload
var iv []byte
if msg.IsEncrypted() {
key, ok := c.KeyBag[msg.FormattedMac()]
if !ok {
return nil, errors.New("No key found")
}
var err error
payload, iv, err = Encrypt(payload, key)
if err != nil {
return nil, err
}
}
binary.Write(b, binary.BigEndian, PROTOCOL_MAGIC)
binary.Write(b, binary.BigEndian, msg.Version)
b.Write(msg.MacAddr)
binary.Write(b, binary.BigEndian, msg.Flags)
b.Write(iv)
binary.Write(b, binary.BigEndian, msg.DataVersion)
binary.Write(b, binary.BigEndian, int32(len(payload)))
b.Write(payload)
return b.Bytes(), nil
}
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