// DecodeFromBytes decodes the bytes of a Diameter AVP.
// It uses the given application id and dictionary for decoding the bytes.
func (a *AVP) DecodeFromBytes(data []byte, application uint32, dictionary *dict.Parser) error {
dl := len(data)
if dl < 8 {
return fmt.Errorf("Not enough data to decode AVP header: %d bytes", dl)
}
a.Code = binary.BigEndian.Uint32(data[0:4])
a.Flags = data[4]
a.Length = int(uint24to32(data[5:8]))
if dl < int(a.Length) {
return fmt.Errorf("Not enough data to decode AVP: %d != %d",
dl, a.Length)
}
data = data[:a.Length] // this cuts padded bytes off
var hdrLength int
var payload []byte
// Read VendorId when required.
if a.Flags&avp.Vbit == avp.Vbit {
a.VendorID = binary.BigEndian.Uint32(data[8:12])
payload = data[12:]
hdrLength = 12
} else {
payload = data[8:]
hdrLength = 8
}
// Find this code in the dictionary.
dictAVP, err := dictionary.FindAVPWithVendor(application, a.Code, a.VendorID)
if err != nil {
return err
}
bodyLen := a.Length - hdrLength
if n := len(payload); n < bodyLen {
return fmt.Errorf(
"Not enough data to decode AVP: %d != %d",
hdrLength, n,
)
}
a.Data, err = datatype.Decode(dictAVP.Data.Type, payload)
if err != nil {
return err
}
// Handle grouped AVPs.
if a.Data.Type() == datatype.GroupedType {
a.Data, err = DecodeGrouped(
a.Data.(datatype.Grouped),
application, dictionary,
)
if err != nil {
return err
}
}
return nil
}
