For UDP packets, applicationLayer.Payload() is not the same of udpLayer.LayerPayload()

[alopumomovia]

I am observing a strange behaviour while filtering UDP packets from a .pcap file and getting their payload.

`
for packet := range packetSource.Packets() {

    if err := packet.ErrorLayer(); err != nil {
        continue
    }

    udpLayer := packet.Layer(layers.LayerTypeUDP)
    if udpLayer == nil {
      continue
    }

    // Condition A
    if len(udpLayer.LayerPayload()) == 0 {
        continue
    }

   /* Condition B
   appLayer := packet.ApplicationLayer()
   if appLayer == nil || len(appLayer.Payload()) == 0 {
            continue
   }*/

`

With condition A I get 179 packets, with condition B (and A disabled) I get 89 packets. Why?

[alopumomovia]

sorry, I made a mistake when pasting, I corrected it now. you can read the post now.