[srslte-users] How can I access the pdu->msg.

[Raghav Rathi]

Hello Everyone,

I am trying to understand how srsLTE handles IP packets. I am running the ping example mentioned in the srsLTE ZeroMQ documentation and I am focusing on the ENB part.
From my understanding, when I call ping command, the flow of control goes to the 'gtpu.cc' file which makes sense as gtp is the GPRS tunneling protocol - U which carries user data from EPC to ENB.
After looking at the gtpu.cc, i found that there is a function named  'handle_gtpu_s1u_rx_packet' and every time i call ping, this function is called which i verified by adding a print statement.

My aim here is to understand the IP packet which from my observation is the 'pdu' present in 'handle_gtpu_s1u_rx_packet' function.  pdu->N_bytes shows the byte size of the msg, but when I access the msg using pdu->msg, it gives me random characters.
Since msg is a buffer I simply used a for loop of range pdu->n_byte and tried to access msg[i] but i am getting the following output. I think it is because the packet is encoded but I don't know how to decode. Can someone please help me with that?

>>>> pdu -> n_byte84
>>>>>>>>>> PDU->msg: E   T � � @  @ 
  � �   
 �      � %    N  � ^     � �
                            
 
 
    ! " # $ % & ' ( ) * + , - . / 0 1 2 3 4 5 6 7


Thank you,

Raghav Rathi
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