Re: [lwip-users] Problems freeing a packet buffer using pbuf_free

[Dance, Brian]

Does the rx packet that you copy from get freed somewhere else?

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From: address@hidden [mailto:address@hidden On Behalf Of Justin Drake
Sent: 18 June 2012 15:31
To: address@hidden
Subject: [lwip-users] Problems freeing a packet buffer using pbuf_free

I am a function to send data packets. Each time a packet is receive, 
I create a buffer using `pbuf_alloc`. I then send the packet using `upd_sendto`. 
Finally, I free the buffer with `pbuf_free`.

For some reason, `pbuf_free` is not freeing the buffers. (I get a buffer overflow after `n` packets, where `n` is the pool size.)

How can I have `pbuf_free` actually free my buffers? How is the buffer overflow avoided?

Below is my implementation:

static err_t IAP_tftp_send_data_packet(struct udp_pcb *upcb, struct ip_addr *to, int to_port, int block)


{


  err_t err;


  struct pbuf *pkt_buf;


  char packet[TFTP_DATA_PKT_LEN_MAX];


  int bytesRead;


  int bytesToSend;



  /* Specify that we are sending data. */


  IAP_tftp_set_opcode(packet, TFTP_DATA); 



  /* Specify the block number that we are sending. */


  IAP_tftp_set_block(packet, block);



  bytesRead = IAP_tftp_set_data(packet, block);



  if(bytesRead != 0) {


    bytesToSend = TFTP_DATA_PKT_LEN_MAX - (512 - bytesRead + 1);


  } else {


    bytesToSend = TFTP_DATA_PKT_LEN_MAX - 512;


  }



  pkt_buf = pbuf_alloc(PBUF_TRANSPORT, bytesToSend, PBUF_POOL);



  if (!pkt_buf)


  {


    print("(TFTP) Buffer overflow!\r\n");


  }



  /* Copy the file data onto pkt_buf. */


  memcpy(pkt_buf->payload, packet, bytesToSend);



  err = udp_sendto(upcb, pkt_buf, to, to_port);



  /* free the buffer pbuf */


  printf("%d\n\r", pbuf_free(pkt_buf));



  return err;


}

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