udp recived packets number

[el3ctrician]

hello,
i would like to know if there is a way to get the number of packets in udp buffer and also to set the packet len according to the payload ?

thanks in advance

[wuwx]

did you mean this:

int packetSize = Udp.parsePacket();

[el3ctrician]

nope, according to the header file WiFiUdp.h this wuold return the size of the packet in bytes. I think it's refearing to the first packet. So my question is how can i get the total number (and not size) of packets recived in the Udp buffer ?

[el3ctrician]

@igrr if it's not implemented i can try to do if you can kindly guide me from where should i start ?

[igrr]

Take a look at UdpContext.h. There is a pbuf chain there, you can add a method to count the number of pbufs in the chain.

[devyte]

@el3ctrician did you get around to implementing this? do you want to make a PR?

[el3ctrician]

@devyte i didn't have enough time to do it since the project that i was working on got cancelled, but i would like to try to implement it so maby i'll fork the code for a try this weekend ...

[devyte]

Ok, post results or ask questions here.

[el3ctrician]

well actually i just saw that the pbuf in the udpContext, it is a linked list right ? i need to count by checking the pbuf.next right? or even here https://github.com/esp8266/Arduino/blob/4897e0006b5b0123a2fa31f67b14a3fff65ce561/tools/sdk/lwip/include/lwip/pbuf.h
i see a method for the length i think it would be enough ... well test any way

[d-a-v]

The pbuf api is lwip's.

WiFiUdp through UdpContext makes use of it: _recv() is called when a packet is received, filling _rx_buf which is a pbuf, using pbuf_cat(). It makes the pbuf grow and it does not chain (in the linked list way) the new incoming data. So pbuf->len == pbuf->tot_len and next is always null.

The notion of packet is then wiped out showing udp's incoming data to the user as a stream, which is what it really is (class UDP: public Stream) but not compatible with the "datagram" way of thinking with udp.
Is that your initial concern ?

If this had to be changed, pbuf_chain() would have to be used instead of pbuf_cat() along with the linked list management. That would put malloc under less stress and restore the notion of packet if this had to be needed.

edit: the notion of packet bounds with the linked list would be trivial, albeit still doable in the current implementation with some way to remember these bounds.

edit2: you may check @me-no-dev's AsyncUDP implementation which keeps the notion of packet.

[devyte]

I am closing this due to age and lack of feedback.
If there is still an idea to be contributed regarding this topic, please open a new issue, follow the template instructions, and explain the idea in detail.