Re: [lwip-devel] Receive a UDP packet on multiple PCBs ? (same port)

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Stéphane Lesage wrote:
> Currently, only the last PCB (socket) receives the packets. (there's no
> bind() problem)
>    
That udp_bind() in this case is a bug. It should only succeed if 
SO_REUSEADDR is set for all pcbs, but this is not implemented yet and 
someone decided to allow multiple-bind as long as that's not 
implemented. However, that wasn't as wise as we can now bind multiple 
pcbs, but not receive data on all of them.

Once SO_REUSEADDR (or whatever we call it) is implemented for UDP, I 
would think that there's no problem in adding extra code that searches 
for all matches and duplicates the received data if more than one match 
is found (and if the first match has REUSEADDR set).

However, that would have to be implemented (and properly integrated into 
the higher level APIs). This is a task targeted at 1.4.0: 
https://savannah.nongnu.org/task/?6995
> I don't know how an IP stack is supposed to behave in this case...
>    
The proper way is to only allow a second bind if all previous 
pcbs/sockets have REUSEADDR set.

Simon