[lwip-devel] pbufs with len = 0

[address@hidden]

Hi all,

when trying to fix UDPLite, I came around a flaw in the whole API: I can 
send UDP packets without data by giving udp_send() a pbuf with len = 0. 
However, if this pbuf is allocated with PBUF_RAW (or a REF type) and UDP 
creates a pbuf chain (extra pbuf for the headers), the resulting chain 
has len==tot_len (which should be the end of a packet) at the first 
element! This leads to an assert in ARP queueing, for example.

If this is not allowed, I think we should check it (using asserts) in 
the protocol's send functions!

Simon