why are error messages suppressed if IP_RECVERR is not set?

[Chris Friesen <cfriesen@xxxxxxxxxxxxxxxxxx>]

I'm tracking down an issue where we are sending udp packets and they are 
being dropped (I suspect) in the device queue.

In ip_build_xmit() we get the error code back saying that the packet was 
dropped, but unless IP_RECVERR is set, it seems that this error is 
hidden from userspace.

I notice that the man page says that sendto will never give an errno of 
ENOBUFS, but if you turn on IP_RECVERR this is exactly what will happen.

I guess I have two questions then: 1) why do we hide the fact that we've 
dropped the packet, and 2) why doesn't the man page talk about the 
IP_RECVERR option?

I'm using 2.4.18, if it matters.

Thanks,

Chris


--
Chris Friesen                    | MailStop: 043/33/F10
Nortel Networks                  | work: (613) 765-0557
3500 Carling Avenue              | fax:  (613) 765-2986
Nepean, ON K2H 8E9 Canada        | email: cfriesen@xxxxxxxxxxxxxxxxxx