Re: [lwip-users] recv_raw race condition?

[Jonathan Larmour]

Siva Velusamy wrote:
> Hello,
> 
> I have an application that opens up a raw socket (SOCK_RAW), and is
> expecting to receive an ICMP packet.
> 
> In this case, depending on the kernel scheduling, sometimes the packet
> received includes the IP header, and sometimes not. This occurs because
> recv_raw (api_msg.c) posts the received packet into the applications
> mbox. However, it does not say that the packet has been processed (or
> "eaten" according to the sorrounding comments), so further layers
> continue processing the packet. Eventually it reaches icmp_input which
> moves the payload past the ip header.
> 
> It seems like the code in recv_raw should return 1 in cases where there
> is an application waiting for the input. I can see that this is ok to do
> for ICMP packets, but I'm not sure if it is generally applicable.
> 
> The issue exists in lwip-1.2.0, and at first glance appears to exist in
> lwip-1.3.0rc1 also.

I agree that this does seem to be a bug. I am posting it to the bug
management system.

Jifl
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