RE: [lwip-devel] lwIP UDP and TFTP

[Atte Kojo]

On Wed, 2003-11-26 at 12:16, Kieran Mansley wrote:
> Having had a read through the relevant bit in TCP/IP Illustrated (Section
> 23.7 - udp_input) it would seem that the standard behaviour is to match
> against both port numbers (as lwIP currently does) *if* they are not
> wildcarded.  If the application has bound to both a local and destination
> port, then those should match.  If the application wants to receive from
> multiple remote ports, then it should leave the remote port wildcarded.
> Maybe lwIP is filling in this value when it shouldn't, but I don't think
> it's quite as simple as just never matching on the remote port.
> 
> The concept of a connection is valid in UDP.  Although it is a
> connectionless protocol (meaning there is no handshake before data are
> sent, or after all data have been received) that doesn't mean a UDP
> socket can't be connected to a particular pair of ip addresses & port
> numbers.  The problem is with English, where the word "connection" is
> overloaded and means many different things.

You're right. My bad.

The original issue still remains, though; so I created a workaround by
excplicitly setting the UDP_FLAGS_CONNECTED off after netconn_connect()
so that I can send a request to one port and receive a response from
another.

-- 
IOW, "not a tty" used to mean "WTF are you using ioctls here?" 

- Al Viro explaining ENOTTY on linux-kernel