Re: sendmsg(2) with IP_PKTINFO

[Roy Marples <roy%marples.name@localhost>]

Hi Ryo

On 25/07/2017 06:53, Ryo Shimizu wrote:
> I implemented IP_PKTINFO for sendmsg(2). For recvmsg(2) IP_PKTINFO is already
> supported, but it is not supported for sending. This causes problems
> described in https://mail-index.netbsd.org/tech-net/2013/09/22/msg004252.html
>
> patch is here.
>       http://www.netbsd.org/~ryo/ip_pktinfo.patch
>    or https://github.com/ryo/netbsd-src/compare/master...ip_pktinfo

+				/* Checking laddr:port already in use? */
+				xinp = in_pcblookup_bind(&udbtable,
+				    laddr.sin_addr, inp->inp_lport);
+				if ((xinp != NULL) && (xinp != inp)) {
+					error = EADDRINUSE;
+					goto release;
+				}
+				break;

Why is this check needed and why is it UDP specific?

In dhcpcd's case it's already bound the local address the socket and the 
kernel then claims the address is already in use which is wrong.

Roy