Hi Nathan, There is such a macro, it is net_ipv4addr_broadcast(). I just used it, as you describe above, and I created PR #6262.
I checked the result with Wireshark, and indeed it solves the issue. Thank you all! Στις Πέμ 12 Μαΐ 2022 στις 7:01 μ.μ., ο/η Nathan Hartman < hartman.nat...@gmail.com> έγραψε: > On Thu, May 12, 2022 at 5:18 AM Bernd Walter <ti...@cicely7.cicely.de> > wrote: > > > > On Wed, May 11, 2022 at 07:13:17PM -0400, Nathan Hartman wrote: > > > On Wed, May 11, 2022 at 5:19 AM Fotis Panagiotopoulos > > > <f.j.pa...@gmail.com> wrote: > > > > > > > > I was thinking the same thing. > > > > > > > > Which layer is responsible for this check? > > > > IP, UDP, or ICMP? > > > > > > > > > Logically it would seem to me that UDP should do the check and trigger > > > sending the ICMP unreachable reply when appropriate, though it seems > > > that it unconditionally calls icmp_reply(), which contains the logic > > > to *avoid* sending it when it's the ANY or BROADCAST address. In other > > > words, it is currently is coded in the ICMP layer. > > > > > > Looking at struct net_driver_s in include/nuttx/net/netdev.h, I am > > > reminded that there is also IPv6, which a grep reveals has a similar > > > handler in the IPv6 ICMP handler in icmpv6_reply() in > > > net/icmpv6/icmpv6_reply.c. > > > > > > There is a function net_is_addr_mcast(), but there is no > > > net_is_addr_bcast() currently. I think that is the function that needs > > > to be coded, and then called from icmp_reply(). > > > > There is no broadcast in IPv6. > > Completely replaced by multicast. > > > Sorry, I was not clear: > > I mentioned IPv6 only because I noticed how icmpv6_reply() is coded; > icmpv6_reply() checks if the address is a multicast address by calling > net_is_addr_mcast(). > > In contrast, the IPv4 version, icmp_reply(), checks against the ANY or > BROADCAST addresses by a simple comparison. > > To fix the issue found by the OP, I proposed that we need a > net_is_address_bcast(), which will be similar in purpose to > net_is_address_mcast(), but for broadcast rather than multicast > addresses. Then, icmp_reply() will call net_is_address_bcast() instead > of the above-mentioned simple comparison that it is currently doing. > The proposed new function net_is_address_bcast() will be smart enough > to check for other broadcast addresses besides 255.255.255.255 by > consulting the netmask. > > Cheers, > Nathan >
