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Posted to dev@nuttx.apache.org by Nathan Hartman <ha...@gmail.com> on 2022/06/28 20:05:46 UTC
net/if_arp.h - standard header?
I have a program that builds under Linux, BSD, and macOS which
includes the net/if_arp.h header.
This header does not seem to exist under NuttX.
It is included for the ARPHRD_ETHER define (and possibly other things).
I see that under NuttX, this is defined in net/arp.h, rather than net/if_arp.h.
Is net/if_arp.h supposed to be a standard header? I cannot seem to
find any meaningful information about it.
Thanks,
Nathan
Re: net/if_arp.h - standard header?
Posted by Xiang Xiao <xi...@gmail.com>.
On Thu, Jun 30, 2022 at 12:40 AM Nathan Hartman <ha...@gmail.com>
wrote:
> On Wed, Jun 29, 2022 at 12:23 PM Xiang Xiao <xi...@gmail.com>
> wrote:
> >
> > On Wed, Jun 29, 2022 at 4:44 AM Nathan Hartman <hartman.nathan@gmail.com
> >
> > wrote:
> >
> > > On Tue, Jun 28, 2022 at 4:05 PM Nathan Hartman <
> hartman.nathan@gmail.com>
> > > wrote:
> > > >
> > > > I have a program that builds under Linux, BSD, and macOS which
> > > > includes the net/if_arp.h header.
> > > >
> > > > This header does not seem to exist under NuttX.
> > > >
> > > > It is included for the ARPHRD_ETHER define (and possibly other
> things).
> > > >
> > > > I see that under NuttX, this is defined in net/arp.h, rather than
> > > net/if_arp.h.
> > > >
> > > > Is net/if_arp.h supposed to be a standard header? I cannot seem to
> > > > find any meaningful information about it.
> > > >
> > >
> >
> > If no standard defines it, it's better to follow other OS(especially,
> other
> > POSIX compliant)'s practices.
>
>
> Hmm... well the net/if_arp.h header seems to exist on Linux and macOS
> (BSD), so maybe we need to do something similar.
>
> I still can't seem to find much information about this header, so for
> now I added a special case: if __NuttX__ is defined then I #include
> <nuttx/net/arp.h>. Otherwise I include <net/if_arp.h>. It builds, but
> I do not know if the code that uses the ARPHRD_ETHER define is working
> correctly because I haven't tested it yet.
>
> The code is trying to get the MAC address of a Ethernet interface
> using ioctl SIOCGIFHWADDR on a temporary socket. In the returned
> struct ifreq, it checks if ifr_hwaddr.sa_family == ARPHRD_ETHER to
> ensure it is a Ethernet MAC and not a different type of interface.
>
>
here is NuttX's implementation:
https://github.com/apache/incubator-nuttx/blob/master/net/netdev/netdev_ioctl.c#L914-L949
If the implementation isn't fully compatible with other OS, I normally
prefer to update NuttX's one.
> Maybe there is a better way to do this in NuttX but I prefer to leave
> the application code unchanged if possible.
>
> More below...
>
>
> > > Also, do we lack the defines IFF_LOOPBACK, IFF_UP, IFF_BROADCAST, and
> > > IFF_MULTICAST? I can't find them anywhere, except in comments.
> > >
> > > For example, a grep for IFF_LOOPBACK shows it in the comments for
> > > getifaddrs():
> > >
> > > [[[
> > > * Depending on whether the bit IFF_BROADCAST or IFF_POINTOPOINT is
> > > * set in ifa_flags (only one can be set at a time), either
> > > * ifa_broadaddr will contain the broadcast address associated with
> > > * ifa_addr (if applicable for the address family) or ifa_dstaddr
> > > * will contain the destination address of the point-to-point
> > > * interface.
> > > ]]]
> > >
> > > but no such define exists in NuttX.
> > >
> >
> > We just added the related code a couple weeks ago. My teammate will
> > upstream the change soon.
>
>
> That is very good news! I'll be looking out for it when it lands. Feel
> free to ping me for review on GitHub.
>
>
It's here:
https://github.com/apache/incubator-nuttx/pull/6543
> Thanks for the reply.
>
> Cheers,
> Nathan
>
Re: net/if_arp.h - standard header?
Posted by Nathan Hartman <ha...@gmail.com>.
On Wed, Jun 29, 2022 at 12:23 PM Xiang Xiao <xi...@gmail.com> wrote:
>
> On Wed, Jun 29, 2022 at 4:44 AM Nathan Hartman <ha...@gmail.com>
> wrote:
>
> > On Tue, Jun 28, 2022 at 4:05 PM Nathan Hartman <ha...@gmail.com>
> > wrote:
> > >
> > > I have a program that builds under Linux, BSD, and macOS which
> > > includes the net/if_arp.h header.
> > >
> > > This header does not seem to exist under NuttX.
> > >
> > > It is included for the ARPHRD_ETHER define (and possibly other things).
> > >
> > > I see that under NuttX, this is defined in net/arp.h, rather than
> > net/if_arp.h.
> > >
> > > Is net/if_arp.h supposed to be a standard header? I cannot seem to
> > > find any meaningful information about it.
> > >
> >
>
> If no standard defines it, it's better to follow other OS(especially, other
> POSIX compliant)'s practices.
Hmm... well the net/if_arp.h header seems to exist on Linux and macOS
(BSD), so maybe we need to do something similar.
I still can't seem to find much information about this header, so for
now I added a special case: if __NuttX__ is defined then I #include
<nuttx/net/arp.h>. Otherwise I include <net/if_arp.h>. It builds, but
I do not know if the code that uses the ARPHRD_ETHER define is working
correctly because I haven't tested it yet.
The code is trying to get the MAC address of a Ethernet interface
using ioctl SIOCGIFHWADDR on a temporary socket. In the returned
struct ifreq, it checks if ifr_hwaddr.sa_family == ARPHRD_ETHER to
ensure it is a Ethernet MAC and not a different type of interface.
Maybe there is a better way to do this in NuttX but I prefer to leave
the application code unchanged if possible.
More below...
> > Also, do we lack the defines IFF_LOOPBACK, IFF_UP, IFF_BROADCAST, and
> > IFF_MULTICAST? I can't find them anywhere, except in comments.
> >
> > For example, a grep for IFF_LOOPBACK shows it in the comments for
> > getifaddrs():
> >
> > [[[
> > * Depending on whether the bit IFF_BROADCAST or IFF_POINTOPOINT is
> > * set in ifa_flags (only one can be set at a time), either
> > * ifa_broadaddr will contain the broadcast address associated with
> > * ifa_addr (if applicable for the address family) or ifa_dstaddr
> > * will contain the destination address of the point-to-point
> > * interface.
> > ]]]
> >
> > but no such define exists in NuttX.
> >
>
> We just added the related code a couple weeks ago. My teammate will
> upstream the change soon.
That is very good news! I'll be looking out for it when it lands. Feel
free to ping me for review on GitHub.
Thanks for the reply.
Cheers,
Nathan
Re: net/if_arp.h - standard header?
Posted by Xiang Xiao <xi...@gmail.com>.
On Wed, Jun 29, 2022 at 4:44 AM Nathan Hartman <ha...@gmail.com>
wrote:
> On Tue, Jun 28, 2022 at 4:05 PM Nathan Hartman <ha...@gmail.com>
> wrote:
> >
> > I have a program that builds under Linux, BSD, and macOS which
> > includes the net/if_arp.h header.
> >
> > This header does not seem to exist under NuttX.
> >
> > It is included for the ARPHRD_ETHER define (and possibly other things).
> >
> > I see that under NuttX, this is defined in net/arp.h, rather than
> net/if_arp.h.
> >
> > Is net/if_arp.h supposed to be a standard header? I cannot seem to
> > find any meaningful information about it.
> >
>
If no standard defines it, it's better to follow other OS(especially, other
POSIX compliant)'s practices.
> > Thanks,
> > Nathan
>
> Also, do we lack the defines IFF_LOOPBACK, IFF_UP, IFF_BROADCAST, and
> IFF_MULTICAST? I can't find them anywhere, except in comments.
>
> For example, a grep for IFF_LOOPBACK shows it in the comments for
> getifaddrs():
>
> [[[
> * Depending on whether the bit IFF_BROADCAST or IFF_POINTOPOINT is
> * set in ifa_flags (only one can be set at a time), either
> * ifa_broadaddr will contain the broadcast address associated with
> * ifa_addr (if applicable for the address family) or ifa_dstaddr
> * will contain the destination address of the point-to-point
> * interface.
> ]]]
>
> but no such define exists in NuttX.
>
We just added the related code a couple weeks ago. My teammate will
upstream the change soon.
Re: net/if_arp.h - standard header?
Posted by Nathan Hartman <ha...@gmail.com>.
On Tue, Jun 28, 2022 at 4:05 PM Nathan Hartman <ha...@gmail.com> wrote:
>
> I have a program that builds under Linux, BSD, and macOS which
> includes the net/if_arp.h header.
>
> This header does not seem to exist under NuttX.
>
> It is included for the ARPHRD_ETHER define (and possibly other things).
>
> I see that under NuttX, this is defined in net/arp.h, rather than net/if_arp.h.
>
> Is net/if_arp.h supposed to be a standard header? I cannot seem to
> find any meaningful information about it.
>
> Thanks,
> Nathan
Also, do we lack the defines IFF_LOOPBACK, IFF_UP, IFF_BROADCAST, and
IFF_MULTICAST? I can't find them anywhere, except in comments.
For example, a grep for IFF_LOOPBACK shows it in the comments for getifaddrs():
[[[
* Depending on whether the bit IFF_BROADCAST or IFF_POINTOPOINT is
* set in ifa_flags (only one can be set at a time), either
* ifa_broadaddr will contain the broadcast address associated with
* ifa_addr (if applicable for the address family) or ifa_dstaddr
* will contain the destination address of the point-to-point
* interface.
]]]
but no such define exists in NuttX.