[Buildroot] [PATCH 1/1] busybox: udhcpc create leases file

[Buildroot] [PATCH 1/1] busybox: udhcpc create leases file

[Matt Weber]

Signed-off-by: Matt Weber <matt@thewebers.ws>
---
 package/busybox/udhcpc.script | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/package/busybox/udhcpc.script b/package/busybox/udhcpc.script
index 50c52e6..d5d81bf 100755
--- a/package/busybox/udhcpc.script
+++ b/package/busybox/udhcpc.script
@@ -61,6 +61,29 @@ case "$1" in
 			echo adding dns $i
 			echo "nameserver $i # $interface" >> $RESOLV_CONF
 		done
+
+		# Based on http://sourceforge.net/p/kboot/mailman/message/1168535/
+		{
+		    echo "lease {"
+		    echo "  interface \"$interface\";"
+		    echo "  fixed-address $ip;"
+		    [ -n "$boot_file" ] && echo "  filename \"$boot_file\";"
+		    [ -n "$subnet" ] && echo "  option subnet-mask $subnet;"
+		    [ -n "$router" ] && echo "  option routers $router;"
+		    echo "  option dhcp-lease-time $lease;"
+		    echo "  option dhcp-message-type $dhcptype;"
+		    [ -n "$dns" ] && echo "  option domain-name-servers $dns;"
+		    echo "  option dhcp-server-identifier ${siaddr:-$serverid};"
+		    [ -n "$domain" ] && echo "  option domain-name \"$domain\";"
+		    d=$(expr "$(date "+%Y.%m.%d-%H:%M:%S")" : "\(.*\):")
+		    t=$(date -d "$d:$(expr $lease / 2)" "+%w %Y/%m/%d %H:%M:%S" 2>/dev/null)
+		    [ -n "$t" ] && echo "  renew $t;"
+		    t=$(date -d "$d:$(expr 7 '*' $lease / 8)" "+%w %Y/%m/%d %H:%M:%S" 2>/dev/null)
+		    [ -n "$t" ] && echo "  rebind $t;"
+		    t=$(date -d "$d:$lease" "+%w %Y/%m/%d %H:%M:%S" 2>/dev/null)
+		    [ -n "$t" ] && echo "  expire $t;"
+		    echo "}"
+		} >> /var/lib/misc/udhcpc-$interface.leases
 		;;
 esac

--
1.9.1

[Buildroot] [PATCH 1/1] busybox: udhcpc create leases file

[Peter Korsgaard]

>>>>> "Matt" == Matt Weber <matt@thewebers.ws> writes:

 > Signed-off-by: Matt Weber <matt@thewebers.ws>
 > ---
 >  package/busybox/udhcpc.script | 23 +++++++++++++++++++++++
 >  1 file changed, 23 insertions(+)

 > diff --git a/package/busybox/udhcpc.script b/package/busybox/udhcpc.script
 > index 50c52e6..d5d81bf 100755
 > --- a/package/busybox/udhcpc.script
 > +++ b/package/busybox/udhcpc.script
 > @@ -61,6 +61,29 @@ case "$1" in
 >  			echo adding dns $i
 >  			echo "nameserver $i # $interface" >> $RESOLV_CONF
 >  		done
 > +
 > +		# Based on http://sourceforge.net/p/kboot/mailman/message/1168535/

A more detailed commit message would be good. After looking at that URL
I'm still not quite sure what this is needed for? It doesn't seem to be
read again anywhere.

> +		} >> /var/lib/misc/udhcpc-$interface.leases

Are you sure this should append the file and not overwrite it? Why would
you want to keep older lease info around when you receive a new one?

Perhaps this belongs in a hook in your rootfs overlay?

-- 
Bye, Peter Korsgaard

[Buildroot] [PATCH 1/1] busybox: udhcpc create leases file

[Matthew Weber]

Peter,

On Thu, Apr 30, 2015 at 9:31 AM, Peter Korsgaard <peter@korsgaard.com> wrote:
>>>>>> "Matt" == Matt Weber <matt@thewebers.ws> writes:
>
>  > Signed-off-by: Matt Weber <matt@thewebers.ws>
>  > ---
>  >  package/busybox/udhcpc.script | 23 +++++++++++++++++++++++
>  >  1 file changed, 23 insertions(+)
>
>  > diff --git a/package/busybox/udhcpc.script b/package/busybox/udhcpc.script
>  > index 50c52e6..d5d81bf 100755
>  > --- a/package/busybox/udhcpc.script
>  > +++ b/package/busybox/udhcpc.script
>  > @@ -61,6 +61,29 @@ case "$1" in
>  >                      echo adding dns $i
>  >                      echo "nameserver $i # $interface" >> $RESOLV_CONF
>  >              done
>  > +
>  > +            # Based on http://sourceforge.net/p/kboot/mailman/message/1168535/
>
> A more detailed commit message would be good. After looking at that URL
> I'm still not quite sure what this is needed for? It doesn't seem to be
> read again anywhere.

Sorry, I can add that.  In general, it adds the leases functionality
that mimics full dhclient behavior.  This file can then be used at a
system level to know least expiration and other server provided
information.

>
>> +             } >> /var/lib/misc/udhcpc-$interface.leases
>
> Are you sure this should append the file and not overwrite it? Why would
> you want to keep older lease info around when you receive a new one?

I just mimic'd dhclient but I could see in a embedded space you might
only want to keep the latest and when a lease expires, removing this
file.  I think the full client usually used this file to set an
interface after reboot to the previous lease if one was still valid.
I wasn't going to keep this behavior since for embedded devices it
doesn't make sense.

>
> Perhaps this belongs in a hook in your rootfs overlay?

Right now there isn't any way to get dhcp lease information after a
lease is provided.  It seemed this should be a standard capability of
the script.  I do agree I should make it not append and clean up when
there isnt' a lease.

Thanks for the feedback!
-- 
Matthew L Weber / Pr Software Engineer
Airborne Information Systems / Security Systems and Software / Secure Platforms
MS 131-100, C Ave NE, Cedar Rapids, IA, 52498, USA
www.rockwellcollins.com

Note: Any Export License Required Information and License Restricted
Third Party Intellectual Property (TPIP) content must be encrypted and
sent to matthew.weber at corp.rockwellcollins.com.

[Buildroot] [PATCH 1/1] busybox: udhcpc create leases file

[Peter Korsgaard]

>>>>> "Matthew" == Matthew Weber <matthew.weber@rockwellcollins.com> writes:

Hi,

 >> > +            # Based on http://sourceforge.net/p/kboot/mailman/message/1168535/
 >> 
 >> A more detailed commit message would be good. After looking at that URL
 >> I'm still not quite sure what this is needed for? It doesn't seem to be
 >> read again anywhere.

 > Sorry, I can add that.  In general, it adds the leases functionality
 > that mimics full dhclient behavior.  This file can then be used at a
 > system level to know least expiration and other server provided
 > information.

Ok, good. Is that really something we want to enforce for everyone using
udhcpc with Buildroot?

 >>> +             } >> /var/lib/misc/udhcpc-$interface.leases
 >> 
 >> Are you sure this should append the file and not overwrite it? Why would
 >> you want to keep older lease info around when you receive a new one?

 > I just mimic'd dhclient but I could see in a embedded space you might
 > only want to keep the latest and when a lease expires, removing this
 > file.  I think the full client usually used this file to set an
 > interface after reboot to the previous lease if one was still valid.
 > I wasn't going to keep this behavior since for embedded devices it
 > doesn't make sense.

Ok.

 >> 
 >> Perhaps this belongs in a hook in your rootfs overlay?

 > Right now there isn't any way to get dhcp lease information after a
 > lease is provided.  It seemed this should be a standard capability of
 > the script.  I do agree I should make it not append and clean up when
 > there isnt' a lease.

I'm still not convinced this isn't something that belongs in a project
specific rootfs overlay instead. That's part of the reason why we now
support custom hooks in the udhcpc script.

-- 
Venlig hilsen,
Peter Korsgaard 

[Buildroot] [PATCH 1/1] busybox: udhcpc create leases file

[Matthew Weber]

Peter,

On Thu, Apr 30, 2015 at 9:59 AM, Peter Korsgaard <peter@korsgaard.com> wrote:
>>>>>> "Matthew" == Matthew Weber <matthew.weber@rockwellcollins.com> writes:
>
> Hi,
>
>  >> > +            # Based on http://sourceforge.net/p/kboot/mailman/message/1168535/
>  >>
>  >> A more detailed commit message would be good. After looking at that URL
>  >> I'm still not quite sure what this is needed for? It doesn't seem to be
>  >> read again anywhere.
>
>  > Sorry, I can add that.  In general, it adds the leases functionality
>  > that mimics full dhclient behavior.  This file can then be used at a
>  > system level to know least expiration and other server provided
>  > information.
>
> Ok, good. Is that really something we want to enforce for everyone using
> udhcpc with Buildroot?

Possibly not.  I'm good with doing a hook script for now.  Half of my
sending this patch in was to just publish the concept if anyone else
wants to use/add to it.

Thanks!

-- 
Matthew L Weber / Pr Software Engineer
Airborne Information Systems / Security Systems and Software / Secure Platforms
MS 131-100, C Ave NE, Cedar Rapids, IA, 52498, USA
www.rockwellcollins.com

Note: Any Export License Required Information and License Restricted
Third Party Intellectual Property (TPIP) content must be encrypted and
sent to matthew.weber at corp.rockwellcollins.com.

[Buildroot] [PATCH 1/1] busybox: udhcpc create leases file

[Arnout Vandecappelle]

On 04/30/15 16:59, Peter Korsgaard wrote:
>>>>>> "Matthew" == Matthew Weber <matthew.weber@rockwellcollins.com> writes:
> 
> Hi,
> 
>  >> > +            # Based on http://sourceforge.net/p/kboot/mailman/message/1168535/
>  >> 
>  >> A more detailed commit message would be good. After looking at that URL
>  >> I'm still not quite sure what this is needed for? It doesn't seem to be
>  >> read again anywhere.
> 
>  > Sorry, I can add that.  In general, it adds the leases functionality
>  > that mimics full dhclient behavior.  This file can then be used at a
>  > system level to know least expiration and other server provided
>  > information.
> 
> Ok, good. Is that really something we want to enforce for everyone using
> udhcpc with Buildroot?

 I don't see why not. It's creating a small file in /tmp, that's all. Except for
the appending, of course, otherwise a long-running system could just fill up
/tmp with leases. Overwriting has the disadvantage that there's a race condition
when the file is truncated at the same time that another process is reading from
it, but I don't think the complexity of fixing that race is worth the bother.


 Regards,
 Arnout

> 
>  >>> +             } >> /var/lib/misc/udhcpc-$interface.leases
>  >> 
>  >> Are you sure this should append the file and not overwrite it? Why would
>  >> you want to keep older lease info around when you receive a new one?
> 
>  > I just mimic'd dhclient but I could see in a embedded space you might
>  > only want to keep the latest and when a lease expires, removing this
>  > file.  I think the full client usually used this file to set an
>  > interface after reboot to the previous lease if one was still valid.
>  > I wasn't going to keep this behavior since for embedded devices it
>  > doesn't make sense.
> 
> Ok.
> 
>  >> 
>  >> Perhaps this belongs in a hook in your rootfs overlay?
> 
>  > Right now there isn't any way to get dhcp lease information after a
>  > lease is provided.  It seemed this should be a standard capability of
>  > the script.  I do agree I should make it not append and clean up when
>  > there isnt' a lease.
> 
> I'm still not convinced this isn't something that belongs in a project
> specific rootfs overlay instead. That's part of the reason why we now
> support custom hooks in the udhcpc script.
> 


-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint:  7CB5 E4CC 6C2E EFD4 6E3D A754 F963 ECAB 2450 2F1F

[Buildroot] [PATCH 1/1] busybox: udhcpc create leases file

[Peter Korsgaard]

>>>>> "Arnout" == Arnout Vandecappelle <arnout@mind.be> writes:

Hi,

 >> > Sorry, I can add that.  In general, it adds the leases functionality
 >> > that mimics full dhclient behavior.  This file can then be used at a
 >> > system level to know least expiration and other server provided
 >> > information.
 >> 
 >> Ok, good. Is that really something we want to enforce for everyone using
 >> udhcpc with Buildroot?

 >  I don't see why not. It's creating a small file in /tmp, that's all. Except for
 > the appending, of course, otherwise a long-running system could just fill up
 > /tmp with leases. Overwriting has the disadvantage that there's a race condition
 > when the file is truncated at the same time that another process is reading from
 > it, but I don't think the complexity of fixing that race is worth the bother.

True. I would like to see this (and other non-essential things like
E.G. avahi-autoipd) move to hooks though.

I wonder if the dhclient format is a sensible choice. Is that something
any "standard" programs can work with? It doesn't seem very easy to
parse in shell scripts. Maybe just shell compatible NAME="<val>" strings
would be better?

-- 
Venlig hilsen,
Peter Korsgaard