DHCPv6 client in base

[Roy Marples]

On 11/10/2019 20:40, Hiroki Sato wrote:
>   I do not have a strong objection on dhcpcd (I am using it on some of
>   my FreeBSD boxes actually) but let me explain the reason why I chose
>   wide-dhcp as the candidate.  That is because it is a small,
>   functional DHCPv6-only implementation.  I am planning to rewrite it
>   to add the missing bits and adjust it for a tighter integration with
>   kernel, ifconfig, rtsold, rtadvd, and sandboxing with Capsicum.  I
>   feel dhcpcd (or others) is too big for that purpose.

How are you measuring that dhcpcd is too big?

On my FreeBSD box

$ size /usr/sbin/rtsold /sbin/dhclient /usr/local/sbin/dhcp6c /sbin/dhcpcd
     text    data     bss      dec       hex   filename
    32327     984    3352    36663    0x8f37   /usr/sbin/rtsold
    86752   10144   82696   179592   0x2bd88   /sbin/dhclient
   145322    1396   11304   158022   0x26946   /usr/local/sbin/dhcp6c
   253258    1532    1184   255974   0x3e7e6   /sbin/dhcpcd

Taken by itself, yes dhcpcd is larger.
But as a whole dhcpcd is quite smaller.
24k of dhcpcd is just a text file with decoding instructions for all 
DHCP/DHCP6/ND6 RFC's I can find.

What's more, dhcpcd can be compiled with things turned on or all, such 
as DHCP, ARP, etc. It's quite flexable. To demonstrate, the above dhcpcd 
size is the full fat dhcpcd.
Here is it with the stock small config and full IPv6 stack support, 
which is the equivalent of dhcp6c and rtsold above + the extra goodies 
you get with dhcpcd.

$ size dhcpcd
     text   data    bss      dec       hex   filename
   176605   1452   1168   179225   0x2bc19   dhcpcd

But wait, there's more.
Lets see how dhcpcd weighs up as just a DHCP client + the extra dhcpcd 
goodies?

$ size dhcpcd
     text   data    bss      dec       hex   filename
   144163   1420   1136   146719   0x23d1f   dhcpcd

I don't consider dhcpcd to be big at all, and would love to know your 
rationale for calling it so.

> 
>   IMHO, the directions of further developments of IPv6 functionality on
>   FreeBSD, NetBSD (dhcpcd), OpenBSD (slaacd + others), and DragonFly
>   BSD (dhcpcd) have already been diverged.  For RFC 7217 I already have
>   an in-kernel implementation (not committed yet), and I am also
>   working on SeND (RFC 3971, not directly related to DHCPv6 though).
>   My goal is to integrate these small implementations into the base
>   system and make them possible to work together.  So for DHCPv6, I
>   think an implementation of only DHCPv6 is the best.
> 
>   If people want a more feature-rich implementation or the same one on
>   other systems, they can still use dhcpcd or ISC's dhclient even after
>   the import.
> 
>   Of course this assumes that wide-dhcp works to some degree.  If it
>   does not, importing it to the base system does not make sense.  I
>   have used it in various scenarios for a long time such as RA + O flag
>   on native IPv6 over Ethernet, DHCPv6-PD over PPPoE/L2TP, and others
>   which are complex enough, and understand what works and what is
>   missing (poor DUID format support, for example).  The popular way to
>   use DHCPv6 is IA_PD, and wide-dhcp works well with it.
> 
>   So I have a question.  What is missing feature in wide-dhcp which you
>   are concerned about?  I know some, but it has most of the basic
>   functionality of DHCPv6 and I think it is enough as a minimal
>   implementation for the base system.  My primary reason is that it is
>   just for DHCPv6 as mentioned earlier and I believe it is maintainable
>   in the base system.  I would like to know other people's opinion if
>   there is something critical.

This isn't a question about wide-dhcp specifically, but I feel it's a 
good question.

Do you plan on supporting a multihomed system with hotpluggable 
interfaces all auto configured?

I'm looking at the BUGS section for rtsold and these bugs
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=138547
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=218191

This is one of dhcpcd's killer features and allows me to use my pinebook 
on the sofa, but hotplug in ethernet to take over so I can compile my 
sources from NFS over distcc much faster.

Roy