[syslinux] Support DHCP sname field in PXELINUX

[Chris Adams]

Once upon a time, H. Peter Anvin <hpa at zytor.com> said:
> Chris Adams wrote:
> >I have discovered that the JUNOS DHCP server in Juniper J-series routers
> >doesn't support setting the next-server IP address field (I have filed a
> >bug report with Juniper and they are working on it).  Instead, it puts
> >the "boot server" in the sname field, which PXELINUX currently ignores.
> >
> >Here's a simple patch (vs. 3.36) that will take an IP string in the
> >field.  My assembly is pretty rusty, and I couldn't quite figure out how
> >to use the DNS resolver, so it doesn't handle a hostname.  This does
> >work for me with an IP string.
> 
> You have no guarantee that sname is an IP string; in fact, in the 
> typical case it will not be.
> 
> I don't think this patch is safe.

Well, it doesn't try to parse a null string, and it only saves the
resulting IP if parse_dotquad says it succeeded.  How can that not be
safe?
-- 
Chris Adams <cmadams at hiwaay.net>
Systems and Network Administrator - HiWAAY Internet Services
I don't speak for anybody but myself - that's enough trouble.