Hi Michał, Le Tue, 30 Jun 2015 17:03:09 +0200, Michał Lipka <michal@lipka.email> a écrit :
> 2015-06-30 16:56 GMT+02:00 Albert ARIBAUD <albert.arib...@free.fr>: > > > Bonjour Maciej, > > > > Le Tue, 30 Jun 2015 15:56:36 +0200, Maciej Soltysiak > > <mac...@soltysiak.com> a écrit : > > > > > On Tue, Jun 30, 2015 at 3:24 PM, Albert ARIBAUD <albert.arib...@free.fr> > > > wrote: > > > > > > > Bonjour Michał, > > > > > > > > Le Tue, 30 Jun 2015 13:54:11 +0200, Michał Lipka <michal@lipka.email> > > a > > > > écrit : > > > > > > > > > 2015-06-30 12:10 GMT+02:00 Maciej Soltysiak <mac...@soltysiak.com>: > > > > > > > > > > > On Tue, Jun 30, 2015 at 4:03 AM, wkitt...@gmail.com < > > > > wkitt...@gmail.com> > > > > > > wrote: > > > > > > > > > > > >> > > > > > >> On 06/29/2015 04:01 PM, Michał Lipka wrote: > > > > > >> > > > > > >>> > > > > > >>> 2015-06-25 16:02 GMT+02:00 wkitt...@gmail.com > > > > > >>> does breaking the line work? > > > > > >>> > > > > > >>> eg: > > > > > >>> dhcp-option=249,10.0.0.1/32,1.2.3.4,192.168.13.15/32,1.2.3.4 > > > > > >>> <http://10.0.0.1/32,1.2.3.4,192.168.13.15/32,1.2.3.4>, \ > > > > > >>> 192.168.13.16/32,1.2.3.4,192.168.13.17/32,1.2.3.4 > > > > > >>> <http://192.168.13.16/32,1.2.3.4,192.168.13.17/32,1.2.3.4>, > > \ > > > > > >>> 192.168.13.18/32,1.2.3.4,192.168.13.19/32,1.2.3.4 > > > > > >>> <http://192.168.13.18/32,1.2.3.4,192.168.13.19/32,1.2.3.4>, > > \ > > > > > >>> 192.168.13.20/32,1.2.3.4 <http://192.168.13.20/32,1.2.3.4> > > > > > >>> > > > > > >>> > > > > > >>> Thank you for this idea. Unfortunately it does not work. dnsmasq > > > > fails > > > > > >>> at first > > > > > >>> line which has no option: > > > > > >>> > > > > > >> > > > > > >> sounds like an option that should maybe be implemented... > > especially > > > > > >> since it is an apparent standard that so many tools do follow ;) > > > > > >> > > > > > > I think dnsmasq has a 1024 characters for config lines. I browsed > > the > > > > > > source briefly last night but couldn't find it. > > > > > > > > > > > > > > > > I checked it more precisely and it turned out that is not line length > > > > that > > > > > bothers dnsmasq. It's routes count. > > > > > I can set up to 28 routes in single dhcp-option line. It doesn't > > matter > > > > if > > > > > it will take 600 or 800 characters. If I set 29th route dnsmasq > > complains > > > > > about option too long: > > > > > > > > > > dnsmasq: dhcp-option too long at line 320 of /etc/dnsmasq.conf > > > > > Can you check the code once again and try to find this limit (28) ? > > Why > > > > it > > > > > is like that? > > > > > > > > Could it be that the total DHCP packet size goes over the maximum > > > > allowed size for an UDP frame? > > > > > > > Perhaps. The offending code is related to the length of the dhcp option, > > > not the number of routes per se: > > > > > > if (!is6 && > > > ((new->len > 255) || > > > (new->len > 253 && (new->flags & (DHOPT_VENDOR | > > DHOPT_ENCAPSULATE))) > > > || > > > (new->len > 250 && (new->flags & DHOPT_RFC3925)))) > > > ret_err(_("dhcp-option too long")); > > > > route can use different number of bytes 17-33 - (1.1.1.1/8,2.2.2.2 > 111.111.111.111/32,222.222.222.222) and I checked that you can insert only > 28 routes despite of the fact how many bytes it will take (if you try to > assign 28 "smallest" routes it will take 28*17+27(commas)=503 and 28 > "largest" routes would take 28*33+27=951 bytes). and you cannot set 29 > "smallest" routes as it will yell "dhcp-option too long" (tested). Er, no, a route once encoded in an option is not a variable-length string, it is a fixed-length, 8-byte binary structure (four bytes to encode the net, four to encode the mask). Theoretically, that makes a maximum of 253/8 routes => 31 routes (and then maybe there is another limit I did not consider which puts the limit down from 31 to 28). > > > > > > I guess you can stick more than 255 bytes in a dhcp packet, anyone knows > > if > > > the limit is coming from RFCs or elsewhere? > > > > There is actually an option's size limit, see RFC 2132 section 2: > > the option second byte contains the length and its content does not > > include the tag and length fields, so the actual option content cannot > > be bigger than 253 bytes. > > > > yes but RFC 3396 is about "Encoding Long Options in the Dynamic Host > Configuration Protocol (DHCPv4)" Yes, it is. The routes are among these long options. > and setting 28 routes is working (client gets them) Which is normal, 28*8+2 = 226 bytes which is below the absolute 253 bytes per option limit and below the 248 bytes route limit (at 8 bytes per route). > Michal Amicalement, -- Albert. _______________________________________________ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
