Re: [libvirt] [PATCH-v4 2/2] Support for static routes on a virtual bridge

On 04/25/2013 04:13 PM, Gene Czarcinski wrote: > On 04/25/2013 03:13 PM, Gene Czarcinski wrote: >> On 04/22/2013 11:59 AM, Laine Stump wrote: >>> address should be optional unless prefix or netmask is non-0, although >>> I've now noticed that won't be handled properly due to >>> virSocketAddrGetIpPrefix returning -1 when there is no address or >>> prefix >>> or netmask (I'm fixing that before I push that patch, so you can just >>> toss your 1/2 patch, rebase, and assume it's fixed). >> I have most of the stuff reworked except for the address, gateway, >> netmask, and prefix code. Getting all of those balanced so they work >> correctly is a bit tricky.. >> >> 1. For <route>, I am requiring that both address= and gateway= be >> specified with address='0.0.0.0' and address='::' being valid >> addresses. For IPv4, netmask='0.0.0.0' works correctly but prefix=0 >> does not. >> >> For IPv4, address='0.0.0.0' results in a default route. I am not >> sure what all these extra default routes are going to do to things >> but lets not get in the way of the experimenter. >> >> For IPv6, this address='::', prefix='0' is a slightly different >> matter as default routes are usually handled differently. I am going >> to go ahead and implement it but I am not sure it is a good idea. >> "Normally," if you do not specify a prefix for IPv6, the default is >> 64. But if you do specify one, then it will be used. >> >> It is getting real close and it should be ready "real soon now" ;)) >> > AARRRRGH!!!! > > With IPv4 using address='0.0.0.0' and netmask='0.0.0.0' things work > just fine but with prefix not so much. The problem is that with > prefix=0, it is not in the xml which then results it it defaulting at > a later time. This is an extreme corner case. Usually a zero prefix > is just ignored. Defaulting to what? I thought that when I pushed the utility function for that, I modified it to return a prefix of 0 if the address was 0.0.0.0 and neither netmask nor prefix was set. I guess it might be problematic if address was *not* 0 and you wanted an explicit 0 prefix, but I don't think that would ever be useful. If you really want prefix to show up in the xml if someone explicitly puts "prefix='0'" in there, you can add a "bool prefix_specified;" to the object, and set that when you see a prefix, even if it's 0. Then in the formatter you'll know that you should write out the value of prefix, even if it's 0. There are a few examples of doing this in either the network or domain xml parser/formatter - just search for occurrences of the word "_specified" in src/conf/*.[ch] and you'll find them.