Re: lpd with IPv6 support -- testing and patch needed
On Mon, Oct 20, 2003 at 08:04:04AM +0200, Pim van Pelt wrote:
> Hoi Adam,
>
> | The current problem is that it cannot tolerate IPv4 addresses [1]
> | as it can only bind to an IPv6 address and cannot do the
> | same port on IPv4... [yes, I know, this is a "feature" of linux 2.4].
> | ie. you will NOT be able to connect from remote IPv4 clients.
> |
> | If anyone knows of a good, quick fix for this, then
> | please send me a patch. Note that lpr must also
> | work on legacy IPv4 only systems...
>
> The only good fix for interoperable code is to have two sockets. Not
> all OS'es support IPv4 transport through IPv6 sockets. Linux does indeed.
> One way is to getaddrinfo() for your fqdn and make a socket for each address
> that gets returned (ipv4, ipv6), then select() or poll() on them all.
This is what is done by OpenBSD's lpr. Now I know that I can use IPV6_V6ONLY
to only bind to ipv6.. This helps.. But now the problem is that it doesn't
bind to IPV6 anymore enough though it doesn't give any errors.
And yes, I checked that IPV6 goes though bind(), listen() and to select()..
It is now the -test2 version at
http://people.debian.org/~adamm/
See if it binds to IPv6 on your system...
> | [1] - It barfs when it compares xxx.yyy.zzz.www to ::ffff:xxx:yyy:zzz:www
> Check Stevens' Vol1, chapter 10, page 267. It handles IPv4/IPv6
> interoperability and your mapped addresses (::ffff:xxx.yyy.zzz.www by the
> way). A pointer to what you need is defined in netinet/in.h, look for
> IN6_IS_ADDR_* macro's.
Is it preferred to bind to IPv4 AND IPv6 at the same time (same socket)
instead of IPv4 and IPv6 on seperate sockets? If yes, then I can get rid of
the IPV6_ONLY thing I added and just add IPv4 mapped address handling.
- Adam
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