On 6/6/07, Lucian Adrian Grijincu <[EMAIL PROTECTED]> wrote:
On 6/6/07, Davi Arnaut <[EMAIL PROTECTED]> wrote:
> Joe Orton wrote:
> > On Wed, Jun 06, 2007 at 06:06:44PM +0300, Lucian Adrian Grijincu wrote:
> >> $>./test ::1 ssh
> >> ./test: getaddrinfo: Address family for hostname not supported
> >>
> >> $> telnet ::1 ssh
> >> Trying ::1...
> >> Connected to ::1.
> >
> > That makes little sense. I presume you do in fact have the "ipv6"
> > module loaded (lsmod | grep ipv6)? What version of glibc is this? Does
> > it make any difference if you set ai_flags to 0 in your test program?
> >
>
[EMAIL PROTECTED]:~$ lsmod | grep ipv6
ipv6 268960 12
I guess 2.5 :)
Ubuntu reports it as 2.5-0ubuntu14
[EMAIL PROTECTED]:~$ ls -al /lib/libc.so.6
lrwxrwxrwx 1 root root 11 2007-05-18 01:12 /lib/libc.so.6 -> libc-2.5.so
I think that telnet could see that "::1" is the IPv6 loopback string
and replace it with "127.0.0.1" if it wanted. Haven' looked at the
code, just why this behaviour may be possible.
> In case anyone wanna try.. test attached.
This is the output:
getaddrinfo AF_UNSPEC/SOCK_STREAM/AI_ADDRCONFIG failed
so, yes: hints.ai_flags = AI_ADDRCONFIG; makes getaddrinfo fail.
commenting out AI_ADDRCONFIG in the malfunctioning code makes it pass all tests.
#ifdef HAVE_GAI_ADDRCONFIG
if (family == APR_UNSPEC) {
/* By default, only look up addresses using address types for
* which a local interface is configured, i.e. no IPv6 if no
* IPv6 interfaces configured. */
//hints.ai_flags = AI_ADDRCONFIG;
}
#endif
I hear that there are real performance reasons to maintain
AI_ADDRCONFIG for AF_UNSPEC:
http://www.ops.ietf.org/lists/v6ops/v6ops.2003/msg01377.html
I first though we could do a strcmp to check for "127.0.0.1" or "::1",
but it's not going to work, because users may have altered the hosts
file to set a specific hostname to loopback and this code should be
able to get things like "localhost" as a valid parameter.
I see three getaways:
1. kill AI_ADDRCONFIG for APR_UNSPEC
2. document "::1" and any other link-local addresses and hostnames as
invalid if APR_UNSPEC is used.
3. retry without AI_ADDRCONFIG if first try fails
1. BAD: this is the only place where AI_ADDRCONFIG is used and not
using it would mean a performance regression for applications that do
not care about loopback.
2. UGLY: APR should work arround platform specific issues and present
a simple interface. Having the user check for link-localness
beforehand is ... ugly. :)
3. GOOD: We already retry for some other errors and retrying would
only harm performance-wise only in case of a:
a) link-local address or hostname. This should be resolved locally,
which means the drawback is little
b) failing external lookup. This can mean we'll take longer to say:
"I can't find the hostname you specified", or (not very probable)
manage to find it at the second try
I've attached a patch against the tarball that does what's needed for 3.
Rebuilt from scratch + patch:
finally, all test pass now :)
--
Lucian Adrian Grijincu
339c339
< if ((error == EAI_BADFLAGS || error == EAI_ADDRFAMILY ) && family == APR_UNSPEC) {
---
> if (error == EAI_BADFLAGS && family == APR_UNSPEC) {
