Re: --inet6-only option
Hrvoje Niksic <[EMAIL PROTECTED]> writes: > * If the machine doesn't support AI_ADDRCONFIG and Wget sets -4 > behind your back, then you shouldn't be allowed to specify -6 > because it clearly contradicts with the automagically set -4. > > (But even then you can still use `--no-inet4-only -6', which will > make Wget resolve IPv6 addresses only, and fail to connect to any > host. After thinking about this some more, I decided to redo the last part. The "feature" of being able to undo the implicit `-4' is not that useful because it's unavailable on machines with AI_ADDRCONFIG, which we expect to become ubiquitous. The whole thing degrades into an ugly and unnecessary special case. I decided to implement (in part) your suggestion to move the socket check to lookup_host. The code now no longer automatically sets --inet4; instead, it does the following: * If -4 is specified, request AF_INET family from getaddrinfo. * If -6 is specified, request AF_INET6 family from getaddrinfo. * Otherwise, request AF_UNSPEC family with the AI_ADDRCONFIG flag. If AI_ADDRCONFIG is not available, simulate it with an explicitly check whether an AF_INET6 socket can be created. If not, simply request AF_INET instead of AF_UNSPEC. And if yes, keep using AF_UNSPEC. This should cause systems without AI_ADDRCONFIG to behave exactly the same as systems that support it. (The only exception would be hypothetical IPv6-only systems that actually cannot create AF_INET sockets. If such were to exist, I assume that they will support AI_ADDRCONFIG.)
Re: --inet6-only option
Hrvoje Niksic <[EMAIL PROTECTED]> writes:
> "Gisle Vanem" <[EMAIL PROTECTED]> writes:
>
>> Running "wget -6 url.." on a machine with no IPv6 installed
>> silently uses IPv4. A warning with fallback to IPv4 is IMHO
>> okay. Or an exit?
I gave this question some more thought. Here are some conclusions.
* -4 and -6 are host lookup options. If you specify -6 on an
IPv4-only host, you get what you asked for -- no addresses will
resolve. Tough luck.
* If the machine doesn't support AI_ADDRCONFIG and Wget sets -4 behind
your back, then you shouldn't be allowed to specify -6 because it
clearly contradicts with the automagically set -4.
(But even then you can still use `--no-inet4-only -6', which will
make Wget resolve IPv6 addresses only, and fail to connect to any
host. Again, tough luck.)
* Furthermore, -4 and -6 don't mix in general. Report an error when
both are present. But the error needs to be different when -4 was
set behind your back from when it was set by the user.
The above sounds complex when stated, but is in fact quite simple
because it explicitly disallows the `-4 -6' which doesn't make sense
anyway, and because it removes the possibility of a "silent fallback
to IPv4" that you observed.
Here is a patch:
2003-11-16 Hrvoje Niksic <[EMAIL PROTECTED]>
* main.c (main): Don't allow setting of both opt.ipv4_only and
opt.ipv6_only.
* init.c (defaults): Mark opt.ipv4_only specially when set
automatically.
Index: src/init.c
===
RCS file: /pack/anoncvs/wget/src/init.c,v
retrieving revision 1.83
diff -u -r1.83 init.c
--- src/init.c 2003/11/15 01:49:52 1.83
+++ src/init.c 2003/11/16 00:12:27
@@ -321,7 +321,8 @@
{
int sock = socket (AF_INET6, SOCK_STREAM, 0);
if (sock < 0)
- opt.ipv4_only = 1;
+ opt.ipv4_only = -1; /* special value -1 because the option
+ was not specified by the user. */
else
close (sock);
}
Index: src/main.c
===
RCS file: /pack/anoncvs/wget/src/main.c,v
retrieving revision 1.102
diff -u -r1.102 main.c
--- src/main.c 2003/11/15 02:05:21 1.102
+++ src/main.c 2003/11/16 00:12:31
@@ -806,6 +806,18 @@
print_usage ();
exit (1);
}
+ if (opt.ipv4_only && opt.ipv6_only)
+{
+ if (opt.ipv4_only == -1)
+ /* ipv4_only was set automatically because the system doesn't
+ support IPv6. */
+ printf (_("Cannot use --inet6-only on a system without IPv6 support.\n"));
+ else
+ printf (_("Cannot specify both --inet4-only and --inet6-only.\n"));
+ print_usage ();
+ exit (1);
+}
+
nurl = argc - optind;
if (!nurl && !opt.input_filename)
{
Re: --inet6-only option
"Gisle Vanem" <[EMAIL PROTECTED]> writes: > Running "wget -6 url.." on a machine with no IPv6 installed silently > uses IPv4. A warning with fallback to IPv4 is IMHO okay. Or an exit? If you don't have IPv6 installed, the effect is as if `-4' were prepended to options. What should Wget do when `-4 -6' is encountered? Currently it works as if neither were present, which is why you see silent use of IPv4. There should probably at least be a warning. > Not sure about the rationale behind '--inet6-only', but the problem > seems to be in defaults(); when socket() fails, 'opt.ipv4_only=1' is > forced before the cmd-line is parsed. So lookup_host() uses > AF_UNSPEC in the hints. > > My suggestion is to move the "socket(AF_INET?)" test to host.c and > call it once from lookup_host(). Putting the check to defaults() allows you to undo it, in case you just want to look at the resolved addresses (or debug IPv6 or whatever else).
--inet6-only option
MingW version compiled with ENABLE_IPV6, HAVE_GETADDRINFO etc. but no HAVE_GETADDRINFO_AI_ADDRCONFIG. Running "wget -6 url.." on a machine with no IPv6 installed silently uses IPv4. A warning with fallback to IPv4 is IMHO okay. Or an exit? Not sure about the rationale behind '--inet6-only', but the problem seems to be in defaults(); when socket() fails, 'opt.ipv4_only=1' is forced before the cmd-line is parsed. So lookup_host() uses AF_UNSPEC in the hints. My suggestion is to move the "socket(AF_INET?)" test to host.c and call it once from lookup_host(). Take action (exit?) if 'opt.ipv?_only' doesn't match returned 'res.ai_family'. Similarily, on a machine with only IPv6 (it they really exist?), '--inet4-only' should also fail or give a warning. Gisle V. # rm /bin/laden /bin/laden: Not found
