4f25ee1644
When a system is completely offline (no interface has an IP address but 'lo'),
xcb could not connect to localhost via TCP, e.g. connections with
DISPLAY=127.0.0.1:0 fail.
AI_ADDRCONFIG will only return IPv4 addresses if the system has an IPv4
address configured (likewise for IPv6). This also takes place when
resolving localhost (or 127.0.0.0/8 or ::1). Also, as per RFC 3493,
loopback addresses are not considered as valid addresses when
determining whether to return IPv4 or IPv6 addresses.
As per mailing-list discussion on the xcb list started with message
20110813215405.5818a0c1@x200, the AI_ADDRCONFIG flag is there for historical
reasons:
In the old days, the "default on-link" assumption in IPv6 made the flag vey
much indispensable for dual-stack hosts on IPv4-only networks. Without it,
there would be long timeouts trying non-existent IPv6 connectivity. Nowadays,
this assumption has been flagged as historic bad practice by IETF, and hosts
should have been updated to not make it anymore.
Then AI_ADDRCONFIG became mostly cosmetic: it avoids phony "Protocol family
not supported" or "Host unreachable" errors while trying to connect to a dual-
stack mode from a host with no support for source address selection.
Nowadays, on up-to-date systems, this flag is completely useless. Then again,
I understood only the very latest MacOS release is "up-to-date" with this
definition.
|
||
|---|---|---|
| doc | ||
| src | ||
| tests | ||
| tools | ||
| .gitignore | ||
| COPYING | ||
| INSTALL | ||
| Makefile.am | ||
| NEWS | ||
| README | ||
| acinclude.m4 | ||
| autogen.sh | ||
| configure.ac | ||
| xcb-composite.pc.in | ||
| xcb-damage.pc.in | ||
| xcb-dpms.pc.in | ||
| xcb-dri2.pc.in | ||
| xcb-glx.pc.in | ||
| xcb-randr.pc.in | ||
| xcb-record.pc.in | ||
| xcb-render.pc.in | ||
| xcb-res.pc.in | ||
| xcb-screensaver.pc.in | ||
| xcb-shape.pc.in | ||
| xcb-shm.pc.in | ||
| xcb-sync.pc.in | ||
| xcb-xevie.pc.in | ||
| xcb-xf86dri.pc.in | ||
| xcb-xfixes.pc.in | ||
| xcb-xinerama.pc.in | ||
| xcb-xinput.pc.in | ||
| xcb-xkb.pc.in | ||
| xcb-xprint.pc.in | ||
| xcb-xselinux.pc.in | ||
| xcb-xtest.pc.in | ||
| xcb-xv.pc.in | ||
| xcb-xvmc.pc.in | ||
| xcb.pc.in | ||
About libxcb
============
libxcb provides an interface to the X Window System protocol, which
replaces the current Xlib interface. It has several advantages over
Xlib, including:
- size: small, simple library, and lower memory footprint
- latency hiding: batch several requests and wait for the replies later
- direct protocol access: interface and protocol correspond exactly
- proven thread support: transparently access XCB from multiple threads
- easy extension implementation: interfaces auto-generated from XML-XCB
Xlib can also use XCB as a transport layer, allowing software to make
requests and receive responses with both, which eases porting to XCB.
However, client programs, libraries, and toolkits will gain the most
benefit from a native XCB port.
Please report any issues you find to the freedesktop.org bug tracker,
at:
<https://bugs.freedesktop.org/enter_bug.cgi?product=XCB>
Discussion about XCB occurs on the XCB mailing list:
<mailto:xcb at lists.freedesktop.org>
<http://lists.freedesktop.org/mailman/listinfo/xcb>
You can obtain the latest development versions of XCB using GIT.
For anonymous checkouts, use:
git clone git://anongit.freedesktop.org/git/xcb/libxcb
For developers, use:
git clone git+ssh://git.freedesktop.org/git/xcb/libxcb