diff options
| author | Michael Stapelberg <michael@stapelberg.de> | 2011-08-18 21:38:28 +0200 |
|---|---|---|
| committer | Jamey Sharp <jamey@minilop.net> | 2011-08-18 13:39:56 -0700 |
| commit | 4f25ee16443b29e1a25bd26a724e1e0a577e21ff (patch) | |
| tree | fb42a2c1326241c67e288ab3da76ff7c9842099e | |
| parent | 662ad589c5d6f03757ae57a926d3800bfb528b30 (diff) | |
Drop AI_ADDRCONFIG when resolving TCP addresses
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.
| -rw-r--r-- | src/xcb_util.c | 3 |
1 files changed, 0 insertions, 3 deletions
diff --git a/src/xcb_util.c b/src/xcb_util.c index fde4f85..1bde7b7 100644 --- a/src/xcb_util.c +++ b/src/xcb_util.c @@ -277,9 +277,6 @@ static int _xcb_open_tcp(const char *host, char *protocol, const unsigned short host = "localhost"; memset(&hints, 0, sizeof(hints)); -#ifdef AI_ADDRCONFIG - hints.ai_flags |= AI_ADDRCONFIG; -#endif #ifdef AI_NUMERICSERV hints.ai_flags |= AI_NUMERICSERV; #endif |