"Daniel P. Berrange" <berrange@redhat.com> wrote:
On Wed, Dec 10, 2008 at 07:33:17PM -0800, David Lutterkort wrote:
The attached patch makes virConnectGetHostname try a little harder to get a FQDN on systems where gethostname only returns a short name without a domain (which is pretty useless). The behavior is equivalent to 'hostname --fqdn'.
From 2ae57d0c8c68c453b3f9715fcc9f83af0ebe84a0 Mon Sep 17 00:00:00 2001 From: David Lutterkort <lutter@redhat.com> Date: Wed, 10 Dec 2008 18:34:39 -0800 Subject: [PATCH] virConnectGetHostname: return a fully qualified hostname
Instead of doing the equivalent of 'hostname', do 'hostname --fqdn', i.e. try to qualify the local host name by an additional call to gethostbyname(3) + +char *virGetHostname(void) +{ + int r; + char hostname[HOST_NAME_MAX+1], *str; + struct hostent *he; + + r = gethostname (hostname, HOST_NAME_MAX+1); + if (r == -1) + return NULL; + if (!(he = gethostbyname(hostname))) + return NULL;
Actually, gethostbyname should never be used in any modern code as it is not thread safe. Instead use getaddrinfo() and the AI_CANONNAME flag
Good point. Yet another reason not to use gethostbyname. I think it's time to make the prohibition official. Here's a patch to do that:
From 5105125b7a91d701ce2dc9f549814a8fa4e352d7 Mon Sep 17 00:00:00 2001 From: Jim Meyering <meyering@redhat.com> Date: Thu, 11 Dec 2008 11:49:40 +0100 Subject: [PATCH] syntax-check: prohibit all new uses of gethostby* functions
* Makefile.maint (sc_prohibit_gethostby): New rule. * .x-sc_prohibit_gethostby: Exempt the few existing uses. --- .x-sc_prohibit_gethostby | 3 +++ Makefile.maint | 6 ++++++ 2 files changed, 9 insertions(+), 0 deletions(-) create mode 100644 .x-sc_prohibit_gethostby diff --git a/.x-sc_prohibit_gethostby b/.x-sc_prohibit_gethostby new file mode 100644 index 0000000..d74ea40 --- /dev/null +++ b/.x-sc_prohibit_gethostby @@ -0,0 +1,3 @@ +gnulib/lib/getaddrinfo.c +gnulib/m4/getaddrinfo.m4 +src/xend_internal.c diff --git a/Makefile.maint b/Makefile.maint index 10d481b..051e4c0 100644 --- a/Makefile.maint +++ b/Makefile.maint @@ -390,6 +390,12 @@ sc_prohibit_virBufferAdd_with_string_literal: { echo '$(ME): use virBufferAddLit, not virBufferAdd,' \ 'with a string literal' 1>&2; exit 1; } || : +# Not only do they fail to deal well with ipv6, but the gethostby* +# functions are also not thread-safe. +sc_prohibit_gethostby: + @grep -nE '\<gethostby(addr|name2?) *\(' $$($(VC_LIST_EXCEPT)) && \ + { echo '$(ME): use getaddrinfo, not gethostby*' 1>&2; exit 1; } || : + # Avoid useless parentheses like those in this example: # #if defined (SYMBOL) || defined (SYM2) sc_useless_cpp_parens: -- 1.6.0.4.1044.g77718