Re: make-network-process's gethostbyname usage

[Jan Djärv]

Kim F. Storm skrev:
> Richard Stallman <address@hidden> writes:
>
> >     make-network-process calles gethostbyname, but never calls
> >     res_init. The problem, which appears is: if contents of
> >     /etc/resolv.conf was changed old dns servers are unavailable,
> >     gethostbyname still tries them, not new ones. So this bug is pretty
> >     much the same as http://bugs.debian.org/438680 (which has a patch).
> >
> > Would someone please DTRT about this, then ack?
> > It needs to be fixed in Emacs 22.
>
> I don't know what to do about this.
>
> configure already has a check for res_init, but on my system (GNU/Linux),
> HAVE_RES_INIT is undefined, indicating that it doesn't exist.
>
> However, I believe that it does exist, but only if -lresolv is specified.
>
> So how can we fix configure to DTRT?
>
> a) Include -lresolv in the check for HAVE_RES_INIT.
>
> b) Include -lresolv in LIBS if and only if HAVE_RES_INIT is defined.

Should we not first try if res_init exists without any special libraries, and 
if that fails, check for -lresolv and try to find res_init again?

But there seems to be some problem with that, comment in configure.in says:

dnl This causes -lresolv to get used in subsequent tests,
dnl which causes failures on some systems such as HPUX 9.
dnl AC_CHECK_LIB(resolv, gethostbyname)


But otherwise:

AC_CHECK_FUNCS(res_init)
if test "X$HAVE_RES_INIT" = X; then
  AC_SEARCH_LIBS(res_init, resolv, HAVE_RES_INIT=yes)
fi

Untested :-)


        Jan D.



> If that is in place, it should be trivial to add
>
> #if HAVE_RES_INIT
>     res_init();
> #endif
>
> before all calls to gethostbyname and getaddrinfo.