glibc/nss/XXX-lookup.c
Florian Weimer b99b0f93ee nss: Use "files dns" as the default for the hosts database (bug 28700)
This matches what is currently in nss/nsswitch.conf.  The new ordering
matches what most distributions use in their installed configuration
files.

It is common to add localhost to /etc/hosts because the name does not
exist in the DNS, but is commonly used as a host name.

With the built-in "dns [!UNAVAIL=return] files" default, dns is
searched first and provides an answer for "localhost" (NXDOMAIN).
We never look at the files database as a result, so the contents of
/etc/hosts is ignored.  This means that "getent hosts localhost"
fail without a /etc/nsswitch.conf file, even though the host name
is listed in /etc/hosts.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2021-12-17 12:01:25 +01:00

60 lines
2.3 KiB
C

/* Copyright (C) 1996-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include "nsswitch.h"
/*******************************************************************\
|* Here we assume one symbol to be defined: *|
|* *|
|* DATABASE_NAME - name of the database the function accesses *|
|* (e.g., hosts, services, ...) *|
|* *|
|* One additional symbol may optionally be defined: *|
|* *|
|* ALTERNATE_NAME - name of another service which is examined in *|
|* case DATABASE_NAME is not found *|
|* *|
|* DEFAULT_CONFIG - string for default conf (e.g. "files dns") *|
|* *|
\*******************************************************************/
#define DB_LOOKUP_FCT CONCAT3_1 (__nss_, DATABASE_NAME, _lookup2)
#define CONCAT3_1(Pre, Name, Post) CONCAT3_2 (Pre, Name, Post)
#define CONCAT3_2(Pre, Name, Post) Pre##Name##Post
#define DATABASE_NAME_ID CONCAT2_1 (nss_database_, DATABASE_NAME)
#define CONCAT2_1(Pre, Name) CONCAT2_2 (Pre, Name)
#define CONCAT2_2(Pre, Name) Pre##Name
#define DATABASE_NAME_SYMBOL CONCAT3_1 (__nss_, DATABASE_NAME, _database)
#define DATABASE_NAME_STRING STRINGIFY1 (DATABASE_NAME)
#define STRINGIFY1(Name) STRINGIFY2 (Name)
#define STRINGIFY2(Name) #Name
int
DB_LOOKUP_FCT (nss_action_list *ni, const char *fct_name, const char *fct2_name,
void **fctp)
{
if (! __nss_database_get (DATABASE_NAME_ID, &DATABASE_NAME_SYMBOL))
return -1;
*ni = DATABASE_NAME_SYMBOL;
return __nss_lookup (ni, fct_name, fct2_name, fctp);
}
libc_hidden_def (DB_LOOKUP_FCT)