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/* -*- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -*- */
/* NetworkManager -- Network link manager
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Copyright (C) 2004 - 2010 Red Hat, Inc.
*/
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <netdb.h>
#include <ctype.h>
#include "nm-policy-hosts.h"
#include "nm-logging.h"
gboolean
nm_policy_hosts_find_token (const char *line, const char *token)
{
const char *start = line, *p = line;
g_return_val_if_fail (line != NULL, FALSE);
g_return_val_if_fail (token != NULL, FALSE);
g_return_val_if_fail (strlen (token) > 0, FALSE);
/* Walk through the line to find the next whitespace character */
while (p <= line + strlen (line)) {
if (isblank (*p) || (*p == '\0')) {
/* Token starts with 'start' and ends with 'end' */
if ((p > start) && *start && (p - start == strlen (token)) && !strncmp (start, token, (p - start)))
return TRUE; /* found */
/* not found; advance start and continue looking */
start = p + 1;
}
p++;
}
return FALSE;
}
static gboolean
is_local_mapping (const char *str, const char *hostname)
{
return ( !strncmp (str, "127.0.0.1", strlen ("127.0.0.1"))
&& nm_policy_hosts_find_token (str, hostname ? hostname : "localhost"));
}
GString *
nm_policy_get_etc_hosts (const char **lines,
gsize existing_len,
const char *hostname,
const char *fallback_hostname,
GError **error)
{
GString *contents = NULL;
const char **line;
gboolean found_host_nonlocal = FALSE;
gboolean found_host = FALSE;
gboolean found_localhost = FALSE;
gboolean initial_comments = TRUE;
gboolean added = FALSE;
g_return_val_if_fail (lines != NULL, FALSE);
g_return_val_if_fail (hostname != NULL, FALSE);
/* /etc/hosts needs at least two things:
*
* 1) current hostname mapped to any address
* 2) 'localhost' mapped to 127.0.0.1
*
* If both these conditions exist in /etc/hosts, we don't need to bother
* updating the file.
*/
/* Look for the two cases from above */
for (line = lines; lines && *line; line++) {
if (strlen (*line) && (*line[0] != '#')) {
if (nm_policy_hosts_find_token (*line, hostname)) {
if (!is_local_mapping (*line, "localhost")) {
/* hostname is not on a 127.0.0.1 line or the line does not
* contain 'localhost'.
*/
found_host_nonlocal = TRUE;
}
found_host = TRUE;
}
if (is_local_mapping (*line, "localhost")) {
/* a 127.0.0.1 line containing 'localhost' */
found_localhost = TRUE;
}
}
if (found_localhost && found_host)
return NULL; /* No update required */
}
contents = g_string_sized_new (existing_len ? existing_len + 100 : 200);
if (!contents) {
g_set_error_literal (error, 0, 0, "not enough memory");
return NULL;
}
/* Construct the new hosts file; replace any 127.0.0.1 entry that is at the
* beginning of the file or right after initial comments and contains
* the string 'localhost'. If there is no 127.0.0.1 entry at the beginning
* or after initial comments that contains 'localhost', add one there
* and ignore any other 127.0.0.1 entries that contain 'localhost'.
*/
for (line = lines, initial_comments = TRUE; lines && *line; line++) {
gboolean add_line = TRUE;
/* This is the first line after the initial comments */
if (strlen (*line) && initial_comments && (*line[0] != '#')) {
initial_comments = FALSE;
/* If some other line contained the hostname but not 'localhost',
* make a simple localhost mapping and assume the user knows what
* they are doing with their manual hostname entry. Otherwise if
* the hostname wasn't found somewhere else, add it to the localhost
* mapping line to make sure it's mapped to something.
*/
if (found_host_nonlocal)
g_string_append (contents, "127.0.0.1");
else
g_string_append_printf (contents, "127.0.0.1\t%s", hostname);
if (strcmp (hostname, fallback_hostname)) {
g_string_append_printf (contents, "\t%s", fallback_hostname);
/* Don't add a standalone 'localhost.localdomain' 127 mapping */
if (is_local_mapping (*line, fallback_hostname))
add_line = FALSE;
}
g_string_append (contents, "\tlocalhost\n");
added = TRUE;
/* Don't add the original line if it is a 'localhost' mapping */
if (is_local_mapping (*line, "localhost"))
add_line = FALSE;
}
if (add_line) {
g_string_append (contents, *line);
/* Only append the new line if this isn't the last line in the file */
if (*(line+1))
g_string_append_c (contents, '\n');
}
}
/* Hmm, /etc/hosts was empty for some reason */
if (!added) {
g_string_append (contents, "# Do not remove the following line, or various programs\n");
g_string_append (contents, "# that require network functionality will fail.\n");
g_string_append_printf (contents, "127.0.0.1\t%s\tlocalhost\n", fallback_hostname);
}
return contents;
}
gboolean
nm_policy_hosts_update_etc_hosts (const char *hostname,
const char *fallback_hostname,
gboolean *out_changed)
{
char *contents = NULL;
char **lines = NULL;
GError *error = NULL;
GString *new_contents = NULL;
gsize contents_len = 0;
gboolean success = FALSE;
g_return_val_if_fail (hostname != NULL, FALSE);
g_return_val_if_fail (out_changed != NULL, FALSE);
if (!g_file_get_contents (SYSCONFDIR "/hosts", &contents, &contents_len, &error)) {
nm_log_warn (LOGD_DNS, "couldn't read " SYSCONFDIR "/hosts: (%d) %s",
error ? error->code : 0,
(error && error->message) ? error->message : "(unknown)");
g_clear_error (&error);
return FALSE;
}
/* Get the new /etc/hosts contents */
lines = g_strsplit_set (contents, "\n\r", 0);
new_contents = nm_policy_get_etc_hosts ((const char **) lines,
contents_len,
hostname,
fallback_hostname,
&error);
g_strfreev (lines);
g_free (contents);
if (new_contents) {
nm_log_info (LOGD_DNS, "Updating /etc/hosts with new system hostname");
g_clear_error (&error);
/* And actually update /etc/hosts */
if (!g_file_set_contents (SYSCONFDIR "/hosts", new_contents->str, -1, &error)) {
nm_log_warn (LOGD_DNS, "couldn't update " SYSCONFDIR "/hosts: (%d) %s",
error ? error->code : 0,
(error && error->message) ? error->message : "(unknown)");
g_clear_error (&error);
} else {
success = TRUE;
*out_changed = TRUE;
}
g_string_free (new_contents, TRUE);
} else if (!error) {
/* No change required */
success = TRUE;
} else {
nm_log_warn (LOGD_DNS, "couldn't read " SYSCONFDIR "/hosts: (%d) %s",
error->code, error->message ? error->message : "(unknown)");
g_clear_error (&error);
}
return success;
}
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