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dns: add trace logging when writing resolv.conf

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It is interesting to find in the logfile when we write to "/etc/resolv.conf"
or our internal version "/var/run/NetworkManager/resolv.conf".
This commit is contained in:
Thomas Haller
2016-04-20 15:14:20 +02:00
parent 2158d6a5a8
commit c486c38962
1 changed files with 79 additions and 22 deletions
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101
src/dns-manager/nm-dns-manager.c
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@@ -468,12 +468,16 @@ write_resolv_conf_contents (FILE *f,
const char *content,
GError **error)
{
int errsv;
if (fprintf (f, "%s", content) < 0) {
errsv = errno;
g_set_error (error,
NM_MANAGER_ERROR,
NM_MANAGER_ERROR_FAILED,
"Could not write " _PATH_RESCONF ": %s",
g_strerror (errno));
g_strerror (errsv));
errno = errsv;
return FALSE;
}
@@ -572,6 +576,7 @@ update_resolv_conf (NMDnsManager *self,
gboolean success;
gs_free char *content = NULL;
SpawnResult write_file_result = SR_SUCCESS;
int errsv;
/* If we are not managing /etc/resolv.conf and it points to
* MY_RESOLV_CONF, don't write the private DNS configuration to
@@ -584,7 +589,7 @@ update_resolv_conf (NMDnsManager *self,
gs_free char *path = g_file_read_link (_PATH_RESCONF, NULL);
if (g_strcmp0 (path, MY_RESOLV_CONF) == 0) {
_LOGD ("not updating " _PATH_RESCONF
_LOGD ("update-resolv-conf: not updating " _PATH_RESCONF
" since it points to " MY_RESOLV_CONF);
return SR_SUCCESS;
}
@@ -593,29 +598,46 @@ update_resolv_conf (NMDnsManager *self,
content = create_resolv_conf (searches, nameservers, options);
if (rc_manager == NM_DNS_MANAGER_RESOLV_CONF_MAN_FILE) {
GError *local = NULL;
/* we first write to /etc/resolv.conf directly. If that fails,
* we still continue to write to runstatedir but remember the
* error. */
if (!g_file_set_contents (_PATH_RESCONF, content, -1, error)) {
if (!g_file_set_contents (_PATH_RESCONF, content, -1, &local)) {
_LOGT ("update-resolv-conf: write to %s failed (rc-managed=file, %s)",
_PATH_RESCONF, local->message);
write_file_result = SR_ERROR;
g_propagate_error (error, local);
error = NULL;
} else {
_LOGT ("update-resolv-conf: write to %s succeeded (rc-managed=file)",
_PATH_RESCONF);
}
}
if ((f = fopen (MY_RESOLV_CONF_TMP, "w")) == NULL) {
errsv = errno;
g_set_error (error,
NM_MANAGER_ERROR,
NM_MANAGER_ERROR_FAILED,
"Could not open %s: %s",
MY_RESOLV_CONF_TMP,
g_strerror (errno));
g_strerror (errsv));
_LOGT ("update-resolv-conf: open temporary file %s failed (%s)",
MY_RESOLV_CONF_TMP, g_strerror (errsv));
return SR_ERROR;
}
success = write_resolv_conf_contents (f, content, error);
if (!success) {
errsv = errno;
_LOGT ("update-resolv-conf: write temporary file %s failed (%s)",
MY_RESOLV_CONF_TMP, g_strerror (errsv));
}
if (fclose (f) < 0) {
if (success) {
errsv = errno;
/* only set an error here if write_resolv_conf() was successful,
* since its error is more important.
*/
@@ -624,39 +646,66 @@ update_resolv_conf (NMDnsManager *self,
NM_MANAGER_ERROR_FAILED,
"Could not close %s: %s",
MY_RESOLV_CONF_TMP,
g_strerror (errno));
g_strerror (errsv));
_LOGT ("update-resolv-conf: close temporary file %s failed (%s)",
MY_RESOLV_CONF_TMP, g_strerror (errsv));
}
return SR_ERROR;
} else if (!success)
return SR_ERROR;
if (rename (MY_RESOLV_CONF_TMP, MY_RESOLV_CONF) < 0) {
errsv = errno;
g_set_error (error,
NM_MANAGER_ERROR,
NM_MANAGER_ERROR_FAILED,
"Could not replace %s: %s",
MY_RESOLV_CONF,
g_strerror (errno));
_LOGT ("update-resolv-conf: failed to rename temporary file %s to %s (%s)",
MY_RESOLV_CONF_TMP, MY_RESOLV_CONF, g_strerror (errsv));
return SR_ERROR;
}
if (rc_manager == NM_DNS_MANAGER_RESOLV_CONF_MAN_FILE)
if (rc_manager == NM_DNS_MANAGER_RESOLV_CONF_MAN_FILE) {
_LOGT ("update-resolv-conf: write internal file %s succeeded (rc-manager=file)",
MY_RESOLV_CONF);
return write_file_result;
}
if (rc_manager != NM_DNS_MANAGER_RESOLV_CONF_MAN_NONE)
if (rc_manager != NM_DNS_MANAGER_RESOLV_CONF_MAN_NONE) {
_LOGT ("update-resolv-conf: write internal file %s succeeded", MY_RESOLV_CONF);
return SR_SUCCESS;
}
/* A symlink pointing to NM's own resolv.conf (MY_RESOLV_CONF) is always
* overwritten to ensure that changes are indicated with inotify. Symlinks
* pointing to any other file are never overwritten.
*/
if (lstat (_PATH_RESCONF, &st) != -1) {
if (lstat (_PATH_RESCONF, &st) != 0) {
errsv = errno;
if (errsv != ENOENT) {
/* NM cannot read /etc/resolv.conf */
_LOGT ("update-resolv-conf: write internal file %s succeeded but lstat(%s) failed (%s)",
MY_RESOLV_CONF, _PATH_RESCONF, g_strerror (errsv));
g_set_error (error,
NM_MANAGER_ERROR,
NM_MANAGER_ERROR_FAILED,
"Could not lstat %s: %s",
_PATH_RESCONF,
g_strerror (errsv));
return SR_ERROR;
}
} else {
if (S_ISLNK (st.st_mode)) {
if (stat (_PATH_RESCONF, &st) != -1) {
gs_free char *path = g_file_read_link (_PATH_RESCONF, NULL);
if (g_strcmp0 (path, MY_RESOLV_CONF) != 0) {
if (!path || !nm_streq (path, MY_RESOLV_CONF)) {
/* It's not NM's symlink; do nothing */
_LOGT ("update-resolv-conf: write internal file %s succeeded "
"but don't update %s as it points to %s",
MY_RESOLV_CONF, _PATH_RESCONF, path ?: "");
return SR_SUCCESS;
}
@@ -667,56 +716,64 @@ update_resolv_conf (NMDnsManager *self,
* some other program is probably managing resolv.conf and
* NM should not touch it.
*/
_LOGT ("update-resolv-conf: write internal file %s succeeded "
"but don't update %s as the symlinks points somewhere else",
MY_RESOLV_CONF, _PATH_RESCONF);
return SR_SUCCESS;
}
}
} else if (errno != ENOENT) {
/* NM cannot read /etc/resolv.conf */
g_set_error (error,
NM_MANAGER_ERROR,
NM_MANAGER_ERROR_FAILED,
"Could not lstat %s: %s",
_PATH_RESCONF,
g_strerror (errno));
return SR_ERROR;
}
/* By this point, either /etc/resolv.conf does not exist, is a regular
* file, or is a symlink already owned by NM. In all cases /etc/resolv.conf
* is replaced with a symlink pointing to NM's resolv.conf in /var/run/.
*/
if (unlink (RESOLV_CONF_TMP) == -1 && errno != ENOENT) {
if ( unlink (RESOLV_CONF_TMP) != 0
&& ((errsv = errno) != ENOENT)) {
g_set_error (error,
NM_MANAGER_ERROR,
NM_MANAGER_ERROR_FAILED,
"Could not unlink %s: %s",
RESOLV_CONF_TMP,
g_strerror (errno));
g_strerror (errsv));
_LOGT ("update-resolv-conf: write internal file %s succeeded "
"but canot delete temporary file %s: %s",
MY_RESOLV_CONF, RESOLV_CONF_TMP, g_strerror (errsv));
return SR_ERROR;
}
if (symlink (MY_RESOLV_CONF, RESOLV_CONF_TMP) == -1) {
errsv = errno;
g_set_error (error,
NM_MANAGER_ERROR,
NM_MANAGER_ERROR_FAILED,
"Could not create symlink %s pointing to %s: %s",
RESOLV_CONF_TMP,
MY_RESOLV_CONF,
g_strerror (errno));
g_strerror (errsv));
_LOGT ("update-resolv-conf: write internal file %s succeeded "
"but failed to symlink %s: %s",
MY_RESOLV_CONF, RESOLV_CONF_TMP, g_strerror (errsv));
return SR_ERROR;
}
if (rename (RESOLV_CONF_TMP, _PATH_RESCONF) == -1) {
errsv = errno;
g_set_error (error,
NM_MANAGER_ERROR,
NM_MANAGER_ERROR_FAILED,
"Could not rename %s to %s: %s",
RESOLV_CONF_TMP,
_PATH_RESCONF,
g_strerror (errno));
g_strerror (errsv));
_LOGT ("update-resolv-conf: write internal file %s succeeded "
"but failed to rename temporary symlink %s to %s: %s",
MY_RESOLV_CONF, RESOLV_CONF_TMP, _PATH_RESCONF, g_strerror (errsv));
return SR_ERROR;
}
_LOGT ("update-resolv-conf: write internal file %s succeeded and update symlink %s",
MY_RESOLV_CONF, _PATH_RESCONF);
return SR_SUCCESS;
}