rdisc: downgrade logging severity and rate-limit logging for sending router solicitation

Downgrade the severity for failure to send router solicitations
to WARN level. Also, repeated (identical) lines will be further
downgraded to DEBUG level.

Also pass the error reason to the caller and combine the message with
the "sending router solicitation" message.

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=775736
https://bugzilla.redhat.com/show_bug.cgi?id=1034443
https://bugzilla.redhat.com/show_bug.cgi?id=1010540
https://lists.launchpad.net/touch-packages/msg75697.html

https://bugzilla.gnome.org/show_bug.cgi?id=759596

src/rdisc/nm-fake-rdisc.c

@@ -223,7 +223,7 @@ nm_fake_rdisc_done (NMFakeRDisc *self)
 /******************************************************************/
 
 static gboolean
-send_rs (NMRDisc *rdisc)
+send_rs (NMRDisc *rdisc, GError **error)
 {
 	g_signal_emit (rdisc, signals[RS_SENT], 0);
 	return TRUE;

src/rdisc/nm-lndp-rdisc.c

@@ -50,20 +50,28 @@ G_DEFINE_TYPE (NMLNDPRDisc, nm_lndp_rdisc, NM_TYPE_RDISC)
 /******************************************************************/
 
 static gboolean
-send_rs (NMRDisc *rdisc)
+send_rs (NMRDisc *rdisc, GError **error)
 {
 	NMLNDPRDiscPrivate *priv = NM_LNDP_RDISC_GET_PRIVATE (rdisc);
 	struct ndp_msg *msg;
-	int error;
+	int errsv;
 
-	error = ndp_msg_new (&msg, NDP_MSG_RS);
-	g_assert (!error);
+	errsv = ndp_msg_new (&msg, NDP_MSG_RS);
+	if (!errsv) {
+		errsv = errsv > 0 ? errsv : -errsv;
+		g_set_error_literal (error, NM_UTILS_ERROR, NM_UTILS_ERROR_UNKNOWN,
+		                     "cannot create router solicitation");
+		return FALSE;
+	}
 	ndp_msg_ifindex_set (msg, rdisc->ifindex);
 
-	error = ndp_msg_send (priv->ndp, msg);
+	errsv = ndp_msg_send (priv->ndp, msg);
 	ndp_msg_destroy (msg);
-	if (error) {
-		_LOGE ("cannot send router solicitation: %d.", error);
+	if (errsv) {
+		errsv = errsv > 0 ? errsv : -errsv;
+		g_set_error (error, NM_UTILS_ERROR, NM_UTILS_ERROR_UNKNOWN,
+		             "%s (%d)",
+		             g_strerror (errsv), errsv);
 		return FALSE;
 	}
 

src/rdisc/nm-rdisc.c

@@ -40,6 +40,7 @@ typedef struct {
 	gint64 last_rs;
 	guint ra_timeout_id;  /* first RA timeout */
 	guint timeout_id;   /* prefix/dns/etc lifetime timeout */
+	char *last_send_rs_error;
 } NMRDiscPrivate;
 
 #define NM_RDISC_GET_PRIVATE(o) (G_TYPE_INSTANCE_GET_PRIVATE ((o), NM_TYPE_RDISC, NMRDiscPrivate))
@@ -319,11 +320,24 @@ send_rs (NMRDisc *rdisc)
 {
 	NMRDiscClass *klass = NM_RDISC_GET_CLASS (rdisc);
 	NMRDiscPrivate *priv = NM_RDISC_GET_PRIVATE (rdisc);
+	GError *error = NULL;
 
-	_LOGD ("sending router solicitation");
-
-	if (klass->send_rs (rdisc))
+	if (klass->send_rs (rdisc, &error)) {
+		_LOGD ("router solicitation sent");
 		priv->solicitations_left--;
+		g_clear_pointer (&priv->last_send_rs_error, g_free);
+	} else {
+		gboolean different_message;
+
+		different_message = g_strcmp0 (priv->last_send_rs_error, error->message) != 0;
+		_NMLOG (different_message ? LOGL_WARN : LOGL_DEBUG,
+		        "failure sending router solicitation: %s", error->message);
+		if (different_message) {
+			g_clear_pointer (&priv->last_send_rs_error, g_free);
+			priv->last_send_rs_error = g_strdup (error->message);
+		}
+		g_clear_error (&error);
+	}
 
 	priv->last_rs = nm_utils_get_monotonic_timestamp_s ();
 	if (priv->solicitations_left > 0) {
@@ -646,6 +660,7 @@ nm_rdisc_ra_received (NMRDisc *rdisc, guint32 now, NMRDiscConfigMap changed)
 
 	nm_clear_g_source (&priv->ra_timeout_id);
 	nm_clear_g_source (&priv->send_rs_id);
+	g_clear_pointer (&priv->last_send_rs_error, g_free);
 	check_timestamps (rdisc, now, changed);
 }
 
@@ -684,6 +699,7 @@ dispose (GObject *object)
 
 	nm_clear_g_source (&priv->ra_timeout_id);
 	nm_clear_g_source (&priv->send_rs_id);
+	g_clear_pointer (&priv->last_send_rs_error, g_free);
 
 	if (priv->timeout_id) {
 		g_source_remove (priv->timeout_id);

src/rdisc/nm-rdisc.h

@@ -137,7 +137,7 @@ typedef struct {
 	GObjectClass parent;
 
 	void (*start) (NMRDisc *rdisc);
-	gboolean (*send_rs) (NMRDisc *rdisc);
+	gboolean (*send_rs) (NMRDisc *rdisc, GError **error);
 	void (*config_changed) (NMRDisc *rdisc, NMRDiscConfigMap changed);
 	void (*ra_process) (NMRDisc *rdisc);
 	void (*ra_timeout) (NMRDisc *rdisc);