Add wpa_msg_ctrl() for ctrl_interface-only messages

This is like wpa_msg(), but the output is directed only to
ctrl_interface listeners. In other words, the output will not be
shown on stdout or in syslog.

Change scan result reporting to use wpa_msg_ctrl() for
CTRL-EVENT-SCAN-RESULTS message at info level and wpa_printf() at
debug level to avoid showing scan result events in syslog in the
common configuration used with NetworkManager.

src/utils/wpa_debug.c

@@ -335,6 +335,30 @@ void wpa_msg(void *ctx, int level, char *fmt, ...)
 		wpa_msg_cb(ctx, level, buf, len);
 	os_free(buf);
 }
+
+
+void wpa_msg_ctrl(void *ctx, int level, char *fmt, ...)
+{
+	va_list ap;
+	char *buf;
+	const int buflen = 2048;
+	int len;
+
+	if (!wpa_msg_cb)
+		return;
+
+	buf = os_malloc(buflen);
+	if (buf == NULL) {
+		wpa_printf(MSG_ERROR, "wpa_msg_ctrl: Failed to allocate "
+			   "message buffer");
+		return;
+	}
+	va_start(ap, fmt);
+	len = vsnprintf(buf, buflen, fmt, ap);
+	va_end(ap);
+	wpa_msg_cb(ctx, level, buf, len);
+	os_free(buf);
+}
 #endif /* CONFIG_NO_WPA_MSG */
 
 

src/utils/wpa_debug.h

@@ -141,6 +141,7 @@ void wpa_hexdump_ascii_key(int level, const char *title, const u8 *buf,
 
 #ifdef CONFIG_NO_WPA_MSG
 #define wpa_msg(args...) do { } while (0)
+#define wpa_msg_ctrl(args...) do { } while (0)
 #define wpa_msg_register_cb(f) do { } while (0)
 #else /* CONFIG_NO_WPA_MSG */
 /**
@@ -159,6 +160,20 @@ void wpa_hexdump_ascii_key(int level, const char *title, const u8 *buf,
  */
 void wpa_msg(void *ctx, int level, char *fmt, ...) PRINTF_FORMAT(3, 4);
 
+/**
+ * wpa_msg_ctrl - Conditional printf for ctrl_iface monitors
+ * @ctx: Pointer to context data; this is the ctx variable registered
+ *	with struct wpa_driver_ops::init()
+ * @level: priority level (MSG_*) of the message
+ * @fmt: printf format string, followed by optional arguments
+ *
+ * This function is used to print conditional debugging and error messages.
+ * This function is like wpa_msg(), but it sends the output only to the
+ * attached ctrl_iface monitors. In other words, it can be used for frequent
+ * events that do not need to be sent to syslog.
+ */
+void wpa_msg_ctrl(void *ctx, int level, char *fmt, ...) PRINTF_FORMAT(3, 4);
+
 typedef void (*wpa_msg_cb_func)(void *ctx, int level, const char *txt,
 				size_t len);
 

wpa_supplicant/events.c

@@ -760,7 +760,8 @@ static void wpa_supplicant_event_scan_results(struct wpa_supplicant *wpa_s)
 		wpa_msg(wpa_s, MSG_DEBUG, "Cached scan results are "
 			"empty - not posting");
 	} else {
-		wpa_msg(wpa_s, MSG_INFO, WPA_EVENT_SCAN_RESULTS);
+		wpa_printf(MSG_DEBUG, "New scan results available");
+		wpa_msg_ctrl(wpa_s, MSG_INFO, WPA_EVENT_SCAN_RESULTS);
 		wpas_notify_scan_results(wpa_s);
 	}