autopair: Add the autopair plugin

The autopair plugin tries standard pincodes for different devices with
dumb pincodes. It also generates a random 6 digit pincode for keyboards
that support any pincode but fallbacks to the agent call in case the
random generated pincode didn't work.

Makefile.plugins

@@ -5,6 +5,9 @@ builtin_sources += plugins/hostname.c
 builtin_modules += wiimote
 builtin_sources += plugins/wiimote.c
 
+builtin_modules += autopair
+builtin_sources += plugins/autopair.c
+
 if MAINTAINER_MODE
 builtin_modules += gatt_example
 builtin_sources += plugins/gatt-example.c

plugins/autopair.c

@@ -0,0 +1,150 @@
+/*
+ *
+ *  BlueZ - Bluetooth protocol stack for Linux
+ *
+ *  Copyright (C) 2012 Google Inc.
+ *
+ *
+ *  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 St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdbool.h>
+#include <stdlib.h>
+
+#include <bluetooth/bluetooth.h>
+#include <glib.h>
+
+#include "plugin.h"
+#include "adapter.h"
+#include "device.h"
+#include "log.h"
+#include "storage.h"
+
+/*
+ * Plugin to handle automatic pairing of devices with reduced user
+ * interaction, including implementing the recommendation of the HID spec
+ * for keyboard devices.
+ *
+ * The plugin works by intercepting the PIN request for devices; if the
+ * device is a keyboard a random six-digit numeric PIN is generated and
+ * returned, flagged for displaying using DisplayPinCode.
+ *
+ */
+
+static ssize_t autopair_pincb(struct btd_adapter *adapter,
+					struct btd_device *device,
+					char *pinbuf, gboolean *display,
+					unsigned int attempt)
+{
+	char addr[18];
+	char pinstr[7];
+	uint32_t class;
+
+	ba2str(device_get_address(device), addr);
+
+	class = btd_device_get_class(device);
+
+	DBG("device %s 0x%x", addr, class);
+
+	/* This is a class-based pincode guesser. Ignore devices with an unknown
+	 * class. */
+	if (class == 0)
+		return 0;
+
+	switch ((class & 0x1f00) >> 8) {
+	case 0x04:		/* Audio/Video */
+		switch ((class & 0xfc) >> 2) {
+		case 0x01:		/* Wearable Headset Device */
+		case 0x02:		/* Hands-free Device */
+		case 0x06:		/* Headphones */
+		case 0x07:		/* Portable Audio */
+		case 0x0a:		/* HiFi Audio Device */
+			if (attempt > 1)
+				return 0;
+			memcpy(pinbuf, "0000", 4);
+			return 4;
+			break;
+		}
+		break;
+	case 0x05:		/* Peripheral */
+		switch ((class & 0xc0) >> 6) {
+		case 0x01:		/* Keyboard */
+		case 0x03:		/* Combo keyboard/pointing device */
+			if (attempt > 1)
+				return 0;
+			snprintf(pinstr, sizeof(pinstr), "%06d",
+						rand() % 1000000);
+			*display = TRUE;
+			memcpy(pinbuf, pinstr, 6);
+			return 6;
+			break;
+		case 0x02: /* Pointing device */
+			if (attempt > 1)
+				return 0;
+			memcpy(pinbuf, "0000", 4);
+			return 4;
+			break;
+		}
+		break;
+	}
+
+	return 0;
+}
+
+
+static int autopair_probe(struct btd_adapter *adapter)
+{
+	btd_adapter_register_pin_cb(adapter, autopair_pincb);
+
+	return 0;
+}
+
+static void autopair_remove(struct btd_adapter *adapter)
+{
+	btd_adapter_unregister_pin_cb(adapter, autopair_pincb);
+}
+
+static struct btd_adapter_driver autopair_driver = {
+	.name = "autopair",
+	.probe = autopair_probe,
+	.remove = autopair_remove,
+};
+
+static int autopair_init(void)
+{
+	/* Initialize the random seed from /dev/urandom */
+	unsigned int seed = time(NULL);
+	FILE *f = fopen("/dev/urandom", "rb");
+	if (f != NULL) {
+		fread(&seed, sizeof(seed), 1, f);
+		fclose(f);
+	}
+	srand(seed);
+
+	return btd_register_adapter_driver(&autopair_driver);
+}
+
+static void autopair_exit(void)
+{
+	btd_unregister_adapter_driver(&autopair_driver);
+}
+
+BLUETOOTH_PLUGIN_DEFINE(autopair, VERSION,
+		BLUETOOTH_PLUGIN_PRIORITY_DEFAULT, autopair_init, autopair_exit)