Bluetooth: Shell: Add name and address scan filters

Add a way to filter scan results by name and/or
address. The idea is that this can be further expanded
by also scanning the content for specific UUIDs, PHY,
RSSI, etc.

This is particularly useful for cases where there are many
devices advertising at once.

Signed-off-by: Emil Gydesen <emil.gydesen@nordicsemi.no>

subsys/bluetooth/shell/bt.c

@@ -13,9 +13,11 @@
 
 #include <errno.h>
 #include <zephyr/types.h>
+#include <ctype.h>
 #include <stddef.h>
 #include <stdlib.h>
 #include <string.h>
+#include <strings.h>
 #include <sys/printk.h>
 #include <sys/byteorder.h>
 #include <sys/util.h>
@@ -85,6 +87,47 @@ static const char *phy2str(uint8_t phy)
 #endif
 
 #if defined(CONFIG_BT_OBSERVER)
+static struct bt_scan_filter {
+	char name[NAME_LEN];
+	bool name_set;
+	char addr[18]; /* fits xx:xx:xx:xx:xx:xx\0 */
+	bool addr_set;
+} scan_filter;
+
+
+/**
+ * @brief Compares two strings without case sensitivy
+ *
+ * @param substr The substring
+ * @param str The string to find the substring in
+ *
+ * @return true if @substr is a substring of @p, else false
+ */
+static bool is_substring(const char *substr, const char *str)
+{
+	const size_t str_len = strlen(str);
+	const size_t sub_str_len = strlen(substr);
+
+	if (sub_str_len > str_len) {
+		return false;
+	}
+
+	for (size_t pos = 0; pos < str_len; pos++) {
+		if (tolower(substr[0]) == tolower(str[pos])) {
+			if (pos + sub_str_len > str_len) {
+				shell_print(ctx_shell, "length fail");
+				return false;
+			}
+
+			if (strncasecmp(substr, &str[pos], sub_str_len) == 0) {
+				return true;
+			}
+		}
+	}
+
+	return false;
+}
+
 static bool data_cb(struct bt_data *data, void *user_data)
 {
 	char *name = user_data;
@@ -99,7 +142,6 @@ static bool data_cb(struct bt_data *data, void *user_data)
 	}
 }
 
-
 static void scan_recv(const struct bt_le_scan_recv_info *info,
 		      struct net_buf_simple *buf)
 {
@@ -111,6 +153,15 @@ static void scan_recv(const struct bt_le_scan_recv_info *info,
 	bt_data_parse(buf, data_cb, name);
 
 	bt_addr_le_to_str(info->addr, le_addr, sizeof(le_addr));
+
+	if (scan_filter.name_set && !is_substring(scan_filter.name, name)) {
+		return;
+	}
+
+	if (scan_filter.addr_set && !is_substring(scan_filter.addr, le_addr)) {
+		return;
+	}
+
 	shell_print(ctx_shell, "[DEVICE]: %s, AD evt type %u, RSSI %i %s "
 		    "C:%u S:%u D:%d SR:%u E:%u Prim: %s, Secn: %s, "
 		    "Interval: 0x%04x (%u ms), SID: 0x%x",
@@ -938,6 +989,81 @@ static int cmd_scan(const struct shell *sh, size_t argc, char *argv[])
 
 	return 0;
 }
+
+static int cmd_scan_filter_set_name(const struct shell *sh, size_t argc,
+				    char *argv[])
+{
+	const char *name_arg = argv[1];
+
+	if (strlen(name_arg) >= sizeof(scan_filter.name)) {
+		shell_error(ctx_shell, "Name is too long (max %zu): %s\n",
+			    sizeof(scan_filter.name), name_arg);
+		return -ENOEXEC;
+	}
+
+	strcpy(scan_filter.name, name_arg);
+	scan_filter.name_set = true;
+
+	return 0;
+}
+
+static int cmd_scan_filter_set_addr(const struct shell *sh, size_t argc,
+				    char *argv[])
+{
+	const char *addr_arg = argv[1];
+
+	/* Validate length */
+	if (strlen(addr_arg) > sizeof(scan_filter.addr)) {
+		shell_error(ctx_shell, "Invalid address string: %s\n",
+			    addr_arg);
+		return -ENOEXEC;
+	}
+
+	/* Validate input to check if valid (subset of) BT address */
+	for (size_t i = 0; i < strlen(addr_arg); i++) {
+		const char c = addr_arg[i];
+		uint8_t tmp;
+
+		if (c != ':' && char2hex(c, &tmp) < 0) {
+			shell_error(ctx_shell,
+					"Invalid address string: %s\n",
+					addr_arg);
+			return -ENOEXEC;
+		}
+	}
+
+	strcpy(scan_filter.addr, addr_arg);
+	scan_filter.addr_set = true;
+
+	return 0;
+}
+
+static int cmd_scan_filter_clear_all(const struct shell *sh, size_t argc,
+				     char *argv[])
+{
+	(void)memset(&scan_filter, 0, sizeof(scan_filter));
+
+	return 0;
+}
+
+static int cmd_scan_filter_clear_name(const struct shell *sh, size_t argc,
+				      char *argv[])
+{
+	(void)memset(scan_filter.name, 0, sizeof(scan_filter.name));
+	scan_filter.name_set = false;
+
+	return 0;
+}
+
+static int cmd_scan_filter_clear_addr(const struct shell *sh, size_t argc,
+				      char *argv[])
+{
+	(void)memset(scan_filter.addr, 0, sizeof(scan_filter.addr));
+	scan_filter.addr_set = false;
+
+	return 0;
+}
+
 #endif /* CONFIG_BT_OBSERVER */
 
 #if defined(CONFIG_BT_BROADCASTER)
@@ -3092,6 +3218,21 @@ static int cmd_auth_oob_tk(const struct shell *sh, size_t argc, char *argv[])
 #define EXT_ADV_SCAN_OPT ""
 #endif /* defined(CONFIG_BT_EXT_ADV) */
 
+#if defined(CONFIG_BT_OBSERVER)
+SHELL_STATIC_SUBCMD_SET_CREATE(bt_scan_filter_set_cmds,
+	SHELL_CMD_ARG(name, NULL, "<name>", cmd_scan_filter_set_name, 2, 0),
+	SHELL_CMD_ARG(addr, NULL, "<addr>", cmd_scan_filter_set_addr, 2, 0),
+	SHELL_SUBCMD_SET_END
+);
+
+SHELL_STATIC_SUBCMD_SET_CREATE(bt_scan_filter_clear_cmds,
+	SHELL_CMD_ARG(all, NULL, "", cmd_scan_filter_clear_all, 1, 0),
+	SHELL_CMD_ARG(name, NULL, "", cmd_scan_filter_clear_name, 1, 0),
+	SHELL_CMD_ARG(addr, NULL, "", cmd_scan_filter_clear_addr, 1, 0),
+	SHELL_SUBCMD_SET_END
+);
+#endif /* CONFIG_BT_OBSERVER */
+
 SHELL_STATIC_SUBCMD_SET_CREATE(bt_cmds,
 	SHELL_CMD_ARG(init, NULL, "[no-settings-load], [sync]",
 		      cmd_init, 1, 2),
@@ -3112,6 +3253,12 @@ SHELL_STATIC_SUBCMD_SET_CREATE(bt_cmds,
 		      "<value: on, passive, off> [filter: dups, nodups] [fal]"
 		      EXT_ADV_SCAN_OPT,
 		      cmd_scan, 2, 4),
+	SHELL_CMD_ARG(scan-filter-set, &bt_scan_filter_set_cmds,
+		      "Scan filter set commands",
+		      NULL, 1, 0),
+	SHELL_CMD_ARG(scan-filter-clear, &bt_scan_filter_clear_cmds,
+		      "Scan filter clear commands",
+		      NULL, 1, 0),
 #endif /* CONFIG_BT_OBSERVER */
 #if defined(CONFIG_BT_BROADCASTER)
 	SHELL_CMD_ARG(advertise, NULL,