Add support for using printf-escaped strings in configuration

P"<escaped string>" can now be used as an alternative method for
specifying non-ASCII strings (including control characters). For
example, ssid=P"abc\x00test".

Signed-hostap: Jouni Malinen <j@w1.fi>

wpa_supplicant/config.c

@@ -68,6 +68,31 @@ static char * wpa_config_parse_string(const char *value, size_t *len)
 			return NULL;
 		os_memcpy(str, value, *len);
 		str[*len] = '\0';
+		return str;
+	} else if (*value == 'P' && value[1] == '"') {
+		const char *pos;
+		char *tstr, *str;
+		size_t tlen;
+		value += 2;
+		pos = os_strrchr(value, '"');
+		if (pos == NULL || pos[1] != '\0')
+			return NULL;
+		tlen = pos - value;
+		tstr = os_malloc(tlen + 1);
+		if (tstr == NULL)
+			return NULL;
+		os_memcpy(tstr, value, tlen);
+		tstr[tlen] = '\0';
+
+		str = os_malloc(tlen + 1);
+		if (str == NULL) {
+			os_free(tstr);
+			return NULL;
+		}
+
+		*len = printf_decode((u8 *) str, tlen + 1, tstr);
+		os_free(tstr);
+
 		return str;
 	} else {
 		u8 *str;

wpa_supplicant/wpa_supplicant.conf

@@ -406,8 +406,10 @@ fast_reauth=1
 #	to external action script through wpa_cli as WPA_ID_STR environment
 #	variable to make it easier to do network specific configuration.
 #
-# ssid: SSID (mandatory); either as an ASCII string with double quotation or
-#	as hex string; network name
+# ssid: SSID (mandatory); network name in one of the optional formats:
+#	- an ASCII string with double quotation
+#	- a hex string (two characters per octet of SSID)
+#	- a printf-escaped ASCII string P"<escaped string>"
 #
 # scan_ssid:
 #	0 = do not scan this SSID with specific Probe Request frames (default)