WPS: Add a standalone tool for building NFC password tokens

nfc_pw_token can be used to build random NFC password token for WPS.
This tool prints out the wpa_supplicant.conf (or hostapd.conf)
parameters and the hexdump of the WPS password token (with and without
NDEF encapsulation) so that it can be written to a NFC tag with an
external program.

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

wpa_supplicant/Makefile

@@ -1366,6 +1366,10 @@ ifndef CONFIG_AP
 OBJS_t += ../src/utils/ip_addr.o
 endif
 OBJS_t2 := $(OBJS) $(OBJS_l2) preauth_test.o
+
+OBJS_nfc := $(OBJS) $(OBJS_l2) nfc_pw_token.o
+OBJS_nfc += $(OBJS_d) ../src/drivers/drivers.o
+
 OBJS += $(CONFIG_MAIN).o
 
 ifdef CONFIG_PRIVSEP
@@ -1474,6 +1478,10 @@ test_wpa: $(OBJS_wpa) $(OBJS_h)
 	$(Q)$(LDO) $(LDFLAGS) -o test_wpa $(OBJS_wpa) $(LIBS)
 	@$(E) "  LD " $@
 
+nfc_pw_token: $(OBJS_nfc)
+	$(Q)$(LDO) $(LDFLAGS) -o nfc_pw_token $(OBJS_nfc) $(LIBS)
+	@$(E) "  LD " $@
+
 win_if_list: win_if_list.c
 	$(Q)$(LDO) $(LDFLAGS) -o $@ win_if_list.c $(CFLAGS) $(LIBS_w)
 	@$(E) "  LD " $@
@@ -1556,5 +1564,6 @@ clean:
 	$(MAKE) -C dbus clean
 	rm -f core *~ *.o *.d eap_*.so $(ALL) $(WINALL) eapol_test preauth_test
 	rm -f wpa_priv
+	rm -f nfc_pw_token
 
 -include $(OBJS:%.o=%.d)

wpa_supplicant/nfc_pw_token.c

@@ -0,0 +1,83 @@
+/*
+ * nfc_pw_token - Tool for building NFC password tokens for WPS
+ * Copyright (c) 2012, Jouni Malinen <j@w1.fi>
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#include "includes.h"
+
+#include "utils/common.h"
+#include "crypto/random.h"
+#include "wpa_supplicant_i.h"
+#include "config.h"
+#include "wps_supplicant.h"
+
+
+static void print_bin(const char *title, const struct wpabuf *buf)
+{
+	size_t i, len;
+	const u8 *pos;
+
+	if (buf == NULL)
+		return;
+
+	printf("%s=", title);
+
+	pos = wpabuf_head(buf);
+	len = wpabuf_len(buf);
+	for (i = 0; i < len; i++)
+		printf("%02X", *pos++);
+
+	printf("\n");
+}
+
+
+int main(int argc, char *argv[])
+{
+	struct wpa_supplicant wpa_s;
+	int ret = -1;
+	struct wpabuf *buf = NULL, *ndef = NULL;
+	char txt[1000];
+
+	if (os_program_init())
+		return -1;
+	random_init(NULL);
+
+	os_memset(&wpa_s, 0, sizeof(wpa_s));
+	wpa_s.conf = os_zalloc(sizeof(*wpa_s.conf));
+	if (wpa_s.conf == NULL)
+		goto fail;
+
+	buf = wpas_wps_nfc_token(&wpa_s, 0);
+	if (buf == NULL)
+		goto fail;
+
+	ndef = ndef_build_wifi(buf);
+	if (ndef == NULL)
+		goto fail;
+
+	wpa_snprintf_hex_uppercase(txt, sizeof(txt), wpabuf_head(buf),
+				   wpabuf_len(buf));
+	printf("#WPS=%s\n", txt);
+
+	wpa_snprintf_hex_uppercase(txt, sizeof(txt), wpabuf_head(ndef),
+				   wpabuf_len(ndef));
+	printf("#NDEF=%s\n", txt);
+
+	printf("wps_nfc_dev_pw_id=%d\n", wpa_s.conf->wps_nfc_dev_pw_id);
+	print_bin("wps_nfc_dh_pubkey", wpa_s.conf->wps_nfc_dh_pubkey);
+	print_bin("wps_nfc_dh_privkey", wpa_s.conf->wps_nfc_dh_privkey);
+	print_bin("wps_nfc_dev_pw", wpa_s.conf->wps_nfc_dev_pw);
+
+	ret = 0;
+fail:
+	wpabuf_free(ndef);
+	wpabuf_free(buf);
+	wpa_config_free(wpa_s.conf);
+	random_deinit();
+	os_program_deinit();
+
+	return ret;
+}