/*
 * Wi-Fi Protected Setup - Enrollee
 * Copyright (c) 2008, 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 "common.h"
#include "crypto/crypto.h"
#include "crypto/sha256.h"
#include "crypto/random.h"
#include "wps_i.h"
#include "wps_dev_attr.h"


static int wps_build_wps_state(struct wps_data *wps, struct wpabuf *msg)
{
	u8 state;
	if (wps->wps->ap)
		state = wps->wps->wps_state;
	else
		state = WPS_STATE_NOT_CONFIGURED;
	wpa_printf(MSG_DEBUG, "WPS:  * Wi-Fi Protected Setup State (%d)",
		   state);
	wpabuf_put_be16(msg, ATTR_WPS_STATE);
	wpabuf_put_be16(msg, 1);
	wpabuf_put_u8(msg, state);
	return 0;
}


static int wps_build_e_hash(struct wps_data *wps, struct wpabuf *msg)
{
	u8 *hash;
	const u8 *addr[4];
	size_t len[4];

	if (random_get_bytes(wps->snonce, 2 * WPS_SECRET_NONCE_LEN) < 0)
		return -1;
	wpa_hexdump(MSG_DEBUG, "WPS: E-S1", wps->snonce, WPS_SECRET_NONCE_LEN);
	wpa_hexdump(MSG_DEBUG, "WPS: E-S2",
		    wps->snonce + WPS_SECRET_NONCE_LEN, WPS_SECRET_NONCE_LEN);

	if (wps->dh_pubkey_e == NULL || wps->dh_pubkey_r == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: DH public keys not available for "
			   "E-Hash derivation");
		return -1;
	}

	wpa_printf(MSG_DEBUG, "WPS:  * E-Hash1");
	wpabuf_put_be16(msg, ATTR_E_HASH1);
	wpabuf_put_be16(msg, SHA256_MAC_LEN);
	hash = wpabuf_put(msg, SHA256_MAC_LEN);
	/* E-Hash1 = HMAC_AuthKey(E-S1 || PSK1 || PK_E || PK_R) */
	addr[0] = wps->snonce;
	len[0] = WPS_SECRET_NONCE_LEN;
	addr[1] = wps->psk1;
	len[1] = WPS_PSK_LEN;
	addr[2] = wpabuf_head(wps->dh_pubkey_e);
	len[2] = wpabuf_len(wps->dh_pubkey_e);
	addr[3] = wpabuf_head(wps->dh_pubkey_r);
	len[3] = wpabuf_len(wps->dh_pubkey_r);
	hmac_sha256_vector(wps->authkey, WPS_AUTHKEY_LEN, 4, addr, len, hash);
	wpa_hexdump(MSG_DEBUG, "WPS: E-Hash1", hash, SHA256_MAC_LEN);

	wpa_printf(MSG_DEBUG, "WPS:  * E-Hash2");
	wpabuf_put_be16(msg, ATTR_E_HASH2);
	wpabuf_put_be16(msg, SHA256_MAC_LEN);
	hash = wpabuf_put(msg, SHA256_MAC_LEN);
	/* E-Hash2 = HMAC_AuthKey(E-S2 || PSK2 || PK_E || PK_R) */
	addr[0] = wps->snonce + WPS_SECRET_NONCE_LEN;
	addr[1] = wps->psk2;
	hmac_sha256_vector(wps->authkey, WPS_AUTHKEY_LEN, 4, addr, len, hash);
	wpa_hexdump(MSG_DEBUG, "WPS: E-Hash2", hash, SHA256_MAC_LEN);

	return 0;
}


static int wps_build_e_snonce1(struct wps_data *wps, struct wpabuf *msg)
{
	wpa_printf(MSG_DEBUG, "WPS:  * E-SNonce1");
	wpabuf_put_be16(msg, ATTR_E_SNONCE1);
	wpabuf_put_be16(msg, WPS_SECRET_NONCE_LEN);
	wpabuf_put_data(msg, wps->snonce, WPS_SECRET_NONCE_LEN);
	return 0;
}


static int wps_build_e_snonce2(struct wps_data *wps, struct wpabuf *msg)
{
	wpa_printf(MSG_DEBUG, "WPS:  * E-SNonce2");
	wpabuf_put_be16(msg, ATTR_E_SNONCE2);
	wpabuf_put_be16(msg, WPS_SECRET_NONCE_LEN);
	wpabuf_put_data(msg, wps->snonce + WPS_SECRET_NONCE_LEN,
			WPS_SECRET_NONCE_LEN);
	return 0;
}


static struct wpabuf * wps_build_m1(struct wps_data *wps)
{
	struct wpabuf *msg;
	u16 config_methods;

	if (random_get_bytes(wps->nonce_e, WPS_NONCE_LEN) < 0)
		return NULL;
	wpa_hexdump(MSG_DEBUG, "WPS: Enrollee Nonce",
		    wps->nonce_e, WPS_NONCE_LEN);

	wpa_printf(MSG_DEBUG, "WPS: Building Message M1");
	msg = wpabuf_alloc(1000);
	if (msg == NULL)
		return NULL;

	config_methods = wps->wps->config_methods;
	if (wps->wps->ap && !wps->pbc_in_m1 &&
	    (wps->dev_password_len != 0 ||
	     (config_methods & WPS_CONFIG_DISPLAY))) {
		/*
		 * These are the methods that the AP supports as an Enrollee
		 * for adding external Registrars, so remove PushButton.
		 *
		 * As a workaround for Windows 7 mechanism for probing WPS
		 * capabilities from M1, leave PushButton option if no PIN
		 * method is available or if WPS configuration enables PBC
		 * workaround.
		 */
		config_methods &= ~WPS_CONFIG_PUSHBUTTON;
		config_methods &= ~(WPS_CONFIG_VIRT_PUSHBUTTON |
				    WPS_CONFIG_PHY_PUSHBUTTON);
	}

	if (wps_build_version(msg) ||
	    wps_build_msg_type(msg, WPS_M1) ||
	    wps_build_uuid_e(msg, wps->uuid_e) ||
	    wps_build_mac_addr(msg, wps->mac_addr_e) ||
	    wps_build_enrollee_nonce(wps, msg) ||
	    wps_build_public_key(wps, msg) ||
	    wps_build_auth_type_flags(wps, msg) ||
	    wps_build_encr_type_flags(wps, msg) ||
	    wps_build_conn_type_flags(wps, msg) ||
	    wps_build_config_methods(msg, config_methods) ||
	    wps_build_wps_state(wps, msg) ||
	    wps_build_device_attrs(&wps->wps->dev, msg) ||
	    wps_build_rf_bands(&wps->wps->dev, msg,
			       wps->wps->rf_band_cb(wps->wps->cb_ctx)) ||
	    wps_build_assoc_state(wps, msg) ||
	    wps_build_dev_password_id(msg, wps->dev_pw_id) ||
	    wps_build_config_error(msg, WPS_CFG_NO_ERROR) ||
	    wps_build_os_version(&wps->wps->dev, msg) ||
	    wps_build_wfa_ext(msg, 0, NULL, 0) ||
	    wps_build_vendor_ext_m1(&wps->wps->dev, msg)) {
		wpabuf_free(msg);
		return NULL;
	}

	wps->state = RECV_M2;
	return msg;
}


static struct wpabuf * wps_build_m3(struct wps_data *wps)
{
	struct wpabuf *msg;

	wpa_printf(MSG_DEBUG, "WPS: Building Message M3");

	if (wps->dev_password == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: No Device Password available");
		return NULL;
	}
	wps_derive_psk(wps, wps->dev_password, wps->dev_password_len);

	if (wps->wps->ap && random_pool_ready() != 1) {
		wpa_printf(MSG_INFO,
			   "WPS: Not enough entropy in random pool to proceed - do not allow AP PIN to be used");
		return NULL;
	}

	msg = wpabuf_alloc(1000);
	if (msg == NULL)
		return NULL;

	if (wps_build_version(msg) ||
	    wps_build_msg_type(msg, WPS_M3) ||
	    wps_build_registrar_nonce(wps, msg) ||
	    wps_build_e_hash(wps, msg) ||
	    wps_build_wfa_ext(msg, 0, NULL, 0) ||
	    wps_build_authenticator(wps, msg)) {
		wpabuf_free(msg);
		return NULL;
	}

	wps->state = RECV_M4;
	return msg;
}


static struct wpabuf * wps_build_m5(struct wps_data *wps)
{
	struct wpabuf *msg, *plain;

	wpa_printf(MSG_DEBUG, "WPS: Building Message M5");

	plain = wpabuf_alloc(200);
	if (plain == NULL)
		return NULL;

	msg = wpabuf_alloc(1000);
	if (msg == NULL) {
		wpabuf_free(plain);
		return NULL;
	}

	if (wps_build_version(msg) ||
	    wps_build_msg_type(msg, WPS_M5) ||
	    wps_build_registrar_nonce(wps, msg) ||
	    wps_build_e_snonce1(wps, plain) ||
	    wps_build_key_wrap_auth(wps, plain) ||
	    wps_build_encr_settings(wps, msg, plain) ||
	    wps_build_wfa_ext(msg, 0, NULL, 0) ||
	    wps_build_authenticator(wps, msg)) {
		wpabuf_free(plain);
		wpabuf_free(msg);
		return NULL;
	}
	wpabuf_free(plain);

	wps->state = RECV_M6;
	return msg;
}


static int wps_build_cred_ssid(struct wps_data *wps, struct wpabuf *msg)
{
	wpa_printf(MSG_DEBUG, "WPS:  * SSID");
	wpabuf_put_be16(msg, ATTR_SSID);
	wpabuf_put_be16(msg, wps->wps->ssid_len);
	wpabuf_put_data(msg, wps->wps->ssid, wps->wps->ssid_len);
	return 0;
}


static int wps_build_cred_auth_type(struct wps_data *wps, struct wpabuf *msg)
{
	u16 auth_type = wps->wps->ap_auth_type;

	/*
	 * Work around issues with Windows 7 WPS implementation not liking
	 * multiple Authentication Type bits in M7 AP Settings attribute by
	 * showing only the most secure option from current configuration.
	 */
	if (auth_type & WPS_AUTH_WPA2PSK)
		auth_type = WPS_AUTH_WPA2PSK;
	else if (auth_type & WPS_AUTH_WPAPSK)
		auth_type = WPS_AUTH_WPAPSK;
	else if (auth_type & WPS_AUTH_OPEN)
		auth_type = WPS_AUTH_OPEN;

	wpa_printf(MSG_DEBUG, "WPS:  * Authentication Type (0x%x)", auth_type);
	wpabuf_put_be16(msg, ATTR_AUTH_TYPE);
	wpabuf_put_be16(msg, 2);
	wpabuf_put_be16(msg, auth_type);
	return 0;
}


static int wps_build_cred_encr_type(struct wps_data *wps, struct wpabuf *msg)
{
	u16 encr_type = wps->wps->ap_encr_type;

	/*
	 * Work around issues with Windows 7 WPS implementation not liking
	 * multiple Encryption Type bits in M7 AP Settings attribute by
	 * showing only the most secure option from current configuration.
	 */
	if (wps->wps->ap_auth_type & (WPS_AUTH_WPA2PSK | WPS_AUTH_WPAPSK)) {
		if (encr_type & WPS_ENCR_AES)
			encr_type = WPS_ENCR_AES;
		else if (encr_type & WPS_ENCR_TKIP)
			encr_type = WPS_ENCR_TKIP;
	}

	wpa_printf(MSG_DEBUG, "WPS:  * Encryption Type (0x%x)", encr_type);
	wpabuf_put_be16(msg, ATTR_ENCR_TYPE);
	wpabuf_put_be16(msg, 2);
	wpabuf_put_be16(msg, encr_type);
	return 0;
}


static int wps_build_cred_network_key(struct wps_data *wps, struct wpabuf *msg)
{
	if ((wps->wps->ap_auth_type & (WPS_AUTH_WPAPSK | WPS_AUTH_WPA2PSK)) &&
	    wps->wps->network_key_len == 0) {
		char hex[65];
		u8 psk[32];
		/* Generate a random per-device PSK */
		if (random_pool_ready() != 1 ||
		    random_get_bytes(psk, sizeof(psk)) < 0) {
			wpa_printf(MSG_INFO,
				   "WPS: Could not generate random PSK");
			return -1;
		}
		wpa_hexdump_key(MSG_DEBUG, "WPS: Generated per-device PSK",
				psk, sizeof(psk));
		wpa_printf(MSG_DEBUG, "WPS:  * Network Key (len=%u)",
			   (unsigned int) wps->new_psk_len * 2);
		wpa_snprintf_hex(hex, sizeof(hex), psk, sizeof(psk));
		wpabuf_put_be16(msg, ATTR_NETWORK_KEY);
		wpabuf_put_be16(msg, sizeof(psk) * 2);
		wpabuf_put_data(msg, hex, sizeof(psk) * 2);
		if (wps->wps->registrar) {
			wps_cb_new_psk(wps->wps->registrar,
				       wps->peer_dev.mac_addr,
				       wps->p2p_dev_addr, psk, sizeof(psk));
		}
		return 0;
	}

	wpa_printf(MSG_DEBUG, "WPS:  * Network Key (len=%u)",
		   (unsigned int) wps->wps->network_key_len);
	wpabuf_put_be16(msg, ATTR_NETWORK_KEY);
	wpabuf_put_be16(msg, wps->wps->network_key_len);
	wpabuf_put_data(msg, wps->wps->network_key, wps->wps->network_key_len);
	return 0;
}


static int wps_build_cred_mac_addr(struct wps_data *wps, struct wpabuf *msg)
{
	wpa_printf(MSG_DEBUG, "WPS:  * MAC Address (AP BSSID)");
	wpabuf_put_be16(msg, ATTR_MAC_ADDR);
	wpabuf_put_be16(msg, ETH_ALEN);
	wpabuf_put_data(msg, wps->wps->dev.mac_addr, ETH_ALEN);
	return 0;
}


static int wps_build_ap_settings(struct wps_data *wps, struct wpabuf *plain)
{
	const u8 *start, *end;
	int ret;

	if (wps->wps->ap_settings) {
		wpa_printf(MSG_DEBUG, "WPS:  * AP Settings (pre-configured)");
		wpabuf_put_data(plain, wps->wps->ap_settings,
				wps->wps->ap_settings_len);
		return 0;
	}

	wpa_printf(MSG_DEBUG, "WPS:  * AP Settings based on current configuration");
	start = wpabuf_put(plain, 0);
	ret = wps_build_cred_ssid(wps, plain) ||
		wps_build_cred_mac_addr(wps, plain) ||
		wps_build_cred_auth_type(wps, plain) ||
		wps_build_cred_encr_type(wps, plain) ||
		wps_build_cred_network_key(wps, plain);
	end = wpabuf_put(plain, 0);

	wpa_hexdump_key(MSG_DEBUG, "WPS: Plaintext AP Settings",
			start, end - start);

	return ret;
}


static struct wpabuf * wps_build_m7(struct wps_data *wps)
{
	struct wpabuf *msg, *plain;

	wpa_printf(MSG_DEBUG, "WPS: Building Message M7");

	plain = wpabuf_alloc(500 + wps->wps->ap_settings_len);
	if (plain == NULL)
		return NULL;

	msg = wpabuf_alloc(1000 + wps->wps->ap_settings_len);
	if (msg == NULL) {
		wpabuf_free(plain);
		return NULL;
	}

	if (wps_build_version(msg) ||
	    wps_build_msg_type(msg, WPS_M7) ||
	    wps_build_registrar_nonce(wps, msg) ||
	    wps_build_e_snonce2(wps, plain) ||
	    (wps->wps->ap && wps_build_ap_settings(wps, plain)) ||
	    wps_build_key_wrap_auth(wps, plain) ||
	    wps_build_encr_settings(wps, msg, plain) ||
	    wps_build_wfa_ext(msg, 0, NULL, 0) ||
	    wps_build_authenticator(wps, msg)) {
		wpabuf_free(plain);
		wpabuf_free(msg);
		return NULL;
	}
	wpabuf_free(plain);

	if (wps->wps->ap && wps->wps->registrar) {
		/*
		 * If the Registrar is only learning our current configuration,
		 * it may not continue protocol run to successful completion.
		 * Store information here to make sure it remains available.
		 */
		wps_device_store(wps->wps->registrar, &wps->peer_dev,
				 wps->uuid_r);
	}

	wps->state = RECV_M8;
	return msg;
}


static struct wpabuf * wps_build_wsc_done(struct wps_data *wps)
{
	struct wpabuf *msg;

	wpa_printf(MSG_DEBUG, "WPS: Building Message WSC_Done");

	msg = wpabuf_alloc(1000);
	if (msg == NULL)
		return NULL;

	if (wps_build_version(msg) ||
	    wps_build_msg_type(msg, WPS_WSC_DONE) ||
	    wps_build_enrollee_nonce(wps, msg) ||
	    wps_build_registrar_nonce(wps, msg) ||
	    wps_build_wfa_ext(msg, 0, NULL, 0)) {
		wpabuf_free(msg);
		return NULL;
	}

	if (wps->wps->ap)
		wps->state = RECV_ACK;
	else {
		wps_success_event(wps->wps, wps->peer_dev.mac_addr);
		wps->state = WPS_FINISHED;
	}
	return msg;
}


struct wpabuf * wps_enrollee_get_msg(struct wps_data *wps,
				     enum wsc_op_code *op_code)
{
	struct wpabuf *msg;

	switch (wps->state) {
	case SEND_M1:
		msg = wps_build_m1(wps);
		*op_code = WSC_MSG;
		break;
	case SEND_M3:
		msg = wps_build_m3(wps);
		*op_code = WSC_MSG;
		break;
	case SEND_M5:
		msg = wps_build_m5(wps);
		*op_code = WSC_MSG;
		break;
	case SEND_M7:
		msg = wps_build_m7(wps);
		*op_code = WSC_MSG;
		break;
	case RECEIVED_M2D:
		if (wps->wps->ap) {
			msg = wps_build_wsc_nack(wps);
			*op_code = WSC_NACK;
			break;
		}
		msg = wps_build_wsc_ack(wps);
		*op_code = WSC_ACK;
		if (msg) {
			/* Another M2/M2D may be received */
			wps->state = RECV_M2;
		}
		break;
	case SEND_WSC_NACK:
		msg = wps_build_wsc_nack(wps);
		*op_code = WSC_NACK;
		break;
	case WPS_MSG_DONE:
		msg = wps_build_wsc_done(wps);
		*op_code = WSC_Done;
		break;
	default:
		wpa_printf(MSG_DEBUG, "WPS: Unsupported state %d for building "
			   "a message", wps->state);
		msg = NULL;
		break;
	}

	if (*op_code == WSC_MSG && msg) {
		/* Save a copy of the last message for Authenticator derivation
		 */
		wpabuf_free(wps->last_msg);
		wps->last_msg = wpabuf_dup(msg);
	}

	return msg;
}


static int wps_process_registrar_nonce(struct wps_data *wps, const u8 *r_nonce)
{
	if (r_nonce == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: No Registrar Nonce received");
		return -1;
	}

	os_memcpy(wps->nonce_r, r_nonce, WPS_NONCE_LEN);
	wpa_hexdump(MSG_DEBUG, "WPS: Registrar Nonce",
		    wps->nonce_r, WPS_NONCE_LEN);

	return 0;
}


static int wps_process_enrollee_nonce(struct wps_data *wps, const u8 *e_nonce)
{
	if (e_nonce == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: No Enrollee Nonce received");
		return -1;
	}

	if (os_memcmp(wps->nonce_e, e_nonce, WPS_NONCE_LEN) != 0) {
		wpa_printf(MSG_DEBUG, "WPS: Invalid Enrollee Nonce received");
		return -1;
	}

	return 0;
}


static int wps_process_uuid_r(struct wps_data *wps, const u8 *uuid_r)
{
	if (uuid_r == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: No UUID-R received");
		return -1;
	}

	os_memcpy(wps->uuid_r, uuid_r, WPS_UUID_LEN);
	wpa_hexdump(MSG_DEBUG, "WPS: UUID-R", wps->uuid_r, WPS_UUID_LEN);

	return 0;
}


static int wps_process_pubkey(struct wps_data *wps, const u8 *pk,
			      size_t pk_len)
{
	if (pk == NULL || pk_len == 0) {
		wpa_printf(MSG_DEBUG, "WPS: No Public Key received");
		return -1;
	}

	if (wps->peer_pubkey_hash_set) {
		u8 hash[WPS_HASH_LEN];
		sha256_vector(1, &pk, &pk_len, hash);
		if (os_memcmp_const(hash, wps->peer_pubkey_hash,
				    WPS_OOB_PUBKEY_HASH_LEN) != 0) {
			wpa_printf(MSG_ERROR, "WPS: Public Key hash mismatch");
			wpa_hexdump(MSG_DEBUG, "WPS: Received public key",
				    pk, pk_len);
			wpa_hexdump(MSG_DEBUG, "WPS: Calculated public key "
				    "hash", hash, WPS_OOB_PUBKEY_HASH_LEN);
			wpa_hexdump(MSG_DEBUG, "WPS: Expected public key hash",
				    wps->peer_pubkey_hash,
				    WPS_OOB_PUBKEY_HASH_LEN);
			wps->config_error = WPS_CFG_PUBLIC_KEY_HASH_MISMATCH;
			return -1;
		}
	}

	wpabuf_free(wps->dh_pubkey_r);
	wps->dh_pubkey_r = wpabuf_alloc_copy(pk, pk_len);
	if (wps->dh_pubkey_r == NULL)
		return -1;

	if (wps_derive_keys(wps) < 0)
		return -1;

	return 0;
}


static int wps_process_r_hash1(struct wps_data *wps, const u8 *r_hash1)
{
	if (r_hash1 == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: No R-Hash1 received");
		return -1;
	}

	os_memcpy(wps->peer_hash1, r_hash1, WPS_HASH_LEN);
	wpa_hexdump(MSG_DEBUG, "WPS: R-Hash1", wps->peer_hash1, WPS_HASH_LEN);

	return 0;
}


static int wps_process_r_hash2(struct wps_data *wps, const u8 *r_hash2)
{
	if (r_hash2 == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: No R-Hash2 received");
		return -1;
	}

	os_memcpy(wps->peer_hash2, r_hash2, WPS_HASH_LEN);
	wpa_hexdump(MSG_DEBUG, "WPS: R-Hash2", wps->peer_hash2, WPS_HASH_LEN);

	return 0;
}


static int wps_process_r_snonce1(struct wps_data *wps, const u8 *r_snonce1)
{
	u8 hash[SHA256_MAC_LEN];
	const u8 *addr[4];
	size_t len[4];

	if (r_snonce1 == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: No R-SNonce1 received");
		return -1;
	}

	wpa_hexdump_key(MSG_DEBUG, "WPS: R-SNonce1", r_snonce1,
			WPS_SECRET_NONCE_LEN);

	/* R-Hash1 = HMAC_AuthKey(R-S1 || PSK1 || PK_E || PK_R) */
	addr[0] = r_snonce1;
	len[0] = WPS_SECRET_NONCE_LEN;
	addr[1] = wps->psk1;
	len[1] = WPS_PSK_LEN;
	addr[2] = wpabuf_head(wps->dh_pubkey_e);
	len[2] = wpabuf_len(wps->dh_pubkey_e);
	addr[3] = wpabuf_head(wps->dh_pubkey_r);
	len[3] = wpabuf_len(wps->dh_pubkey_r);
	hmac_sha256_vector(wps->authkey, WPS_AUTHKEY_LEN, 4, addr, len, hash);

	if (os_memcmp_const(wps->peer_hash1, hash, WPS_HASH_LEN) != 0) {
		wpa_printf(MSG_DEBUG, "WPS: R-Hash1 derived from R-S1 does "
			   "not match with the pre-committed value");
		wps->config_error = WPS_CFG_DEV_PASSWORD_AUTH_FAILURE;
		wps_pwd_auth_fail_event(wps->wps, 1, 1, wps->peer_dev.mac_addr);
		return -1;
	}

	wpa_printf(MSG_DEBUG, "WPS: Registrar proved knowledge of the first "
		   "half of the device password");

	return 0;
}


static int wps_process_r_snonce2(struct wps_data *wps, const u8 *r_snonce2)
{
	u8 hash[SHA256_MAC_LEN];
	const u8 *addr[4];
	size_t len[4];

	if (r_snonce2 == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: No R-SNonce2 received");
		return -1;
	}

	wpa_hexdump_key(MSG_DEBUG, "WPS: R-SNonce2", r_snonce2,
			WPS_SECRET_NONCE_LEN);

	/* R-Hash2 = HMAC_AuthKey(R-S2 || PSK2 || PK_E || PK_R) */
	addr[0] = r_snonce2;
	len[0] = WPS_SECRET_NONCE_LEN;
	addr[1] = wps->psk2;
	len[1] = WPS_PSK_LEN;
	addr[2] = wpabuf_head(wps->dh_pubkey_e);
	len[2] = wpabuf_len(wps->dh_pubkey_e);
	addr[3] = wpabuf_head(wps->dh_pubkey_r);
	len[3] = wpabuf_len(wps->dh_pubkey_r);
	hmac_sha256_vector(wps->authkey, WPS_AUTHKEY_LEN, 4, addr, len, hash);

	if (os_memcmp_const(wps->peer_hash2, hash, WPS_HASH_LEN) != 0) {
		wpa_printf(MSG_DEBUG, "WPS: R-Hash2 derived from R-S2 does "
			   "not match with the pre-committed value");
		wps->config_error = WPS_CFG_DEV_PASSWORD_AUTH_FAILURE;
		wps_pwd_auth_fail_event(wps->wps, 1, 2, wps->peer_dev.mac_addr);
		return -1;
	}

	wpa_printf(MSG_DEBUG, "WPS: Registrar proved knowledge of the second "
		   "half of the device password");

	return 0;
}


static int wps_process_cred_e(struct wps_data *wps, const u8 *cred,
			      size_t cred_len, int wps2)
{
	struct wps_parse_attr attr;
	struct wpabuf msg;
	int ret = 0;

	wpa_printf(MSG_DEBUG, "WPS: Received Credential");
	os_memset(&wps->cred, 0, sizeof(wps->cred));
	wpabuf_set(&msg, cred, cred_len);
	if (wps_parse_msg(&msg, &attr) < 0 ||
	    wps_process_cred(&attr, &wps->cred))
		return -1;

	if (os_memcmp(wps->cred.mac_addr, wps->wps->dev.mac_addr, ETH_ALEN) !=
	    0) {
		wpa_printf(MSG_DEBUG, "WPS: MAC Address in the Credential ("
			   MACSTR ") does not match with own address (" MACSTR
			   ")", MAC2STR(wps->cred.mac_addr),
			   MAC2STR(wps->wps->dev.mac_addr));
		/*
		 * In theory, this could be consider fatal error, but there are
		 * number of deployed implementations using other address here
		 * due to unclarity in the specification. For interoperability
		 * reasons, allow this to be processed since we do not really
		 * use the MAC Address information for anything.
		 */
#ifdef CONFIG_WPS_STRICT
		if (wps2) {
			wpa_printf(MSG_INFO, "WPS: Do not accept incorrect "
				   "MAC Address in AP Settings");
			return -1;
		}
#endif /* CONFIG_WPS_STRICT */
	}

	if (!(wps->cred.encr_type &
	      (WPS_ENCR_NONE | WPS_ENCR_TKIP | WPS_ENCR_AES))) {
		if (wps->cred.encr_type & WPS_ENCR_WEP) {
			wpa_printf(MSG_INFO, "WPS: Reject Credential "
				   "due to WEP configuration");
			wps->error_indication = WPS_EI_SECURITY_WEP_PROHIBITED;
			return -2;
		}

		wpa_printf(MSG_INFO, "WPS: Reject Credential due to "
			   "invalid encr_type 0x%x", wps->cred.encr_type);
		return -1;
	}

	if (wps->wps->cred_cb) {
		wps->cred.cred_attr = cred - 4;
		wps->cred.cred_attr_len = cred_len + 4;
		ret = wps->wps->cred_cb(wps->wps->cb_ctx, &wps->cred);
		wps->cred.cred_attr = NULL;
		wps->cred.cred_attr_len = 0;
	}

	return ret;
}


static int wps_process_creds(struct wps_data *wps, const u8 *cred[],
			     size_t cred_len[], size_t num_cred, int wps2)
{
	size_t i;
	int ok = 0;

	if (wps->wps->ap)
		return 0;

	if (num_cred == 0) {
		wpa_printf(MSG_DEBUG, "WPS: No Credential attributes "
			   "received");
		return -1;
	}

	for (i = 0; i < num_cred; i++) {
		int res;
		res = wps_process_cred_e(wps, cred[i], cred_len[i], wps2);
		if (res == 0)
			ok++;
		else if (res == -2)
			wpa_printf(MSG_DEBUG, "WPS: WEP credential skipped");
		else
			return -1;
	}

	if (ok == 0) {
		wpa_printf(MSG_DEBUG, "WPS: No valid Credential attribute "
			   "received");
		return -1;
	}

	return 0;
}


static int wps_process_ap_settings_e(struct wps_data *wps,
				     struct wps_parse_attr *attr,
				     struct wpabuf *attrs, int wps2)
{
	struct wps_credential cred;

	if (!wps->wps->ap)
		return 0;

	if (wps_process_ap_settings(attr, &cred) < 0)
		return -1;

	wpa_printf(MSG_INFO, "WPS: Received new AP configuration from "
		   "Registrar");

	if (os_memcmp(cred.mac_addr, wps->wps->dev.mac_addr, ETH_ALEN) !=
	    0) {
		wpa_printf(MSG_DEBUG, "WPS: MAC Address in the AP Settings ("
			   MACSTR ") does not match with own address (" MACSTR
			   ")", MAC2STR(cred.mac_addr),
			   MAC2STR(wps->wps->dev.mac_addr));
		/*
		 * In theory, this could be consider fatal error, but there are
		 * number of deployed implementations using other address here
		 * due to unclarity in the specification. For interoperability
		 * reasons, allow this to be processed since we do not really
		 * use the MAC Address information for anything.
		 */
#ifdef CONFIG_WPS_STRICT
		if (wps2) {
			wpa_printf(MSG_INFO, "WPS: Do not accept incorrect "
				   "MAC Address in AP Settings");
			return -1;
		}
#endif /* CONFIG_WPS_STRICT */
	}

	if (!(cred.encr_type & (WPS_ENCR_NONE | WPS_ENCR_TKIP | WPS_ENCR_AES)))
	{
		if (cred.encr_type & WPS_ENCR_WEP) {
			wpa_printf(MSG_INFO, "WPS: Reject new AP settings "
				   "due to WEP configuration");
			wps->error_indication = WPS_EI_SECURITY_WEP_PROHIBITED;
			return -1;
		}

		wpa_printf(MSG_INFO, "WPS: Reject new AP settings due to "
			   "invalid encr_type 0x%x", cred.encr_type);
		return -1;
	}

#ifdef CONFIG_WPS_STRICT
	if (wps2) {
		if ((cred.encr_type & (WPS_ENCR_TKIP | WPS_ENCR_AES)) ==
		    WPS_ENCR_TKIP ||
		    (cred.auth_type & (WPS_AUTH_WPAPSK | WPS_AUTH_WPA2PSK)) ==
		    WPS_AUTH_WPAPSK) {
			wpa_printf(MSG_INFO, "WPS-STRICT: Invalid WSC 2.0 "
				   "AP Settings: WPA-Personal/TKIP only");
			wps->error_indication =
				WPS_EI_SECURITY_TKIP_ONLY_PROHIBITED;
			return -1;
		}
	}
#endif /* CONFIG_WPS_STRICT */

	if ((cred.encr_type & (WPS_ENCR_TKIP | WPS_ENCR_AES)) == WPS_ENCR_TKIP)
	{
		wpa_printf(MSG_DEBUG, "WPS: Upgrade encr_type TKIP -> "
			   "TKIP+AES");
		cred.encr_type |= WPS_ENCR_AES;
	}

	if ((cred.auth_type & (WPS_AUTH_WPAPSK | WPS_AUTH_WPA2PSK)) ==
	    WPS_AUTH_WPAPSK) {
		wpa_printf(MSG_DEBUG, "WPS: Upgrade auth_type WPAPSK -> "
			   "WPAPSK+WPA2PSK");
		cred.auth_type |= WPS_AUTH_WPA2PSK;
	}

	if (wps->wps->cred_cb) {
		cred.cred_attr = wpabuf_head(attrs);
		cred.cred_attr_len = wpabuf_len(attrs);
		wps->wps->cred_cb(wps->wps->cb_ctx, &cred);
	}

	return 0;
}


static int wps_process_dev_pw_id(struct wps_data *wps, const u8 *dev_pw_id)
{
	u16 id;

	if (dev_pw_id == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: Device Password ID");
		return -1;
	}

	id = WPA_GET_BE16(dev_pw_id);
	if (wps->dev_pw_id == id) {
		wpa_printf(MSG_DEBUG, "WPS: Device Password ID %u", id);
		return 0;
	}

#ifdef CONFIG_P2P
	if ((id == DEV_PW_DEFAULT &&
	     wps->dev_pw_id == DEV_PW_REGISTRAR_SPECIFIED) ||
	    (id == DEV_PW_REGISTRAR_SPECIFIED &&
	     wps->dev_pw_id == DEV_PW_DEFAULT)) {
		/*
		 * Common P2P use cases indicate whether the PIN is from the
		 * client or GO using Device Password Id in M1/M2 in a way that
		 * does not look fully compliant with WSC specification. Anyway,
		 * this is deployed and needs to be allowed, so ignore changes
		 * between Registrar-Specified and Default PIN.
		 */
		wpa_printf(MSG_DEBUG, "WPS: Allow PIN Device Password ID "
			   "change");
		return 0;
	}
#endif /* CONFIG_P2P */

	wpa_printf(MSG_DEBUG, "WPS: Registrar trying to change Device Password "
		   "ID from %u to %u", wps->dev_pw_id, id);

	if (wps->dev_pw_id == DEV_PW_PUSHBUTTON && id == DEV_PW_DEFAULT) {
		wpa_printf(MSG_DEBUG,
			   "WPS: Workaround - ignore PBC-to-PIN change");
		return 0;
	}

	if (wps->alt_dev_password && wps->alt_dev_pw_id == id) {
		wpa_printf(MSG_DEBUG, "WPS: Found a matching Device Password");
		bin_clear_free(wps->dev_password, wps->dev_password_len);
		wps->dev_pw_id = wps->alt_dev_pw_id;
		wps->dev_password = wps->alt_dev_password;
		wps->dev_password_len = wps->alt_dev_password_len;
		wps->alt_dev_password = NULL;
		wps->alt_dev_password_len = 0;
		return 0;
	}

	return -1;
}


static enum wps_process_res wps_process_m2(struct wps_data *wps,
					   const struct wpabuf *msg,
					   struct wps_parse_attr *attr)
{
	wpa_printf(MSG_DEBUG, "WPS: Received M2");

	if (wps->state != RECV_M2) {
		wpa_printf(MSG_DEBUG, "WPS: Unexpected state (%d) for "
			   "receiving M2", wps->state);
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	if (wps_process_registrar_nonce(wps, attr->registrar_nonce) ||
	    wps_process_enrollee_nonce(wps, attr->enrollee_nonce) ||
	    wps_process_uuid_r(wps, attr->uuid_r) ||
	    wps_process_dev_pw_id(wps, attr->dev_password_id)) {
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	/*
	 * Stop here on an AP as an Enrollee if AP Setup is locked unless the
	 * special locked mode is used to allow protocol run up to M7 in order
	 * to support external Registrars that only learn the current AP
	 * configuration without changing it.
	 */
	if (wps->wps->ap &&
	    ((wps->wps->ap_setup_locked && wps->wps->ap_setup_locked != 2) ||
	     wps->dev_password == NULL)) {
		wpa_printf(MSG_DEBUG, "WPS: AP Setup is locked - refuse "
			   "registration of a new Registrar");
		wps->config_error = WPS_CFG_SETUP_LOCKED;
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	if (wps_process_pubkey(wps, attr->public_key, attr->public_key_len) ||
	    wps_process_authenticator(wps, attr->authenticator, msg) ||
	    wps_process_device_attrs(&wps->peer_dev, attr)) {
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

#ifdef CONFIG_WPS_NFC
	if (wps->peer_pubkey_hash_set) {
		struct wpabuf *decrypted;
		struct wps_parse_attr eattr;

		decrypted = wps_decrypt_encr_settings(wps, attr->encr_settings,
						      attr->encr_settings_len);
		if (decrypted == NULL) {
			wpa_printf(MSG_DEBUG, "WPS: Failed to decrypt "
				   "Encrypted Settings attribute");
			wps->state = SEND_WSC_NACK;
			return WPS_CONTINUE;
		}

		wpa_printf(MSG_DEBUG, "WPS: Processing decrypted Encrypted "
			   "Settings attribute");
		if (wps_parse_msg(decrypted, &eattr) < 0 ||
		    wps_process_key_wrap_auth(wps, decrypted,
					      eattr.key_wrap_auth) ||
		    wps_process_creds(wps, eattr.cred, eattr.cred_len,
				      eattr.num_cred, attr->version2 != NULL)) {
			wpabuf_free(decrypted);
			wps->state = SEND_WSC_NACK;
			return WPS_CONTINUE;
		}
		wpabuf_free(decrypted);

		wps->state = WPS_MSG_DONE;
		return WPS_CONTINUE;
	}
#endif /* CONFIG_WPS_NFC */

	wps->state = SEND_M3;
	return WPS_CONTINUE;
}


static enum wps_process_res wps_process_m2d(struct wps_data *wps,
					    struct wps_parse_attr *attr)
{
	wpa_printf(MSG_DEBUG, "WPS: Received M2D");

	if (wps->state != RECV_M2) {
		wpa_printf(MSG_DEBUG, "WPS: Unexpected state (%d) for "
			   "receiving M2D", wps->state);
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	wpa_hexdump_ascii(MSG_DEBUG, "WPS: Manufacturer",
			  attr->manufacturer, attr->manufacturer_len);
	wpa_hexdump_ascii(MSG_DEBUG, "WPS: Model Name",
			  attr->model_name, attr->model_name_len);
	wpa_hexdump_ascii(MSG_DEBUG, "WPS: Model Number",
			  attr->model_number, attr->model_number_len);
	wpa_hexdump_ascii(MSG_DEBUG, "WPS: Serial Number",
			  attr->serial_number, attr->serial_number_len);
	wpa_hexdump_ascii(MSG_DEBUG, "WPS: Device Name",
			  attr->dev_name, attr->dev_name_len);

	if (wps->wps->event_cb) {
		union wps_event_data data;
		struct wps_event_m2d *m2d = &data.m2d;
		os_memset(&data, 0, sizeof(data));
		if (attr->config_methods)
			m2d->config_methods =
				WPA_GET_BE16(attr->config_methods);
		m2d->manufacturer = attr->manufacturer;
		m2d->manufacturer_len = attr->manufacturer_len;
		m2d->model_name = attr->model_name;
		m2d->model_name_len = attr->model_name_len;
		m2d->model_number = attr->model_number;
		m2d->model_number_len = attr->model_number_len;
		m2d->serial_number = attr->serial_number;
		m2d->serial_number_len = attr->serial_number_len;
		m2d->dev_name = attr->dev_name;
		m2d->dev_name_len = attr->dev_name_len;
		m2d->primary_dev_type = attr->primary_dev_type;
		if (attr->config_error)
			m2d->config_error =
				WPA_GET_BE16(attr->config_error);
		if (attr->dev_password_id)
			m2d->dev_password_id =
				WPA_GET_BE16(attr->dev_password_id);
		wps->wps->event_cb(wps->wps->cb_ctx, WPS_EV_M2D, &data);
	}

	wps->state = RECEIVED_M2D;
	return WPS_CONTINUE;
}


static enum wps_process_res wps_process_m4(struct wps_data *wps,
					   const struct wpabuf *msg,
					   struct wps_parse_attr *attr)
{
	struct wpabuf *decrypted;
	struct wps_parse_attr eattr;

	wpa_printf(MSG_DEBUG, "WPS: Received M4");

	if (wps->state != RECV_M4) {
		wpa_printf(MSG_DEBUG, "WPS: Unexpected state (%d) for "
			   "receiving M4", wps->state);
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	if (wps_process_enrollee_nonce(wps, attr->enrollee_nonce) ||
	    wps_process_authenticator(wps, attr->authenticator, msg) ||
	    wps_process_r_hash1(wps, attr->r_hash1) ||
	    wps_process_r_hash2(wps, attr->r_hash2)) {
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	decrypted = wps_decrypt_encr_settings(wps, attr->encr_settings,
					      attr->encr_settings_len);
	if (decrypted == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: Failed to decrypted Encrypted "
			   "Settings attribute");
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	if (wps_validate_m4_encr(decrypted, attr->version2 != NULL) < 0) {
		wpabuf_free(decrypted);
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	wpa_printf(MSG_DEBUG, "WPS: Processing decrypted Encrypted Settings "
		   "attribute");
	if (wps_parse_msg(decrypted, &eattr) < 0 ||
	    wps_process_key_wrap_auth(wps, decrypted, eattr.key_wrap_auth) ||
	    wps_process_r_snonce1(wps, eattr.r_snonce1)) {
		wpabuf_free(decrypted);
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}
	wpabuf_free(decrypted);

	wps->state = SEND_M5;
	return WPS_CONTINUE;
}


static enum wps_process_res wps_process_m6(struct wps_data *wps,
					   const struct wpabuf *msg,
					   struct wps_parse_attr *attr)
{
	struct wpabuf *decrypted;
	struct wps_parse_attr eattr;

	wpa_printf(MSG_DEBUG, "WPS: Received M6");

	if (wps->state != RECV_M6) {
		wpa_printf(MSG_DEBUG, "WPS: Unexpected state (%d) for "
			   "receiving M6", wps->state);
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	if (wps_process_enrollee_nonce(wps, attr->enrollee_nonce) ||
	    wps_process_authenticator(wps, attr->authenticator, msg)) {
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	decrypted = wps_decrypt_encr_settings(wps, attr->encr_settings,
					      attr->encr_settings_len);
	if (decrypted == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: Failed to decrypted Encrypted "
			   "Settings attribute");
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	if (wps_validate_m6_encr(decrypted, attr->version2 != NULL) < 0) {
		wpabuf_free(decrypted);
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	wpa_printf(MSG_DEBUG, "WPS: Processing decrypted Encrypted Settings "
		   "attribute");
	if (wps_parse_msg(decrypted, &eattr) < 0 ||
	    wps_process_key_wrap_auth(wps, decrypted, eattr.key_wrap_auth) ||
	    wps_process_r_snonce2(wps, eattr.r_snonce2)) {
		wpabuf_free(decrypted);
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}
	wpabuf_free(decrypted);

	if (wps->wps->ap)
		wps->wps->event_cb(wps->wps->cb_ctx, WPS_EV_AP_PIN_SUCCESS,
				   NULL);

	wps->state = SEND_M7;
	return WPS_CONTINUE;
}


static enum wps_process_res wps_process_m8(struct wps_data *wps,
					   const struct wpabuf *msg,
					   struct wps_parse_attr *attr)
{
	struct wpabuf *decrypted;
	struct wps_parse_attr eattr;

	wpa_printf(MSG_DEBUG, "WPS: Received M8");

	if (wps->state != RECV_M8) {
		wpa_printf(MSG_DEBUG, "WPS: Unexpected state (%d) for "
			   "receiving M8", wps->state);
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	if (wps_process_enrollee_nonce(wps, attr->enrollee_nonce) ||
	    wps_process_authenticator(wps, attr->authenticator, msg)) {
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	if (wps->wps->ap && wps->wps->ap_setup_locked) {
		/*
		 * Stop here if special ap_setup_locked == 2 mode allowed the
		 * protocol to continue beyond M2. This allows ER to learn the
		 * current AP settings without changing them.
		 */
		wpa_printf(MSG_DEBUG, "WPS: AP Setup is locked - refuse "
			   "registration of a new Registrar");
		wps->config_error = WPS_CFG_SETUP_LOCKED;
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	decrypted = wps_decrypt_encr_settings(wps, attr->encr_settings,
					      attr->encr_settings_len);
	if (decrypted == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: Failed to decrypted Encrypted "
			   "Settings attribute");
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	if (wps_validate_m8_encr(decrypted, wps->wps->ap,
				 attr->version2 != NULL) < 0) {
		wpabuf_free(decrypted);
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	wpa_printf(MSG_DEBUG, "WPS: Processing decrypted Encrypted Settings "
		   "attribute");
	if (wps_parse_msg(decrypted, &eattr) < 0 ||
	    wps_process_key_wrap_auth(wps, decrypted, eattr.key_wrap_auth) ||
	    wps_process_creds(wps, eattr.cred, eattr.cred_len,
			      eattr.num_cred, attr->version2 != NULL) ||
	    wps_process_ap_settings_e(wps, &eattr, decrypted,
				      attr->version2 != NULL)) {
		wpabuf_free(decrypted);
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}
	wpabuf_free(decrypted);

	wps->state = WPS_MSG_DONE;
	return WPS_CONTINUE;
}


static enum wps_process_res wps_process_wsc_msg(struct wps_data *wps,
						const struct wpabuf *msg)
{
	struct wps_parse_attr attr;
	enum wps_process_res ret = WPS_CONTINUE;

	wpa_printf(MSG_DEBUG, "WPS: Received WSC_MSG");

	if (wps_parse_msg(msg, &attr) < 0)
		return WPS_FAILURE;

	if (attr.enrollee_nonce == NULL ||
	    os_memcmp(wps->nonce_e, attr.enrollee_nonce, WPS_NONCE_LEN) != 0) {
		wpa_printf(MSG_DEBUG, "WPS: Mismatch in enrollee nonce");
		return WPS_FAILURE;
	}

	if (attr.msg_type == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: No Message Type attribute");
		wps->state = SEND_WSC_NACK;
		return WPS_CONTINUE;
	}

	switch (*attr.msg_type) {
	case WPS_M2:
		if (wps_validate_m2(msg) < 0)
			return WPS_FAILURE;
		ret = wps_process_m2(wps, msg, &attr);
		break;
	case WPS_M2D:
		if (wps_validate_m2d(msg) < 0)
			return WPS_FAILURE;
		ret = wps_process_m2d(wps, &attr);
		break;
	case WPS_M4:
		if (wps_validate_m4(msg) < 0)
			return WPS_FAILURE;
		ret = wps_process_m4(wps, msg, &attr);
		if (ret == WPS_FAILURE || wps->state == SEND_WSC_NACK)
			wps_fail_event(wps->wps, WPS_M4, wps->config_error,
				       wps->error_indication,
				       wps->peer_dev.mac_addr);
		break;
	case WPS_M6:
		if (wps_validate_m6(msg) < 0)
			return WPS_FAILURE;
		ret = wps_process_m6(wps, msg, &attr);
		if (ret == WPS_FAILURE || wps->state == SEND_WSC_NACK)
			wps_fail_event(wps->wps, WPS_M6, wps->config_error,
				       wps->error_indication,
				       wps->peer_dev.mac_addr);
		break;
	case WPS_M8:
		if (wps_validate_m8(msg) < 0)
			return WPS_FAILURE;
		ret = wps_process_m8(wps, msg, &attr);
		if (ret == WPS_FAILURE || wps->state == SEND_WSC_NACK)
			wps_fail_event(wps->wps, WPS_M8, wps->config_error,
				       wps->error_indication,
				       wps->peer_dev.mac_addr);
		break;
	default:
		wpa_printf(MSG_DEBUG, "WPS: Unsupported Message Type %d",
			   *attr.msg_type);
		return WPS_FAILURE;
	}

	/*
	 * Save a copy of the last message for Authenticator derivation if we
	 * are continuing. However, skip M2D since it is not authenticated and
	 * neither is the ACK/NACK response frame. This allows the possibly
	 * following M2 to be processed correctly by using the previously sent
	 * M1 in Authenticator derivation.
	 */
	if (ret == WPS_CONTINUE && *attr.msg_type != WPS_M2D) {
		/* Save a copy of the last message for Authenticator derivation
		 */
		wpabuf_free(wps->last_msg);
		wps->last_msg = wpabuf_dup(msg);
	}

	return ret;
}


static enum wps_process_res wps_process_wsc_ack(struct wps_data *wps,
						const struct wpabuf *msg)
{
	struct wps_parse_attr attr;

	wpa_printf(MSG_DEBUG, "WPS: Received WSC_ACK");

	if (wps_parse_msg(msg, &attr) < 0)
		return WPS_FAILURE;

	if (attr.msg_type == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: No Message Type attribute");
		return WPS_FAILURE;
	}

	if (*attr.msg_type != WPS_WSC_ACK) {
		wpa_printf(MSG_DEBUG, "WPS: Invalid Message Type %d",
			   *attr.msg_type);
		return WPS_FAILURE;
	}

	if (attr.registrar_nonce == NULL ||
	    os_memcmp(wps->nonce_r, attr.registrar_nonce, WPS_NONCE_LEN) != 0)
	{
		wpa_printf(MSG_DEBUG, "WPS: Mismatch in registrar nonce");
		return WPS_FAILURE;
	}

	if (attr.enrollee_nonce == NULL ||
	    os_memcmp(wps->nonce_e, attr.enrollee_nonce, WPS_NONCE_LEN) != 0) {
		wpa_printf(MSG_DEBUG, "WPS: Mismatch in enrollee nonce");
		return WPS_FAILURE;
	}

	if (wps->state == RECV_ACK && wps->wps->ap) {
		wpa_printf(MSG_DEBUG, "WPS: External Registrar registration "
			   "completed successfully");
		wps_success_event(wps->wps, wps->peer_dev.mac_addr);
		wps->state = WPS_FINISHED;
		return WPS_DONE;
	}

	return WPS_FAILURE;
}


static enum wps_process_res wps_process_wsc_nack(struct wps_data *wps,
						 const struct wpabuf *msg)
{
	struct wps_parse_attr attr;
	u16 config_error;

	wpa_printf(MSG_DEBUG, "WPS: Received WSC_NACK");

	if (wps_parse_msg(msg, &attr) < 0)
		return WPS_FAILURE;

	if (attr.msg_type == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: No Message Type attribute");
		return WPS_FAILURE;
	}

	if (*attr.msg_type != WPS_WSC_NACK) {
		wpa_printf(MSG_DEBUG, "WPS: Invalid Message Type %d",
			   *attr.msg_type);
		return WPS_FAILURE;
	}

	if (attr.registrar_nonce == NULL ||
	    os_memcmp(wps->nonce_r, attr.registrar_nonce, WPS_NONCE_LEN) != 0)
	{
		wpa_printf(MSG_DEBUG, "WPS: Mismatch in registrar nonce");
		wpa_hexdump(MSG_DEBUG, "WPS: Received Registrar Nonce",
			    attr.registrar_nonce, WPS_NONCE_LEN);
		wpa_hexdump(MSG_DEBUG, "WPS: Expected Registrar Nonce",
			    wps->nonce_r, WPS_NONCE_LEN);
		return WPS_FAILURE;
	}

	if (attr.enrollee_nonce == NULL ||
	    os_memcmp(wps->nonce_e, attr.enrollee_nonce, WPS_NONCE_LEN) != 0) {
		wpa_printf(MSG_DEBUG, "WPS: Mismatch in enrollee nonce");
		wpa_hexdump(MSG_DEBUG, "WPS: Received Enrollee Nonce",
			    attr.enrollee_nonce, WPS_NONCE_LEN);
		wpa_hexdump(MSG_DEBUG, "WPS: Expected Enrollee Nonce",
			    wps->nonce_e, WPS_NONCE_LEN);
		return WPS_FAILURE;
	}

	if (attr.config_error == NULL) {
		wpa_printf(MSG_DEBUG, "WPS: No Configuration Error attribute "
			   "in WSC_NACK");
		return WPS_FAILURE;
	}

	config_error = WPA_GET_BE16(attr.config_error);
	wpa_printf(MSG_DEBUG, "WPS: Registrar terminated negotiation with "
		   "Configuration Error %d", config_error);

	switch (wps->state) {
	case RECV_M4:
		wps_fail_event(wps->wps, WPS_M3, config_error,
			       wps->error_indication, wps->peer_dev.mac_addr);
		break;
	case RECV_M6:
		wps_fail_event(wps->wps, WPS_M5, config_error,
			       wps->error_indication, wps->peer_dev.mac_addr);
		break;
	case RECV_M8:
		wps_fail_event(wps->wps, WPS_M7, config_error,
			       wps->error_indication, wps->peer_dev.mac_addr);
		break;
	default:
		break;
	}

	/* Followed by NACK if Enrollee is Supplicant or EAP-Failure if
	 * Enrollee is Authenticator */
	wps->state = SEND_WSC_NACK;

	return WPS_FAILURE;
}


enum wps_process_res wps_enrollee_process_msg(struct wps_data *wps,
					      enum wsc_op_code op_code,
					      const struct wpabuf *msg)
{

	wpa_printf(MSG_DEBUG, "WPS: Processing received message (len=%lu "
		   "op_code=%d)",
		   (unsigned long) wpabuf_len(msg), op_code);

	if (op_code == WSC_UPnP) {
		/* Determine the OpCode based on message type attribute */
		struct wps_parse_attr attr;
		if (wps_parse_msg(msg, &attr) == 0 && attr.msg_type) {
			if (*attr.msg_type == WPS_WSC_ACK)
				op_code = WSC_ACK;
			else if (*attr.msg_type == WPS_WSC_NACK)
				op_code = WSC_NACK;
		}
	}

	switch (op_code) {
	case WSC_MSG:
	case WSC_UPnP:
		return wps_process_wsc_msg(wps, msg);
	case WSC_ACK:
		if (wps_validate_wsc_ack(msg) < 0)
			return WPS_FAILURE;
		return wps_process_wsc_ack(wps, msg);
	case WSC_NACK:
		if (wps_validate_wsc_nack(msg) < 0)
			return WPS_FAILURE;
		return wps_process_wsc_nack(wps, msg);
	default:
		wpa_printf(MSG_DEBUG, "WPS: Unsupported op_code %d", op_code);
		return WPS_FAILURE;
	}
}