DPP: Move PKEX Commit-Reveal Request building to a helper function

This cleans up dpp_pkex_rx_exchange_resp() a bit and makes it easier to
add protocol testing functionality to PKEX exchange similarly to the
previously added DPP Authentication case.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

src/common/dpp.c

@@ -5905,6 +5905,80 @@ static int dpp_pkex_derive_z(const u8 *mac_init, const u8 *mac_resp,
 }
 
 
+static struct wpabuf *
+dpp_pkex_build_commit_reveal_req(struct dpp_pkex *pkex,
+				 const struct wpabuf *A_pub, const u8 *u)
+{
+	const struct dpp_curve_params *curve = pkex->own_bi->curve;
+	struct wpabuf *msg = NULL;
+	size_t clear_len, attr_len;
+	struct wpabuf *clear = NULL;
+	u8 *wrapped;
+	u8 octet;
+	const u8 *addr[2];
+	size_t len[2];
+
+	/* {A, u, [bootstrapping info]}z */
+	clear_len = 4 + 2 * curve->prime_len + 4 + curve->hash_len;
+	clear = wpabuf_alloc(clear_len);
+	attr_len = 4 + clear_len + AES_BLOCK_SIZE;
+#ifdef CONFIG_TESTING_OPTIONS
+	if (dpp_test == DPP_TEST_AFTER_WRAPPED_DATA_PKEX_CR_REQ)
+		attr_len += 4;
+#endif /* CONFIG_TESTING_OPTIONS */
+	msg = dpp_alloc_msg(DPP_PA_PKEX_COMMIT_REVEAL_REQ, attr_len);
+	if (!clear || !msg)
+		goto fail;
+
+	/* A in Bootstrap Key attribute */
+	wpabuf_put_le16(clear, DPP_ATTR_BOOTSTRAP_KEY);
+	wpabuf_put_le16(clear, wpabuf_len(A_pub));
+	wpabuf_put_buf(clear, A_pub);
+
+	/* u in I-Auth tag attribute */
+	wpabuf_put_le16(clear, DPP_ATTR_I_AUTH_TAG);
+	wpabuf_put_le16(clear, curve->hash_len);
+	wpabuf_put_data(clear, u, curve->hash_len);
+
+	addr[0] = wpabuf_head_u8(msg) + 2;
+	len[0] = DPP_HDR_LEN;
+	octet = 0;
+	addr[1] = &octet;
+	len[1] = sizeof(octet);
+	wpa_hexdump(MSG_DEBUG, "DDP: AES-SIV AD[0]", addr[0], len[0]);
+	wpa_hexdump(MSG_DEBUG, "DDP: AES-SIV AD[1]", addr[1], len[1]);
+
+	wpabuf_put_le16(msg, DPP_ATTR_WRAPPED_DATA);
+	wpabuf_put_le16(msg, wpabuf_len(clear) + AES_BLOCK_SIZE);
+	wrapped = wpabuf_put(msg, wpabuf_len(clear) + AES_BLOCK_SIZE);
+
+	wpa_hexdump_buf(MSG_DEBUG, "DPP: AES-SIV cleartext", clear);
+	if (aes_siv_encrypt(pkex->z, curve->hash_len,
+			    wpabuf_head(clear), wpabuf_len(clear),
+			    2, addr, len, wrapped) < 0)
+		goto fail;
+	wpa_hexdump(MSG_DEBUG, "DPP: AES-SIV ciphertext",
+		    wrapped, wpabuf_len(clear) + AES_BLOCK_SIZE);
+
+#ifdef CONFIG_TESTING_OPTIONS
+	if (dpp_test == DPP_TEST_AFTER_WRAPPED_DATA_PKEX_CR_REQ) {
+		wpa_printf(MSG_INFO, "DPP: TESTING - attr after Wrapped Data");
+		wpabuf_put_le16(msg, DPP_ATTR_TESTING);
+		wpabuf_put_le16(msg, 0);
+	}
+#endif /* CONFIG_TESTING_OPTIONS */
+
+out:
+	wpabuf_free(clear);
+	return msg;
+
+fail:
+	wpabuf_free(msg);
+	msg = NULL;
+	goto out;
+}
+
+
 struct wpabuf * dpp_pkex_rx_exchange_resp(struct dpp_pkex *pkex,
 					  const u8 *buf, size_t buflen)
 {
@@ -5912,9 +5986,6 @@ struct wpabuf * dpp_pkex_rx_exchange_resp(struct dpp_pkex *pkex,
 	u16 attr_status_len, attr_id_len, attr_key_len;
 	const EC_GROUP *group;
 	BN_CTX *bnctx = NULL;
-	size_t clear_len, attr_len;
-	struct wpabuf *clear = NULL;
-	u8 *wrapped;
 	struct wpabuf *msg = NULL, *A_pub = NULL, *X_pub = NULL, *Y_pub = NULL;
 	const struct dpp_curve_params *curve = pkex->own_bi->curve;
 	EC_POINT *Qr = NULL, *Y = NULL, *N = NULL;
@@ -5926,7 +5997,6 @@ struct wpabuf * dpp_pkex_rx_exchange_resp(struct dpp_pkex *pkex,
 	const u8 *addr[4];
 	size_t len[4];
 	u8 u[DPP_MAX_HASH_LEN];
-	u8 octet;
 	int res;
 
 	attr_status = dpp_get_attr(buf, buflen, DPP_ATTR_STATUS,
@@ -6062,58 +6132,11 @@ struct wpabuf * dpp_pkex_rx_exchange_resp(struct dpp_pkex *pkex,
 	if (res < 0)
 		goto fail;
 
-	/* {A, u, [bootstrapping info]}z */
-	clear_len = 4 + 2 * curve->prime_len + 4 + curve->hash_len;
-	clear = wpabuf_alloc(clear_len);
-	attr_len = 4 + clear_len + AES_BLOCK_SIZE;
-#ifdef CONFIG_TESTING_OPTIONS
-	if (dpp_test == DPP_TEST_AFTER_WRAPPED_DATA_PKEX_CR_REQ)
-		attr_len += 4;
-#endif /* CONFIG_TESTING_OPTIONS */
-	msg = dpp_alloc_msg(DPP_PA_PKEX_COMMIT_REVEAL_REQ, attr_len);
-	if (!clear || !msg)
-		goto fail;
-
-	/* A in Bootstrap Key attribute */
-	wpabuf_put_le16(clear, DPP_ATTR_BOOTSTRAP_KEY);
-	wpabuf_put_le16(clear, wpabuf_len(A_pub));
-	wpabuf_put_buf(clear, A_pub);
-
-	/* u in I-Auth tag attribute */
-	wpabuf_put_le16(clear, DPP_ATTR_I_AUTH_TAG);
-	wpabuf_put_le16(clear, curve->hash_len);
-	wpabuf_put_data(clear, u, curve->hash_len);
-
-	addr[0] = wpabuf_head_u8(msg) + 2;
-	len[0] = DPP_HDR_LEN;
-	octet = 0;
-	addr[1] = &octet;
-	len[1] = sizeof(octet);
-	wpa_hexdump(MSG_DEBUG, "DDP: AES-SIV AD[0]", addr[0], len[0]);
-	wpa_hexdump(MSG_DEBUG, "DDP: AES-SIV AD[1]", addr[1], len[1]);
-
-	wpabuf_put_le16(msg, DPP_ATTR_WRAPPED_DATA);
-	wpabuf_put_le16(msg, wpabuf_len(clear) + AES_BLOCK_SIZE);
-	wrapped = wpabuf_put(msg, wpabuf_len(clear) + AES_BLOCK_SIZE);
-
-	wpa_hexdump_buf(MSG_DEBUG, "DPP: AES-SIV cleartext", clear);
-	if (aes_siv_encrypt(pkex->z, curve->hash_len,
-			    wpabuf_head(clear), wpabuf_len(clear),
-			    2, addr, len, wrapped) < 0)
+	msg = dpp_pkex_build_commit_reveal_req(pkex, A_pub, u);
+	if (!msg)
 		goto fail;
-	wpa_hexdump(MSG_DEBUG, "DPP: AES-SIV ciphertext",
-		    wrapped, wpabuf_len(clear) + AES_BLOCK_SIZE);
-
-#ifdef CONFIG_TESTING_OPTIONS
-	if (dpp_test == DPP_TEST_AFTER_WRAPPED_DATA_PKEX_CR_REQ) {
-		wpa_printf(MSG_INFO, "DPP: TESTING - attr after Wrapped Data");
-		wpabuf_put_le16(msg, DPP_ATTR_TESTING);
-		wpabuf_put_le16(msg, 0);
-	}
-#endif /* CONFIG_TESTING_OPTIONS */
 
 out:
-	wpabuf_free(clear);
 	wpabuf_free(A_pub);
 	wpabuf_free(X_pub);
 	wpabuf_free(Y_pub);
@@ -6128,8 +6151,6 @@ out:
 	return msg;
 fail:
 	wpa_printf(MSG_DEBUG, "DPP: PKEX Exchange Response processing failed");
-	wpabuf_free(msg);
-	msg = NULL;
 	goto out;
 }