EAP-IKEv2: Try to make transform parser simpler to understand

Use a local variable to try to make ikev2_parse_proposal() easier for
static analyzers to understand. Bounds checking in the loop is really
done by the ikev2_parse_transform() function, so the p->num_transforms
value itself is of no importance for that part and even that was already
implicitly limited in range.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>

src/eap_peer/ikev2.c

@@ -201,7 +201,8 @@ static int ikev2_parse_proposal(struct ikev2_proposal_data *prop,
 				const u8 *pos, const u8 *end)
 {
 	const u8 *pend, *ppos;
-	int proposal_len, i;
+	int proposal_len;
+	unsigned int i, num;
 	const struct ikev2_proposal *p;
 
 	if (end - pos < (int) sizeof(*p)) {
@@ -269,12 +270,13 @@ static int ikev2_parse_proposal(struct ikev2_proposal_data *prop,
 		return -1;
 	}
 
-	if (p->num_transforms == 0) {
+	num = p->num_transforms;
+	if (num == 0 || num > 255) {
 		wpa_printf(MSG_INFO, "IKEV2: At least one transform required");
 		return -1;
 	}
 
-	for (i = 0; i < (int) p->num_transforms; i++) {
+	for (i = 0; i < num; i++) {
 		int tlen = ikev2_parse_transform(prop, ppos, pend);
 		if (tlen < 0)
 			return -1;
@@ -411,7 +413,7 @@ static int ikev2_process_kei(struct ikev2_responder_data *data,
 
 	wpa_hexdump_buf(MSG_DEBUG, "IKEV2: KEi Diffie-Hellman Public Value",
 			data->i_dh_public);
-	
+
 	return 0;
 }