MT#55283 refactor SDES reordering

Split the code that handles reordering offerer SDES suites based on the
respective option into its own function. Rework it slightly so that it
reorders the list in place for simplicity. Remove the part that honours
SDES-no and SDES-only as these should affect the opposite (outgoing)
direction. This requires changing one of the test cases, which seems
more correct now.

Change-Id: Ie284d052d72031fad64c94767fa95c74639ae331

daemon/call.c

@@ -1527,6 +1527,42 @@ static void __sdes_flags(struct crypto_params_sdes *cps, const sdp_ng_flags *fla
 		cps->params.session_params.unauthenticated_srtp = 0;
 }
 
+static bool reorder_sdes_preferences(sdes_q *sdes_in, const str_q *offered_order) {
+	if (!sdes_in || !sdes_in->length || !offered_order || !offered_order->length)
+		return false; // nothing to do
+
+	ilog(LOG_DEBUG, "The crypto suites for the offerer may be re-ordered");
+
+	bool ret = false;
+	sdes_list *insert_pos = sdes_in->head; // first preffered suite goes first in the list
+
+	for (str_list *l = offered_order->head; l; l = l->next) {
+		str * cs_name = l->data;
+
+		// find matching suites in `sdes_in` after the current insert position and
+		// move them up
+		__auto_type elem = t_list_find_custom(insert_pos->next, cs_name, crypto_params_sdes_cmp);
+
+		if (!elem)
+			continue;
+
+		// found a match: remove from list at current position and insert at
+		// the insert position, then advance insert position
+		__auto_type cps_found = elem->data;
+
+		ilog(LOG_DEBUG, "Reordering suites for offerer, prioritising: %s (cps tag: %d)",
+				cps_found->params.crypto_suite->name, cps_found->tag);
+
+		t_queue_delete_link(sdes_in, elem);
+		t_queue_insert_before(sdes_in, insert_pos, cps_found);
+		insert_pos = insert_pos->next;
+
+		ret = true;
+	}
+
+	return ret;
+}
+
 /**
  *  Only generates SDES parameters for outgoing SDP, which is our media "out" direction.
  * `this` is the receiver of the message.
@@ -1757,61 +1793,10 @@ static void __generate_crypto(const sdp_ng_flags *flags, struct call_media *this
 		}
 
 		/* set preferences list of crypto suites for the offerer, if given */
-		if ((offered_order && offered_order->head) && (offered_cpq && offered_cpq->head)) {
-			ilog(LOG_DEBUG, "The crypto suites for the offerer will be re-ordered.");
-
-			struct crypto_params_sdes * cps_found;
-			sdes_q offered_cpq_orig_list = *offered_cpq;
-
-			t_queue_init(offered_cpq); /* re-initialize offered crypto suites */
-
-			for (auto_iter(l, offered_order->head); l; l = l->next)
-			{
-				str * cs_name = l->data;
-				__auto_type elem = t_queue_find_custom(&offered_cpq_orig_list, cs_name, crypto_params_sdes_cmp);
-
-				if (!elem)
-					continue;
-
-				cps_found = elem->data;
-
-				/* check sdes_only limitations */
-				if (crypto_params_sdes_check_limitations(flags->sdes_only,
-						flags->sdes_no, cps_found->params.crypto_suite)) {
-					t_queue_delete_link(&offered_cpq_orig_list, elem);
-					crypto_params_sdes_free(cps_found);
-					continue;
-				}
-
-				ilog(LOG_DEBUG, "Reordering suites for offerer, adding: %s (cps tag: %d)",
-					cps_found->params.crypto_suite->name, cps_found->tag);
-
-				/* affects a proper handling of crypto suites ordering,
-				 * when sending processed answer to the media session originator */
-				MEDIA_SET(other, REORDER_FORCED);
-
-				t_queue_push_tail(offered_cpq, cps_found);
-				t_queue_delete_link(&offered_cpq_orig_list, elem);
-			}
-
-			/* now add the rest */
-			while ((cps_found = t_queue_pop_head(&offered_cpq_orig_list)))
-			{
-				ilog(LOG_DEBUG, "Reordering suites for offerer, adding: %s (cps tag: %d)",
-						cps_found->params.crypto_suite->name, cps_found->tag);
-
-				/* check sdes_only limitations */
-				if (crypto_params_sdes_check_limitations(flags->sdes_only,
-						flags->sdes_no, cps_found->params.crypto_suite)) {
-					crypto_params_sdes_free(cps_found);
-					continue;
-				}
-
-				t_queue_push_tail(offered_cpq, cps_found);
-			}
-
-			/* clear older data we are poiting using a copy now */
-			crypto_params_sdes_queue_clear(&offered_cpq_orig_list);
+		if (reorder_sdes_preferences(offered_cpq, offered_order)) {
+			/* affects a proper handling of crypto suites ordering,
+			 * when sending processed answer to the media session originator */
+			MEDIA_SET(other, REORDER_FORCED);
 		}
 	}
 

t/auto-daemon-tests.pl

@@ -17647,7 +17647,7 @@ sub stun_succ {
 a=rtpmap:0 PCMU/8000
 a=sendrecv
 a=rtcp:PORT
-a=crypto:3 AES_256_CM_HMAC_SHA1_80 inline:CRYPTO256
+a=crypto:4 AES_256_CM_HMAC_SHA1_32 inline:CRYPTO256
 SDP