TT#81850 fix SRTP re-offer and RTP to SRTP switch

1) In an SRTP re-invite offer, fixes not a full set of crypto suites
   being present
2) In a re-invite offer that switches from RTP to SRTP, fixes SRTP not
   being initialised at all

Change-Id: I911442d2cba17ecf6af482cfe922d4e9db2eda8d
(cherry picked from commit 66642f4a6c)
(cherry picked from commit bc1cec26ee)

daemon/call.c

@@ -1288,7 +1288,7 @@ static void __generate_crypto(const struct sdp_ng_flags *flags, struct call_medi
 			MEDIA_CLEAR(this, SETUP_PASSIVE);
 	}
 
-	if (!MEDIA_ISSET(this, INITIALIZED)) {
+	if (!MEDIA_ARESET2(this, DTLS, SDES) && flags->opmode == OP_OFFER) {
 		/* we offer both DTLS and SDES by default */
 		/* unless this is overridden by flags */
 		if (!flags->dtls_off)
@@ -1315,60 +1315,84 @@ static void __generate_crypto(const struct sdp_ng_flags *flags, struct call_medi
 	/* SDES parameters below */
 
 	if (flags->opmode == OP_OFFER) {
-		if (!cpq->head) {
-			// generate a new set of params
-			// if we were offered some crypto suites, copy those first into our offer
-			unsigned int c_tag = 1; // tag for next crypto suite generated by us
-			unsigned long types_offered = 0;
+		// generate full set of params
+		// re-create the entire list - steal for later flushing
+		GQueue cpq_orig = *cpq;
+		g_queue_init(cpq);
 
-			// make sure our bit field is large enough
-			assert(num_crypto_suites <= sizeof(types_offered) * 8);
+		// if we were offered some crypto suites, copy those first into our offer
+		unsigned int c_tag = 1; // tag for next crypto suite generated by us
+		unsigned long types_offered = 0;
 
-			for (GList *l = offered_cpq->head; l; l = l->next) {
-				struct crypto_params_sdes *offered_cps = l->data;
+		// make sure our bit field is large enough
+		assert(num_crypto_suites <= sizeof(types_offered) * 8);
 
-				struct crypto_params_sdes *cps = g_slice_alloc0(sizeof(*cps));
-				g_queue_push_tail(cpq, cps);
+		for (GList *l = offered_cpq->head; l; l = l->next) {
+			struct crypto_params_sdes *offered_cps = l->data;
 
-				cps->tag = offered_cps->tag;
-				// our own offered tags will be higher than the ones we received
-				if (cps->tag >= c_tag)
-					c_tag = cps->tag + 1;
-				crypto_params_copy(&cps->params, &offered_cps->params, 1);
+			struct crypto_params_sdes *cps = g_slice_alloc0(sizeof(*cps));
+			g_queue_push_tail(cpq, cps);
+
+			cps->tag = offered_cps->tag;
+			// our own offered tags will be higher than the ones we received
+			if (cps->tag >= c_tag)
+				c_tag = cps->tag + 1;
+			crypto_params_copy(&cps->params, &offered_cps->params, 1);
 
-				// we use a bit field to keep track of which types we've seen here
-				types_offered |= 1 << cps->params.crypto_suite->idx;
+			// we use a bit field to keep track of which types we've seen here
+			types_offered |= 1 << cps->params.crypto_suite->idx;
+
+			__sdes_flags(cps, flags);
+		}
 
-				__sdes_flags(cps, flags);
+		// if we had any suites added before, re-add those that aren't there yet
+		struct crypto_params_sdes *cps_orig;
+		while ((cps_orig = g_queue_pop_head(&cpq_orig))) {
+			if ((types_offered & (1 << cps_orig->params.crypto_suite->idx))) {
+				crypto_params_sdes_free(cps_orig);
+				continue;
 			}
 
-			// generate crypto suite offers for any types that we haven't seen above
-			for (unsigned int i = 0; i < num_crypto_suites; i++) {
-				if ((types_offered & (1 << i)))
-					continue;
+			// make sure our tag is higher than what we've seen
+			if (cps_orig->tag < c_tag)
+				cps_orig->tag = c_tag;
+			if (cps_orig->tag >= c_tag)
+				c_tag = cps_orig->tag + 1;
 
-				if (flags->sdes_no && g_hash_table_lookup(flags->sdes_no,
-							&crypto_suites[i].name_str))
-				{
-					ilog(LOG_DEBUG, "Not offering crypto suite '%s' "
-							"due to 'SDES-no' option",
-							crypto_suites[i].name);
-					continue;
-				}
+			g_queue_push_tail(cpq, cps_orig);
 
-				struct crypto_params_sdes *cps = g_slice_alloc0(sizeof(*cps));
-				g_queue_push_tail(cpq, cps);
+			types_offered |= 1 << cps_orig->params.crypto_suite->idx;
+		}
 
-				cps->tag = c_tag++;
-				cps->params.crypto_suite = &crypto_suites[i];
-				random_string((unsigned char *) cps->params.master_key,
-						cps->params.crypto_suite->master_key_len);
-				random_string((unsigned char *) cps->params.master_salt,
-						cps->params.crypto_suite->master_salt_len);
-				/* mki = mki_len = 0 */
+		// generate crypto suite offers for any types that we haven't seen above
+		// XXX for re-invites, this always creates new crypto keys for suites
+		// that weren't accepted before, instead of re-using the same keys (and
+		// suites) that were previously offered but not accepted
+		for (unsigned int i = 0; i < num_crypto_suites; i++) {
+			if ((types_offered & (1 << i)))
+				continue;
 
-				__sdes_flags(cps, flags);
+			if (flags->sdes_no && g_hash_table_lookup(flags->sdes_no,
+						&crypto_suites[i].name_str))
+			{
+				ilog(LOG_DEBUG, "Not offering crypto suite '%s' "
+						"due to 'SDES-no' option",
+						crypto_suites[i].name);
+				continue;
 			}
+
+			struct crypto_params_sdes *cps = g_slice_alloc0(sizeof(*cps));
+			g_queue_push_tail(cpq, cps);
+
+			cps->tag = c_tag++;
+			cps->params.crypto_suite = &crypto_suites[i];
+			random_string((unsigned char *) cps->params.master_key,
+					cps->params.crypto_suite->master_key_len);
+			random_string((unsigned char *) cps->params.master_salt,
+					cps->params.crypto_suite->master_salt_len);
+			/* mki = mki_len = 0 */
+
+			__sdes_flags(cps, flags);
 		}
 	}
 	else { // OP_ANSWER