[Asterisk-code-review] res_pjsip_session: Always produce offer on re-INVITE without SDP. (asterisk[18])
Joshua Colp
asteriskteam at digium.com
Wed Feb 17 08:53:53 CST 2021
Joshua Colp has uploaded this change for review. ( https://gerrit.asterisk.org/c/asterisk/+/15432 )
Change subject: res_pjsip_session: Always produce offer on re-INVITE without SDP.
......................................................................
res_pjsip_session: Always produce offer on re-INVITE without SDP.
When PJSIP receives a re-INVITE without an SDP offer the INVITE
session library will first call the on_create_offer callback and
if unavailable then use the active negotiated SDP as the offer.
In some cases this would result in a different SDP then was
previously used without an incremented SDP version number. The two
known cases are:
1. Sending an initial INVITE with a set of codecs and having the
remote side answer with a subset. The active negotiated SDP would
have the pruned list but would not have an incremented SDP version
number.
2. Using re-INVITE for unhold. We would modify the active negotiated
SDP but would not increment the SDP version.
To solve these, and potential other unknown cases, the on_create_offer
callback has now been implemented which produces a fresh offer with
incremented SDP version number. This better fits within the model
provided by the INVITE session library.
ASTERISK-28452
Change-Id: I2d81048d54edcb80fe38fdbb954a86f0a58281a1
---
M res/res_pjsip_session.c
1 file changed, 62 insertions(+), 53 deletions(-)
git pull ssh://gerrit.asterisk.org:29418/asterisk refs/changes/32/15432/1
diff --git a/res/res_pjsip_session.c b/res/res_pjsip_session.c
index d841aca..d953dc0 100644
--- a/res/res_pjsip_session.c
+++ b/res/res_pjsip_session.c
@@ -2782,56 +2782,6 @@
}
if (!sdp_info->sdp) {
- const pjmedia_sdp_session *local;
- int i;
-
- ast_queue_unhold(session->channel);
-
- pjmedia_sdp_neg_get_active_local(session->inv_session->neg, &local);
- if (!local) {
- return PJ_FALSE;
- }
-
- /*
- * Some devices indicate hold with deferred SDP reinvites (i.e. no SDP in the reinvite).
- * When hold is initially indicated, we
- * - Receive an INVITE with no SDP
- * - Send a 200 OK with SDP, indicating sendrecv in the media streams
- * - Receive an ACK with SDP, indicating sendonly in the media streams
- *
- * At this point, the pjmedia negotiator saves the state of the media direction so that
- * if we are to send any offers, we'll offer recvonly in the media streams. This is
- * problematic if the device is attempting to unhold, though. If the device unholds
- * by sending a reinvite with no SDP, then we will respond with a 200 OK with recvonly.
- * According to RFC 3264, if an offerer offers recvonly, then the answerer MUST respond
- * with sendonly or inactive. The result of this is that the stream is not off hold.
- *
- * Therefore, in this case, when we receive a reinvite while the stream is on hold, we
- * need to be sure to offer sendrecv. This way, the answerer can respond with sendrecv
- * in order to get the stream off hold. If this is actually a different purpose reinvite
- * (like a session timer refresh), then the answerer can respond to our sendrecv with
- * sendonly, keeping the stream on hold.
- */
- for (i = 0; i < local->media_count; ++i) {
- pjmedia_sdp_media *m = local->media[i];
- pjmedia_sdp_attr *recvonly;
- pjmedia_sdp_attr *inactive;
- pjmedia_sdp_attr *sendonly;
-
- recvonly = pjmedia_sdp_attr_find2(m->attr_count, m->attr, "recvonly", NULL);
- inactive = pjmedia_sdp_attr_find2(m->attr_count, m->attr, "inactive", NULL);
- sendonly = pjmedia_sdp_attr_find2(m->attr_count, m->attr, "sendonly", NULL);
- if (recvonly || inactive || sendonly) {
- pjmedia_sdp_attr *to_remove = recvonly ?: inactive ?: sendonly;
- pjmedia_sdp_attr *sendrecv;
-
- pjmedia_sdp_attr_remove(&m->attr_count, m->attr, to_remove);
-
- sendrecv = pjmedia_sdp_attr_create(session->inv_session->pool, "sendrecv", NULL);
- pjmedia_sdp_media_add_attr(m, sendrecv);
- }
- }
-
return PJ_FALSE;
}
@@ -5281,12 +5231,70 @@
SCOPE_EXIT_RTN("%s: create_local_sdp failed\n", ast_sip_session_get_name(session));
}
-#if 0
static void session_inv_on_create_offer(pjsip_inv_session *inv, pjmedia_sdp_session **p_offer)
{
- /* XXX STUB */
+ struct ast_sip_session *session = inv->mod_data[session_module.id];
+ const pjmedia_sdp_session *previous_sdp = NULL;
+ pjmedia_sdp_session *offer;
+ int i;
+
+ if (inv->neg) {
+ if (pjmedia_sdp_neg_was_answer_remote(inv->neg)) {
+ pjmedia_sdp_neg_get_active_remote(inv->neg, &previous_sdp);
+ } else {
+ pjmedia_sdp_neg_get_active_local(inv->neg, &previous_sdp);
+ }
+ }
+
+ offer = create_local_sdp(inv, session, previous_sdp);
+ if (!offer) {
+ return;
+ }
+
+ ast_queue_unhold(session->channel);
+
+ /*
+ * Some devices indicate hold with deferred SDP reinvites (i.e. no SDP in the reinvite).
+ * When hold is initially indicated, we
+ * - Receive an INVITE with no SDP
+ * - Send a 200 OK with SDP, indicating sendrecv in the media streams
+ * - Receive an ACK with SDP, indicating sendonly in the media streams
+ *
+ * At this point, the pjmedia negotiator saves the state of the media direction so that
+ * if we are to send any offers, we'll offer recvonly in the media streams. This is
+ * problematic if the device is attempting to unhold, though. If the device unholds
+ * by sending a reinvite with no SDP, then we will respond with a 200 OK with recvonly.
+ * According to RFC 3264, if an offerer offers recvonly, then the answerer MUST respond
+ * with sendonly or inactive. The result of this is that the stream is not off hold.
+ *
+ * Therefore, in this case, when we receive a reinvite while the stream is on hold, we
+ * need to be sure to offer sendrecv. This way, the answerer can respond with sendrecv
+ * in order to get the stream off hold. If this is actually a different purpose reinvite
+ * (like a session timer refresh), then the answerer can respond to our sendrecv with
+ * sendonly, keeping the stream on hold.
+ */
+ for (i = 0; i < offer->media_count; ++i) {
+ pjmedia_sdp_media *m = offer->media[i];
+ pjmedia_sdp_attr *recvonly;
+ pjmedia_sdp_attr *inactive;
+ pjmedia_sdp_attr *sendonly;
+
+ recvonly = pjmedia_sdp_attr_find2(m->attr_count, m->attr, "recvonly", NULL);
+ inactive = pjmedia_sdp_attr_find2(m->attr_count, m->attr, "inactive", NULL);
+ sendonly = pjmedia_sdp_attr_find2(m->attr_count, m->attr, "sendonly", NULL);
+ if (recvonly || inactive || sendonly) {
+ pjmedia_sdp_attr *to_remove = recvonly ?: inactive ?: sendonly;
+ pjmedia_sdp_attr *sendrecv;
+
+ pjmedia_sdp_attr_remove(&m->attr_count, m->attr, to_remove);
+
+ sendrecv = pjmedia_sdp_attr_create(session->inv_session->pool, "sendrecv", NULL);
+ pjmedia_sdp_media_add_attr(m, sendrecv);
+ }
+ }
+
+ *p_offer = offer;
}
-#endif
static void session_inv_on_media_update(pjsip_inv_session *inv, pj_status_t status)
{
@@ -5415,6 +5423,7 @@
.on_new_session = session_inv_on_new_session,
.on_tsx_state_changed = session_inv_on_tsx_state_changed,
.on_rx_offer = session_inv_on_rx_offer,
+ .on_create_offer = session_inv_on_create_offer,
.on_media_update = session_inv_on_media_update,
.on_redirected = session_inv_on_redirected,
};
--
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Gerrit-Project: asterisk
Gerrit-Branch: 18
Gerrit-Change-Id: I2d81048d54edcb80fe38fdbb954a86f0a58281a1
Gerrit-Change-Number: 15432
Gerrit-PatchSet: 1
Gerrit-Owner: Joshua Colp <jcolp at sangoma.com>
Gerrit-MessageType: newchange
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