<p>Richard Mudgett has uploaded this change for <strong>review</strong>.</p><p><a href="https://gerrit.asterisk.org/6413">View Change</a></p><pre style="font-family: monospace,monospace; white-space: pre-wrap;">res_rtp_asterisk.c: Make strict RTP learning more flexible.<br><br>Direct media can cause strict RTP to attempt to learn a remote address<br>again before it has had a chance to learn the remote address the first<br>time. Because of the rapid relearn requests, strict RTP could latch onto<br>the first remote address and fail to latch onto the direct media remote<br>address. As a result, you have one way audio until the call is placed on<br>and off hold.<br><br>The new algorythm learns remote addresses for a set time (1.5 seconds)<br>before locking the remote address. In addition, we must see a configured<br>number of remote packets from the same address in a row before switching.<br><br>* Fixed strict RTP learning from always accepting the first new address<br>packet as the new stream.<br><br>* Fixed strict RTP to initialize the expected sequence number with the<br>last received sequence number instead of the last transmitted sequence<br>number.<br><br>* Fixed the predicted next sequence number calculation in<br>rtp_learning_rtp_seq_update() to handle overflow.<br><br>ASTERISK-27252<br><br>Change-Id: Ia2d3aa6e0f22906c25971e74f10027d96525f31c<br>---<br>M res/res_rtp_asterisk.c<br>1 file changed, 92 insertions(+), 42 deletions(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;">git pull ssh://gerrit.asterisk.org:29418/asterisk refs/changes/13/6413/1</pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;">diff --git a/res/res_rtp_asterisk.c b/res/res_rtp_asterisk.c<br>index 091533e..165d70f 100644<br>--- a/res/res_rtp_asterisk.c<br>+++ b/res/res_rtp_asterisk.c<br>@@ -118,7 +118,9 @@<br> STRICT_RTP_CLOSED, /*! Drop all RTP packets not coming from source that was learned */<br> };<br> <br>-#define DEFAULT_STRICT_RTP STRICT_RTP_CLOSED<br>+#define STRICT_RTP_LEARN_TIMEOUT 1500 /*!< milliseconds */<br>+<br>+#define DEFAULT_STRICT_RTP -1 /*!< Enabled */<br> #define DEFAULT_ICESUPPORT 1<br> <br> extern struct ast_srtp_res *res_srtp;<br>@@ -219,9 +221,11 @@<br> <br> /*! \brief RTP learning mode tracking information */<br> struct rtp_learning_info {<br>- int max_seq; /*!< The highest sequence number received */<br>- int packets; /*!< The number of remaining packets before the source is accepted */<br>+ struct ast_sockaddr proposed_address; /*!< Proposed remote address for strict RTP */<br>+ struct timeval start; /*!< The time learning mode was started */<br> struct timeval received; /*!< The time of the last received packet */<br>+ int max_seq; /*!< The highest sequence number received */<br>+ int packets; /*!< The number of remaining packets before the source is accepted */<br> };<br> <br> #ifdef HAVE_OPENSSL_SRTP<br>@@ -2029,7 +2033,7 @@<br> #endif<br> <br> #ifdef HAVE_PJPROJECT<br>-static void rtp_learning_seq_init(struct rtp_learning_info *info, uint16_t seq);<br>+static void rtp_learning_start(struct ast_rtp *rtp);<br> <br> /* PJPROJECT ICE callback */<br> static void ast_rtp_on_ice_complete(pj_ice_sess *ice, pj_status_t status)<br>@@ -2071,8 +2075,8 @@<br> return;<br> }<br> <br>- rtp->strict_rtp_state = STRICT_RTP_LEARN;<br>- rtp_learning_seq_init(&rtp->rtp_source_learn, (uint16_t)rtp->seqno);<br>+ ast_verb(4, "%p -- Strict RTP learning after ICE completion\n", rtp);<br>+ rtp_learning_start(rtp);<br> ao2_unlock(instance);<br> }<br> <br>@@ -2821,7 +2825,7 @@<br> */<br> static void rtp_learning_seq_init(struct rtp_learning_info *info, uint16_t seq)<br> {<br>- info->max_seq = seq - 1;<br>+ info->max_seq = seq;<br> info->packets = learning_min_sequential;<br> memset(&info->received, 0, sizeof(info->received));<br> }<br>@@ -2838,14 +2842,17 @@<br> */<br> static int rtp_learning_rtp_seq_update(struct rtp_learning_info *info, uint16_t seq)<br> {<br>+ /*<br>+ * During the learning mode the minimum amount of media we'll accept is<br>+ * 10ms so give a reasonable 5ms buffer just in case we get it sporadically.<br>+ */<br> if (!ast_tvzero(info->received) && ast_tvdiff_ms(ast_tvnow(), info->received) < 5) {<br>- /* During the probation period the minimum amount of media we'll accept is<br>- * 10ms so give a reasonable 5ms buffer just in case we get it sporadically.<br>+ /*<br>+ * Reject a flood of packets as acceptable for learning.<br>+ * Reset the needed packets.<br> */<br>- return 1;<br>- }<br>-<br>- if (seq == info->max_seq + 1) {<br>+ info->packets = learning_min_sequential - 1;<br>+ } else if (seq == (uint16_t) (info->max_seq + 1)) {<br> /* packet is in sequence */<br> info->packets--;<br> } else {<br>@@ -2855,7 +2862,24 @@<br> info->max_seq = seq;<br> info->received = ast_tvnow();<br> <br>- return (info->packets == 0);<br>+ return info->packets;<br>+}<br>+<br>+/*!<br>+ * \brief Start the strictrtp learning mode.<br>+ * \since 13.18.0<br>+ *<br>+ * \param rtp RTP session description<br>+ *<br>+ * \return Nothing<br>+ */<br>+static void rtp_learning_start(struct ast_rtp *rtp)<br>+{<br>+ rtp->strict_rtp_state = STRICT_RTP_LEARN;<br>+ memset(&rtp->rtp_source_learn.proposed_address, 0,<br>+ sizeof(rtp->rtp_source_learn.proposed_address));<br>+ rtp->rtp_source_learn.start = ast_tvnow();<br>+ rtp_learning_seq_init(&rtp->rtp_source_learn, (uint16_t) rtp->lastrxseqno);<br> }<br> <br> #ifdef HAVE_PJPROJECT<br>@@ -3116,10 +3140,7 @@<br> {<br> int x, startplace;<br> <br>- rtp->strict_rtp_state = (strictrtp ? STRICT_RTP_LEARN : STRICT_RTP_OPEN);<br>- if (strictrtp) {<br>- rtp_learning_seq_init(&rtp->rtp_source_learn, (uint16_t)rtp->seqno);<br>- }<br>+ rtp->strict_rtp_state = (strictrtp ? STRICT_RTP_CLOSED : STRICT_RTP_OPEN);<br> <br> /* Create a new socket for us to listen on and use */<br> if ((rtp->s =<br>@@ -5336,31 +5357,59 @@<br> }<br> <br> /* If strict RTP protection is enabled see if we need to learn the remote address or if we need to drop the packet */<br>- if (rtp->strict_rtp_state == STRICT_RTP_LEARN) {<br>- if (!ast_sockaddr_cmp(&rtp->strict_rtp_address, &addr)) {<br>- /* We are learning a new address but have received traffic from the existing address,<br>- * accept it but reset the current learning for the new source so it only takes over<br>- * once sufficient traffic has been received. */<br>- rtp_learning_seq_init(&rtp->rtp_source_learn, seqno);<br>- } else {<br>- /* Start trying to learn from the new address. If we pass a probationary period with<br>- * it, that means we've stopped getting RTP from the original source and we should<br>- * switch to it.<br>- */<br>- if (rtp_learning_rtp_seq_update(&rtp->rtp_source_learn, seqno)) {<br>- ast_debug(1, "%p -- Received RTP packet from %s, dropping due to strict RTP protection. Will switch to it in %d packets\n",<br>- rtp, ast_sockaddr_stringify(&addr), rtp->rtp_source_learn.packets);<br>- return &ast_null_frame;<br>- }<br>- ast_sockaddr_copy(&rtp->strict_rtp_address, &addr);<br>-<br>- ast_verb(4, "%p -- Probation passed - setting RTP source address to %s\n", rtp, ast_sockaddr_stringify(&addr));<br>+ switch (rtp->strict_rtp_state) {<br>+ case STRICT_RTP_LEARN:<br>+ if (!ast_sockaddr_isnull(&rtp->strict_rtp_address)<br>+ && STRICT_RTP_LEARN_TIMEOUT < ast_tvdiff_ms(ast_tvnow(), rtp->rtp_source_learn.start)) {<br>+ ast_verb(4, "%p -- Strict RTP learning complete - Locking on source address %s\n",<br>+ rtp, ast_sockaddr_stringify(&rtp->strict_rtp_address));<br> rtp->strict_rtp_state = STRICT_RTP_CLOSED;<br>+ } else {<br>+ if (!ast_sockaddr_cmp(&rtp->strict_rtp_address, &addr)) {<br>+ /*<br>+ * We are learning a new address but have received traffic from the existing address,<br>+ * accept it but reset the current learning for the new source so it only takes over<br>+ * once sufficient traffic has been received.<br>+ */<br>+ rtp_learning_seq_init(&rtp->rtp_source_learn, seqno);<br>+ break;<br>+ }<br>+ /*<br>+ * Trying to learn a new address. If we pass a probationary period with<br>+ * it, that means we've stopped getting RTP from the original source and<br>+ * we should switch to it.<br>+ */<br>+ if (!ast_sockaddr_cmp(&rtp->rtp_source_learn.proposed_address, &addr)) {<br>+ if (!rtp_learning_rtp_seq_update(&rtp->rtp_source_learn, seqno)) {<br>+ /* Accept the new RTP stream */<br>+ ast_verb(4, "%p -- Strict RTP switching source address to %s\n",<br>+ rtp, ast_sockaddr_stringify(&addr));<br>+ ast_sockaddr_copy(&rtp->strict_rtp_address, &addr);<br>+ break;<br>+ }<br>+ /* Not ready to accept the RTP stream candidate */<br>+ } else {<br>+ /*<br>+ * This is either an attacking stream or<br>+ * the start of the expected new stream.<br>+ */<br>+ ast_sockaddr_copy(&rtp->rtp_source_learn.proposed_address, &addr);<br>+ rtp_learning_seq_init(&rtp->rtp_source_learn, seqno);<br>+ }<br>+ ast_debug(1, "%p -- Received RTP packet from %s, dropping due to strict RTP protection. Will switch to it in %d packets\n",<br>+ rtp, ast_sockaddr_stringify(&addr), rtp->rtp_source_learn.packets);<br>+ return &ast_null_frame;<br> }<br>- } else if (rtp->strict_rtp_state == STRICT_RTP_CLOSED && ast_sockaddr_cmp(&rtp->strict_rtp_address, &addr)) {<br>+ /* Fall through */<br>+ case STRICT_RTP_CLOSED:<br>+ if (!ast_sockaddr_cmp(&rtp->strict_rtp_address, &addr)) {<br>+ break;<br>+ }<br> ast_debug(1, "%p -- Received RTP packet from %s, dropping due to strict RTP protection.\n",<br> rtp, ast_sockaddr_stringify(&addr));<br> return &ast_null_frame;<br>+ case STRICT_RTP_OPEN:<br>+ break;<br> }<br> <br> /* If symmetric RTP is enabled see if the remote side is not what we expected and change where we are sending audio */<br>@@ -5892,13 +5941,14 @@<br> <br> rtp->rxseqno = 0;<br> <br>- if (strictrtp && rtp->strict_rtp_state != STRICT_RTP_OPEN && !ast_sockaddr_isnull(addr) &&<br>- ast_sockaddr_cmp(addr, &rtp->strict_rtp_address)) {<br>+ if (strictrtp && rtp->strict_rtp_state != STRICT_RTP_OPEN<br>+ && !ast_sockaddr_isnull(addr) && ast_sockaddr_cmp(addr, &rtp->strict_rtp_address)) {<br> /* We only need to learn a new strict source address if we've been told the source is<br> * changing to something different.<br> */<br>- rtp->strict_rtp_state = STRICT_RTP_LEARN;<br>- rtp_learning_seq_init(&rtp->rtp_source_learn, rtp->seqno);<br>+ ast_verb(4, "%p -- Strict RTP learning after remote address set to: %s\n",<br>+ rtp, ast_sockaddr_stringify(addr));<br>+ rtp_learning_start(rtp);<br> }<br> }<br> <br></pre><p>To view, visit <a href="https://gerrit.asterisk.org/6413">change 6413</a>. To unsubscribe, visit <a href="https://gerrit.asterisk.org/settings">settings</a>.</p><div itemscope itemtype="http://schema.org/EmailMessage"><div itemscope itemprop="action" itemtype="http://schema.org/ViewAction"><link itemprop="url" href="https://gerrit.asterisk.org/6413"/><meta itemprop="name" content="View Change"/></div></div>
<div style="display:none"> Gerrit-Project: asterisk </div>
<div style="display:none"> Gerrit-Branch: 15 </div>
<div style="display:none"> Gerrit-MessageType: newchange </div>
<div style="display:none"> Gerrit-Change-Id: Ia2d3aa6e0f22906c25971e74f10027d96525f31c </div>
<div style="display:none"> Gerrit-Change-Number: 6413 </div>
<div style="display:none"> Gerrit-PatchSet: 1 </div>
<div style="display:none"> Gerrit-Owner: Richard Mudgett <rmudgett@digium.com> </div>