Re-send non-100 provisional responses to prevent cancellation

From section 13.3.1.1 of RFC 3261:

   If the UAS desires an extended period of time to answer the INVITE,
   it will need to ask for an "extension" in order to prevent proxies
   from canceling the transaction. A proxy has the option of canceling
   a transaction when there is a gap of 3 minutes between responses in a
   transaction. To prevent cancellation, the UAS MUST send a non-100
   provisional response at every minute, to handle the possibility of
   lost provisional responses.

(closes issue #11157)
Reported by: rjain
Tested by: twilson

Review: https://reviewboard.asterisk.org/r/315/

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@215682 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 87b4c6aa344d278fe915f698ef942f8ca1199801..684bff098a1bf32f2d6d37a63888911fc2a150a8 100644 (file)
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -211,6 +211,7 @@ static char seen_lastms = 0;
                                                       \todo Use known T1 for timeout (peerpoke)
                                                       */
 #define DEFAULT_TRANS_TIMEOUT        -1               /* Use default SIP transaction timeout */
+#define PROVIS_KEEPALIVE_TIMEOUT     60000            /*!< How long to wait before retransmitting a provisional response (rfc 3261 13.3.1.1) */
 #define MAX_AUTHTRIES                3                /*!< Try authentication three times, then fail */
 
 #define SIP_MAX_HEADERS              64               /*!< Max amount of SIP headers to read */
@@ -1034,6 +1035,8 @@ static struct sip_pvt {
        struct ast_variable *chanvars;          /*!< Channel variables to set for inbound call */
        AST_LIST_HEAD_NOLOCK(request_queue, sip_request) request_queue; /*!< Requests that arrived but could not be processed immediately */
        int request_queue_sched_id;             /*!< Scheduler ID of any scheduled action to process queued requests */
+       int provisional_keepalive_sched_id; /*!< Scheduler ID for provisional responses that need to be sent out to avoid cancellation */
+       const char *last_provisional;   /*!< The last successfully transmitted provisonal response message */
        struct sip_pvt *next;                   /*!< Next dialog in chain */
        struct sip_invite_param *options;       /*!< Options for INVITE */
        int autoframing;
@@ -1290,6 +1293,7 @@ static int transmit_response_with_date(struct sip_pvt *p, const char *msg, const
 static int transmit_response_with_sdp(struct sip_pvt *p, const char *msg, const struct sip_request *req, enum xmittype reliable);
 static int transmit_response_with_unsupported(struct sip_pvt *p, const char *msg, const struct sip_request *req, const char *unsupported);
 static int transmit_response_with_auth(struct sip_pvt *p, const char *msg, const struct sip_request *req, const char *rand, enum xmittype reliable, const char *header, int stale);
+static int transmit_provisional_response(struct sip_pvt *p, const char *msg, const struct sip_request *req, int with_sdp);
 static int transmit_response_with_allow(struct sip_pvt *p, const char *msg, const struct sip_request *req, enum xmittype reliable);
 static void transmit_fake_auth_response(struct sip_pvt *p, int sipmethod, struct sip_request *req, enum xmittype reliable);
 static int transmit_request(struct sip_pvt *p, int sipmethod, int inc, enum xmittype reliable, int newbranch);
@@ -2321,6 +2325,46 @@ static void add_blank(struct sip_request *req)
        }
 }
 
+static int send_provisional_keepalive_full(struct sip_pvt *pvt, int with_sdp)
+{
+       const char *msg = NULL;
+
+       if (!pvt->last_provisional || !strncasecmp(pvt->last_provisional, "100", 3)) {
+               msg = "183 Session Progress";
+       }
+
+       if (pvt->invitestate < INV_COMPLETED) {
+               if (with_sdp) {
+                       transmit_response_with_sdp(pvt, S_OR(msg, pvt->last_provisional), &pvt->initreq, XMIT_UNRELIABLE);
+               } else {
+                       transmit_response(pvt, S_OR(msg, pvt->last_provisional), &pvt->initreq);
+               }
+               return PROVIS_KEEPALIVE_TIMEOUT;
+       }
+
+       return 0;
+}
+
+static int send_provisional_keepalive(const void *data) {
+       struct sip_pvt *pvt = (struct sip_pvt *) data;
+
+       return send_provisional_keepalive_full(pvt, 0);
+}
+
+static int send_provisional_keepalive_with_sdp(const void *data) {
+       struct sip_pvt *pvt = (void *)data;
+
+       return send_provisional_keepalive_full(pvt, 1);
+}
+
+static void update_provisional_keepalive(struct sip_pvt *pvt, int with_sdp)
+{
+       AST_SCHED_DEL(sched, pvt->provisional_keepalive_sched_id);
+
+       pvt->provisional_keepalive_sched_id = ast_sched_add(sched, PROVIS_KEEPALIVE_TIMEOUT,
+               with_sdp ? send_provisional_keepalive_with_sdp : send_provisional_keepalive, pvt);
+}
+
 /*! \brief Transmit response on SIP request*/
 static int send_response(struct sip_pvt *p, struct sip_request *req, enum xmittype reliable, int seqno)
 {
@@ -2341,6 +2385,12 @@ static int send_response(struct sip_pvt *p, struct sip_request *req, enum xmitty
                append_history(p, reliable ? "TxRespRel" : "TxResp", "%s / %s - %s", tmp.data, get_header(&tmp, "CSeq"), 
                        (tmp.method == SIP_RESPONSE || tmp.method == SIP_UNKNOWN) ? tmp.rlPart2 : sip_methods[tmp.method].text);
        }
+
+       /* If we are sending a final response to an INVITE, stop retransmitting provisional responses */
+       if (p->initreq.method == SIP_INVITE && reliable == XMIT_CRITICAL) {
+               AST_SCHED_DEL(sched, p->provisional_keepalive_sched_id);
+       }
+
        res = (reliable) ?
                 __sip_reliable_xmit(p, seqno, 1, req->data, req->len, (reliable == XMIT_CRITICAL), req->method) :
                __sip_xmit(p, req->data, req->len);
@@ -3228,6 +3278,7 @@ static int __sip_destroy(struct sip_pvt *p, int lockowner)
        AST_SCHED_DEL(sched, p->waitid);
        AST_SCHED_DEL(sched, p->autokillid);
        AST_SCHED_DEL(sched, p->request_queue_sched_id);
+       AST_SCHED_DEL(sched, p->provisional_keepalive_sched_id);
 
        if (p->rtp) {
                ast_rtp_destroy(p->rtp);
@@ -3844,7 +3895,7 @@ static int sip_write(struct ast_channel *ast, struct ast_frame *frame)
                                    !ast_test_flag(&p->flags[0], SIP_OUTGOING)) {
                                        ast_rtp_new_source(p->rtp);
                                        p->invitestate = INV_EARLY_MEDIA;
-                                       transmit_response_with_sdp(p, "183 Session Progress", &p->initreq, XMIT_UNRELIABLE);
+                                       transmit_provisional_response(p, "183 Session Progress", &p->initreq, 1);
                                        ast_set_flag(&p->flags[0], SIP_PROGRESS_SENT);
                                } else if (p->t38.state == T38_ENABLED && !p->t38.direct) {
                                        p->t38.state = T38_DISABLED;
@@ -3866,7 +3917,7 @@ static int sip_write(struct ast_channel *ast, struct ast_frame *frame)
                                    !ast_test_flag(&p->flags[0], SIP_PROGRESS_SENT) &&
                                    !ast_test_flag(&p->flags[0], SIP_OUTGOING)) {
                                        p->invitestate = INV_EARLY_MEDIA;
-                                       transmit_response_with_sdp(p, "183 Session Progress", &p->initreq, XMIT_UNRELIABLE);
+                                       transmit_provisional_response(p, "183 Session Progress", &p->initreq, 1);
                                        ast_set_flag(&p->flags[0], SIP_PROGRESS_SENT);  
                                }
                                p->lastrtptx = time(NULL);
@@ -4037,7 +4088,7 @@ static int sip_indicate(struct ast_channel *ast, int condition, const void *data
                        if (!ast_test_flag(&p->flags[0], SIP_PROGRESS_SENT) ||
                            (ast_test_flag(&p->flags[0], SIP_PROG_INBAND) == SIP_PROG_INBAND_NEVER)) {                          
                                /* Send 180 ringing if out-of-band seems reasonable */
-                               transmit_response(p, "180 Ringing", &p->initreq);
+                               transmit_provisional_response(p, "180 Ringing", &p->initreq, 0);
                                ast_set_flag(&p->flags[0], SIP_RINGING);
                                if (ast_test_flag(&p->flags[0], SIP_PROG_INBAND) != SIP_PROG_INBAND_YES)
                                        break;
@@ -4082,7 +4133,7 @@ static int sip_indicate(struct ast_channel *ast, int condition, const void *data
                    !ast_test_flag(&p->flags[0], SIP_PROGRESS_SENT) &&
                    !ast_test_flag(&p->flags[0], SIP_OUTGOING)) {
                        p->invitestate = INV_EARLY_MEDIA;
-                       transmit_response_with_sdp(p, "183 Session Progress", &p->initreq, XMIT_UNRELIABLE);
+                       transmit_provisional_response(p, "183 Session Progress", &p->initreq, 1);
                        ast_set_flag(&p->flags[0], SIP_PROGRESS_SENT);  
                        break;
                }
@@ -4594,6 +4645,7 @@ static struct sip_pvt *sip_alloc(ast_string_field callid, struct sockaddr_in *si
        p->waitid = -1;
        p->autokillid = -1;
        p->request_queue_sched_id = -1;
+       p->provisional_keepalive_sched_id = -1;
        p->subscribed = NONE;
        p->stateid = -1;
        p->prefs = default_prefs;               /* Set default codecs for this call */
@@ -6519,6 +6571,19 @@ static int transmit_response_with_auth(struct sip_pvt *p, const char *msg, const
        return send_response(p, &resp, reliable, seqno);
 }
 
+/* Only use a static string for the msg, here! */
+static int transmit_provisional_response(struct sip_pvt *p, const char *msg, const struct sip_request *req, int with_sdp)
+{
+       int res;
+
+       if (!(res = with_sdp ? transmit_response_with_sdp(p, msg, req, XMIT_UNRELIABLE) : transmit_response(p, msg, req))) {
+               p->last_provisional = msg;
+               update_provisional_keepalive(p, with_sdp);
+       }
+
+       return res;
+}
+
 /*! \brief Add text body to SIP message */
 static int add_text(struct sip_request *req, const char *text)
 {
@@ -14975,7 +15040,7 @@ static int handle_request_invite(struct sip_pvt *p, struct sip_request *req, int
                case AST_STATE_DOWN:
                        if (option_debug > 1)
                                ast_log(LOG_DEBUG, "%s: New call is still down.... Trying... \n", c->name);
-                       transmit_response(p, "100 Trying", req);
+                       transmit_provisional_response(p, "100 Trying", req, 0);
                        p->invitestate = INV_PROCEEDING;
                        ast_setstate(c, AST_STATE_RING);
                        if (strcmp(p->exten, ast_pickup_ext())) {       /* Call to extension -start pbx on this call */
@@ -15039,11 +15104,11 @@ static int handle_request_invite(struct sip_pvt *p, struct sip_request *req, int
                        }
                        break;
                case AST_STATE_RING:
-                       transmit_response(p, "100 Trying", req);
+                       transmit_provisional_response(p, "100 Trying", req, 0);
                        p->invitestate = INV_PROCEEDING;
                        break;
                case AST_STATE_RINGING:
-                       transmit_response(p, "180 Ringing", req);
+                       transmit_provisional_response(p, "180 Ringing", req, 0);
                        p->invitestate = INV_PROCEEDING;
                        break;
                case AST_STATE_UP: