start introducing hooks for reference counts on dialog descriptors.

This commit is, for all practical purposes, a no-op, as it only
introduces the dialog_ref() and dialog_unref() methods, and uses them
in a few places (not all the places where they would be needed).

The goal is to start annotating the code with these calls, so the transition
to a proper container will be easier.

Nothing to backport.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@77647 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index eac831d532e2f07f81c989d58dfddf8a8b29a857..341a0a0a31d6284ce0dc61f2622dc237db7e0f94 100644 (file)
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -1116,6 +1116,15 @@ struct sip_pvt {
                                                        you know more) */
 };
 
+/*
+ * Here we implement the container for dialogs (sip_pvt), defining
+ * generic wrapper functions to ease the transition from the current
+ * implementation (a single linked list) to a different container.
+ * In addition to a reference to the container, we need functions to lock/unlock
+ * the container and individual items, and functions to add/remove
+ * references to the individual items.
+ */
+
 static struct sip_pvt *dialoglist = NULL;
 
 /*! \brief Protect the SIP dialog list (of sip_pvt's) */
@@ -1132,6 +1141,21 @@ static void dialoglist_unlock(void)
        ast_mutex_unlock(&dialoglock);
 }
 
+/*!
+ * when we create or delete references, make sure to use these
+ * functions so we keep track of the refcounts.
+ * To simplify the code, we allow a NULL to be passed to dialog_unref().
+ */
+static struct sip_pvt *dialog_ref(struct sip_pvt *p)
+{
+       return p;
+}
+
+static struct sip_pvt *dialog_unref(struct sip_pvt *p)
+{
+       return NULL;
+}
+
 /*! \brief sip packet - raw format for outbound packets that are sent or scheduled for transmission
  * Packets are linked in a list, whose head is in the struct sip_pvt they belong to.
  * Each packet holds a reference to the parent struct sip_pvt.
@@ -2329,7 +2353,7 @@ static enum sip_result __sip_reliable_xmit(struct sip_pvt *p, int seqno, int res
        pkt->method = sipmethod;
        pkt->packetlen = len;
        pkt->next = p->packets;
-       pkt->owner = p;
+       pkt->owner = dialog_ref(p);
        pkt->seqno = seqno;
        if (resp)
                pkt->is_resp = 1;
@@ -2459,6 +2483,7 @@ static void __sip_ack(struct sip_pvt *p, int seqno, int resp, int sipmethod)
                                cur->retransid = -1;
                        }
                        UNLINK(cur, p->packets, prev);
+                       dialog_unref(cur->owner);
                        ast_free(cur);
                        break;
                }
@@ -3466,7 +3491,7 @@ static void __sip_destroy(struct sip_pvt *p, int lockowner, int lockdialoglist)
 
        /* Remove link from peer to subscription of MWI */
        if (p->relatedpeer && p->relatedpeer->mwipvt) 
-               p->relatedpeer->mwipvt = NULL;
+               p->relatedpeer->mwipvt = dialog_unref(p->relatedpeer->mwipvt);
 
        if (dumphistory)
                sip_dump_history(p);
@@ -3540,6 +3565,7 @@ static void __sip_destroy(struct sip_pvt *p, int lockowner, int lockdialoglist)
                p->packets = p->packets->next;
                if (cp->retransid > -1)
                        ast_sched_del(sched, cp->retransid);
+               dialog_unref(cp->owner);
                ast_free(cp);
        }
        if (p->chanvars) {
@@ -3873,7 +3899,7 @@ static int sip_hangup(struct ast_channel *ast)
                sip_scheddestroy(p, DEFAULT_TRANS_TIMEOUT);
                ast_clear_flag(&p->flags[0], SIP_DEFER_BYE_ON_TRANSFER);        /* Really hang up next time */
                p->needdestroy = 0;
-               p->owner->tech_pvt = NULL;
+               p->owner->tech_pvt = dialog_unref(p->owner->tech_pvt);
                p->owner = NULL;  /* Owner will be gone after we return, so take it away */
                return 0;
        }
@@ -3914,7 +3940,7 @@ static int sip_hangup(struct ast_channel *ast)
                ast_dsp_free(p->vad);
 
        p->owner = NULL;
-       ast->tech_pvt = NULL;
+       ast->tech_pvt = dialog_unref(ast->tech_pvt);
 
        ast_module_unref(ast_module_info->self);
        /* Do not destroy this pvt until we have timeout or
@@ -4461,7 +4487,7 @@ static struct ast_channel *sip_new(struct sip_pvt *i, int state, const char *tit
        tmp->rawwriteformat = fmt;
        tmp->readformat = fmt;
        tmp->rawreadformat = fmt;
-       tmp->tech_pvt = i;
+       tmp->tech_pvt = dialog_ref(i);
 
        tmp->callgroup = i->callgroup;
        tmp->pickupgroup = i->pickupgroup;
@@ -4935,7 +4961,7 @@ static struct sip_pvt *sip_alloc(ast_string_field callid, struct sockaddr_in *si
        /* Add to active dialog list */
        dialoglist_lock();
        p->next = dialoglist;
-       dialoglist = p;
+       dialoglist = dialog_ref(p);
        dialoglist_unlock();
        ast_debug(1, "Allocating new SIP dialog for %s - %s (%s)\n", callid ? callid : "(No Call-ID)", sip_methods[intended_method].text, p->rtp ? "With RTP" : "No RTP");
        return p;
@@ -9691,7 +9717,7 @@ static int get_also_info(struct sip_pvt *p, struct sip_request *oreq)
                ast_copy_string(referdata->refer_to, c, sizeof(referdata->refer_to));
                ast_copy_string(referdata->referred_by, "", sizeof(referdata->referred_by));
                ast_copy_string(referdata->refer_contact, "", sizeof(referdata->refer_contact));
-               referdata->refer_call = NULL;
+               referdata->refer_call = dialog_unref(referdata->refer_call);
                /* Set new context */
                ast_string_field_set(p, context, transfer_context);
                return 0;
@@ -16139,7 +16165,7 @@ static int sip_send_mwi_to_peer(struct sip_peer *peer, const struct ast_event *e
        
        if (peer->mwipvt) {
                /* Base message on subscription */
-               p = peer->mwipvt;
+               p = dialog_ref(peer->mwipvt);
        } else {
                /* Build temporary dialog for this message */
                if (!(p = sip_alloc(NULL, NULL, 0, SIP_NOTIFY)))