Fix improper usage of scheduler exposed by 5c713fdf18

When 5c713fdf18 was merged, it allowed for scheduled items to have an ID of
'0' returned. While this was valid per the documentation for the API, it was
apparently never returned previously. As a result, several users of the
scheduler API viewed the result as being invalid, causing them to reschedule
already scheduled items or otherwise fail in interesting ways.

This patch corrects the users such that they view '0' as valid, and a returned
ID of -1 as being invalid.

Note that the failing HEP RTCP tests now pass with this patch. These tests
failed due to a duplicate scheduling of the RTCP transmissions.

ASTERISK-25449 #close

Change-Id: I019a9aa8b6997584f66876331675981ac9e07e39

channels/chan_sip.c

@@ -4333,7 +4333,7 @@ void sip_scheddestroy(struct sip_pvt *p, int ms)
 	}
 	p->autokillid = ast_sched_add(sched, ms, __sip_autodestruct, dialog_ref(p, "setting ref as passing into ast_sched_add for __sip_autodestruct"));
 
-	if (p->stimer && p->stimer->st_active == TRUE && p->stimer->st_schedid > 0) {
+	if (p->stimer && p->stimer->st_active == TRUE && p->stimer->st_schedid > -1) {
 		stop_session_timer(p);
 	}
 }
@@ -22595,7 +22595,7 @@ static void check_pendings(struct sip_pvt *p)
 		sip_scheddestroy(p, DEFAULT_TRANS_TIMEOUT);
 	} else if (ast_test_flag(&p->flags[0], SIP_NEEDREINVITE)) {
 		/* if we can't REINVITE, hold it for later */
-		if (p->pendinginvite || p->invitestate == INV_CALLING || p->invitestate == INV_PROCEEDING || p->invitestate == INV_EARLY_MEDIA || p->waitid > 0) {
+		if (p->pendinginvite || p->invitestate == INV_CALLING || p->invitestate == INV_PROCEEDING || p->invitestate == INV_EARLY_MEDIA || p->waitid > -1) {
 			ast_debug(2, "NOT Sending pending reinvite (yet) on '%s'\n", p->callid);
 		} else {
 			ast_debug(2, "Sending pending reinvite on '%s'\n", p->callid);

channels/chan_skinny.c

@@ -4332,7 +4332,7 @@ static int skinny_dialer_cb(const void *data)
 {
 	struct skinny_subchannel *sub = (struct skinny_subchannel *)data;
 	SKINNY_DEBUG(DEBUG_SUB, 3, "Sub %u - Dialer called from SCHED %d\n", sub->callid, sub->dialer_sched);
-	sub->dialer_sched = 0;
+	sub->dialer_sched = -1;
 	skinny_dialer(sub, 1);
 	return 0;
 }
@@ -4340,7 +4340,7 @@ static int skinny_dialer_cb(const void *data)
 static int skinny_autoanswer_cb(const void *data)
 {
 	struct skinny_subchannel *sub = (struct skinny_subchannel *)data;
-	sub->aa_sched = 0;
+	sub->aa_sched = -1;
 	setsubstate(sub, SKINNY_CONNECTED);
 	return 0;
 }
@@ -4379,7 +4379,7 @@ static int skinny_call(struct ast_channel *ast, const char *dest, int timeout)
 
 	AST_LIST_TRAVERSE(ast_channel_varshead(ast), current, entries) {
 		if (!(strcasecmp(ast_var_name(current),"SKINNY_AUTOANSWER"))) {
-			if (d->hookstate == SKINNY_ONHOOK && !sub->aa_sched) {
+			if (d->hookstate == SKINNY_ONHOOK && !sub->aa_sched < 0) {
 				char buf[24];
 				int aatime;
 				char *stringp = buf, *curstr;
@@ -4841,8 +4841,8 @@ static struct ast_channel *skinny_new(struct skinny_line *l, struct skinny_subli
 			sub->xferor = 0;
 			sub->related = NULL;
 			sub->calldirection = direction;
-			sub->aa_sched = 0;
-			sub->dialer_sched = 0;
+			sub->aa_sched = -1;
+			sub->dialer_sched = -1;
 
 			if (subline) {
 				sub->subline = subline;
@@ -4983,12 +4983,12 @@ static void setsubstate(struct skinny_subchannel *sub, int state)
 
 	if (sub->dialer_sched) {
 		skinny_sched_del(sub->dialer_sched, sub);
-		sub->dialer_sched = 0;
+		sub->dialer_sched = -1;
 	}
 
 	if (state != SUBSTATE_RINGIN && sub->aa_sched) {
 		skinny_sched_del(sub->aa_sched, sub);
-		sub->aa_sched = 0;
+		sub->aa_sched = -1;
 		sub->aa_beep = 0;
 		sub->aa_mute = 0;
 	}
@@ -5642,7 +5642,7 @@ static int handle_keypad_button_message(struct skinny_req *req, struct skinnyses
 	if ((sub->owner && ast_channel_state(sub->owner) <  AST_STATE_UP)) {
 		if (sub->dialer_sched &&	!skinny_sched_del(sub->dialer_sched, sub)) {
 			SKINNY_DEBUG(DEBUG_SUB, 3, "Sub %u - Got a digit and not timed out, so try dialing\n", sub->callid);
-			sub->dialer_sched = 0;
+			sub->dialer_sched = -1;
 			len = strlen(sub->exten);
 			if (len == 0) {
 				transmit_stop_tone(d, l->instance, sub->callid);
@@ -6526,7 +6526,7 @@ static int handle_soft_key_event_message(struct skinny_req *req, struct skinnyse
 			d->name, instance, callreference);
 		if (sub->dialer_sched && !skinny_sched_del(sub->dialer_sched, sub)) {
 			size_t len;
-			sub->dialer_sched = 0;
+			sub->dialer_sched = -1;
 			len = strlen(sub->exten);
 			if (len > 0) {
 				sub->exten[len-1] = '\0';

res/res_rtp_asterisk.c

@@ -3278,7 +3278,7 @@ static int ast_rtp_raw_write(struct ast_rtp_instance *instance, struct ast_frame
 			rtp->txcount++;
 			rtp->txoctetcount += (res - hdrlen);
 
-			if (rtp->rtcp && rtp->rtcp->schedid < 1) {
+			if (rtp->rtcp && rtp->rtcp->schedid < 0) {
 				ast_debug(1, "Starting RTCP transmission on RTP instance '%p'\n", instance);
 				ao2_ref(instance, +1);
 				rtp->rtcp->schedid = ast_sched_add(rtp->sched, ast_rtcp_calc_interval(rtp), ast_rtcp_write, instance);
@@ -4397,7 +4397,7 @@ static struct ast_frame *ast_rtp_read(struct ast_rtp_instance *instance, int rtc
 	}
 
 	/* Do not schedule RR if RTCP isn't run */
-	if (rtp->rtcp && !ast_sockaddr_isnull(&rtp->rtcp->them) && rtp->rtcp->schedid < 1) {
+	if (rtp->rtcp && !ast_sockaddr_isnull(&rtp->rtcp->them) && rtp->rtcp->schedid < 0) {
 		/* Schedule transmission of Receiver Report */
 		ao2_ref(instance, +1);
 		rtp->rtcp->schedid = ast_sched_add(rtp->sched, ast_rtcp_calc_interval(rtp), ast_rtcp_write, instance);