sl: new pv $ltt(key) - return local generated to tag

- the to-tag used when kamailio sends a reply
- $ltt(s) - the to-tag used in stateless replies
- $ltt(t) - the to-tag used in transaction stateful replies (transaction
has to be created at that time, eg., by t_newtran() or in a
branch/failure route, otherwise it returns $null)
- $ltt(x) - $ltt(t) if the transaction was created already, otherwise
$ltt(s)

src/modules/sl/sl.c

@@ -78,6 +78,17 @@ static int child_init(int rank);
 static void mod_destroy();
 static int fixup_sl_reply(void** param, int param_no);
 
+static int pv_get_ltt(sip_msg_t *msg, pv_param_t *param, pv_value_t *res);
+static int pv_parse_ltt_name(pv_spec_p sp, str *in);
+
+
+static pv_export_t mod_pvs[] = {
+	{ {"ltt", (sizeof("ltt")-1)}, PVT_OTHER, pv_get_ltt, 0,
+		pv_parse_ltt_name, 0, 0, 0 },
+
+	{ {0, 0}, 0, 0, 0, 0, 0, 0, 0 }
+};
+
 static cmd_export_t cmds[]={
 	{"sl_send_reply",  w_sl_send_reply,             2, fixup_sl_reply, 0,
 		REQUEST_ROUTE},
@@ -120,7 +131,7 @@ struct module_exports exports= {
 	cmds,				/* cmd (cfg function) exports */
 	params,			    /* param exports */
 	sl_rpc,			    /* RPC method exports */
-	0,					/* pv exports */
+	mod_pvs,			/* pv exports */
 	0,					/* response handling function */
 	mod_init,			/* module init function */
 	child_init,			/* per-child init function */
@@ -485,6 +496,83 @@ static int w_sl_forward_reply2(sip_msg_t* msg, char* str1, char* str2)
 	return w_sl_forward_reply(msg, &code, &reason);
 }
 
+/**
+ *
+ */
+static int pv_get_ltt(sip_msg_t *msg, pv_param_t *param, pv_value_t *res)
+{
+	str ttag = STR_NULL;
+	tm_cell_t *t = NULL;
+
+	if(msg==NULL)
+		return pv_get_null(msg, param, res);
+
+	if(param==NULL)
+		return pv_get_null(msg, param, res);
+
+	switch(param->pvn.u.isname.name.n) {
+		case 0: /* mixed */
+			if(get_reply_totag(msg, &ttag)<0) {
+				return pv_get_null(msg, param, res);
+			}
+			return pv_get_strval(msg, param, res, &ttag);
+		case 1: /* stateless */
+			if(sl_get_reply_totag(msg, &ttag)<0) {
+				return pv_get_null(msg, param, res);
+			}
+			return pv_get_strval(msg, param, res, &ttag);
+		case 2: /* transaction stateful */
+			if(sl_bind_tm==0 || tmb.t_gett==0) {
+				return pv_get_null(msg, param, res);
+			}
+
+			t = tmb.t_gett();
+			if(t== NULL || t==T_UNDEFINED) {
+				return pv_get_null(msg, param, res);
+			}
+			if(tmb.t_get_reply_totag(msg, &ttag)<0) {
+				return pv_get_null(msg, param, res);
+			}
+			return pv_get_strval(msg, param, res, &ttag);
+		default:
+			return pv_get_null(msg, param, res);
+	}
+}
+
+/**
+ *
+ */
+static int pv_parse_ltt_name(pv_spec_p sp, str *in)
+{
+	if(sp==NULL || in==NULL || in->len<=0)
+		return -1;
+
+	switch(in->len) {
+		case 1:
+			if(strncmp(in->s, "x", 1)==0) {
+				sp->pvp.pvn.u.isname.name.n = 0;
+			} else if(strncmp(in->s, "s", 1)==0) {
+				sp->pvp.pvn.u.isname.name.n = 1;
+			} else if(strncmp(in->s, "t", 1)==0) {
+				sp->pvp.pvn.u.isname.name.n = 2;
+			} else {
+				goto error;
+			}
+		break;
+		default:
+			goto error;
+	}
+	sp->pvp.pvn.type = PV_NAME_INTSTR;
+	sp->pvp.pvn.u.isname.type = 0;
+
+	return 0;
+
+error:
+	LM_ERR("unknown PV ltt key: %.*s\n", in->len, in->s);
+	return -1;
+}
+
+
 /**
  * @brief bind functions to SL API structure
  */