modules/drouting Improvement for do_routing in failure route

Improvement for sort_order 2 : if the failure groups have repeating
gateways the module will take care internally not to try again a gateway
that was already tried.

modules/drouting/README

@@ -304,18 +304,18 @@ Chapter 1. Admin Guide
        draft 09):
        Table 1.4. Time recurrence attributes
 
-   Attribute Description
-   dastard Start of interval (RFC 2445 DATE-TIME)
-   duration Length of interval (RFC 2445 DURATION)
-   freq Frequency of recurrence (secondly,minutely,hourly, daily,weekly,
-   monthly, or yearly).
-   until bound of recurrence (RFC 2445 DATE-TIME)
-   interval How often the recurrence repeats
-   byday List of days of the week
-   bymonthday List of days of the month
-   byyearday List of days of the year
-   byweekno List of weeks of the year
-   bymonth List of months of the year
+     Attribute                            Description
+     dastard    Start of interval (RFC 2445 DATE-TIME)
+     duration   Length of interval (RFC 2445 DURATION)
+     freq       Frequency of recurrence (secondly,minutely,hourly, daily,weekly,
+                monthly, or yearly).
+     until      bound of recurrence (RFC 2445 DATE-TIME)
+     interval   How often the recurrence repeats
+     byday      List of days of the week
+     bymonthday List of days of the month
+     byyearday  List of days of the year
+     byweekno   List of weeks of the year
+     bymonth    List of months of the year
        The value stored in database has the format of:
        <dtstart>|<duration>|<freq>|<until>|<interval>|<byday>|<bymonthday>
        |<byyearday>|<byweekno>|<bymonth>
@@ -570,9 +570,16 @@ modparam("drouting", "drl_table", "my_gw_lists")
        destinations). Ex: 1,2;3,4,5;6 -> randomizer -> (A) 2,1;4,3,5;6 ->
        usage 2,1,4,3,5,6 (B) 1,2;3,5,4;6 -> usage 1,2,3,5,4,6
      * 2 - from each destination group, only a single destination is
-       randomly selected; groups do maintain their order (as given); Ex:
-       1,2;3,4,5;6 -> randomizer -> (A) 2;4;6 -> usage 2,4,6 (B) 1;5;6 ->
-       usage 1,5,6
+       randomly selected; groups do maintain their order (as given);
+       Ex: 1,2;3,4,5;6 -> randomizer ->
+       (A) 2;4;6 -> usage 2,4,6
+       (B) 1;5;6 -> usage 1,5,6
+       It is ok to have repeating gateways in different groups. The module
+       will take care internally in case of failure not to choose a
+       gateway that was tried already.
+       Ex: 1,2,3; 1,2,3; 1,2,3 -> no gateway will be choosen twice. So in
+       case there are 2 failures, all the three gateways (1,2,3) will be
+       tried in a random order.
 
    Default value is “0”.
 

modules/drouting/doc/drouting_admin.xml

@@ -942,9 +942,24 @@ modparam("drouting", "drl_table", "my_gw_lists")
 			<emphasis>2</emphasis> - from each destination group, only a 
 			single destination is randomly selected; groups do maintain their
 			order (as given);
+			<para>
 			Ex: 1,2;3,4,5;6 -> randomizer ->
+			</para>
+			<para>
 			(A) 2;4;6  -> usage 2,4,6
+			</para>
+			<para>
 			(B) 1;5;6  -> usage 1,5,6
+			</para>
+			<para>
+			It is ok to have repeating gateways in different groups. The module will
+			take care internally in case of failure not to choose a gateway that
+			was tried already.
+			</para>
+			<para>
+			Ex: 1,2,3; 1,2,3; 1,2,3 -> no gateway will be choosen twice. So in case there
+			are 2 failures, all the three gateways (1,2,3) will be tried in a random order.
+			</para>
 		</listitem>
 		</itemizedlist>
 		</para>

modules/drouting/drouting.c

@@ -646,6 +646,20 @@ static int use_next_gw(struct sip_msg* msg)
 	return 1;
 }
 
+int dr_already_choosen(rt_info_t* rt_info, int* local_gwlist, int lgw_size, int check)
+{
+	int l;
+
+	for ( l = 0; l<lgw_size; l++ ) {
+		if ( rt_info->pgwl[local_gwlist[l]].pgw == rt_info->pgwl[check].pgw ) {
+			LM_INFO("Gateway already choosen %.*s, local_gwlist[%d]=%d, %d\n",
+					rt_info->pgwl[check].pgw->ip.len, rt_info->pgwl[check].pgw->ip.s, l, local_gwlist[l], check);
+			return 1;
+		}
+	}
+
+	return 0;
+}
 
 static int do_routing(struct sip_msg* msg, dr_group_t *drg)
 {
@@ -806,6 +820,30 @@ again:
 					}
 				}
 			}
+
+			if ( sort_order == 2 ) {
+				/* check not to use the same gateway as before */
+				if ( t>1 ) {
+					/* check if all in the current set were already chosen */
+					if (i-j <= t-1) {
+						for( l = j; l< i; l++) {
+							if ( ! dr_already_choosen(rt_info, local_gwlist, t-1, l) )
+								break;
+						}
+						if ( l == i ) {
+							LM_INFO("All gateways in group from %d - %d were already used\n", j, i);
+							t--; /* jump over this group, nothing to choose here */
+							j=i; continue;
+						}
+					}
+					while ( dr_already_choosen(rt_info, local_gwlist, t-1, local_gwlist[t-1]) ) {
+						local_gwlist[t-1]   = j + rand()%(i-j);
+					}
+				}
+				LM_DBG("The %d gateway is %.*s [%d]\n", t, rt_info->pgwl[local_gwlist[t-1]].pgw->ip.len,
+						rt_info->pgwl[local_gwlist[t-1]].pgw->ip.s, local_gwlist[t-1]);
+			}
+
 			/* next group starts from i */
 			j=i;
 		}