[collectd] multicast ttl

[e f]

hi

i'm using collectd in an vlan environment and had some troubles get this 
right to work...
after some googling i found the right info:

---
Even more important for the multicast sender is to set the TTL to 
something greater
then 1 (which is the default).  TTL, or time to live, is a counter 
attached to every sent packet. 
The TTL value gets decremented at every router and when it reaches 0 is 
dropped. 
Thus multicast data will not get very far if the TTL value is 1.
---

so i have done the following changes to multicast.c
in function  "multicast_send (char *type, char *instance, char *value)"

---multicast.c---
#define MCAST_TTL 2

int ttl = MCAST_TTL;

if (setsockopt(sd,IPPROTO_IP,IP_MULTICAST_TTL,&ttl,sizeof(ttl)) < 0)
{
 syslog (LOG_WARNING, "multicast_ttl: set ip ttl");
 return (-1);
}
---

in future releases it would be great, if this could be done via a 
config-parameter ;)

eric

===
diff multicast.c_new 
multicast.c_org                                                              

51d50
< #define MCAST_TTL 2
186d184
<       int ttl = MCAST_TTL;
195,200d192
<       if (setsockopt(sd,IPPROTO_IP,IP_MULTICAST_TTL,&ttl,sizeof(ttl)) < 0)
<       {
<               syslog (LOG_WARNING, "multicast_ttl: increase failure");
<               return (-1);
<       }
<