[sr-dev] rtpengine request don't fragment flag

[Richard Fuchs]

On 29/06/15 02:11 AM, Juha Heinanen wrote:
> as i reported on sr-users list, i noticed that sometimes rtpengine
> requests from kamailio set ip header don't fragment flag that causes
> icmp error message from a router on the path to rtpengine.  as result,
> rtpengine modules things that the rtpengine is dead.
>
> enclosed is an example of such an ip packet.
>
> after i made this kind of patch to rtpengine.c, the flag is not set
> anymore:
>
> *** /usr/src/orig/kamailio/modules/rtpengine/rtpengine.c	2015-06-16 12:33:56.497242900 +0300
> --- rtpengine.c	2015-06-29 09:03:26.959479313 +0300
> ***************
> *** 1059,1064 ****
> --- 1059,1065 ----
>    	struct addrinfo hints, *res;
>    	struct rtpp_set  *rtpp_list;
>    	struct rtpp_node *pnode;
> + 	int ip_mtu_discover = IP_PMTUDISC_DONT;
>
>    	if(rtpp_set_list==NULL )
>    		return 0;
> ***************
> *** 1121,1126 ****
> --- 1122,1131 ----
>    				return -1;
>    			}
>
> + 			setsockopt(rtpp_socks[pnode->idx], IPPROTO_IP,
> + 				   IP_MTU_DISCOVER, &ip_mtu_discover,
> + 				   sizeof(ip_mtu_discover));
> +
>    			if (bind_force_send_ip(pnode->idx) == -1) {
>    				LM_ERR("can't bind socket\n");
>    				close(rtpp_socks[pnode->idx]);
>
> any comments on this?

Good idea. I'm not sure how well this is supported on other (non-Linux) 
Unixes, so it might be advisable to enclose this in #ifdefs.

Cheers