While using `networkInterfaces` Kurento considers only a single IP per interface

[alangecker]

Prerequisites

• [x] I have read the SUPPORT document

• [x] I have checked the Troubleshooting Guide

• [x] I have tested with the latest version of Kurento

Issue description

If networkInterfaces in WebRtcEndpoint.conf.ini is set, kurento picks only a signle IP of this interface.

Context

I try to accomplish IPv6 Support with the networkInterfaces setting as a filter.

How to reproduce?

(replace eth0 with your interface name)

• verify you have multiple IP addresses assigned to this interface with $ ip addr show eth0
• set networkInterfaces=eth0 in WebRtcEndpoint.conf.ini
• start kurento
• establish a WebRTC Connection
• check, which IP's are included in the candidates list

Expected & current behavior

I would expect that with the setting 'networkInterfaces' a connection should be possible over any IP of the mentioned interfaces, not just a single (random? first?) one.

Possible solution

kms_webrtc_base_connection_agent_add_net_addr currently uses nice_interfaces_get_ip_for_interface (gchar *interface_name) which responds with a single IP. It could use a different method for getting all IPs assigned to this interface and adding all of them to the nice_agent.

https://github.com/Kurento/kms-elements/blob/cbe7516a0e6f20ab380f4d530ad9162d5464547b/src/gst-plugins/webrtcendpoint/kmswebrtcbaseconnection.c#L220

/**
 * Add new local IP address to NiceAgent instance.
 */
static void
kms_webrtc_base_connection_agent_add_net_addr (const gchar * net_name,
    NiceAgent * agent)
{
  NiceAddress *nice_address = nice_address_new ();
  gchar *ip_address = nice_interfaces_get_ip_for_interface ((gchar *)net_name);

  nice_address_set_from_string (nice_address, ip_address);
  nice_agent_add_local_address (agent, nice_address);

  GST_INFO_OBJECT (agent, "Added local address: %s", ip_address);

  nice_address_free (nice_address);
  g_free (ip_address);
}

INFO about Kurento Media Server

• Kurento version: 6.14.0

[j1elo]

nice_interfaces_get_ip_for_interface code is here, where the important bit is the call to ioctl (sockfd, SIOCGIFADDR, &ifr).

SIOCGIFADDR docs say:

SIOCGIFADDR, SIOCSIFADDR Get or set the address of the device using ifr_addr. Setting the interface address is a privileged operation. For compati‐ bility, only AF_INET addresses are accepted or returned.

It doesn't even specify if this will be returning the first available IP address, or which one. I would assume it's the first one.

This issue doesn't look like a bug to me, more like a limitation of the current implementation / a feature request. I cannot spend time on this right now, so as always, PRs are welcome.

[prlanzarin]

@j1elo I'm going to try and take a look at this to make it dual stack compatible.