When using the drouting module in b2bua configuration, it's highly possible to receive a modified from uri for anonymous purposes per RFC 3323. Here is a snippet from RFC 3323 on page 9:
"For these reasons, the hostname value 'anonymous.invalid' SHOULD be used for anonymous URIs"
This patch adds a parameter (use_src_ip) that notifies the get_group_id() method to use the actual source IP address from the IP packet instead of parsing the information from the SIP INVITE from uri. This retains the original design by default, but allows for changing the default behavior.