The following fields are defined for the IGMP header, as described in [RFC2236]:
Because field names generally follow the corresponding naming conventions used in BSD /usr/include/netinet/ include files, the ``Max Response Time'' field is called igmp_code (for ``routing code'').
Note that igmp_group is of type ``IPv4 address''.
All fields listed above are based on igmp_hdr, which in turn is defined as follows:
field igmp_hdr = ip_nexthdr if ip_proto == IPPROTO_IGMP;