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io_net_msg_mcast

Structure used for multicast address filtering

Synopsis:

typedef struct _io_net_msg_mcast;

struct _io_net_msg_mcast {
      uint16_t     type;
      uint32_t     flags;
      uint16_t     next; 
      uint32_t     mc_min;
      uint32_t     mc_max;
};

Description:

The io_net_msg_mcast structure contains information concerning the changes required to multicast addresses that have been identified by the DCMD_IO_NET_CHANGE_MCAST devctl.

The members include:

type

The type of request. If it's set to _IO_NET_JOIN_MCAST, the request specifies a range of multicast addresses for which reception should be enabled. If it's set to IO_NET_REMOVE_MCAST, the request specifies a range of addresses for which multicast packet reception should no longer be enabled. (In this case, the address range was previously enabled via an _IO_NET_JOIN_MCAST request.)

If the field doesn't contain either of these two values, it means that the networking subsystem is responding to a DCMD_IO_NET_CHANGE_MCAST devctl that the driver issued.

flags

Currently only one flag is defined:

• _IO_NET_MCAST_ALL -- if set, specifies that the device should be put into, or taken out of, promiscuous multicast mode.

  If the type field was set to _IO_NET_JOIN_MCAST, the device should be put into promiscuous multicast mode.

  If the type field was set to _IO_NET_REMOVE_MCAST, the device should be taken out of promiscuous multicast mode, in which case the device should revert to filtering based on the enabled range(s) of multicast addresses. When in promiscuous mode, the device should receive all multicast packets.

next

Used to chain multiple _io_net_msg_mcast structures into a linked-list when the driver issues a DCMD_IO_NET_CHANGE devctl. When the driver traverses the list, it accesses the entire database of currently enabled multicast address ranges.

mc_min and mc_max

Specifies the minimum and maximum addresses within a range of multicast addresses. The LLADDR macro, defined in <net/if_dl.h>, can be used to obtain a pointer to the actual, physical MAC address, e.g. if mcast points to struct io_net_msg_mcast, the start and end of the address range can be obtained as follows:

    LLADDR(mcast->mc_min.addr_dl)
    LLADDR(mcast->mc_max.addr_dl)

If type was _IO_NET_JOIN_MCAST, the driver should enable reception of packets whose destination addresses are within these inclusive address ranges.

If type was _IO_NET_REMOVE_MCAST, the driver should disable reception of packets whose destination addresses are within these inclusive address ranges (in this case, the address range will have previously been enabled via an _IO_NET_JOIN_MCAST message).

If the _IO_NET_MCAST_ALL flag was set, mc_min and mc_max are irrelevant, and shouldn't be referenced.

Classification:

QNX Neutrino