pSOSystem System Calls - Read

pNA+ System Calls setsockopt
IP Level Options
level must be set to IPPROTO_IP for IP protocol level operations. The argument
optname can have one of the following values (defined in ):
IP_ADD_MEMBERSHIP Join a multicast group. For this option, optval is
a pointer to the ip_mreq structure (defined in
). The group multicast address must be
specified in the field imr_mcastaddr. This is a
CLASS-D IP multicast address. The
imr_interface parameter may be set to the IP
address of a specific interface for which group
membership will be enabled. The interface must
of course support multicasting. Optionally the
imr_interface parameter may be set to
INADDR_ANY in which case pNA+ will decide the
interface to join on (for example, if a route exists
for a matching multicast address that specifies
the interface). The maximum number of groups
that can be joined per multicast socket is defined
by the constant IP_MAX_MEMBERSHIPS in pna.h.
The structure below is defined in and
used with the IP_ADD_MEMBERSHIP option.
struct ip_mreq {
struct in_addr imr_mcastaddr;
/* IP multicast address of group */
struct in_addr imr_interface;
/* local IP address of interface */
};
pSOSystem System Calls 4-69
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