pSOSystem System Calls - Read

getsockopt pNA+ System Calls
Return Value
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:
IP_HDRINCL Specifies that the IP Header will be included in the output
packets. The following fields will be set by pNA+ if they are
set to 0 in the included IP header: IP identification number
and IP source address. The fragmentation offset and
checksum fields are always computed by pNA+. The rest
of the IP header fields must be set appropriately.
IP_MULTICAST_IF Specifies the outgoing interface for multicast packets. For
this option, optval is a pointer to struct in_addr. If
set to INADDR_ANY then the routing table will be used to
select an appropriate interface.
IP_MULTICAST_INTF Specifies the outgoing interface for multicast packets. The
outgoing interface is defined by its interface number. The
optval is a pointer to a long. If set to -1 then the routing
table will be used to select an appropriate interface,
which is also the default case.
IP_MULTICAST_LOOP Specifies whether or not to loopback multicast packets.
optval is a pointer to an unsigned char. By default the
packets are looped back
(IP_DEFAULT_MULTICAST_LOOP.) A value of 0 disables
loopback.
IP_MULTICAST_TTL Specifies the time-to-live for outgoing IP multicast datagrams.
optval is a pointer to an unsigned char. The default
is IP_DEFAULT_MULTICAST_TTL.
This system call returns 0 if successful, otherwise it returns -1.
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