Open System Services System Calls Reference Manual (G06.29+, H06.08+, J06.03+)

System Functions (f - i) getsockopt(2)
• -1 to indicate that the default value should be used.
IPV6_MULTICAST_LOOP
Indicates that the host belongs to the multicast group that it is
sending to, and a copy of the datagram should be sent by loop-
back to the originating host.
IPV6_UNICAST_HOPS
Indicates the hop limit for outbound unicast UDP datagrams.
The limit is an int that is either:
• Between 0 and 255 to indicate the maximum number of
hops allowed.
• -1 to indicate that the default value should be used.
IPV6_V6ONLY
Indicates that AF_INET6 sockets are restricted to IPv6-only
communication.
The getsockopt() function retrieves information about the following
IPPROTO_IP (IP protocol-level IPv4) options:
IP_OPTIONS Indicates that the value of the IP_OPTIONS flag should be
returned. The IP_OPTIONS flag indicates that options
specified in a setsockopt() function call are set for each outgo-
ing packet, in conformance with RFC 791.
IP_MULTICAST_IF
Indicates the interface (subnet) used for outbound multicast
UDP datagrams. The interface value is an unsigned int.
IP_MULTICAST_TTL
Indicates the hop limit for outbound multicast UDP datagrams.
The limit is an int that is either:
• Between 0 and 255 to indicate the maximum number of
hops allowed.
• -1 to indicate that the default value should be used.
IP_MULTICAST_LOOP
Indicates that the host belongs to the multicast group that it is
sending to, and a copy of the datagram should be sent by loop-
back to the originating host.
The getsockopt() function retrieves information about the following
SOL_SOCKET (socket protocol-level) options:
SO_ACCEPTCONN
Reports whether socket listening is enabled. This option returns
an int value in the buffer pointed to by the option_value parame-
ter.
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