SCTP Programmer's Guide

NOTE: If an application calls a send function without user and ancillary data, SCTP

rejects the request with an appropriate error message.

The setsocktopt() and getsockopt() Socket Calls

Applications use the setsockopt() and the getsockopt() calls to set and retrieve

socket options. You can use the socket options to modify the default behavior of the

sockets calls. For information on socket options, see “API Options to Modify Socket

Behavior” (page 52).

NOTE: While using the SCTP_ASSOCINFO option to set the maximum number of

retransmissions, the sctp_opt_info() call does not fail if this number is greater than

the sum of all maximum path retransmissions for each remote address. Therefore, the

success or failure of this option does not depend on the number of remote addresses

and whether the association is up.

Following are the syntaxes for the getsockopt() and setsockopt() socket calls,

respectively:

getsockopt(int sd, int level, int optname, void *optval,

socklen_t *optlen);

setsockopt(int sd, int level, int optname, const void *optval,

socklen_t optlen);

where:

Specifies the socket description.

level Specifies the type of protocol. You must set the level to IPPROTO_SCTP

for all SCTP options.

optname

Specifies the option name.

optval

Specifies the buffer to store the value of the option.

optlen

Specifies the size of the buffer (or the length of the option returned).

NOTE: A positive linger time for the SO_LINGER option results in an immediate

termination of the process following the SCTP shutdown.

The read() and write() Socket Calls

Applications use read() and write() socket calls to send and receive data to and

from a peer. These socket calls have the same functionality as the send() and recv()

socket calls, except that the flags parameter is not present in the read() and write()

calls.

If these calls are used in one-to-many style sockets, applications can use these calls only

with branched off socket descriptors.

56 SCTP Socket APIs