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cc [ flag... ] file... -lsocket -lnsl -lsctp [ library... ] #include <sys/types.h> #include <sys/socket.h> #include <netinet/sctp.h> int sctp_opt_info(int sock, sctp_assoc_t id, int opt, void *arg, socklen_t *len);
The sctp_opt_info() returns SCTP level options associated with the SCTP socket sock. If sock is a one-to-many style socket, id refers to the association of interest. If sock is a one-to-one socket or if sock is a branched-off one-to-many style socket, id is ignored. The opt parameter specifies the SCTP option to get. The arg structure is an option-specific structure buffer allocated by the caller. The len parameter is the length of the option specified.
Following are the currently supported values for the opt parameter. When one of the options below specifies an association id, the id is relevant for only one-to-many style SCTP sockets. The associatation id can be ignored for one-to-one style or branched-off one-to-many style SCTP sockets. SCTP_RTOINFO
Returns the protocol parameters used to initialize and bind retransmission timeout (RTO) tunable. The following structure is used to access these parameters:
struct sctp_rtoinfo {
sctp_assoc_t srto_assoc_id;
uint32_t srto_initial;
uint32_t srto_max;
uint32_t srto_min;
};
where:
srto_assoc_id Association ID specified by the caller
srto_initial Initial RTO value
srto_max Maximum value for the RTO
srto_min Minimum value for the RTO
Returns association-specific parameters. The following structure is used to access the parameters:
struct sctp_assocparams {
sctp_assoc_t sasoc_assoc_id;
uint16_t sasoc_asocmaxrxt;
uint16_t sasoc_number_peer_destinations;
uint32_t sasoc_peer_rwnd;
uint32_t sasoc_local_rwnd;
uint32_t sasoc_cookie_life;
};
where:
srto_assoc_id Association ID specified by the caller
sasoc_asocmaxrxt Maximum retransmission count for
the association
sasoc_number_peer_destinations
Number of addresses the peer has
sasoc_peer_rwnd Current value of the peer's
receive window
sasoc_local_rwnd Last reported receive window sent
to the peer
sasoc_cookie_life Association cookie lifetime used
when issuing cookies
All parameters with time values are in milliseconds.
Returns the default set of parameters used by the sendto() function on this association. The following structure is used to access the parameters:
struct sctp_sndrcvinfo {
uint16_t sinfo_stream;
uint16_t sinfo_ssn;
uint16_t sinfo_flags;
uint32_t sinfo_ppid;
uint32_t sinfo_context;
uint32_t sinfo_timetolive;
uint32_t sinfo_tsn;
uint32_t sinfo_cumtsn;
sctp_assoc_t sinfo_assoc_id;
};
where:
sinfo_stream Default stream for sendmsg()
sinfo_ssn Always returned as 0
sinfo_flags Default flags for sendmsg()
that include the following:
MSG_UNORDERED
MSG_ADDR_OVER
MSG_ABORT
MSG_EOF
MSG_PR_SCTP
sinfo_ppid Default payload protocol identifier
for sendmsg()
sinfo_context Default context for sendmsg()
sinfo_timetolive Time to live in milliseconds for a
message on the sending side.
The message expires if the sending
side does not start the first
transmission for the message within
the specified time period. If the
sending side starts the first
transmission before the time period
expires, the message is sent as a
normal reliable message. A value of
0 indicates that the message does not
expire. When MSG_PR_SCTP is set in
sinfo_flags, the message expires if
it is not acknowledged within the
time period.
sinfo_tsn Always returned as 0
sinfo_cumtsn Always returned as 0
sinfo_assoc_id Association ID specified by the caller
Returns the parameters for a specified peer address of the association. The following structure is used to access the parameters:
struct sctp_paddrparams {
sctp_assoc_t spp_assoc_id;
struct sockaddr_storage spp_address;
uint32_t spp_hbinterval;
uint16_t spp_pathmaxrxt;
};
where:
spp_assoc_id Association ID specified by the caller
spp_address Peer's address
spp_hbinterval Heartbeat interval in milliseconds
spp_pathmaxrxt Maximum number of retransmissions
to an address before it is
considered unreachable
Returns the current status information about the association. The following structure is used to access the parameters:
struct sctp_status {
sctp_assoc_t sstat_assoc_id;
int32_t sstat_state;
uint32_t sstat_rwnd;
uint16_t sstat_unackdata;
uint16_t sstat_penddata;
uint16_t sstat_instrms;
uint16_t sstat_outstrms;
uint16_t sstat_fragmentation_point;
struct sctp_paddrinfo sstat_primary;
};
where:
sstat_assoc_id Association ID specified by the caller
sstat_state Current state of the association
which might be one of the following:
SCTP_CLOSED
SCTP_BOUND
SCTP_LISTEN
SCTP_COOKIE_WAIT
SCTP_COOKIE_ECHOED
SCTP_ESTABLISHED
SCTP_SHUTDOWN_PENDING
SCTP_SHUTDOWN_SENT
SCTP_SHUTDOWN_RECEIVED
SCTP_SHUTDOWN_ACK_SENT
sstat_rwnd Current receive window of the
association peer
sstat_unackdata Number of unacked DATA chunks
sstat_penddata Number of DATA chunks pending
receipt
sstat_instrms Number of inbound streams
sstat_outstrms Number of outbound streams
sstat_fragmentation_point
Size at which SCTP fragmentation occurs
sstat_primary Information about the primary
peer address
sstat_primary has the following structure
struct sctp_paddrinfo {
sctp_assoc_t spinfo_assoc_id;
struct sockaddr_storage spinfo_address;
int32_t spinfo_state;
uint32_t spinfo cwnd;
uint32_t spinfo_srtt;
uint32_t spinfo_rto;
uint32_t spinfo_mtu;
};
where:
spinfo_assoc_id Association ID
specified by
the caller
spinfo_address Primary peer
address
spinfo_state State of the peer
address:
SCTP_ACTIVE or
SCTP_INACTIVE
spinfo_cwnd Congestion window
of the peer
address
spinfo_srtt Smoothed round-trip
time calculation of
the peer address
spinfo_rto Current retransmission
timeout value of the
peer address in
milliseconds
spinfo_mtu P-MTU of the address
Upon successful completion, the sctp_opt_info() function returns 0. Otherwise, the function returns -1 and sets errno to indicate the error.
The sctp_opt_info() call fails under the following conditions. EBADF
The sock argument is an invalid file descriptor.
The sock argument is not a socket.
The association id is invalid for a one-to-many style SCTP socket.
The input buffer length is insufficient for the option specified.
The peer address is invalid or does not belong to the association.
The address family for the peer's address is other than AF_INET or AF_INET6.
See attributes(5) for descriptions of the following attributes:
| ATTRIBUTE TYPE ATTRIBUTE VALUE |
| Interface Stability Evolving |
| MT-Level Safe |
in.h(3HEAD), libsctp(3LIB), getsockopt(3SOCKET), setsockopt(3SOCKET), sockaddr(3SOCKET), socket(3SOCKET), inet(7P), inet6(7P), ip(7P), ip6(7P), sctp(7P)