sctp_opt_info - examine SCTP level options for an SCTP endpoint
cc [ flag... ] file... –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 association id can be ignored for one-to-one style or branched-off one-to-many style SCTP sockets.
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:
Association ID specified by the caller
Initial RTO value
Maximum value for the RTO
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:
Association ID specified by the caller
Maximum retransmission count for the association
Number of addresses the peer has
Current value of the peer's receive window
Last reported receive window sent to the peer
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:
Default stream for sendmsg()
Always returned as 0
Default flags for sendmsg() that include the following:
Default payload protocol identifier for sendmsg()
Default context for sendmsg()
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.
Always returned as 0
Always returned as 0
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;
uint32_t spp_pathmtu;
uint32_t spp_flags;
uint32_t spp_ipv6_flowlabel;
uint8_t spp_ipv4_tos;
};
where:
Association ID specified by the caller.
Peer's address.
Heartbeat interval in milliseconds.
Maximum number of retransmissions to an address before it is considered unreachable.
The current path MTU of the peer address. It is the number of bytes available in an SCTP packet for chunks. Providing a value of 0 does not change the current setting. If a positive value is provided and SPP_PMTUD_DISABLE is set in spp_flags, the given value is used as the path MTU. If SPP_PMTUD_ENABLE is set in spp_flags, the spp_pathmtu field is ignored.
This field is used in conjunction with the SPP_IPV6_FLOWLABEL flag. This setting has precedence over any IPv6 layer setting.
This field is used in conjunction with the SPP_IPV4_TOS flag. This setting has precedence over any IPv4 layer setting.
These flags are used to control various features on an association. The flag field is a bit mask which may contain zero or more of the following options:
Enable heartbeats on the specified address.
Disable heartbeats on the specified address. Note that SPP_HB_ENABLE and SPP_HB_DISABLE are mutually exclusive, only one of these two should be specified. Enabling both fields will have undetermined results.
Request a user initiated heartbeat to be made immediately. This must not be used in conjunction with a wildcard address.
Specifies that the time for heartbeat delay is to be set to the value of 0 milliseconds.
This field will enable PMTU discovery upon the specified address.
This field will disable PMTU discovery upon the specified address. Note that if the address field is empty then all addresses on the association are affected. Note also that SPP_PMTUD_ENABLE and SPP_PMTUD_DISABLE are mutually exclusive. Enabling both will have undetermined results.
Setting this flag enables the setting of the IPV6 flowlabel value. The value is obtained in the spp_ipv6_flowlabel field.
Upon retrieval, this flag will be set to indicate that the spp_ipv6_flowlabel field has a valid value returned. If a specific destination address is set (in the spp_address field), the value returned is that of the address. If just an association is specified (and no address), then the association's default flowlabel is returned. If neither an association nor a destination is specified, then the socket's default flowlabel is returned. For non IPv6 sockets, this flag will be left cleared.
Setting this flag enables the setting of the IPV4 TOS value associated with either the association or a specific address. The value is obtained in the spp_ipv4_tos field.
Upon retrieval, this flag will be set to indicate that the spp_ipv4_tos field has a valid value returned. If a specific destination address is set when called (in the spp_address field) then that specific destination address' TOS value is returned. If just an association is specified then the association default TOS is returned. If neither an association nor a destination is specified, then the sockets default TOS is returned.
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:
Association ID specified by the caller
Current state of the association which might be one of the following:
Current receive window of the association peer
Number of unacked DATA chunks
Number of DATA chunks pending receipt
Number of inbound streams
Number of outbound streams
Size at which SCTP fragmentation occurs
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:
Association ID specified by the caller
Primary peer address
State of the peer address: SCTP_ACTIVE or SCTP_INACTIVE
Congestion window of the peer address
Smoothed round-trip time calculation of the peer address
Current retransmission timeout value of the peer address in milliseconds
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.
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(7) for descriptions of the following attributes:
|
getsockopt(3C), setsockopt(3C), socket(3C), in.h(3HEAD), libsctp(3LIB), inet(4P), inet6(4P), ip(4P), ip6(4P), sctp(4P)