is used to transmit a message to another SCTP endpoint.
may be used at any time.
If the socket is a one-to-many type (SOCK_SEQPACKET)
socket then an attempt to send to an address that no association exists to will
implicitly create a new association.
Data sent in such an instance will result in
the data being sent on the third leg of the SCTP four-way handshake.
Note that if
the socket is a one-to-one type (SOCK_STREAM) socket then an association must
be in existence (by use of the
on a non-connected one-to-one socket will result in
being set to
-1 being returned, and the message not being transmitted.
The address of the target is given by
specifying its size.
The length of the message
is given by
If the message is too long to pass atomically through the
is set to
-1 is returned, and
the message is not transmitted.
No indication of failure to deliver is implicit in a
Locally detected errors are indicated by a return value of -1.
If no space is available at the socket to hold
the message to be transmitted, then
normally blocks, unless the socket has been placed in
non-blocking I/O mode.
system call may be used to determine when it is possible to
send more data on one-to-one type (SOCK_STREAM) sockets.
argument is an opaque 32 bit value that is passed transparently
through the stack to the peer endpoint.
It will be available on
reception of a message (see
Note that the stack passes this value without regard to byte
argument may include one or more of the following:
#define SCTP_EOF 0x0100 /* Start a shutdown procedures */
#define SCTP_ABORT 0x0200 /* Send an ABORT to peer */
#define SCTP_UNORDERED 0x0400 /* Message is un-ordered */
#define SCTP_ADDR_OVER 0x0800 /* Override the primary-address */
#define SCTP_SENDALL 0x1000 /* Send this on all associations */
/* for the endpoint */
/* The lower byte is an enumeration of PR-SCTP policies */
#define SCTP_PR_SCTP_TTL 0x0001 /* Time based PR-SCTP */
#define SCTP_PR_SCTP_BUF 0x0002 /* Buffer based PR-SCTP */
#define SCTP_PR_SCTP_RTX 0x0003 /* Number of retransmissions based PR-SCTP */
is used to instruct the SCTP stack to queue this message
and then start a graceful shutdown of the association.
remaining data in queue will be sent after which the association
will be shut down.
is used to immediately terminate an association.
is sent to the peer and the local TCB is destroyed.
is used to specify that the message being sent has no
specific order and should be delivered to the peer application
as soon as possible.
When this flag is absent messages
are delivered in order within the stream they are sent, but without
respect to order to peer streams.
is used to specify that an specific address should be used.
SCTP will use only one of a multi-homed peers addresses as the primary
address to send to.
By default, no matter what the
argument is, this primary address is used to send data.
this flag, the user is asking the stack to ignore the primary address
and instead use the specified address not only as a lookup mechanism
to find the association but also as the actual address to send to.
For a one-to-many type (SOCK_SEQPACKET) socket the flag
can be used as a convenient way to make one send call and have
all associations that are under the socket get a copy of the message.
Note that this mechanism is quite efficient and makes only one actual
copy of the data which is shared by all the associations for sending.
The remaining flags are used for the partial reliability extension (RFC3758)
and will only be effective if the peer endpoint supports this extension.
This option specifies what local policy the local endpoint should use
in skipping data.
If none of these options are set, then data is
never skipped over.
is used to indicate that a time based lifetime is being applied
to the data.
argument is then a number of milliseconds for which the data is
attempted to be transmitted.
If that many milliseconds elapse
and the peer has not acknowledged the data, the data will be
skipped and no longer transmitted.
Note that this policy does
not even assure that the data will ever be sent.
In times of a congestion
with large amounts of data being queued, the
may expire before the first transmission is ever made.
based policy transforms the
field into a total number of bytes allowed on the outbound
If that number or more bytes are in queue, then
other buffer based sends are looked to be removed and
Note that this policy may also result in the data
never being sent if no buffer based sends are in queue and
the maximum specified by
bytes is in queue.
policy transforms the
into a number of retransmissions to allow.
always assures that at a minimum one send attempt is
made of the data.
After which no more than
retransmissions will be made before the data is skipped.
is the SCTP stream that you wish to send the
Streams in SCTP are reliable (or partially reliable) flows of ordered
field is used only in the event the message cannot be sent.
This is an opaque
value that the stack retains and will give to the user when a failed send
is given if that notification is enabled (see
Normally a user process can use this value to index some application
specific data structure when a send cannot be fulfilled.
is identical to
with the exception that it takes an array of sockaddr structures in the
and adds the additional argument
which specifies how many addresses are in the array.
This allows a
caller to implicitly set up an association passing multiple addresses
had been called to set up the association.