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28 .\" From: @(#)send.2 8.2 (Berkeley) 2/21/94
37 .Nd send a message from an SCTP socket
46 .Fa "int s" "const void *msg" "size_t len" "const struct sockaddr *to"
47 .Fa "socklen_t tolen" "uint32_t ppid" "uint32_t flags" "uint16_t stream_no"
48 .Fa "uint32_t timetolive" "uint32_t context"
52 .Fa "int s" "const void *msg" "size_t len" "const struct sockaddr *to"
53 .Fa "int addrcnt" "uint32_t ppid" "uint32_t flags" "uint16_t stream_no"
54 .Fa "uint32_t timetolive" "uint32_t context"
60 is used to transmit a message to another SCTP endpoint.
63 may be used at any time.
64 If the socket is a one-to-many type (SOCK_SEQPACKET)
65 socket then an attempt to send to an address that no association exists to will
66 implicitly create a new association.
67 Data sent in such an instance will result in
68 the data being sent on the third leg of the SCTP four-way handshake.
70 the socket is a one-to-one type (SOCK_STREAM) socket then an association must
71 be in existence (by use of the
78 on a non-connected one-to-one socket will result in
82 -1 being returned, and the message not being transmitted.
84 The address of the target is given by
89 The length of the message
93 If the message is too long to pass atomically through the
99 the message is not transmitted.
101 No indication of failure to deliver is implicit in a
104 Locally detected errors are indicated by a return value of -1.
106 If no space is available at the socket to hold
107 the message to be transmitted, then
109 normally blocks, unless the socket has been placed in
110 non-blocking I/O mode.
113 system call may be used to determine when it is possible to
114 send more data on one-to-one type (SOCK_STREAM) sockets.
118 argument is an opaque 32 bit value that is passed transparently
119 through the stack to the peer endpoint.
120 It will be available on
121 reception of a message (see
122 .Xr sctp_recvmsg 3 ) .
123 Note that the stack passes this value without regard to byte
128 argument may include one or more of the following:
130 #define SCTP_EOF 0x0100 /* Start a shutdown procedures */
131 #define SCTP_ABORT 0x0200 /* Send an ABORT to peer */
132 #define SCTP_UNORDERED 0x0400 /* Message is un-ordered */
133 #define SCTP_ADDR_OVER 0x0800 /* Override the primary-address */
134 #define SCTP_SENDALL 0x1000 /* Send this on all associations */
135 /* for the endpoint */
136 /* The lower byte is an enumeration of PR-SCTP policies */
137 #define SCTP_PR_SCTP_TTL 0x0001 /* Time based PR-SCTP */
138 #define SCTP_PR_SCTP_BUF 0x0002 /* Buffer based PR-SCTP */
139 #define SCTP_PR_SCTP_RTX 0x0003 /* Number of retransmissions based PR-SCTP */
144 is used to instruct the SCTP stack to queue this message
145 and then start a graceful shutdown of the association.
147 remaining data in queue will be sent after which the association
151 is used to immediately terminate an association.
153 is sent to the peer and the local TCB is destroyed.
156 is used to specify that the message being sent has no
157 specific order and should be delivered to the peer application
159 When this flag is absent messages
160 are delivered in order within the stream they are sent, but without
161 respect to order to peer streams.
165 is used to specify that an specific address should be used.
167 SCTP will use only one of a multi-homed peers addresses as the primary
169 By default, no matter what the
171 argument is, this primary address is used to send data.
173 this flag, the user is asking the stack to ignore the primary address
174 and instead use the specified address not only as a lookup mechanism
175 to find the association but also as the actual address to send to.
177 For a one-to-many type (SOCK_SEQPACKET) socket the flag
179 can be used as a convenient way to make one send call and have
180 all associations that are under the socket get a copy of the message.
181 Note that this mechanism is quite efficient and makes only one actual
182 copy of the data which is shared by all the associations for sending.
184 The remaining flags are used for the partial reliability extension (RFC3758)
185 and will only be effective if the peer endpoint supports this extension.
186 This option specifies what local policy the local endpoint should use
188 If none of these options are set, then data is
192 is used to indicate that a time based lifetime is being applied
196 argument is then a number of milliseconds for which the data is
197 attempted to be transmitted.
198 If that many milliseconds elapse
199 and the peer has not acknowledged the data, the data will be
200 skipped and no longer transmitted.
201 Note that this policy does
202 not even assure that the data will ever be sent.
203 In times of a congestion
204 with large amounts of data being queued, the
206 may expire before the first transmission is ever made.
210 based policy transforms the
212 field into a total number of bytes allowed on the outbound
214 If that number or more bytes are in queue, then
215 other buffer based sends are looked to be removed and
217 Note that this policy may also result in the data
218 never being sent if no buffer based sends are in queue and
219 the maximum specified by
225 policy transforms the
227 into a number of retransmissions to allow.
229 always assures that at a minimum one send attempt is
231 After which no more than
233 retransmissions will be made before the data is skipped.
236 is the SCTP stream that you wish to send the
238 Streams in SCTP are reliable (or partially reliable) flows of ordered
242 field is used only in the event the message cannot be sent.
244 value that the stack retains and will give to the user when a failed send
245 is given if that notification is enabled (see
247 Normally a user process can use this value to index some application
248 specific data structure when a send cannot be fulfilled.
252 with the exception that it takes an array of sockaddr structures in the
255 and adds the additional argument
257 which specifies how many addresses are in the array.
259 caller to implicitly set up an association passing multiple addresses
262 had been called to set up the association.
264 The call returns the number of characters sent, or -1
265 if an error occurred.
273 An invalid descriptor was specified.
279 An invalid user space address was specified for an argument.
281 The socket requires that message be sent atomically,
282 and the size of the message to be sent made this impossible.
284 The socket is marked non-blocking and the requested operation
287 The system was unable to allocate an internal buffer.
288 The operation may succeed when buffers become available.
290 The output queue for a network interface was full.
291 This generally indicates that the interface has stopped sending,
292 but may be caused by transient congestion.
293 .It Bq Er EHOSTUNREACH
294 The remote host was unreachable.
296 On a one-to-one style socket no association exists.
298 An abort was received by the stack while the user was
299 attempting to send data to the peer.
301 On a one-to-many style socket no address is specified
302 so that the association cannot be located or the
304 flag was specified on a non-existing association.
306 The socket is unable to send anymore data
307 .Dv ( SBS_CANTSENDMORE
308 has been set on the socket).
309 This typically means that the socket
310 is not connected and is a one-to-one style socket.
320 .Xr sctp_connectx 3 ,
323 Because in the one-to-many style socket
327 may have multiple associations under one endpoint, a
328 select on write will only work for a one-to-one style