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32 .\" From: @(#)send.2 8.2 (Berkeley) 2/21/94
41 .Nd send a message from an SCTP socket
50 .Fa "int s" "const void *msg" "size_t len" "const struct sockaddr *to"
51 .Fa "socklen_t tolen" "uint32_t ppid" "uint32_t flags" "uint16_t stream_no"
52 .Fa "uint32_t timetolive" "uint32_t context"
56 .Fa "int s" "const void *msg" "size_t len" "const struct sockaddr *to"
57 .Fa "int addrcnt" "uint32_t ppid" "uint32_t flags" "uint16_t stream_no"
58 .Fa "uint32_t timetolive" "uint32_t context"
64 is used to transmit a message to another SCTP endpoint.
67 may be used at any time.
68 If the socket is a one-to-many type (SOCK_SEQPACKET)
69 socket then an attempt to send to an address that no association exists to will
70 implicitly create a new association.
71 Data sent in such an instance will result in
72 the data being sent on the third leg of the SCTP four-way handshake.
74 the socket is a one-to-one type (SOCK_STREAM) socket then an association must
75 be in existance (by use of the
82 on a non-connected one-to-one socket will result in
86 -1 being returned, and the message not being transmitted.
88 The address of the target is given by
93 The length of the message
97 If the message is too long to pass atomically through the
103 the message is not transmitted.
105 No indication of failure to deliver is implicit in a
108 Locally detected errors are indicated by a return value of -1.
110 If no space is available at the socket to hold
111 the message to be transmitted, then
113 normally blocks, unless the socket has been placed in
114 non-blocking I/O mode.
117 system call may be used to determine when it is possible to
118 send more data on one-to-one type (SOCK_STREAM) sockets.
122 argument is an opaque 32 bit value that is passed transparently
123 through the stack to the peer endpoint.
124 It will be available on
125 reception of a message (see
126 .Xr sctp_recvmsg 2 ) .
127 Note that the stack passes this value without regard to byte
132 argument may include one or more of the following:
134 #define SCTP_EOF 0x0100 /* Start a shutdown procedures */
135 #define SCTP_ABORT 0x0200 /* Send an ABORT to peer */
136 #define SCTP_UNORDERED 0x0400 /* Message is un-ordered */
137 #define SCTP_ADDR_OVER 0x0800 /* Override the primary-address */
138 #define SCTP_SENDALL 0x1000 /* Send this on all associations */
139 /* for the endpoint */
140 /* The lower byte is an enumeration of PR-SCTP policies */
141 #define SCTP_PR_SCTP_TTL 0x0001 /* Time based PR-SCTP */
142 #define SCTP_PR_SCTP_BUF 0x0002 /* Buffer based PR-SCTP */
143 #define SCTP_PR_SCTP_RTX 0x0003 /* Number of retransmissions based PR-SCTP */
148 is used to instruct the SCTP stack to queue this message
149 and then start a graceful shutdown of the association.
151 remaining data in queue will be sent after which the association
155 is used to immediately terminate an association.
157 is sent to the peer and the local TCB is destroyed.
160 is used to specify that the message being sent has no
161 specific order and should be delivered to the peer application
163 When this flag is absent messages
164 are delivered in order within the stream they are sent, but without
165 respect to order to peer streams.
169 is used to specify that an specific address should be used.
171 SCTP will use only one of a multi-homed peers addresses as the primary
173 By default, no matter what the
175 argument is, this primary address is used to send data.
177 this flag, the user is asking the stack to ignore the primary address
178 and instead use the specified address not only as a lookup mechanism
179 to find the association but also as the actual address to send to.
181 For a one-to-many type (SOCK_SEQPACKET) socket the flag
183 can be used as a convient way to make one send call and have
184 all associations that are under the socket get a copy of the message.
185 Note that this mechanism is quite efficent and makes only one actual
186 copy of the data which is shared by all the associations for sending.
188 The remaining flags are used for the partial reliability extension (RFC3758)
189 and will only be effective if the peer endpoint supports this extension.
190 This option specifies what local policy the local endpoint should use
192 If none of these options are set, then data is
196 is used to indicate that a time based lifetime is being applied
200 argument is then a number of milliseconds for which the data is
201 attempted to be transmitted.
202 If that many milliseconds ellapse
203 and the peer has not acknowledged the data, the data will be
204 skipped and no longer transmitted.
205 Note that this policy does
206 not even assure that the data will ever be sent.
207 In times of a congestion
208 with large amounts of data being queued, the
210 may expire before the first transmission is ever made.
214 based policy transforms the
216 field into a total number of bytes allowed on the outbound
218 If that number or more bytes are in queue, then
219 other buffer based sends are looked to be removed and
221 Note that this policy may also result in the data
222 never being sent if no buffer based sends are in queue and
223 the maximum specified by
229 policy transforms the
231 into a number of retransmissions to allow.
233 always assures that at a minimum one send attempt is
235 After which no more than
237 retransmissions will be made before the data is skipped.
240 is the SCTP stream that you wish to send the
242 Streams in SCTP are reliable (or partially reliable) flows of ordered
246 field is used only in the event the message cannot be sent.
248 value that the stack retains and will give to the user when a failed send
249 is given if that notification is enabled (see
251 Normally a user process can use this value to index some application
252 specific data structure when a send cannot be fulfilled.
256 with the exception that it takes an array of sockaddr structures in the
259 and adds the additional argument
261 which specifies how many addresses are in the array.
263 caller to implicitly set up an association passing multiple addresses
266 had been called to set up the association.
268 The call returns the number of characters sent, or -1
269 if an error occurred.
277 An invalid descriptor was specified.
283 An invalid user space address was specified for an argument.
285 The socket requires that message be sent atomically,
286 and the size of the message to be sent made this impossible.
288 The socket is marked non-blocking and the requested operation
291 The system was unable to allocate an internal buffer.
292 The operation may succeed when buffers become available.
294 The output queue for a network interface was full.
295 This generally indicates that the interface has stopped sending,
296 but may be caused by transient congestion.
297 .It Bq Er EHOSTUNREACH
298 The remote host was unreachable.
300 On a one-to-one style socket no association exists.
302 An abort was received by the stack while the user was
303 attempting to send data to the peer.
305 On a one-to-many style socket no address is specified
306 so that the association cannot be located or the
308 flag was specified on a non-existing association.
310 The socket is unable to send anymore data
311 .Dv ( SBS_CANTSENDMORE
312 has been set on the socket).
313 This typically means that the socket
314 is not connected and is a one-to-one style socket.
323 .Xr sctp_connectx 3 ,
327 Because in the one-to-many style socket
331 may have multiple associations under one endpoint, a
332 select on write will only work for a one-to-one style