1
<?xml version="1.0" encoding="latin1" ?>
2
<!DOCTYPE erlref SYSTEM "erlref.dtd">
9
<holder>Ericsson AB, All Rights Reserved</holder>
12
The contents of this file are subject to the Erlang Public License,
13
Version 1.1, (the "License"); you may not use this file except in
14
compliance with the License. You should have received a copy of the
15
Erlang Public License along with this software. If not, it can be
16
retrieved online at http://www.erlang.org/.
18
Software distributed under the License is distributed on an "AS IS"
19
basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
20
the License for the specific language governing rights and limitations
23
The Initial Developer of the Original Code is Ericsson AB.
26
<title>gen_sctp</title>
27
<prepared>raimo@erix.ericsson.se</prepared>
28
<responsible></responsible>
32
<date>2007-03-21</date>
34
<file>gen_sctp.sgml</file>
36
<module>gen_sctp</module>
37
<modulesummary>The gen_sctp module provides functions for communicating with sockets using the SCTP protocol.</modulesummary>
39
<p>The <c>gen_sctp</c> module provides functions for communicating with
40
sockets using the SCTP protocol. The implementation assumes that
41
the OS kernel supports SCTP
42
<url href="http://www.rfc-archive.org/getrfc.php?rfc=2960">(RFC2960)</url> through the user-level
43
<url href="http://tools.ietf.org/html/draft-ietf-tsvwg-sctpsocket-13">Sockets API Extensions.</url>
44
During development this implementation was tested on
45
Linux Fedora Core 5.0 (kernel 2.6.15-2054 or later is needed),
46
and on Solaris 10, 11. During OTP adaptation it was tested on
47
SUSE Linux Enterprise Server 10 (x86_64) kernel 2.6.16.27-0.6-smp,
48
with lksctp-tools-1.0.6, briefly on Solaris 10, and later on
49
SUSE Linux Enterprise Server 10 Service Pack 1 (x86_64)
50
kernel 2.6.16.54-0.2.3-smp with lksctp-tools-1.0.7.</p>
51
<p>Record definitions for the <c>gen_sctp</c> module can be found using:</p>
53
-include_lib("kernel/include/inet_sctp.hrl"). </pre>
54
<p>These record definitions use the "new" spelling 'adaptation',
55
not the deprecated 'adaption', regardless of which
56
spelling the underlying C API uses.</p>
60
<marker id="contents"></marker>
61
<title>CONTENTS</title>
62
<list type="bulleted">
63
<item><seealso marker="#types">DATA TYPES</seealso></item>
64
<item><seealso marker="#exports">EXPORTS</seealso></item>
65
<item><seealso marker="#options">SCTP SOCKET OPTIONS</seealso></item>
66
<item><seealso marker="#examples">SCTP EXAMPLES</seealso></item>
67
<item><seealso marker="#seealso">SEE ALSO</seealso></item>
68
<item><seealso marker="#authors">AUTHORS</seealso></item>
73
<marker id="types"></marker>
74
<title>DATA TYPES</title>
75
<marker id="type-assoc_id"></marker>
77
<tag><c>assoc_id()</c></tag>
79
<p>An opaque term returned in for example #sctp_paddr_change{}
80
that identifies an association for an SCTP socket. The term
81
is opaque except for the special value <c>0</c> that has a
82
meaning such as "the whole endpoint" or "all future associations".</p>
83
<marker id="type-charlist"></marker>
85
<tag><c>charlist() = [char()]</c></tag>
86
<item> <marker id="type-iolist"></marker>
88
<tag><c>iolist() = [char() | binary()]</c></tag>
89
<item> <marker id="type-ip_address"></marker>
91
<tag><c>ip_address()</c></tag>
93
<p>Represents an address of an SCTP socket.
94
It is a tuple as explained in
95
<seealso marker="inet">inet(3)</seealso>.</p>
96
<marker id="type-port_number"></marker>
98
<tag><c>port_number() = 0 .. 65535</c></tag>
99
<item> <marker id="type-posix"></marker>
101
<tag><c>posix()</c></tag>
104
<seealso marker="inet#error_codes">inet(3); POSIX Error Codes.</seealso></p>
105
<marker id="type-sctp_option"></marker>
107
<tag><c>sctp_option()</c></tag>
110
<seealso marker="#options">SCTP Socket Options.</seealso></p>
111
<marker id="type-sctp_socket"></marker>
113
<tag><c>sctp_socket()</c></tag>
115
<p>Socket identifier returned from <c>open/*</c>.</p>
116
<marker id="type-timeout"></marker>
118
<tag><c>timeout() = int() | infinity</c></tag>
120
<p>Timeout used in SCTP connect and receive calls.</p>
123
<marker id="exports"></marker>
127
<name>abort(sctp_socket(), Assoc) -> ok | {error, posix()}</name>
128
<fsummary>Abnormally terminate the association given by Assoc, without flushing of unsent data</fsummary>
130
<v>Assoc = #sctp_assoc_change{}</v>
133
<p>Abnormally terminates the association given by <c>Assoc</c>, without
134
flushing of unsent data. The socket itself remains open. Other
135
associations opened on this socket are still valid, and it can be
136
used in new associations.</p>
140
<name>close(sctp_socket()) -> ok | {error, posix()}</name>
141
<fsummary>Completely close the socket and all associations on it</fsummary>
143
<p>Completely closes the socket and all associations on it. The unsent
144
data is flushed as in <c>eof/2</c>. The <c>close/1</c> call
145
is blocking or otherwise depending of the value of
146
the <seealso marker="#option-linger">linger</seealso> socket
147
<seealso marker="#options">option</seealso>.
148
If <c>close</c> does not linger or linger timeout expires,
149
the call returns and the data is flushed in the background.</p>
153
<name>connect(Socket, Addr, Port, Opts) -> {ok,Assoc} | {error, posix()}</name>
154
<fsummary>Same as <c>connect(Socket, Addr, Port, Opts, infinity)</c>.</fsummary>
156
<p>Same as <c>connect(Socket, Addr, Port, Opts, infinity)</c>.</p>
160
<name>connect(Socket, Addr, Port, [Opt], Timeout) -> {ok, Assoc} | {error, posix()}</name>
161
<fsummary>Establish a new association for the socket <c>Socket</c>, with a peer (SCTP server socket)</fsummary>
163
<v>Socket = sctp_socket()</v>
164
<v>Addr = ip_address() | Host</v>
165
<v>Port = port_number()</v>
166
<v>Opt = sctp_option()</v>
167
<v>Timeout = timeout()</v>
168
<v>Host = atom() | string()</v>
169
<v>Assoc = #sctp_assoc_change{}</v>
172
<p>Establishes a new association for the socket <c>Socket</c>,
173
with the peer (SCTP server socket) given by
174
<c>Addr</c> and <c>Port</c>. The <c>Timeout</c>,
175
is expressed in milliseconds.</p>
176
<p>A socket can be associated with multiple peers.
177
<marker id="record-sctp_assoc_change"></marker>
179
The result of <c>connect/*</c> is an <c>#sctp_assoc_change{}</c>
180
event which contains, in particular, the new
181
<seealso marker="#type-assoc_id">Association ID:</seealso></p>
186
outbound_streams = int(),
187
inbound_streams = int(),
188
assoc_id = assoc_id()
190
<p>The number of outbound and inbound streams can be set by
191
giving an <c>sctp_initmsg</c> option to <c>connect</c>
194
connect(Socket, Ip, Port,
195
[{sctp_initmsg,#sctp_initmsg{num_ostreams=OutStreams,
196
max_instreams=MaxInStreams}}]) </pre>
197
<p>All options <c>Opt</c> are set on the socket before the
198
association is attempted. If an option record has got undefined
199
field values, the options record is first read from the socket
200
for those values. In effect, <c>Opt</c> option records only
201
define field values to change before connecting.</p>
202
<p>The returned <c>outbound_streams</c> and <c>inbound_streams</c>
203
are the actual stream numbers on the socket, which may be different
204
from the requested values (<c>OutStreams</c> and <c>MaxInStreams</c>
205
respectively) if the peer requires lower values.</p>
206
<p>The following values of <c>state</c> are possible:</p>
207
<list type="bulleted">
209
<p><c>comm_up</c>: association successfully established. This
210
indicates a successful completion of <c>connect</c>.</p>
213
<p><c>cant_assoc</c>: association cannot be established
214
(<c>connect/*</c> failure).</p>
217
<p>All other states do not normally occur in the output from
218
<c>connect/*</c>. Rather, they may occur in
219
<c>#sctp_assoc_change{}</c> events received instead of data in
220
<seealso marker="#recv/1">recv/*</seealso> calls.
221
All of them indicate losing the association due to various
222
error conditions, and are listed here for the sake of completeness.
223
The <c>error</c> field may provide more detailed diagnostics.</p>
224
<list type="bulleted">
226
<p><c>comm_lost</c>;</p>
229
<p><c>restart</c>;</p>
232
<p><c>shutdown_comp</c>.</p>
238
<name>controlling_process(sctp_socket(), pid()) -> ok</name>
239
<fsummary>Assign a new controlling process pid to the socket</fsummary>
241
<p>Assigns a new controlling process Pid to Socket. Same implementation
242
as <c>gen_udp:controlling_process/2</c>.</p>
246
<name>eof(Socket, Assoc) -> ok | {error, Reason}</name>
247
<fsummary>Gracefully terminate the association given by Assoc, with flushing of all unsent data</fsummary>
249
<v>Socket = sctp_socket()</v>
250
<v>Assoc = #sctp_assoc_change{}</v>
253
<p>Gracefully terminates the association given by <c>Assoc</c>, with
254
flushing of all unsent data. The socket itself remains open. Other
255
associations opened on this socket are still valid, and it can be
256
used in new associations.</p>
260
<name>listen(Socket, IsServer) -> ok | {error, Reason}</name>
261
<fsummary>Set up a socket to listen.</fsummary>
263
<v>Socket = sctp_socket()</v>
264
<v>IsServer = bool()</v>
267
<p>Sets up a socket to listen on the IP address and port number
268
it is bound to. IsServer must be 'true' or 'false'.
269
In the contrast to TCP, in SCTP there is no listening queue length.
270
If IsServer is 'true' the socket accepts new associations, i.e.
271
it will become an SCTP server socket.</p>
275
<name>open() -> {ok, Socket} | {error, posix()}</name>
276
<name>open(Port) -> {ok, Socket} | {error, posix()}</name>
277
<name>open([Opt]) -> {ok, Socket} | {error, posix()}</name>
278
<name>open(Port, [Opt]) -> {ok, Socket} | {error, posix()}</name>
279
<fsummary>Create an SCTP socket and bind it to local addresses</fsummary>
281
<v>Opt = {ip,IP} | {ifaddr,IP} | {port,Port} | sctp_option()</v>
282
<v>IP = ip_address() | any | loopback</v>
283
<v>Port = port_number()</v>
286
<p>Creates an SCTP socket and binds it to the local addresses
287
specified by all <c>{ip,IP}</c> (or synonymously <c>{ifaddr,IP}</c>)
288
options (this feature is called SCTP multi-homing).
289
The default <c>IP</c> and <c>Port</c> are <c>any</c>
290
and <c>0</c>, meaning bind to all local addresses on any
292
<p>A default set of socket <seealso marker="#options">options</seealso>
293
is used. In particular, the socket is opened in
294
<seealso marker="#option-binary">binary</seealso> and
295
<seealso marker="#option-active">passive</seealso> mode,
296
and with reasonably large
297
<seealso marker="#option-sndbuf">kernel</seealso> and driver
298
<seealso marker="#option-buffer">buffers.</seealso></p>
302
<name>recv(sctp_socket()) -> {ok, {FromIP, FromPort, AncData, BinMsg}} | {error, Reason}</name>
303
<name>recv(sctp_socket(), timeout()) -> {ok, {FromIP, FromPort, AncData, Data}} | {error, Reason}</name>
304
<fsummary>Receive a message from a socket</fsummary>
306
<v>FromIP = ip_address()</v>
307
<v>FromPort = port_number()</v>
308
<v>AncData = [#sctp_sndrcvinfo{}]</v>
309
<v>Data = binary() | charlist() | #sctp_sndrcvinfo{} |
310
#sctp_assoc_change{} | #sctp_paddr_change{} |
311
#sctp_adaptation_event{} </v>
312
<v>Reason = posix() | #sctp_send_failed{} | #scpt_paddr_change{} |
313
#sctp_pdapi_event{} | #sctp_remote_error{} |
314
#sctp_shutdown_event{}</v>
317
<p>Receives the <c>Data</c> message from any association of the socket.
318
If the receive times out <c>{error,timeout</c> is returned.
319
The default timeout is <c>infinity</c>.
320
<c>FromIP</c> and <c>FromPort</c> indicate the sender's address.</p>
321
<p><c>AncData</c> is a list of Ancillary Data items which
322
may be received along with the main <c>Data</c>.
323
This list can be empty, or contain a single
324
<seealso marker="#record-sctp_sndrcvinfo">#sctp_sndrcvinfo{}</seealso>
325
record, if receiving of such ancillary data is enabled
327
<seealso marker="#option-sctp_events">sctp_events</seealso>).
328
It is enabled by default, since such ancillary data
329
provide an easy way of determining the association and stream
330
over which the message has been received.
331
(An alternative way would be to get the Association ID from the
332
<c>FromIP</c> and <c>FromPort</c> using the
333
<seealso marker="#option-sctp_get_peer_addr_info">sctp_get_peer_addr_info</seealso> socket option,
334
but this would still not produce the Stream number).</p>
335
<p>The actual <c>Data</c> received may be a <c>binary()</c>,
336
or <c>list()</c> of bytes (integers in the range 0 through 255)
337
depending on the socket mode, or an SCTP Event.
338
<marker id="sctp_events"></marker>
340
The following SCTP Events are possible:</p>
341
<list type="bulleted">
343
<p><seealso marker="#record-sctp_sndrcvinfo">#sctp_sndrcvinfo{}</seealso></p>
346
<p><seealso marker="#record-sctp_assoc_change">#sctp_assoc_change{}</seealso>;</p>
354
assoc_id = assoc_id()
356
<p>Indicates change of the status of the peer's IP address given by
357
<c>addr</c> within the association <c>assoc_id</c>.
358
Possible values of <c>state</c> (mostly self-explanatory) include:</p>
359
<list type="bulleted">
361
<p><c>addr_unreachable</c>;</p>
364
<p><c>addr_available</c>;</p>
367
<p><c>addr_removed</c>;</p>
370
<p><c>addr_added</c>;</p>
373
<p><c>addr_made_prim</c>.</p>
376
<p>In case of an error (e.g. <c>addr_unreachable</c>), the
377
<c>error</c> field provides additional diagnostics. In such cases,
378
the <c>#sctp_paddr_change{}</c> Event is automatically
379
converted into an <c>error</c> term returned by
380
<c>gen_sctp:recv</c>. The <c>error</c> field value can be
381
converted into a string using <c>error_string/1</c>.</p>
386
flags = true | false,
388
info = #sctp_sndrcvinfo{},
389
assoc_id = assoc_id()
392
<p>The sender may receive this event if a send operation fails.
393
The <c>flags</c> is a Boolean specifying whether the data have
394
actually been transmitted over the wire; <c>error</c> provides
395
extended diagnostics, use <c>error_string/1</c>;
396
<c>info</c> is the original
397
<seealso marker="#record-sctp_sndrcvinfo">#sctp_sndrcvinfo{}</seealso> record used in the failed
398
<seealso marker="#send/3">send/*,</seealso> and <c>data</c>
399
is the whole original data chunk attempted to be sent.</p>
400
<p>In the current implementation of the Erlang/SCTP binding,
401
this Event is internally converted into an <c>error</c> term
402
returned by <c>recv/*</c>.</p>
406
#sctp_adaptation_event{
407
adaptation_ind = int(),
408
assoc_id = assoc_id()
410
<p>Delivered when a peer sends an Adaptation Layer Indication
411
parameter (configured through the option
412
<seealso marker="#option-sctp_adaptation_layer">sctp_adaptation_layer</seealso>).
413
Note that with the current implementation of
414
the Erlang/SCTP binding, this event is disabled by default.</p>
419
indication = sctp_partial_delivery_aborted,
420
assoc_id = assoc_id()
422
<p>A partial delivery failure. In the current implementation of
423
the Erlang/SCTP binding, this Event is internally converted
424
into an <c>error</c> term returned by <c>recv/*</c>.</p>
430
<name>send(Socket, SndRcvInfo, Data) -> ok | {error, Reason}</name>
431
<fsummary>Send a message using an <c>#sctp_sndrcvinfo{}</c>record</fsummary>
433
<v>Socket = sctp_socket()</v>
434
<v>SndRcvInfo = #sctp_sndrcvinfo{}</v>
435
<v>Data = binary() | iolist()</v>
438
<p>Sends the <c>Data</c> message with all sending parameters from a
439
<seealso marker="#record-sctp_sndrcvinfo">#sctp_sndrcvinfo{}</seealso> record.
440
This way, the user can specify the PPID (passed to the remote end)
441
and Context (passed to the local SCTP layer) which can be used
442
for example for error identification.
443
However, such a fine level of user control is rarely required.
444
The send/4 function is sufficient for most applications.</p>
448
<name>send(Socket, Assoc, Stream, Data) -> ok | {error, Reason}</name>
449
<fsummary>Send a message over an existing association and given stream</fsummary>
451
<v>Socket = sctp_socket()</v>
452
<v>Assoc = #sctp_assoc_change{} | assoc_id()</v>
453
<v>Stream = integer()</v>
454
<v>Data = binary() | iolist()</v>
457
<p>Sends <c>Data</c> message over an existing association and given
462
<name>error_string(integer()) -> ok | string() | undefined</name>
463
<fsummary>Translate an SCTP error number into a string</fsummary>
465
<p>Translates an SCTP error number from for example
466
<c>#sctp_remote_error{}</c> or <c>#sctp_send_failed{}</c> into
467
an explanatory string, or one of the atoms <c>ok</c> for no
468
error and <c>undefined</c> for an unrecognized error.</p>
474
<marker id="options"></marker>
475
<title>SCTP SOCKET OPTIONS</title>
476
<p>The set of admissible SCTP socket options is by construction
477
orthogonal to the sets of TCP, UDP and generic INET options:
478
only those options which are explicitly listed below are allowed
479
for SCTP sockets. Options can be set on the socket using
480
<c>gen_sctp:open/1,2</c> or <c>inet:setopts/2</c>,
481
retrieved using <c>inet:getopts/2</c>, and when calling
482
<c>gen_sctp:connect/4,5</c> options can be changed.</p>
483
<marker id="option-binary"></marker>
484
<marker id="option-list"></marker>
486
<tag><c>{mode, list|binary}</c>or just <c>list</c> or <c>binary</c>.</tag>
488
<p>Determines the type of data returned from <c>gen_sctp:recv/1,2</c>.</p>
489
<marker id="option-active"></marker>
491
<tag><c>{active, true|false|once}</c></tag>
493
<list type="bulleted">
495
<p>If <c>false</c> (passive mode, the default),
496
the caller needs to do an explicit <c>gen_sctp:recv</c> call
497
in order to retrieve the available data from the socket.</p>
500
<p>If <c>true</c> (full active mode), the pending data or events are
501
sent to the owning process.</p>
502
<p><em>NB:</em> This can cause the message queue to overflow,
503
as there is no way to throttle the sender in this case
504
(no flow control!).</p>
507
<p>If <c>once</c>, only one message is automatically placed
508
in the message queue, after that the mode is automatically
509
re-set to passive. This provides flow control as well as
510
the possibility for the receiver to listen for its incoming
511
SCTP data interleaved with other inter-process messages.</p>
514
<marker id="option-buffer"></marker>
516
<tag><c>{buffer, int()}</c></tag>
518
<p>Determines the size of the user-level software buffer used by
519
the SCTP driver. Not to be confused with <c>sndbuf</c>
520
and <c>recbuf</c> options which correspond to
521
the kernel socket buffers. It is recommended
522
to have <c>val(buffer) >= max(val(sndbuf),val(recbuf))</c>.
523
In fact, the <c>val(buffer)</c> is automatically set to
524
the above maximum when <c>sndbuf</c> or <c>recbuf</c> values are set.</p>
526
<tag><c>{tos, int()}</c></tag>
528
<p>Sets the Type-Of-Service field on the IP datagrams being sent,
529
to the given value, which effectively determines a prioritization
530
policy for the outbound packets. The acceptable values
531
are system-dependent. TODO: we do not provide
532
symbolic names for these values yet.</p>
534
<tag><c>{priority, int()}</c></tag>
536
<p>A protocol-independent equivalent of <c>tos</c> above. Setting
537
priority implies setting tos as well.</p>
539
<tag><c>{dontroute, true|false}</c></tag>
541
<p>By default <c>false</c>. If <c>true</c>, the kernel does not
542
send packets via any gateway, only sends them to directly
545
<tag><c>{reuseaddr, true|false}</c></tag>
547
<p>By default <c>false</c>. If true, the local binding address
548
<c>{IP,Port}</c> of the socket can be re-used immediately:
549
no waiting in the CLOSE_WAIT state is performed (may be
550
required for high-throughput servers).</p>
551
<marker id="option-linger"></marker>
553
<tag><c>{linger, {true|false, int()}</c></tag>
555
<p>Determines the timeout in seconds for flushing unsent data in the
556
<c>gen_sctp:close/1</c> socket call. If the 1st component of the value
557
tuple is <c>false</c>, the 2nd one is ignored, which means that
558
<c>gen_sctp:close/1</c> returns immediately not waiting
559
for data to be flushed. Otherwise, the 2nd component is
560
the flushing time-out in seconds.</p>
561
<marker id="option-sndbuf"></marker>
563
<tag><c>{sndbuf, int()}</c></tag>
565
<p>The size, in bytes, of the *kernel* send buffer for this socket.
566
Sending errors would occur for datagrams larger than
567
<c>val(sndbuf)</c>. Setting this option also adjusts
568
the size of the driver buffer (see <c>buffer</c> above).</p>
570
<tag><c>{recbuf, int()}</c></tag>
572
<p>The size, in bytes, of the *kernel* recv buffer for this socket.
573
Sending errors would occur for datagrams larger than
574
<c>val(sndbuf)</c>. Setting this option also adjusts
575
the size of the driver buffer (see <c>buffer</c> above).</p>
577
<tag><c>{sctp_rtoinfo, #sctp_rtoinfo{}}</c></tag>
581
assoc_id = assoc_id(),
586
<p>Determines re-transmission time-out parameters, in milliseconds,
587
for the association(s) given by <c>assoc_id</c>.
588
If <c>assoc_id = 0</c> (default) indicates the whole endpoint. See
589
<url href="http://www.rfc-archive.org/getrfc.php?rfc=2960">RFC2960</url> and
590
<url href="http://tools.ietf.org/html/draft-ietf-tsvwg-sctpsocket-13">Sockets API Extensions for SCTP</url> for the exact semantics of the fields values.</p>
592
<tag><c>{sctp_associnfo, #sctp_assocparams{}}</c></tag>
596
assoc_id = assoc_id(),
598
number_peer_destinations = int(),
603
<p>Determines association parameters for the association(s) given by
604
<c>assoc_id</c>. <c>assoc_id = 0</c> (default) indicates
605
the whole endpoint. See
606
<url href="http://tools.ietf.org/html/draft-ietf-tsvwg-sctpsocket-13">Sockets API Extensions for SCTP</url> for the discussion of their semantics. Rarely used.</p>
608
<tag><c>{sctp_initmsg, #sctp_initmsg{}}</c></tag>
612
num_ostreams = int(),
613
max_instreams = int(),
614
max_attempts = int(),
615
max_init_timeo = int()
617
<p>Determines the default parameters which this socket attempts
618
to negotiate with its peer while establishing an association with it.
619
Should be set after <c>open/*</c> but before the first
620
<c>connect/*</c>. <c>#sctp_initmsg{}</c> can also be used
621
as ancillary data with the first call of <c>send/*</c> to
622
a new peer (when a new association is created).</p>
623
<list type="bulleted">
625
<p><c>num_ostreams</c>: number of outbound streams;</p>
628
<p><c>max_instreams</c>: max number of in-bound streams;</p>
631
<p><c>max_attempts</c>: max re-transmissions while
632
establishing an association;</p>
635
<p><c>max_init_timeo</c>: time-out in milliseconds
636
for establishing an association.</p>
641
<tag><c>{sctp_autoclose, int()|infinity}</c></tag>
643
<p>Determines the time (in seconds) after which an idle association is
644
automatically closed.</p>
646
<tag><c>{sctp_nodelay, true|false}</c></tag>
648
<p>Turns on|off the Nagle algorithm for merging small packets
649
into larger ones (which improves throughput at the expense
652
<tag><c>{sctp_disable_fragments, true|false}</c></tag>
654
<p>If <c>true</c>, induces an error on an attempt to send
655
a message which is larger than the current PMTU size
656
(which would require fragmentation/re-assembling).
657
Note that message fragmentation does not affect
658
the logical atomicity of its delivery; this option
659
is provided for performance reasons only.</p>
661
<tag><c>{sctp_i_want_mapped_v4_addr, true|false}</c></tag>
663
<p>Turns on|off automatic mapping of IPv4 addresses into IPv6 ones
664
(if the socket address family is AF_INET6).</p>
666
<tag><c>{sctp_maxseg, int()}</c></tag>
668
<p>Determines the maximum chunk size if message fragmentation is used.
669
If <c>0</c>, the chunk size is limited by the Path MTU only.</p>
671
<tag><c>{sctp_primary_addr, #sctp_prim{}}</c></tag>
675
assoc_id = assoc_id(),
679
Port = port_number() </pre>
680
<p>For the association given by <c>assoc_id</c>,
681
<c>{IP,Port}</c> must be one of the peer's addresses.
682
This option determines that the given address is
683
treated by the local SCTP stack as the peer's primary address.</p>
685
<tag><c>{sctp_set_peer_primary_addr, #sctp_setpeerprim{}}</c></tag>
689
assoc_id = assoc_id(),
693
Port = port_number() </pre>
694
<p>When set, informs the peer that it should use <c>{IP, Port}</c>
695
as the primary address of the local endpoint for the association
696
given by <c>assoc_id</c>.</p>
697
<marker id="option-sctp_adaptation_layer"></marker>
699
<tag><c>{sctp_adaptation_layer, #sctp_setadaptation{}}</c></tag>
701
<marker id="record-sctp_setadaptation"></marker>
704
adaptation_ind = int()
706
<p>When set, requests that the local endpoint uses the value given by
707
<c>adaptation_ind</c> as the Adaptation Indication parameter for
708
establishing new associations. See
709
<url href="http://www.rfc-archive.org/getrfc.php?rfc=2960">RFC2960</url> and
710
<url href="http://tools.ietf.org/html/draft-ietf-tsvwg-sctpsocket-13">Sockets API Extenstions for SCTP</url> for more details.</p>
712
<tag><c>{sctp_peer_addr_params, #sctp_paddrparams{}}</c></tag>
716
assoc_id = assoc_id(),
717
address = {IP, Port},
725
Port = port_number() </pre>
726
<p>This option determines various per-address parameters for
727
the association given by <c>assoc_id</c> and the peer address
728
<c>address</c> (the SCTP protocol supports multi-homing,
729
so more than 1 address can correspond to a given association).</p>
730
<list type="bulleted">
732
<p><c>hbinterval</c>: heartbeat interval, in milliseconds;</p>
735
<p><c>pathmaxrxt</c>: max number of retransmissions
736
before this address is considered unreachable (and an
737
alternative address is selected);</p>
740
<p><c>pathmtu</c>: fixed Path MTU, if automatic discovery is
741
disabled (see <c>flags</c> below);</p>
744
<p><c>sackdelay</c>: delay in milliseconds for SAC messages
745
(if the delay is enabled, see <c>flags</c> below);</p>
748
<p><c>flags</c>: the following flags are available:</p>
749
<list type="bulleted">
751
<p><c>hb_enable</c>: enable heartbeat; </p>
754
<p><c>hb_disable</c>: disable heartbeat;</p>
757
<p><c>hb_demand</c>: initiate heartbeat immediately;</p>
760
<p><c>pmtud_enable</c>: enable automatic Path MTU discovery;</p>
763
<p><c>pmtud_disable</c>: disable automatic Path MTU discovery;</p>
766
<p><c>sackdelay_enable</c>: enable SAC delay;</p>
769
<p><c>sackdelay_disable</c>: disable SAC delay.</p>
777
<tag><c>{sctp_default_send_param, #sctp_sndrcvinfo{}}</c></tag>
779
<marker id="record-sctp_sndrcvinfo"></marker>
790
assoc_id = assoc_id()
792
<p><c>#sctp_sndrcvinfo{}</c> is used both in this socket option, and as
793
ancillary data while sending or receiving SCTP messages. When
794
set as an option, it provides a default values for subsequent
795
<c>gen_sctp:send</c>calls on the association given by
796
<c>assoc_id</c>. <c>assoc_id = 0</c> (default) indicates
797
the whole endpoint. The following fields typically need
798
to be specified by the sender:</p>
799
<list type="bulleted">
801
<p><c>sinfo_stream</c>: stream number (0-base) within the association
802
to send the messages through;</p>
805
<p><c>sinfo_flags</c>: the following flags are recognised:</p>
806
<list type="bulleted">
808
<p><c>unordered</c>: the message is to be sent unordered;</p>
811
<p><c>addr_over</c>: the address specified in
812
<c>gen_sctp:send</c> overwrites the primary peer address;</p>
815
<p><c>abort</c>: abort the current association without
816
flushing any unsent data;</p>
819
<p><c>eof</c>: gracefully shut down the current
820
association, with flushing of unsent data.</p>
824
<p>Other fields are rarely used. See
825
<url href="http://www.rfc-archive.org/getrfc.php?rfc=2960">RFC2960</url> and
826
<url href="http://tools.ietf.org/html/draft-ietf-tsvwg-sctpsocket-13">Sockets API Extensions for SCTP</url> for full information.</p>
830
<marker id="option-sctp_events"></marker>
832
<tag><c>{sctp_events, #sctp_event_subscribe{}}</c></tag>
834
<marker id="record-sctp_event_subscribe"></marker>
836
#sctp_event_subscribe{
837
data_io_event = true | false,
838
association_event = true | false,
839
address_event = true | false,
840
send_failure_event = true | false,
841
peer_error_event = true | false,
842
shutdown_event = true | false,
843
partial_delivery_event = true | false,
844
adaptation_layer_event = true | false
846
<p>This option determines which
847
<seealso marker="#sctp_events">SCTP Events</seealso> are to be
848
received (via <seealso marker="#recv/1">recv/*</seealso>)
849
along with the data. The only
850
exception is <c>data_io_event</c> which enables or disables
852
<seealso marker="#record-sctp_sndrcvinfo">#sctp_sndrcvinfo{}</seealso>
853
ancillary data, not events.
854
By default, all flags except <c>adaptation_layer_event</c> are
855
enabled, although <c>sctp_data_io_event</c> and
856
<c>association_event</c> are used by the driver itself and not
857
exported to the user level.</p>
859
<tag><c>{sctp_delayed_ack_time, #sctp_assoc_value{}}</c></tag>
863
assoc_id = assoc_id(),
866
<p>Rarely used. Determines the ACK time
867
(given by <c>assoc_value</c> in milliseconds) for
868
the given association or the whole endpoint
869
if <c>assoc_value = 0</c> (default).</p>
871
<tag><c>{sctp_status, #sctp_status{}}</c></tag>
875
assoc_id = assoc_id(),
882
fragmentation_point = int(),
883
primary = #sctp_paddrinfo{}
885
<p>This option is read-only. It determines the status of
886
the SCTP association given by <c>assoc_id</c>. Possible values of
887
<c>state</c> follows. The state designations are mostly
888
self-explanatory. <c>state_empty</c> is the default which means
889
that no other state is active:</p>
890
<list type="bulleted">
892
<p><c>sctp_state_empty</c></p>
895
<p><c>sctp_state_closed</c></p>
898
<p><c>sctp_state_cookie_wait</c></p>
901
<p><c>sctp_state_cookie_echoed</c></p>
904
<p><c>sctp_state_established</c></p>
907
<p><c>sctp_state_shutdown_pending</c></p>
910
<p><c>sctp_state_shutdown_sent</c></p>
913
<p><c>sctp_state_shutdown_received</c></p>
916
<p><c>sctp_state_shutdown_ack_sent</c></p>
919
<p>The semantics of other fields is the following:</p>
920
<list type="bulleted">
922
<p><c>sstat_rwnd</c>: the association peer's current receiver
926
<p><c>sstat_unackdata</c>: number of unacked data chunks;</p>
929
<p><c>sstat_penddata</c>: number of data chunks pending receipt;</p>
932
<p><c>sstat_instrms</c>: number of inbound streams;</p>
935
<p><c>sstat_outstrms</c>: number of outbound streams;</p>
938
<p><c>sstat_fragmentation_point</c>: message size at which SCTP
939
fragmentation will occur;</p>
942
<p><c>sstat_primary</c>: information on the current primary peer
943
address (see below for the format of <c>#sctp_paddrinfo{}</c>).</p>
947
<marker id="option-sctp_get_peer_addr_info"></marker>
949
<tag><c>{sctp_get_peer_addr_info, #sctp_paddrinfo{}}</c></tag>
951
<marker id="record-sctp_paddrinfo"></marker>
954
assoc_id = assoc_id(),
955
address = {IP, Port},
956
state = inactive | active,
963
Port = port_number() </pre>
964
<p>This option is read-only. It determines the parameters specific to
965
the peer's address given by <c>address</c> within the association
966
given by <c>assoc_id</c>. The <c>address</c> field must be set by the
967
caller; all other fields are filled in on return.
968
If <c>assoc_id = 0</c> (default), the <c>address</c>
969
is automatically translated into the corresponding
970
association ID. This option is rarely used; see
971
<url href="http://www.rfc-archive.org/getrfc.php?rfc=2960">RFC2960</url> and
972
<url href="http://tools.ietf.org/html/draft-ietf-tsvwg-sctpsocket-13">Sockets API Extensions for SCTP</url> for the semantics of all fields.</p>
978
<marker id="examples"></marker>
979
<title>SCTP EXAMPLES</title>
980
<list type="bulleted">
982
<p>Example of an Erlang SCTP Server which receives SCTP messages and
983
prints them on the standard output:</p>
985
-module(sctp_server).
987
-export([server/0,server/1,server/2]).
988
-include_lib("kernel/include/inet.hrl").
989
-include_lib("kernel/include/inet_sctp.hrl").
994
server([Host,Port]) when is_list(Host), is_list(Port) ->
995
{ok, #hostent{h_addr_list = [IP|_]}} = inet:gethostbyname(Host),
996
io:format("~w -> ~w~n", [Host, IP]),
997
server([IP, list_to_integer(Port)]);
999
server(IP, Port) when is_tuple(IP) orlese IP == any orelse IP == loopback,
1000
is_integer(Port) ->
1001
{ok,S} = gen_sctp:open([{ip,IP},{port,Port}],[{sctp_recbuf,65536}]),
1002
io:format("Listening on ~w:~w. ~w~n", [IP,Port,S]),
1003
ok = gen_sctp:listen(S, true),
1006
server_loop(S) ->
1007
case gen_sctp:recv(S) of
1008
{error, Error} ->
1009
io:format("SCTP RECV ERROR: ~p~n", [Error]);
1011
io:format("Error: ~p~n", [Data])
1013
server_loop(S). </pre>
1017
<p>Example of an Erlang SCTP Client which interacts with the above Server.
1018
Note that in this example, the Client creates an association with
1019
the Server with 5 outbound streams. For this reason, sending of
1020
"Test 0" over Stream 0 succeeds, but sending of "Test 5"
1021
over Stream 5 fails. The client then <c>abort</c>s the association,
1022
which results in the corresponding Event being received on
1023
the Server side.</p>
1025
-module(sctp_client).
1027
-export([client/0, client/1, client/2]).
1028
-include("inet.hrl").
1031
client([localhost]).
1033
client([Host]) ->
1034
client([Host,2006]);
1036
client([Host, Port]) when is_list(Host), is_list(Port) ->
1037
client(Host,list_to_integer(Port)),
1040
client(Host, Port) when is_integer(Port) ->
1041
{ok,S} = gen_sctp:open(),
1042
{ok Assoc} = gen_sctp:connect
1043
(S, Host, Port, [{sctp_initmsg,#sctp_initmsg{num_ostreams=5}}]),
1044
io:format("Connection Successful, Assoc=~p~n", [Assoc]),
1046
io:write(gen_sctp:send(S, Assoc, 0, <<"Test 0">>)),
1049
io:write(gen_sctp:send(S, Assoc, 5, <<"Test 5">>)),
1052
io:write(gen_sctp:abort(S, Assoc)),
1056
gen_sctp:close(S). </pre>
1063
<marker id="seealso"></marker>
1064
<title>SEE ALSO</title>
1065
<p><seealso marker="inet">inet(3)</seealso>,
1066
<seealso marker="gen_tcp">gen_tcp(3)</seealso>,
1067
<seealso marker="gen_udp">gen_upd(3)</seealso>,
1068
<url href="http://www.rfc-archive.org/getrfc.php?rfc=2960">RFC2960</url> (Stream Control Transmission Protocol),
1069
<url href="http://tools.ietf.org/html/draft-ietf-tsvwg-sctpsocket-13">Sockets API Extensions for SCTP.</url></p>
1070
<marker id="authors"></marker>
added
removed
lib/kernel/doc/src/gen_sctp.xml
