1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
|
<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE erlref SYSTEM "erlref.dtd">
<erlref>
<header>
<copyright>
<year>1997</year><year>2018</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
</legalnotice>
<title>gen_udp</title>
<prepared>[email protected]</prepared>
<docno></docno>
<date>1997-12-03</date>
<rev>A</rev>
</header>
<module since="">gen_udp</module>
<modulesummary>Interface to UDP sockets.</modulesummary>
<description>
<p>This module provides functions for communicating
with sockets using the UDP protocol.</p>
</description>
<datatypes>
<datatype>
<name name="option"/>
</datatype>
<datatype>
<name name="option_name"/>
</datatype>
<datatype>
<name>socket()</name>
<desc>
<p>As returned by
<seealso marker="#open/1"><c>open/1,2</c></seealso>.</p>
</desc>
</datatype>
</datatypes>
<funcs>
<func>
<name name="close" arity="1" since=""/>
<fsummary>Close a UDP socket.</fsummary>
<desc>
<p>Closes a UDP socket.</p>
</desc>
</func>
<func>
<name name="controlling_process" arity="2" since=""/>
<fsummary>Change controlling process of a socket.</fsummary>
<desc>
<p>Assigns a new controlling process <c><anno>Pid</anno></c> to
<c><anno>Socket</anno></c>. The controlling process is the process
that receives messages from the socket. If called by any other
process than the current controlling process,
<c>{error, not_owner}</c> is returned. If the process identified
by <c><anno>Pid</anno></c> is not an existing local pid,
<c>{error, badarg}</c> is returned. <c>{error, badarg}</c> may also
be returned in some cases when <c><anno>Socket</anno></c> is closed
during the execution of this function.</p>
</desc>
</func>
<func>
<name name="open" arity="1" since=""/>
<name name="open" arity="2" since=""/>
<fsummary>Associate a UDP port number with the process calling it.</fsummary>
<desc>
<p>Associates a UDP port number (<c><anno>Port</anno></c>) with the
calling process.</p>
<p>The following options are available:</p>
<taglist>
<tag><c>list</c></tag>
<item><p>Received <c>Packet</c> is delivered as a list.</p></item>
<tag><c>binary</c></tag>
<item><p>Received <c>Packet</c> is delivered as a binary.</p></item>
<tag><c>{ip, Address}</c></tag>
<item><p>If the host has many network interfaces, this option
specifies which one to use.</p></item>
<tag><c>{ifaddr, Address}</c></tag>
<item><p>Same as <c>{ip, Address}</c>. If the host has many
network interfaces, this option specifies which one to
use.</p></item>
<tag><c>{fd, integer() >= 0}</c></tag>
<item><p>If a socket has somehow been opened without using
<c>gen_udp</c>, use this option to pass the file descriptor
for it. If <c><anno>Port</anno></c> is not set to <c>0</c> and/or
<c>{ip, ip_address()}</c> is combined with this option, the
<c>fd</c> is bound to the specified interface and port after it is
being opened. If these options are not specified, it is assumed that
the <c>fd</c> is already bound appropriately.</p></item>
<tag><c>inet6</c></tag>
<item><p>Sets up the socket for IPv6.</p></item>
<tag><c>inet</c></tag>
<item><p>Sets up the socket for IPv4.</p></item>
<tag><c>local</c></tag>
<item>
<p>
Sets up a Unix Domain Socket. See
<seealso marker="inet#type-local_address">
<c>inet:local_address()</c>
</seealso>
</p>
</item>
<tag><c>{udp_module, module()}</c></tag>
<item><p>Overrides which callback module is used. Defaults to
<c>inet_udp</c> for IPv4 and <c>inet6_udp</c> for IPv6.</p></item>
<tag><c>{multicast_if, Address}</c></tag>
<item><p>Sets the local device for a multicast socket.</p></item>
<tag><c>{multicast_loop, true | false}</c></tag>
<item><p>When <c>true</c>, sent multicast packets are looped back to
the local sockets.</p></item>
<tag><c>{multicast_ttl, Integer}</c></tag>
<item><p>Option <c>multicast_ttl</c> changes the time-to-live (TTL)
for outgoing multicast datagrams to control the scope of the
multicasts.</p>
<p>Datagrams with a TTL of 1 are not forwarded beyond the local
network. Defaults to <c>1</c>.</p></item>
<tag><c>{add_membership, {MultiAddress, InterfaceAddress}}</c></tag>
<item><p>Joins a multicast group.</p></item>
<tag><c>{drop_membership, {MultiAddress, InterfaceAddress}}</c></tag>
<item><p>Leaves a multicast group.</p></item>
<tag><c>Opt</c></tag>
<item><p>See
<seealso marker="inet#setopts/2"><c>inet:setopts/2</c></seealso>.
</p></item>
</taglist>
<p>The returned socket <c><anno>Socket</anno></c> is used to send
packets from this port with
<seealso marker="#send/4"><c>send/4</c></seealso>.
When UDP packets arrive
at the opened port, if the socket is in an active mode, the packets
are delivered as messages to the controlling process:</p>
<code type="none">
{udp, Socket, IP, InPortNo, Packet} % Without ancillary data
{udp, Socket, IP, InPortNo, AncData, Packet} % With ancillary data
</code>
<p>
The message contains an <c>AncData</c> field
if any of the socket
<seealso marker="#type-option">options</seealso>
<seealso marker="inet#option-recvtos"><c>recvtos</c></seealso>,
<seealso marker="inet#option-recvtclass"><c>recvtclass</c></seealso>
or
<seealso marker="inet#option-recvttl"><c>recvttl</c></seealso>
are active, otherwise it does not.
</p>
<p>
</p>
<p>If the socket is not in an active mode, data can be
retrieved through the
<seealso marker="#recv/2"><c>recv/2,3</c></seealso> calls.
Notice that arriving UDP packets that are longer than
the receive buffer option specifies can be truncated
without warning.</p>
<p>When a socket in <c>{active, N}</c> mode (see
<seealso marker="inet#setopts/2"><c>inet:setopts/2</c></seealso>
for details), transitions to passive (<c>{active, false}</c>) mode,
the controlling process is notified by a message of the following
form:</p>
<code type="none">
{udp_passive, Socket}</code>
<p><c>IP</c> and <c>InPortNo</c> define the address from which
<c>Packet</c> comes. <c>Packet</c> is a list of bytes if
option <c>list</c> is specified. <c>Packet</c> is a
binary if option <c>binary</c> is specified.</p>
<p>Default value for the receive buffer option is
<c>{recbuf, 8192}</c>.</p>
<p>If <c><anno>Port</anno> == 0</c>, the underlying OS assigns a free
UDP port, use
<seealso marker="inet#port/1"><c>inet:port/1</c></seealso>
to retrieve it.</p>
</desc>
</func>
<func>
<name name="recv" arity="2" since=""/>
<name name="recv" arity="3" since=""/>
<fsummary>Receive a packet from a passive socket.</fsummary>
<desc>
<p>
Receives a packet from a socket in passive mode. Optional parameter
<c><anno>Timeout</anno></c> specifies a time-out in milliseconds.
Defaults to <c>infinity</c>.
</p>
<p>
If any of the socket
<seealso marker="#type-option">options</seealso>
<seealso marker="inet#option-recvtos"><c>recvtos</c></seealso>,
<seealso marker="inet#option-recvtclass"><c>recvtclass</c></seealso>
or
<seealso marker="inet#option-recvttl"><c>recvttl</c></seealso>
are active, the <c><anno>RecvData</anno></c> tuple contains an
<c><anno>AncData</anno></c> field,
otherwise it does not.
</p>
</desc>
</func>
<func>
<name name="send" arity="3" since="OTP @OTP-15747@"/>
<fsummary>Send a packet.</fsummary>
<desc>
<p>
Sends a packet to the specified <c><anno>Destination</anno></c>.
</p>
<p>
This function is equivalent to
<seealso marker="#send-4-AncData"><c>send(<anno>Socket</anno>, <anno>Destination</anno>, [], <anno>Packet</anno>)</c></seealso>.
</p>
</desc>
</func>
<func>
<name name="send" arity="4" clause_i="1" since=""/>
<fsummary>Send a packet.</fsummary>
<desc>
<p>
Sends a packet to the specified <c><anno>Host</anno></c>
and <c><anno>Port</anno></c>.
</p>
<p>
This clause is equivalent to
<seealso marker="#send/5"><c>send(<anno>Socket</anno>, <anno>Host</anno>, <anno>Port</anno>, [], <anno>Packet</anno>)</c></seealso>.
</p>
</desc>
</func>
<func>
<name name="send" arity="4" clause_i="2" anchor="send-4-AncData" since="OTP @OTP-15747@"/>
<fsummary>Send a packet.</fsummary>
<desc>
<p>
Sends a packet to the specified <c><anno>Destination</anno></c>
with ancillary data <c><anno>AncData</anno></c>.
</p>
<note>
<p>
The ancillary data <c><anno>AncData</anno></c>
contains options that for this single message
override the default options for the socket,
an operation that may not be supported on all platforms,
and if so return <c>{error, einval}</c>.
Using more than one of an ancillary data item type
may also not be supported.
<c><anno>AncData</anno> =:= []</c> is always supported.
</p>
</note>
</desc>
</func>
<func>
<name name="send" arity="4" clause_i="3" since="OTP @OTP-15747@"/>
<fsummary>Send a packet.</fsummary>
<desc>
<p>
Sends a packet to the specified <c><anno>Destination</anno></c>.
Since <c><anno>Destination</anno></c> is complete,
<c><anno>PortZero</anno></c> is redundant and has to be <c>0</c>.
</p>
<p>
This is a legacy clause mostly for
<c><anno>Destination</anno> = {local, Binary}</c>
where <c><anno>PortZero</anno></c> is superfluous.
It is equivalent to
<seealso marker="#send-4-AncData"><c>send(<anno>Socket</anno>, <anno>Destination</anno>, [], <anno>Packet</anno>)</c></seealso>, the clause right above here.
</p>
</desc>
</func>
<func>
<name name="send" arity="5" since="OTP @OTP-15747@"/>
<fsummary>Send a packet.</fsummary>
<desc>
<p>
Sends a packet to the specified <c><anno>Host</anno></c>
and <c><anno>Port</anno></c>,
with ancillary data <c><anno>AncData</anno></c>.
</p>
<p>
Argument <c><anno>Host</anno></c> can be
a hostname or a socket address,
and <c><anno>Port</anno></c> can be a port number
or a service name atom.
These are resolved into a <c>Destination</c> and after that
this function is equivalent to
<seealso marker="#send-4-AncData"><c>send(<anno>Socket</anno>, Destination, <anno>AncData</anno>, <anno>Packet</anno>)</c></seealso>, read there about ancillary data.
</p>
</desc>
</func>
</funcs>
</erlref>
|
