<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE erlref SYSTEM "erlref.dtd" [
  <!ENTITY start '<seealso marker="#start-3">start/3</seealso>'>
  <!ENTITY gen_tcp_connect3
  '<seealso marker="kernel:gen_tcp#connect-3">gen_tcp:connect/3</seealso>'>
  <!ENTITY gen_tcp_listen2
  '<seealso marker="kernel:gen_tcp#listen-2">gen_tcp:listen/2</seealso>'>
  <!ENTITY ip_address
  '<seealso marker="kernel:inet#type-ip_address">inet:ip_address()</seealso>'>
  <!ENTITY ssl_connect2
  '<seealso marker="ssl:ssl#connect-2">ssl:connect/2</seealso>'>
  <!ENTITY ssl_connect3
  '<seealso marker="ssl:ssl#connect-3">ssl:connect/3</seealso>'>
  <!ENTITY ssl_accept2
  '<seealso marker="ssl:ssl#ssl_accept-2">ssl:ssl_accept/2</seealso>'>
  <!ENTITY ssl_listen2
  '<seealso marker="ssl:ssl#listen-2">ssl:listen/2</seealso>'>
  <!ENTITY gen_tcp '<seealso marker="kernel:gen_tcp">gen_tcp(3)</seealso>'>
  <!ENTITY inet '<seealso marker="kernel:inet">inet(3)</seealso>'>
  <!ENTITY ssl '<seealso marker="ssl:ssl">ssl(3)</seealso>'>
  <!ENTITY % also SYSTEM "seealso.ent" >
  <!ENTITY % here SYSTEM "seehere.ent" >
  %also;
  %here;
]>

<erlref>
<header>
<copyright>
<year>2011</year><year>2016</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>diameter_tcp(3)</title>
<prepared>Anders Svensson</prepared>
<responsible></responsible>
<docno></docno>
<approved></approved>
<checked></checked>
<date></date>
<rev></rev>
<file>diameter_tcp.xml</file>
</header>

<module>diameter_tcp</module>
<modulesummary>Diameter transport over TCP.</modulesummary>

<description>

<p>
This module implements diameter transport over TCP using &gen_tcp;.
It can be specified as the value of a <c>transport_module</c> option to
&mod_add_transport;
and implements the behaviour documented in
&man_transport;.
TLS security is supported, either as an upgrade following
capabilities exchange or at connection establishment.</p>

<p>
Note that the ssl application is required for TLS and must be started
before configuring TLS capability on diameter transports.</p>

<marker id="start"/>
</description>

<!-- ===================================================================== -->

<funcs>

<func>
<name>start({Type, Ref}, Svc, [Opt])
         -> {ok, Pid}
          | {ok, Pid, [LAddr]}
          | {error, Reason}</name>
<fsummary>Start a transport process.</fsummary>
<type>
<v>Type = connect | accept</v>
<v>Ref = &mod_transport_ref;</v>
<v>Svc = #diameter_service{}</v>
<v>Opt = OwnOpt | SslOpt | TcpOpt</v>
<v>Pid = pid()</v>
<v>LAddr = &ip_address;</v>
<v>Reason = term()</v>
<v>OwnOpt = {raddr, &ip_address;}
          | {rport, integer()}
          | {accept, Match}
          | {port, integer()}
          | {fragment_timer, infinity | 0..16#FFFFFFFF}</v>
<v>SslOpt = {ssl_options, true | list()}</v>
<v>TcpOpt = term()</v>
<v>Match = &ip_address; | string() | [Match]</v>
</type>
<desc>

<p>
The start function required by &man_transport;.</p>

<p>
Options <c>raddr</c> and <c>rport</c> specify the remote address
and port for a connecting transport and are not valid for a listening
transport.</p>

<p>
Option <c>accept</c> specifies remote addresses for a listening
transport and is not valid for a connecting transport.
If specified, a remote address that does not match one of the
specified addresses causes the connection to be aborted.
Multiple <c>accept</c> options can be specified.
A string-valued <c>Match</c> that does not parse as an address is
interpreted as a regular expression.</p>

<p>
Option <c>ssl_options</c> must be specified for a transport
that should support TLS: a value of <c>true</c> results in a
TLS handshake immediately upon connection establishment while
<c>list()</c> specifies options to be passed to &ssl_connect2; or
&ssl_accept2;
after capabilities exchange if TLS is negotiated.</p>

<p>
Option <c>fragment_timer</c> specifies the timeout, in milliseconds,
of a timer used to flush messages from the incoming byte
stream even if the number of bytes indicated in the Message Length
field of its Diameter Header have not yet been accumulated:
such a message is received over the transport interface after
two successive timeouts without the reception of additional bytes.
Defaults to 1000.</p>

<p>
Remaining options are any accepted by &ssl_connect3; or
&gen_tcp_connect3; for
a connecting transport, or &ssl_listen2; or &gen_tcp_listen2; for
a listening transport, depending on whether or not <c>{ssl_options, true}</c>
has been specified.
Options <c>binary</c>,
<c>packet</c> and <c>active</c> cannot be specified.
Also, option <c>port</c> can be specified for a listening transport
to specify the local listening port, the default being the standardized
3868.
Note that the option <c>ip</c> specifies the local address.</p>

<p>
An <c>ssl_options</c> list must be specified if and only if
the transport in question has set <c>Inband-Security-Id</c> to
1 (<c>TLS</c>), as
specified to either &mod_start_service; or
&mod_add_transport;,
so that the transport process will receive notification of
whether or not to commence with a TLS handshake following capabilities
exchange.
Failing to specify an options list on a TLS-capable transport
for which TLS is negotiated will cause TLS handshake to fail.
Failing to specify TLS capability when <c>ssl_options</c> has been
specified will cause the transport process to wait for a notification
that will not be forthcoming, which will eventually cause the RFC 3539
watchdog to take down the connection.</p>

<p>
If an <c>ip</c> option is not specified then the first element of a
non-empty <c>Host-IP-Address</c> list in <c>Svc</c> provides the local
IP address.
If neither is specified then the default address selected by &gen_tcp;
is used.
In all cases, the selected address is either returned from
&start; or passed in a <c>connected</c> message over the transport
interface.</p>
</desc>
</func>

</funcs>

<!-- ===================================================================== -->
<!-- ===================================================================== -->

<section>
<title>SEE ALSO</title>

<p>
&man_main;, &man_transport;, &gen_tcp;, &inet;, &ssl;</p>

</section>

</erlref>
