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<chapter>
  <header>
    <copyright>
      <year>2003</year><year>2011</year>
      <holder>Ericsson AB. All Rights Reserved.</holder>
    </copyright>
    <legalnotice>
      The contents of this file are subject to the Erlang Public License,
      Version 1.1, (the "License"); you may not use this file except in
      compliance with the License. You should have received a copy of the
      Erlang Public License along with this software. If not, it can be
      retrieved online at http://www.erlang.org/.
    
      Software distributed under the License is distributed on an "AS IS"
      basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
      the License for the specific language governing rights and limitations
      under the License.
    
    </legalnotice>

    <title>Using the SSL API</title>
    <file>using_ssl.xml</file>
  </header>

  <section>
    <title>General information</title>
    <p>To see relevant version information for ssl you can
    call ssl:versions/0</p>
    
    <p>To see all supported cipher suites 
    call ssl:cipher_suites/0. Note that available cipher suites
    for a connection will depend on your certificate. It is also
    possible to specify a specific cipher suite(s) that you
    want your connection to use. Default is to use the  strongest
    available.</p>

  </section>
  
  <section>
    <title>Setting up connections</title>
    
    <p>Here follows some small example of how to set up client/server connections
    using the erlang shell. The returned value of the sslsocket has been abbreviated with
    <c>[...]</c> as it can be fairly large and is opaque.</p>
    
    <section>
      <title>Minmal example</title>
      
      <note><p> The minimal setup is not the  most secure setup of ssl.</p>    
      </note>
      
      <p> Start server side</p>
      <code type="erl">1 server> ssl:start().
ok</code>
      
      <p>Create a ssl listen socket</p>
      <code type="erl">2 server> {ok, ListenSocket} =
ssl:listen(9999, [{certfile, "cert.pem"}, {keyfile, "key.pem"},{reuseaddr, true}]).
{ok,{sslsocket, [...]}}</code>
      
      <p>Do a transport accept on the ssl listen socket</p>
      <code type="erl">3 server> {ok, Socket} = ssl:transport_accept(ListenSocket).
{ok,{sslsocket, [...]}}</code>

      <p>Start client side</p>
      <code type="erl">1 client> ssl:start().
ok</code>
      
      <code type="erl">2 client> {ok, Socket} = ssl:connect("localhost", 9999,  [], infinity).
{ok,{sslsocket, [...]}}</code>
      
      <p>Do the ssl handshake</p>
      <code type="erl">4 server> ok = ssl:ssl_accept(Socket).
ok</code>
      
      <p>Send a messag over ssl</p>
      <code type="erl">5 server> ssl:send(Socket, "foo").
ok</code>
      
      <p>Flush the shell message queue to see that we got the message
      sent on the server side</p>
      <code type="erl">3 client> flush().
Shell got {ssl,{sslsocket,[...]},"foo"}
ok</code>
    </section>
    
    <section>
      <title>Upgrade example</title>
      
      <note><p> To upgrade a TCP/IP connection to a ssl connection the
      client and server have to aggre to do so. Agreement
      may be accompliced by using a protocol such the one used by HTTP
      specified in RFC 2817.</p> </note>
      
      <p>Start server side</p>
      <code type="erl">1 server> ssl:start().
ok</code>
      
      <p>Create a normal tcp listen socket</p>
      <code type="erl">2 server> {ok, ListenSocket} = gen_tcp:listen(9999, [{reuseaddr, true}]).
{ok, #Port&lt;0.475&gt;}</code>
      
      <p>Accept client connection</p>
      <code type="erl">3 server> {ok, Socket} = gen_tcp:accept(ListenSocket).
{ok, #Port&lt;0.476&gt;}</code>
      
      <p>Start client side</p>
      <code type="erl">1 client> ssl:start().
ok</code>
      
      <code type="erl">2 client> {ok, Socket} = gen_tcp:connect("localhost", 9999,  [], infinity).</code>
      
      <p>Make sure active is set to false before trying
      to upgrade a connection to a ssl connection, otherwhise
      ssl handshake messages may be deliverd to the wrong process.</p>
      <code type="erl">4 server> inet:setopts(Socket, [{active, false}]).
ok</code>
      
      <p>Do the ssl handshake.</p>
      <code type="erl">5 server> {ok, SSLSocket} = ssl:ssl_accept(Socket, [{cacertfile, "cacerts.pem"},
{certfile, "cert.pem"}, {keyfile, "key.pem"}]).
{ok,{sslsocket,[...]}}</code>
      
      <p> Upgrade to a ssl connection. Note that the client and server
      must agree upon the upgrade and the server must call
      ssl:accept/2 before the client calls ssl:connect/3.</p>
      <code type="erl">3 client>{ok, SSLSocket} = ssl:connect(Socket, [{cacertfile, "cacerts.pem"},
{certfile, "cert.pem"}, {keyfile, "key.pem"}], infinity).
{ok,{sslsocket,[...]}}</code>
      
      <p>Send a messag over ssl</p>
      <code type="erl">4 client> ssl:send(SSLSocket, "foo").
ok</code>
      
      <p>Set active true on the ssl socket</p>
      <code type="erl">4 server> ssl:setopts(SSLSocket, [{active, true}]).
ok</code>
      
      <p>Flush the shell message queue to see that we got the message
      sent on the client side</p>
      <code type="erl">5 server> flush().
Shell got {ssl,{sslsocket,[...]},"foo"}
ok</code>
    </section>
  </section>
 </chapter>
