<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE chapter SYSTEM "chapter.dtd">

<chapter>
  <header>
    <copyright>
      <year>2018</year><year>2019</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>Socket Usage</title>
    <prepared>Micael Karlberg</prepared>
    <docno></docno>
    <date>2018-07-17</date>
    <rev>PA1</rev>
    <file>socket_usage.xml</file>
  </header>

  <section>
    <title>Introduction</title>
    <p>The socket interface (module) is basically an "thin" layer on top of
    the OS socket interface. It is assumed that, unless you have special needs,
    gen_[tcp|udp|sctp] should be sufficent. </p>
    <p>Note that just because we have a documented and described option,
    it does <em>not</em> mean that the OS supports it. So its recommended
    that the user reads the platform specific documentation for the
    option used. </p>
  </section>

  <section>
    <marker id="socket_options"></marker>
    <title>Socket Options</title>

    <p>Options for level <c>otp</c>: </p>
    <table>
      <row>
	<cell><em>Option Name</em></cell>
	<cell><em>Value Type</em></cell>
	<cell><em>Set</em></cell>
	<cell><em>Get</em></cell>
	<cell><em>Other Requirements and comments</em></cell>
      </row>
      <row>
	<cell>assoc_id</cell>
	<cell>integer()</cell>
	<cell>no</cell>
	<cell>yes</cell>
	<cell>type = seqpacket, protocol = sctp, is an association</cell>
      </row>
      <row>
	<cell>debug</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>iow</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>controlling_process</cell>
	<cell>pid()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>rcvbuf</cell>
	<cell>default | pos_integer() | {pos_integer(), pos_ineteger()}</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>'default' only valid for set.
	The tuple form is only valid for type 'stream' and protocol 'tcp'.</cell>
      </row>
      <row>
	<cell>rcvctrlbuf</cell>
	<cell>default | pos_integer()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>default only valid for set</cell>
      </row>
      <row>
	<cell>sndctrlbuf</cell>
	<cell>default | pos_integer()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>default only valid for set</cell>
      </row>
      <row>
	<cell>fd</cell>
	<cell>integer()</cell>
	<cell>no</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <tcaption>option levels</tcaption>
    </table>
    
    <p>Options for level <c>socket</c>: </p>
    <table>
      <row>
	<cell><em>Option Name</em></cell>
	<cell><em>Value Type</em></cell>
	<cell><em>Set</em></cell>
	<cell><em>Get</em></cell>
	<cell><em>Other Requirements and comments</em></cell>
      </row>
      <row>
	<cell>acceptcon</cell>
	<cell>boolean()</cell>
	<cell>no</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>bindtodevice</cell>
	<cell>string()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>broadcast</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type = dgram</cell>
      </row>
      <row>
	<cell>debug</cell>
	<cell>integer()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>requires admin capability</cell>
      </row>
      <row>
	<cell>domain</cell>
	<cell>domain()</cell>
	<cell>no</cell>
	<cell>yes</cell>
	<cell><em>Not</em> on FreeBSD (for instance)</cell>
      </row>
      <row>
	<cell>dontroute</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>keepalive</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>linger</cell>
	<cell>abort | linger()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>oobinline</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>peek_off</cell>
	<cell>integer()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>domain = local (unix)</cell>
      </row>
      <row>
	<cell>priority</cell>
	<cell>integer()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>protocol</cell>
	<cell>protocol()</cell>
	<cell>no</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>rcvbuf</cell>
	<cell>non_neg_integer()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>rcvlowat</cell>
	<cell>non_neg_integer()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>rcvtimeo</cell>
	<cell>timeval()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>reuseaddr</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>reuseport</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>domain = inet | inet6</cell>
      </row>
      <row>
	<cell>sndbuf</cell>
	<cell>non_neg_integer()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>sndlowat</cell>
	<cell>non_neg_integer()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>not changeable on Linux</cell>
      </row>
      <row>
	<cell>sndtimeo</cell>
	<cell>timeval()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>timestamp</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>type</cell>
	<cell>type()</cell>
	<cell>no</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <tcaption>socket options</tcaption>
    </table>
    
    <p>Options for level <c>ip</c>: </p>
    <table>
      <row>
	<cell><em>Option Name</em></cell>
	<cell><em>Value Type</em></cell>
	<cell><em>Set</em></cell>
	<cell><em>Get</em></cell>
	<cell><em>Other Requirements and comments</em></cell>
      </row>
      <row>
	<cell>add_membership</cell>
	<cell>ip_mreq()</cell>
	<cell>yes</cell>
	<cell>no</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>add_source_membership</cell>
	<cell>ip_mreq_source()</cell>
	<cell>yes</cell>
	<cell>no</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>block_source</cell>
	<cell>ip_mreq_source()</cell>
	<cell>yes</cell>
	<cell>no</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>drop_membership</cell>
	<cell>ip_mreq()</cell>
	<cell>yes</cell>
	<cell>no</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>drop_source_membership</cell>
	<cell>ip_mreq_source()</cell>
	<cell>yes</cell>
	<cell>no</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>freebind</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>hdrincl</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type = raw</cell>
      </row>
      <row>
	<cell>minttl</cell>
	<cell>integer()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type = raw</cell>
      </row>
      <row>
	<cell>msfilter</cell>
	<cell>null | ip_msfilter()</cell>
	<cell>yes</cell>
	<cell>no</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>mtu</cell>
	<cell>integer()</cell>
	<cell>no</cell>
	<cell>yes</cell>
	<cell>type = raw</cell>
      </row>
      <row>
	<cell>mtu_discover</cell>
	<cell>ip_pmtudisc()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>multicast_all</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>multicast_if</cell>
	<cell>any | ip4_address()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>multicast_loop</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>multicast_ttl</cell>
	<cell>uint8()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>nodefrag</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type = raw</cell>
      </row>
      <row>
	<cell>pktinfo</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type = dgram</cell>
      </row>
      <row>
	<cell>recvdstaddr</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type = dgram</cell>
      </row>
      <row>
	<cell>recverr</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>recvif</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type = dgram | raw</cell>
      </row>
      <row>
	<cell>recvopts</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type =/= stream</cell>
      </row>
      <row>
	<cell>recvorigdstaddr</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>recvttl</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type =/= stream</cell>
      </row>
      <row>
	<cell>retopts</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type =/= stream</cell>
      </row>
      <row>
	<cell>router_alert</cell>
	<cell>integer()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type = raw</cell>
      </row>
      <row>
	<cell>sendsrcaddr</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>tos</cell>
	<cell>ip_tos()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>some high-priority levels may require superuser capability</cell>
      </row>
      <row>
	<cell>transparent</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>requires admin capability</cell>
      </row>
      <row>
	<cell>ttl</cell>
	<cell>integer()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>unblock_source</cell>
	<cell>ip_mreq_source()</cell>
	<cell>yes</cell>
	<cell>no</cell>
	<cell>none</cell>
      </row>
      <tcaption>ip options</tcaption>
    </table>
    
    <p>Options for level <c>ipv6</c>: </p>
    <table>
      <row>
	<cell><em>Option Name</em></cell>
	<cell><em>Value Type</em></cell>
	<cell><em>Set</em></cell>
	<cell><em>Get</em></cell>
	<cell><em>Other Requirements and comments</em></cell>
      </row>
      <row>
	<cell>addrform</cell>
	<cell>inet</cell>
	<cell>yes</cell>
	<cell>no</cell>
	<cell>allowed only for IPv6 sockets that are connected and bound to a
	v4-mapped-on-v6 address</cell>
      </row>
      <row>
	<cell>add_membership</cell>
	<cell>ipv6_mreq()</cell>
	<cell>yes</cell>
	<cell>no</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>authhdr</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type = dgram | raw, obsolete?</cell>
      </row>
      <row>
	<cell>drop_membership</cell>
	<cell>ipv6_mreq()</cell>
	<cell>yes</cell>
	<cell>no</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>dstopts</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type = dgram | raw, requires superuser privileges to update</cell>
      </row>
      <row>
	<cell>flowinfo</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type = dgram | raw, requires superuser privileges to update</cell>
      </row>
      <row>
	<cell>hoplimit</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type = dgram | raw, requires superuser privileges to update</cell>
      </row>
      <row>
	<cell>hopopts</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type = dgram | raw, requires superuser privileges to update</cell>
      </row>
      <row>
	<cell>mtu</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>Get: Only after the socket has been connected</cell>
      </row>
      <row>
	<cell>mtu_discover</cell>
	<cell>ipv6_pmtudisc()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>multicast_hops</cell>
	<cell>default | uint8()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>multicast_if</cell>
	<cell>integer()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type = dgram | raw</cell>
      </row>
      <row>
	<cell>multicast_loop</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>recverr</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>recvpktinfo | pktinfo</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type = dgram | raw</cell>
      </row>
      <row>
	<cell>router_alert</cell>
	<cell>integer()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type = raw</cell>
      </row>
      <row>
	<cell>rthdr</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>type = dgram | raw, requires superuser privileges to update</cell>
      </row>
      <row>
	<cell>unicast_hops</cell>
	<cell>default | uint8()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>v6only</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>no</cell>
	<cell>none</cell>
      </row>
      <tcaption>ipv6 options</tcaption>
    </table>
    
    <p>Options for level <c>tcp</c>: </p>
    <table>
      <row>
	<cell><em>Option Name</em></cell>
	<cell><em>Value Type</em></cell>
	<cell><em>Set</em></cell>
	<cell><em>Get</em></cell>
	<cell><em>Other Requirements and comments</em></cell>
      </row>
      <row>
	<cell>congestion</cell>
	<cell>string()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>maxseg</cell>
	<cell>integer()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>nodelay</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <tcaption>tcp options</tcaption>
    </table>
    
    <p>Options for level <c>udp</c>: </p>
    <table>
      <row>
	<cell><em>Option Name</em></cell>
	<cell><em>Value Type</em></cell>
	<cell><em>Set</em></cell>
	<cell><em>Get</em></cell>
	<cell><em>Other Requirements and comments</em></cell>
      </row>
      <row>
	<cell>cork</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <tcaption>udp options</tcaption>
    </table>
    
    <p>Options for level <c>sctp</c>: </p>
    <table>
      <row>
	<cell><em>Option Name</em></cell>
	<cell><em>Value Type</em></cell>
	<cell><em>Set</em></cell>
	<cell><em>Get</em></cell>
	<cell><em>Other Requirements and comments</em></cell>
      </row>
      <row>
	<cell>associnfo</cell>
	<cell>sctp_assocparams()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>autoclose</cell>
	<cell>non_neg_integer()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>disable_fragments</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>events</cell>
	<cell>sctp_event_subscribe()</cell>
	<cell>yes</cell>
	<cell>no</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>initmsg</cell>
	<cell>sctp_initmsg()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>maxseg</cell>
	<cell>non_neg_integer()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>nodelay</cell>
	<cell>boolean()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <row>
	<cell>rtoinfo</cell>
	<cell>sctp_rtoinfo()</cell>
	<cell>yes</cell>
	<cell>yes</cell>
	<cell>none</cell>
      </row>
      <tcaption>sctp options</tcaption>
    </table>
    
  </section>
</chapter>

