Determines the type of data returned from recv/1,2.

Sets the Type-Of-Service field on the IP datagrams that are sent, to the specified value. This effectively determines a prioritization policy for the outbound packets. The acceptable values are system-dependent.

A protocol-independent equivalent of tos above. Setting priority implies setting tos as well.

Defaults to false. If true, the kernel does not send packets through any gateway, only sends them to directly connected hosts.

Defaults to false. If true, the local binding address {IP,Port} of the socket can be reused immediately. No waiting in state CLOSE_WAIT is performed (can be required for high-throughput servers).

The size, in bytes, of the OS kernel send buffer for this socket. Sending errors would occur for datagrams larger than val(sndbuf). Setting this option also adjusts the size of the driver buffer (see buffer above).

The size, in bytes, of the OS kernel receive buffer for this socket. Sending errors would occur for datagrams larger than val(recbuf). Setting this option also adjusts the size of the driver buffer (see buffer above).

Overrides which callback module is used. Defaults to inet_sctp for IPv4 and inet6_sctp for IPv6.

#sctp_rtoinfo{
      assoc_id = assoc_id(),
      initial  = integer(),
      max      = integer(),
      min      = integer()
}

Determines retransmission time-out parameters, in milliseconds, for the association(s) specified by assoc_id.

assoc_id = 0 (default) indicates the whole endpoint. See RFC 2960 and Sockets API Extensions for SCTP for the exact semantics of the field values.

#sctp_assocparams{
      assoc_id                 = assoc_id(),
      asocmaxrxt               = integer(),
      number_peer_destinations = integer(),
      peer_rwnd                = integer(),
      local_rwnd               = integer(),
      cookie_life              = integer()
}

Determines association parameters for the association(s) specified by assoc_id.

assoc_id = 0 (default) indicates the whole endpoint. See Sockets API Extensions for SCTP for the discussion of their semantics. Rarely used.

#sctp_initmsg{
     num_ostreams   = integer(),
     max_instreams  = integer(),
     max_attempts   = integer(),
     max_init_timeo = integer()
}

Determines the default parameters that this socket tries to negotiate with its peer while establishing an association with it. Is to be set after open/* but before the first connect/*. #sctp_initmsg{} can also be used as ancillary data with the first call of send/* to a new peer (when a new association is created).

Determines the time, in seconds, after which an idle association is automatically closed. 0 means that the association is never automatically closed.

Turns on|off the Nagle algorithm for merging small packets into larger ones. This improves throughput at the expense of latency.

If true, induces an error on an attempt to send a message larger than the current PMTU size (which would require fragmentation/reassembling). Notice that message fragmentation does not affect the logical atomicity of its delivery; this option is provided for performance reasons only.

Turns on|off automatic mapping of IPv4 addresses into IPv6 ones (if the socket address family is AF_INET6).

Determines the maximum chunk size if message fragmentation is used. If 0, the chunk size is limited by the Path MTU only.

#sctp_prim{
      assoc_id = assoc_id(),
      addr     = {IP, Port}
}
 IP = ip_address()
 Port = port_number()

For the association specified by assoc_id, {IP,Port} must be one of the peer addresses. This option determines that the specified address is treated by the local SCTP stack as the primary address of the peer.

#sctp_setpeerprim{
      assoc_id = assoc_id(),
      addr     = {IP, Port}
}
 IP = ip_address()
 Port = port_number()

When set, informs the peer to use {IP, Port} as the primary address of the local endpoint for the association specified by assoc_id.

#sctp_setadaptation{
      adaptation_ind = integer()
}

When set, requests that the local endpoint uses the value specified by adaptation_ind as the Adaptation Indication parameter for establishing new associations. For details, see RFC 2960 and Sockets API Extenstions for SCTP.

#sctp_paddrparams{
      assoc_id   = assoc_id(),
      address    = {IP, Port},
      hbinterval = integer(),
      pathmaxrxt = integer(),
      pathmtu    = integer(),
      sackdelay  = integer(),
      flags      = list()
}
IP = ip_address()
Port = port_number()

Determines various per-address parameters for the association specified by assoc_id and the peer address address (the SCTP protocol supports multi-homing, so more than one address can correspond to a specified association).

#sctp_sndrcvinfo{
      stream     = integer(),
      ssn        = integer(),
      flags      = list(),
      ppid       = integer(),
      context    = integer(),
      timetolive = integer(),
      tsn        = integer(),
      cumtsn     = integer(),
      assoc_id   = assoc_id()
}

#sctp_sndrcvinfo{} is used both in this socket option, and as ancillary data while sending or receiving SCTP messages. When set as an option, it provides default values for subsequent send calls on the association specified by assoc_id.

assoc_id = 0 (default) indicates the whole endpoint.

The following fields typically must be specified by the sender:

#sctp_event_subscribe{
        data_io_event          = true | false,
        association_event      = true | false,
        address_event          = true | false,
        send_failure_event     = true | false,
        peer_error_event       = true | false,
        shutdown_event         = true | false,
        partial_delivery_event = true | false,
        adaptation_layer_event = true | false
}

This option determines which SCTP Events are to be received (through recv/*) along with the data. The only exception is data_io_event, which enables or disables receiving of #sctp_sndrcvinfo{} ancillary data, not events. By default, all flags except adaptation_layer_event are enabled, although sctp_data_io_event and association_event are used by the driver itself and not exported to the user level.

#sctp_assoc_value{
      assoc_id    = assoc_id(),
      assoc_value = integer()
}

Rarely used. Determines the ACK time (specified by assoc_value, in milliseconds) for the specified association or the whole endpoint if assoc_value = 0 (default).

#sctp_status{
      assoc_id            = assoc_id(),
      state               = atom(),
      rwnd                = integer(),
      unackdata           = integer(),
      penddata            = integer(),
      instrms             = integer(),
      outstrms            = integer(),
      fragmentation_point = integer(),
      primary             = #sctp_paddrinfo{}
}

This option is read-only. It determines the status of the SCTP association specified by assoc_id. The following are the possible values of state (the state designations are mostly self-explanatory):

Semantics of the other fields:

#sctp_paddrinfo{
      assoc_id  = assoc_id(),
      address   = {IP, Port},
      state     = inactive | active | unconfirmed,
      cwnd      = integer(),
      srtt      = integer(),
      rto       = integer(),
      mtu       = integer()
}
IP = ip_address()
Port = port_number()

This option is read-only. It determines the parameters specific to the peer address specified by address within the association specified by assoc_id. Field address fmust be set by the caller; all other fields are filled in on return. If assoc_id = 0 (default), the address is automatically translated into the corresponding association ID. This option is rarely used. For the semantics of all fields, see RFC 2960 and Sockets API Extensions for SCTP.