gen_sctp

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

Sets the Type-Of-Service field on the IP datagrams being sent, to the given value, which effectively determines a prioritization policy for the outbound packets. The acceptable values are system-dependent. TODO: we do not provide symbolic names for these values yet.

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

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

By default false. If true, the local binding address {IP,Port} of the socket can be re-used immediately: no waiting in the CLOSE_WAIT state is performed (may be required for high-throughput servers).

The size, in bytes, of the *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 *kernel* recv 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).

Override 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 re-transmission time-out parameters, in milliseconds, for the association(s) given by assoc_id. If assoc_id = 0 (default) indicates the whole endpoint. See RFC2960 and Sockets API Extensions for SCTP for the exact semantics of the fields 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) given 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 which this socket attempts to negotiate with its peer while establishing an association with it. Should 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 (which improves throughput at the expense of latency).

If true, induces an error on an attempt to send a message which is larger than the current PMTU size (which would require fragmentation/re-assembling). Note 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 given by assoc_id, {IP,Port} must be one of the peer's addresses. This option determines that the given address is treated by the local SCTP stack as the peer's primary address.

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

When set, informs the peer that it should use {IP, Port} as the primary address of the local endpoint for the association given by assoc_id.

  #sctp_setadaptation{
        adaptation_ind = integer()
  }        

When set, requests that the local endpoint uses the value given by adaptation_ind as the Adaptation Indication parameter for establishing new associations. See RFC2960 and Sockets API Extenstions for SCTP for more details.

  #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()        

This option determines various per-address parameters for the association given by assoc_id and the peer address address (the SCTP protocol supports multi-homing, so more than 1 address can correspond to a given 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 a default values for subsequent gen_sctp:sendcalls on the association given by assoc_id. assoc_id = 0 (default) indicates the whole endpoint. The following fields typically need to 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 (via 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 (given by assoc_value in milliseconds) for the given 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 given by assoc_id. Possible values of state follows. The state designations are mostly self-explanatory. state_empty is the default which means that no other state is active:

The semantics of other fields is the following:

  #sctp_paddrinfo{
        assoc_id  = assoc_id(),
        address   = {IP, Port},
        state     = inactive | active,
        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's address given by address within the association given by assoc_id. The address field must 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; see RFC2960 and Sockets API Extensions for SCTP for the semantics of all fields.