NAME

       diameter_sctp - Diameter transport over SCTP.

DESCRIPTION

       This  module  implements  diameter  transport  over  SCTP  using gen_sctp(3erl). It can be
       specified as the value  of  a  transport_module  option  to  diameter:add_transport/2  and
       implements the behaviour documented in diameter_transport(3erl).

EXPORTS

       start({Type, Ref}, Svc, [Opt]) -> {ok, Pid, [LAddr]} | {error, Reason}

              Types:

                 Type = connect | accept
                 Ref = diameter:transport_ref()
                 Svc = #diameter_service{}
                 Opt = OwnOpt | SctpOpt
                 Pid = pid()
                 LAddr = inet:ip_address()
                 Reason = term()
                 OwnOpt  =  {raddr,  inet:ip_address()}  | {rport, integer()} | {accept, Match} |
                 {unordered,  boolean()  |  pos_integer()}  |  {packet,  boolean()   |   raw}   |
                 {message_cb, diameter:eval()} | {sender, boolean()}
                 SctpOpt = term()
                 Match = inet:ip_address() | string() | [Match]

              The start function required by diameter_transport(3erl).

              Options  raddr  and  rport  specify  the  remote  address and port for a connecting
              transport and not valid for a listening transport: the  former  is  required  while
              latter defaults to 3868 if unspecified. Multiple raddr options can be specified, in
              which case the connecting transport in question attempts each in sequence until  an
              association is established.

              Option accept 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 association to be aborted. Multiple accept
              options can be specified. A string-valued Match that does not parse as  an  address
              is interpreted as a regular expression.

              Option  unordered  specifies  whether  or  not to use unordered delivery, integer N
              being equivalent to N =< OS, where OS is the number of outbound streams  negotiated
              on  the association in question. Regardless of configuration, sending is ordered on
              stream 0 until reception of a second  incoming  message,  to  ensure  that  a  peer
              receives capabilities exchange messages before any other. Defaults to false.

              Option   packet   determines   how/if  an  incoming  message  is  packaged  into  a
              diameter_packet record. If false then messages are received as  binary().  If  true
              then  as  a  record  with  the binary() message in the bin field and a {stream, Id}
              tuple in the transport_data field, where Id is the identifier of the inbound stream
              the  message  was  received on. If raw then as a record with the received ancillary
              sctp_sndrcvinfo record in the transport_data field. Defaults to true.

              Options message_cb and sender have  semantics  identical  to  those  documented  in
              diameter_tcp(3erl),  but  with  the  message  argument  to a recv callback being as
              directed by the packet option.

              An {outstream, Id} tuple in the transport_data field of a outgoing  diameter_packet
              record sets the outbound stream on which the message is sent, modulo the negotiated
              number of outbound streams. Any other value causes successive such sends  to  cycle
              though all outbound streams.

              Remaining  options  are  any  accepted  by  gen_sctp:open/1,  with the exception of
              options mode, binary, list, active and sctp_events. Note that options ip  and  port
              specify the local address and port respectively.

              Multiple  ip  options can be specified for a multihomed peer. If none are specified
              then the values of Host-IP-Address in the diameter_service record are used.  Option
              port defaults to 3868 for a listening transport and 0 for a connecting transport.

          Warning:
              An  small  receive  buffer may result in a peer having to resend incoming messages:
              set the inet(3erl) option recbuf to increase the buffer size.

              An small send buffer may result in  outgoing  messages  being  discarded:  set  the
              inet(3erl) option sndbuf to increase the buffer size.

SEE ALSO

       diameter(3erl), diameter_transport(3erl), gen_sctp(3erl), inet(3erl)