NAME

       brsscla - BRSS-based BP convergence layer adapter (input and output) task

SYNOPSIS

       brsscla local_hostname[:local_port_nbr][ first_duct_nbr_in_scope[ last_duct_nbr_in_scope]]

DESCRIPTION

       BRSS is the "server" side of the Bundle Relay Service (BRS) convergence layer protocol for BP.  It is
       complemented by BRSC, the "client" side of the BRS convergence layer protocol for BP.

       brsscla is a background "daemon" task that spawns two plus N threads: one that handles BRSS client
       connections and spawns sockets for continued data interchange with connected clients; one that handles
       BRSS protocol output by transmitting over those spawned sockets to the associated clients; and one input
       thread for each spawned socket, to handle BRSS protocol input from the associated connected client.

       The connection thread simply accepts connections on a TCP socket bound to local_hostname and
       local_port_nbr and spawns reception threads.  The default value for local_port_nbr, if omitted, is 80.

       Each reception thread receives over the socket connection the node number of the connecting client (in
       SDNV representation), followed by a 32-bit time tag and a 160-bit HMAC-SHA1 digest of that time tag.  The
       node number must be in the range first_duct_nbr_in_scope through last_duct_nbr_in_scope inclusive; when
       omitted, first_duct_nbr_in_scope defaults to 1 and last_duct_nbr_in_scope defaults to
       first_duct_nbr_in_scope plus 255.  The receiving thread also checks the time tag, requiring that it
       differ from the current time by no more than BRSTERM (default value 5) seconds.  It then recomputes the
       digest value using the HMAC-SHA1 key named "node_number.brs" as recorded in the ION security database
       (see ionsecrc(5)), requiring that the supplied and computed digests be identical.  If all registration
       conditions are met, the receiving thread sends the client a countersign -- a similarly computed HMAC-SHA1
       digest, for the time tag that is 1 second later than the provided time tag -- to assure the client of its
       own authenticity, then commences receiving bundles over the connected socket.  Each bundle received on
       the connection is preceded by its length, a 32-bit unsigned integer in network byte order.  The received
       bundles are passed to the bundle protocol agent on the local ION node.

       The output thread extracts bundles from the queues of bundles ready for transmission via BRSS to remote
       bundle protocol agents, finds the connected clients whose node numbers match the proximate receiver node
       numbers assigned to the bundles by the routing daemons that enqueued them, and transmits the bundles over
       the sockets to those clients.  Each transmitted bundle is preceded by its length, a 32-bit unsigned
       integer in network byte order.

       Note that brsscla is a "promiscuous" convergence layer daemon, able to transmit bundles to any BRSS
       destination induct for which it has received a connection.  Its sole outduct's name is the name of the
       corresponding induct, rather than the induct name of any single BRSS destination induct to which the
       outduct might be dedicated, so scheme configuration directives that cite this outduct must provide
       destination induct IDs.  For the BRS convergence-layer protocol, destination induct IDs are simply the
       node numbers of connected clients.

       brsscla is spawned automatically by bpadmin in response to the 's' (START) command that starts operation
       of the Bundle Protocol, and it is terminated by bpadmin in response to an 'x' (STOP) command.  brsscla
       can also be spawned and terminated in response to START and STOP commands that pertain specifically to
       the BRSS convergence layer protocol.

EXIT STATUS

       "0" brsscla terminated normally, for reasons noted in the ion.log file.  If this termination was not
           commanded, investigate and solve the problem identified in the log file and use bpadmin to restart
           the BRSS protocol.

       "1" brsscla terminated abnormally, for reasons noted in the ion.log file.  Investigate and solve the
           problem identified in the log file, then use bpadmin to restart the BRSS protocol.

FILES

       No configuration files are needed.

ENVIRONMENT

       No environment variables apply.

DIAGNOSTICS

       The following diagnostics may be issued to the ion.log log file:

       brsscla can't attach to BP.
           bpadmin has not yet initialized Bundle Protocol operations.

       No such brss induct.
           No BRSS induct with duct name matching local_hostname and local_port_nbr has been added to the BP
           database.  Use bpadmin to stop the BRSS convergence-layer protocol, add the induct, and then restart
           the BRSS protocol.

       CLI task is already started for this duct.
           Redundant initiation of brsscla.

       No such brss outduct.
           No BRSS outduct with duct name matching local_hostname and local_port_nbr has been added to the BP
           database.  Use bpadmin to stop the BRSS convergence-layer protocol, add the outduct, and then restart
           the BRSS protocol.

       Can't get IP address for host
           Operating system error.  Check errtext, correct problem, and restart BRSS.

       Can't open TCP socket
           Operating system error -- unable to open TCP socket for accepting connections.  Check errtext,
           correct problem, and restart BRSS.

       Can't initialize socket (note: must be root for port 80)
           Operating system error.  Check errtext, correct problem, and restart BRSS.

       brsscla can't create sender thread
           Operating system error.  Check errtext, correct problem, and restart BRSS.

       brsscla can't create access thread
           Operating system error.  Check errtext, correct problem, and restart BRSS.

BUGS

       Report bugs to <ion-bugs@korgano.eecs.ohiou.edu>

SEE ALSO

       bpadmin(1), bprc(5), brsccla(1)