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)