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NAME

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

SYNOPSIS

brsscla local_hostname[:local_port_nbr]

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 2*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 two thread for each spawned socket, an input thread to handle BRSS protocol input from the associated connected client and an output thread to forward BRSS protocol output to 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 receiving thread 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.

Each output thread extracts bundles from the queues of bundles ready for transmission via BRSS to the corresponding connected client and transmits the bundles over the socket to that client. Each transmitted bundle is preceded by its length, a 32-bit unsigned integer in network byte order.

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.

  • 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 <https://github.com/nasa-jpl/ION-DTN/issues>

SEE ALSO

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