106 lines
4.3 KiB
Plaintext
106 lines
4.3 KiB
Plaintext
== remsim-bankd
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The `remsim-bankd` (SIM Bank Daemon) manages one given SIM bank. The
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initial implementation supports a PC/SC driver to expose any PC/SC
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compatible card readers as SIM bank.
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`remsim-bankd` initially connects via a RSPRO control connection to
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`remsim-server` at startup, and will in turn receive a set of initial
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[client,slot]:[bankd,slot] mappings. These mappings determine which
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slot on the client (corresponding to a modem) is mapped to which slot on
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the SIM bank. Mappings can be updated by `remsim-server` at any given
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point in time.
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`remsim-bankd` implements a RSPRO server, where it listens to connections
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from `remsim-clients`.
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As PC/SC only offers a blocking API, there is one thread per PC/SC slot.
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This thread will perform blocking I/O on the socket towards the client,
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and blocking API calls on PC/SC.
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In terms of thread handling, we do:
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* accept() handling in [spare] worker threads
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** this means blocking I/O can be used, as each worker thread only has
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one TCP connection
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** client identifies itself with client:slot
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** lookup mapping based on client:slot (using mutex for protection)
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** open the reader based on the lookup result
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The worker threads initially don't have any mapping to a specific
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reader, and that mapping is only established at a later point after the
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client has identified itself. The advantage is that the entire bankd
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can live without any non-blocking I/O.
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The main thread handles the connection to `remsim-server`, where it can
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also use non-blocking I/O. However, re-connection would be required, to
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avoid stalling all banks/cards in the event of a connection loss to the
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server.
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worker threads have the following states:
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* INIT (just started)
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* ACCEPTING (they're blocking in the accept() call on the server socket fd)
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* CONNECTED_WAIT_ID (TCP established, but peer not yet identified itself)
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* CONNECTED_CLIENT (TCP established, client has identified itself, no mapping)
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* CONNECTED_CLIENT_MAPPED (TCP established, client has identified itself, mapping exists)
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* CONNECTED_CLIENT_MAPPED_CARD (TCP established, client identified, mapping exists, card opened)
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* CONNECTED_SERVER (TCP established, server has identified itself)
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Once the client disconnects, or any other error occurs (such as card I/O
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errors), the worker thread either returns to INIT state (closing client
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socket and reader), or it terminates. Termination would mean that the
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main thread would have to do non-blocking join to detect client
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termination and then re-spawn clients, so the "return to INIT state"
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approach seems to make more sense.
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=== Running
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`remsim-bankd` currently has the following command-line options:
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==== SYNOPSIS
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*remsim-bankd* [-h] [-i A.B.C.D] [-p <1-65535>] [-b <1-65535>] [-I A.B.C.D] [-P <1-65535> ]
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==== OPTIONS
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*-h, --help*::
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Print a short help message about the supported options
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*-i, --server-host A.B.C.D*::
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Specify the remote IP address/hostname of the remsim-server to which this bankd
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shall establish its RSPRO control connection
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*-p, --server-port <1-65535>*::
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Specify the remote TCP port number of the remsim-server to whihc this bankd
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shall establish its RSPRO control connection
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*-b, --bank-id <1-65535>*::
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Specify the numeric bank identifier of the SIM bank this bankd instance
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operates. Must be unique among all banks connecting to the same remsim-server.
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*-I, --bind-IP A.B.C.D*::
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Specify the local IP address to which the socket for incoming connections
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from remsim-clients is bound to.
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*-P, --bind-port <1-65535>*::
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Specify the local TCP port to whicc the socket for incoming connections
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from remsim-clients is bound to.
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=== Logging
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remsim-bankd currently logs to stdout only, and the logging verbosity
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is not yet configurable. However, as the libosmocore logging framework
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is used, extending this is an easy modification.
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=== `bankd_pcsc_slots.csv` CSV file
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bankd expects a CSV file `bankd_pcsc_slots.csv` in the current working directory at startup.
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This CSV file specifies the mapping between the string names of the PCSC
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readers and the RSPRO bandk/slot numbers. The format is as follows:
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.Example: CSV file mapping bankd slots 0..4 to an ACS ACR33U-A1 reader slots
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----
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"1","0","ACS ACR33 ICC Reader 00 00"
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"1","1","ACS ACR33 ICC Reader 00 01"
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"1","2","ACS ACR33 ICC Reader 00 02"
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"1","3","ACS ACR33 ICC Reader 00 03"
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"1","4","ACS ACR33 ICC Reader 00 04"
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----
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