dvb-ci-runtime

Pure-Rust EN 50221 DVB Common Interface runtime — the driver loop over the dvb-ci wire codecs.

dvb-ci is no_std and owns the wire layer (TPDU / SPDU / APDU parse+serialize, CA_PMT building, CI Plus extensions). dvb-ci-runtime adds the runtime: device I/O, the TPDU poll loop, SPDU session management, and the per-resource state machines that drive a physical CAM (ETSI EN 50221, TS 101 699).

Design

Everything is written against the CaDevice trait, so the runtime runs against either a real Linux CA device (/dev/dvb/adapterN/caM, the linux feature) or an in-memory MockCaDevice. The mock makes the state machines testable without hardware and enables differential testing against an external reference — drive both with the same scripted mock CAM, assert the emitted write/ioctl byte sequences match.

Implemented from the EN 50221 specification.

What's implemented

• Transport (TPDU, §A.4): Create_T_C handshake, poll cadence, T_SB data-available → T_RCV, T_Data_More/Last reassembly, reply timeout.
• Session (SPDU, §7.2): session table; open_session/create_session/ close; session_number + APDU routing.
• Resources (§8): Resource Manager handshake → CamReady, application_information, conditional_access (ca_pmt/ca_pmt_reply), date_time (MJD + BCD), mmi (surfaces module menus/enquiries).
• Descramble helper: Driver::descramble(pmt) / HostRequest::Descramble runs the full ca_pmt query → reply → ok_descrambling sequence, filtered to the CAM's advertised CAIDs (from ca_info).
• Devices: in-memory MockCaDevice + MockCiDataDevice; Linux /dev/dvb/adapterN/caM (control plane) and ciM (TS data plane, CiDataDevice — scrambled-in / descrambled-out for separate-CI hardware) behind the linux feature (libc).
• Diagnostics: RecordingCaDevice captures the link both ways; trace::decode_frame / decode_log annotate a capture (TPDU → SPDU → APDU) for live-CAM debugging.
• MMI answering: Driver::mmi_menu_answer / mmi_enquiry_answer / mmi_cancel send menu_answ / answ back to the module.

ci-probe — discover and engage an installed CAM

A command-line tool that drives a real Common Interface module end-to-end over a Linux DVB CA device. It is the reference consumer of this crate: it wires Driver + LinuxCaDevice + RecordingCaDevice + trace together with nothing but std::env::args.

Build / install

Linux only; gated behind the linux feature (it opens /dev/dvb/... and uses libc ioctls):

cargo build  -p dvb-ci-runtime --features linux --release   # target/release/ci-probe
cargo install dvb-ci-runtime   --features linux             # ~/.cargo/bin/ci-probe

Device access usually needs membership of the video group (or root).

Commands

Append --trace to any command to dump an annotated link trace on exit (every TPDU/SPDU/APDU both directions) — invaluable for diagnosing a CAM that won't complete a handshake.

Examples

Discover what's installed:

$ ci-probe list
/dev/dvb/adapter0/ca0  slot 0  module_ready=true

Identify the module and its CA systems:

$ ci-probe info 0 0
CAM ready (resource-manager handshake complete)
application_info: type=0x01 manufacturer=0x1234 code=0x5678 menu="Irdeto CAM"
ca_info: 18 CA_system_id(s): 0x0604, 0x0606, 0x0608, ...

Diagnose a stuck handshake (annotated trace):

$ ci-probe info 0 0 --trace
...
--- link trace ---
  reset()
  slot_info() -> ready=true
W Create_T_C tcid=1
R C_T_C_Reply tcid=1
R T_Data_Last tcid=1 · open_session_request
W T_Data_Last tcid=1 · open_session_response
W T_Data_Last tcid=1 · session 1 · profile_enq (9F8010)
R T_Data_Last tcid=1 · session 1 · profile (9F8011)
...

Request descrambling for a service (PMT extracted with e.g. dvbsnoop or the dvb-si tools):

$ ci-probe descramble 0 0 service.pmt
CAM ready (resource-manager handshake complete)
ca_info: 18 CA_system_id(s): ...
ca_info received → sending descramble request
ca_pmt_reply: program 1019 descrambling_ok=true

Hardware notes

• The device read/write exchange one whole kernel link frame [slot, connection_id, <TPDU + T_SB>]; the LinuxCaDevice handles that framing.
• EN 50221's link is polled half-duplex — one T_Data_Last per module T_SB. The transport enforces this (a real CAM drops a second block sent before it answers the first — see #337).
• If info times out before ca_info, re-run with --trace and read the last few lines — they show exactly which step the module stopped responding at.

The EN 50221 link is polled half-duplex — the host sends one T_Data_Last per module T_SB. The transport queues outbound SPDUs and releases one per turn (a real CAM drops a second block sent before it answers the first — #337).

#![deny(unsafe_code)] — the Linux device leaf is the sole #[allow]; the sans-IO core is unsafe-free. 27 tests, no hardware required.

Roadmap: the host_control resource, MMI answering (menu_answ/answ), and a differential test harness against an external reference.

Example

use std::time::Duration;
use dvb_ci_runtime::{Driver, MockCaDevice, Notification};
use dvb_ci_runtime::dvb_ci::tpdu::tags;

// Script a module that accepts the transport connection.
let dev = MockCaDevice::new([vec![tags::C_T_C_REPLY, 0x01, 0x01]]);
let mut driver = Driver::new(dev);

driver.init()?;                       // reset + open the transport connection
for _ in 0..4 {
    driver.pump(Duration::from_millis(100))?;   // read frames / advance poll cadence
}
for note in driver.take_notifications() {
    if let Notification::CamReady = note { /* now safe to send a ca_pmt */ }
}
# Ok::<(), std::io::Error>(())

See examples/ for a runnable version.

License

MIT OR Apache-2.0.