go-cotp v1.1.0

Date: 2026-10-28
Previous release: v1.0.4

Summary

Full-duplex fix: reads and writes now use independent deadlines, so a *Conn
can be read by one goroutine while others write — as MMS does — without one
direction's context cutting, extending, or clearing the other's. Consumers
that wrapped the stream to split deadlines themselves (go-mms
transport/iso splitDeadlineConn) can drop that shim. No API additions;
minor bump because timeout and error classification changed (see below).

Changes

Behaviour

• Per-direction deadlines. ReadTSDU applies its context with
  SetReadDeadline only and WriteTSDU with SetWriteDeadline only; each
  restores its own direction to no deadline when it returns. Previously both
  armed SetDeadline (both directions) and cleared it afterwards, so a write
  with a short context could time out a concurrent read, and a finishing
  read cleared a stalled write's deadline (and vice versa). Only the
  Connect/Accept handshake still uses SetDeadline.
• Cancellation is race-free and honoured with a deadline too. A context
  cancelled right as an operation returned could leave a past deadline on the
  stream and break every later operation; the cancellation callback is now
  ordered against the operation's end. A context that has a deadline and is
  cancelled early now interrupts the operation too (before, only contexts
  without a deadline were watched).
• Context expiry before any octet moved is not fatal. If a context ends
  ReadTSDU/WriteTSDU before a single octet of the TSDU crossed the stream
  (an idle read, a stalled first write), the call returns the bare
  ctx.Err() and the connection stays open; the other direction is
  untouched. Once octets have moved, the connection is still aborted with
  ErrClosed + the context error, as before.
• Serialized callers honour their context while queued. Concurrent
  WriteTSDU calls are serialized for a whole TSDU (segments of different
  TSDUs never interleave), as are concurrent ReadTSDU calls; a caller
  waiting for its turn now returns ctx.Err() when its context ends, without
  aborting the connection.
• Reset / broken pipe classify as ErrDisconnected. A TCP reset, broken
  pipe, stream closed underneath go-cotp, or EOF inside a packet now aborts
  with a *DisconnectError carrying the cause (joined with
  ErrIncompleteTSDU mid-TSDU), as docs/TP0_API_DESIGN.md specified.
  Previously these returned the raw network error.

Tests

• Full-duplex regressions (duplex_test.go): a reader survives a concurrent
  write whose context expires, and the reverse; a completing write keeps the
  reader's deadline, and the reverse; cancelled-right-after-return writes
  never poison the stream; queued callers honour their context.
• 16 parallel senders per side alongside one reader per side over net.Pipe
  and TCP with multi-segment TSDUs, verified by per-TSDU CRC and per-sender
  order (-race).
• Chaos stream: short writes, short reads, jitter, and random resets.
• FuzzSegmentedRoundTrip: fuzz-chosen TSDUs over fuzz-chosen stream
  chunking.
• Deadline controller unit tests, including a cancel/disarm race.

Documentation

• README, API.md, doc.go, docs/TP0_API_DESIGN.md §7, docs/ARCHITECTURE.md:
  concurrency and deadline rules updated.
• ERRORS.md: typed error structs and ConnectionPhase constants corrected to
  match the code; idle-timeout and disconnect classification documented.
• Coverage gate raised to 90% (make coverage-check, CONTRIBUTING.md).

Dependencies

• go-tpkt stays at v1.0.1: it is stateless and sets no deadlines.