Channel wraps the post-handshake socket and carries 4-byte length-
prefixed distribution messages: pass-through byte ('p') + ETF control
tuple + optional payload term.
API surface:
send_raw / recv_raw -- raw 4-byte framed bytes, empty == net_tick
send_tick -- send keepalive frame
send_control / recv_message -- structured control + payload
send_reg_send -- helper for the REG_SEND case (FromPid,
registered name, payload)
recv_message() transparently skips inbound ticks; callers wanting tick
awareness use recv_raw().
etf.decode_term(data, offset) exposed as a streaming decoder so the
channel can read control + payload back-to-back from one frame body.
Tests:
- pure encode/decode round-trips
- socketpair tests for framing, ticks, helper signatures
- live end-to-end against an erl node with a registered echo process:
EPMD -> handshake -> REG_SEND -> recv reply, payload matches
- boot script writes a /tmp ready-flag after registering `echo`;
fixture waits for both EPMD registration AND the flag to dodge
the race where EPMD registers the node before -eval runs
101 tests green, lint clean.
handshake(sock, our_name=..., cookie=...) drives the OTP 23+ dance over
a 2-byte length-prefixed frame stream:
send_name (N) client -> server
recv_status (s) server -> client
recv_challenge (N) server -> client
challenge_reply (r) client -> server
challenge_ack (a) server -> client
Cookie digest formula md5(cookie ++ integer_to_list(challenge)) was
cross-checked against erlang:md5/1 output as a test reference.
Distribution flags in erldistpy/flags.py advertise the minimum useful
set: extended refs/pids, new fun tags, utf8 atoms, maps, big creation,
v6 handshake, unlink id, v4 node containers.
86 tests green: frame builders + parsers as pure functions, digest
reference, full live handshake against `erl -sname -setcookie`, and a
wrong-cookie rejection test.
Newer SHA-256 digest (DFLAG_MANDATORY_25_DIGEST) deferred until a peer
requires it.
