v0.2.0

Changelog

v0.2.0

New instructions, three of them:

• & - accept a connection like ~, but fork instead of blocking. A
  new thread continues right after & with the new connection and the
  current cell set to 1; the original thread also continues right
  after &, with the current cell set to 0 and no connection, and
  loops back around for the next one. This is what makes actual
  concurrent connections possible - previously ~ meant one
  connection had to fully finish before the next could even be
  accepted.
• ? - writes the connected peer's IPv4 address and port into the
  current cell and the five after it (4 bytes IP, 2 bytes port,
  big-endian), no pointer movement. Zeroed out if there's no
  connection or the peer isn't IPv4.
• @ - reads a NUL-terminated "host:port" string starting at the
  current cell, tries to connect to it, and swaps it in as the new
  , / . target on success. Writes 1 or 0 to the current cell
  depending on whether it worked. Closes whatever connection was
  there before.

Fixed: closing a connection while there were still unread bytes sitting
in the receive buffer made the kernel send an RST instead of a clean
FIN, which shows up client-side as "connection reset" even after a
full response had already gone out. Every path that closes or replaces
a connection now drains it first.

New examples:

• examples/concurrent.bf - same fixed response as v0.1, but via &,
  so multiple connections actually overlap instead of queueing
• examples/whoami.bf - reads the peer's IP and port with ? and
  prints them back as readable decimal, not raw bytes
• examples/notify.bf - responds to the caller, then uses @ to fire
  a fixed request at a second host as a side effect
• examples/router.bf - real path-based routing: incoming path bytes
  get compared against each route byte by byte, no checksum shortcuts.
  Generated by tools/route_gen.py rather than hand-written, since the
  comparison logic gets long fast

New tools:

• tools/bfbuilder.py - a small cursor-based code builder (tracks
  pointer position automatically instead of hand-counting </>),
  plus a decimal-printing subroutine built on it
• tools/route_gen.py - turns a (path, response) table into a
  routed server
• tools/build_examples.py - regenerates all the generated examples
  above from source, so they're reproducible rather than one-off output

Known limitation worth calling out: @ only gives you one connection
slot, same as ~ and & did. Once you connect out, the original
inbound connection is gone - there's no way to read from one
connection and write to another at the same time, so a true relay/
proxy isn't possible with the current instruction set. notify.bf
works around this by answering the real client before ever touching
@.

v0.1.0

First tagged release.

• bf.py, brainfuck interpreter (standard 8 instructions, no more, no
  less), plus ~ for TCP: block for the next connection, close
  whatever was there before, become the new , / . target
• run.sh - socat handles the actual TCP listening, hands each
  connection to the interpreter over stdin/stdout
• examples/hello-json.bf, examples/hello-text.bf - fixed responses,
  same for every request regardless of path
• tools/text2bf.py - turns raw bytes into the +/-/. sequence
  that prints them

Superseded by the bfnet binary in v0.2.0, which replaces the
socat + Python interpreter pair with a single compiled interpreter
that also owns the TCP accept loop.