Amr Gharbeia
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92 lines
3.9 KiB
Org Mode
92 lines
3.9 KiB
Org Mode
#+TITLE: Communication Protocol (communication.lisp)
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#+AUTHOR: Amr
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#+FILETAGS: :harness:protocol:
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#+STARTUP: content
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* Communication Protocol (communication.lisp)
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** Architectural Intent: Secure Inter-Process Communication
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The Communication Protocol is the bridge between the OpenCortex microharness and the outside world. To maintain the "Zero-Bloat" mandate, the protocol must be:
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1. **Lightweight:** Minimal overhead for low-latency terminal interaction.
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2. **Deterministic:** Strict S-expression framing to prevent injection attacks.
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3. **Transport-Agnostic:** Capable of running over TCP, Unix Sockets, or Standard I/O.
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By utilizing a length-prefixed S-expression format (the "Unified Envelope"), we ensure that both human-readable text and complex Lisp data structures can be transmitted securely without the fragility of JSON or the overhead of Protobuf.
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** Pipeline Initialization
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#+begin_src lisp :tangle ../src/communication.lisp
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(in-package :opencortex)
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#+end_src
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* Message Framing
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** Frame Serialization (frame-message)
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Every message leaving the harness must be "framed." This involves two steps:
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1. *Sanitization:* Stripping raw Lisp objects (like streams or sockets) that cannot be serialized.
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2. *Prefixed Framing:* Calculating the length of the S-expression and prepending it as a 6-character hexadecimal string.
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Example Frame: ~00001c(:TYPE :STATUS :SCRIBE :IDLE)~
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#+begin_src lisp :tangle ../src/communication.lisp
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(defun sanitize-protocol-message (msg)
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"Recursively strips non-serializable objects (streams, sockets) from a protocol plist."
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(if (and msg (listp msg))
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(let ((clean nil))
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(loop for (k v) on msg by #'cddr
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do (unless (member k '(:reply-stream :socket :stream))
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(push k clean)
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(push (if (listp v) (sanitize-protocol-message v) v) clean)))
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(nreverse clean))
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msg))
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#+end_src
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#+begin_src lisp :tangle ../src/communication.lisp
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(defun frame-message (msg)
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"Serializes a message plist and prefixes it with a 6-character hex length."
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(let* ((sanitized (sanitize-protocol-message msg))
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(payload (let ((*print-pretty* nil) (*read-eval* nil)) (format nil "~s" sanitized)))
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(len (length payload)))
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(format nil "~6,'0x~a" len payload)))
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#+end_src
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* Message Ingestion
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** Framed Message Reader (read-framed-message)
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The inverse of framing. This function reads exactly the number of bytes specified by the hex-length prefix. This "byte-counted" reading is a critical security measure—it prevents buffer overflow attacks and "slowloris" type hung connections.
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#+begin_src lisp :tangle ../src/communication.lisp
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(defun read-framed-message (stream)
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"Reads a hex-prefixed message from a stream. Returns the parsed Lisp plist or :EOF."
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(handler-case
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(let ((len-buf (make-string 6)))
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;; 1. Read the length prefix
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(let ((count (read-sequence len-buf stream)))
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(if (< count 6)
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:eof
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(let ((len (ignore-errors (parse-integer len-buf :radix 16))))
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(if (and len (> len 0))
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;; 2. Read exactly 'len' bytes
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(let ((payload-buf (make-string len)))
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(read-sequence payload-buf stream)
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(let ((*read-eval* nil))
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(read-from-string payload-buf)))
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:error)))))
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(error (c)
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(harness-log "PROTOCOL ERROR: ~a" c)
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:error)))
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#+end_src
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* Semantic Handshakes
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** Hello Message (make-hello-message)
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The first message sent by the daemon upon client connection. It advertises the protocol version and the agent's current capabilities.
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#+begin_src lisp :tangle ../src/communication.lisp
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(defun make-hello-message (version)
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"Constructs the standard HELLO handshake message."
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(list :TYPE :EVENT
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:PAYLOAD (list :ACTION :handshake
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:VERSION version
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:CAPABILITIES '(:AUTH :SWANK :ORG-AST))))
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#+end_src
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