Cthulhu is no longer a fork. Now it is a screen reader written in Golang.

internal/tentaclewire/wire.go

@@ -0,0 +1,106 @@
+// Copyright (c) 2026 Storm Dragon
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+// Package tentaclewire shares bounded framing between the host and Go SDK.
+package tentaclewire
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/json"
+	"errors"
+	"io"
+	"unicode/utf8"
+)
+
+const MaxFrameBytes = 64 * 1024
+
+var ErrProtocol = errors.New("invalid tentacle protocol message")
+var ErrLimit = errors.New("tentacle resource limit exceeded")
+
+// ReadFrame bounds allocation even when the child never writes a newline.
+func ReadFrame(reader *bufio.Reader) ([]byte, error) {
+	var frame []byte
+	for {
+		part, err := reader.ReadSlice('\n')
+		if len(frame)+len(part) > MaxFrameBytes+1 {
+			return nil, ErrLimit
+		}
+		frame = append(frame, part...)
+		if err == nil {
+			return frame[:len(frame)-1], nil
+		}
+		if errors.Is(err, bufio.ErrBufferFull) {
+			continue
+		}
+		if errors.Is(err, io.EOF) && len(frame) != 0 {
+			return nil, io.ErrUnexpectedEOF
+		}
+		return nil, err
+	}
+}
+
+// Reject duplicate keys and excessive nesting, including in command arguments
+// and results. Different languages must not interpret the same frame differently.
+func ValidateJSON(data []byte) error {
+	if !utf8.Valid(data) {
+		return ErrProtocol
+	}
+	decoder := json.NewDecoder(bytes.NewReader(data))
+	decoder.UseNumber()
+	if err := validate_value(decoder, 0); err != nil {
+		return ErrProtocol
+	}
+	if _, err := decoder.Token(); err != io.EOF {
+		return ErrProtocol
+	}
+	return nil
+}
+
+func validate_value(decoder *json.Decoder, depth int) error {
+	if depth > 32 {
+		return ErrLimit
+	}
+	token, err := decoder.Token()
+	if err != nil {
+		return err
+	}
+	delimiter, composite := token.(json.Delim)
+	if !composite {
+		return nil
+	}
+	if delimiter != '{' && delimiter != '[' {
+		return ErrProtocol
+	}
+	keys := map[string]bool{}
+	for decoder.More() {
+		if delimiter == '{' {
+			keyToken, err := decoder.Token()
+			if err != nil {
+				return err
+			}
+			key, ok := keyToken.(string)
+			if !ok || keys[key] {
+				return ErrProtocol
+			}
+			keys[key] = true
+		}
+		if err := validate_value(decoder, depth+1); err != nil {
+			return err
+		}
+	}
+	_, err = decoder.Token()
+	return err
+}
+
+func DecodeStrict(data []byte, target any) error {
+	if err := ValidateJSON(data); err != nil {
+		return err
+	}
+	decoder := json.NewDecoder(bytes.NewReader(data))
+	decoder.DisallowUnknownFields()
+	if err := decoder.Decode(target); err != nil {
+		return ErrProtocol
+	}
+	return nil
+}