145 lines
3.9 KiB
Markdown
145 lines
3.9 KiB
Markdown
# SecLink Terminal Demo
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Standalone DOS terminal emulator combining the DVX windowed GUI with
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SecLink encrypted serial communication. Part of the DVX GUI project.
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This is NOT a DXE app -- it is a freestanding program with its own
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`main()` that initializes the DVX GUI directly and manages its own
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event loop. Unlike the DXE apps (progman, notepad, clock, dvxdemo)
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which run inside the DVX Shell, this program demonstrates how to use
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the DVX widget system outside the shell framework.
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Connects to a remote BBS through the SecLink proxy, providing a full
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ANSI terminal in a DVX-style window with encrypted transport.
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NOTE: This program predates the DXE module refactoring and links
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against static libraries from `lib/`. It may need Makefile updates
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to build against the current source tree layout.
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## Architecture
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```
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termdemo (DOS, 86Box)
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+--- DVX GUI windowed desktop, ANSI terminal widget
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+--- SecLink encrypted serial link
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| +--- packet HDLC framing, CRC-16, Go-Back-N ARQ
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| +--- security DH key exchange, XTEA-CTR cipher
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| +--- rs232 ISR-driven UART I/O
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COM port (86Box emulated modem)
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TCP:2323
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secproxy (Linux)
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TCP:23
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Remote BBS
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```
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All traffic between the terminal and the proxy is encrypted via
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XTEA-CTR on SecLink channel 0. The proxy decrypts and forwards
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plaintext to the BBS over telnet.
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## Usage
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```
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termdemo [com_port] [baud_rate]
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```
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| Argument | Default | Description |
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|-------------|---------|--------------------------|
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| `com_port` | 1 | COM port number (1-4) |
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| `baud_rate` | 115200 | Serial baud rate |
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Examples:
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```
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termdemo # COM1 at 115200
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termdemo 2 # COM2 at 115200
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termdemo 1 57600 # COM1 at 57600
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termdemo -h # show usage
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```
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## Startup Sequence
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1. Seed the RNG from hardware entropy (PIT-based on DOS).
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2. Open SecLink on the specified COM port (8N1, no handshake).
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3. Perform DH key exchange (blocks until the proxy completes its side).
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4. Initialize the DVX GUI (1024x768, 16bpp VESA).
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5. Create a resizable terminal window with menu bar and status bar.
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6. Register an idle callback so serial data is polled during GUI idle.
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7. Enter the main loop.
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The handshake completes in text mode before the GUI starts, so the
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DOS console shows progress messages during connection setup.
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## Data Flow
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```
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BBS -> proxy -> serial -> secLinkPoll() -> onRecv() -> ring buffer
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-> commRead() -> wgtAnsiTermWrite() -> ANSI parser -> screen
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Keyboard -> widgetAnsiTermOnKey() -> commWrite()
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-> secLinkSend() -> serial -> proxy -> BBS
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```
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A 4KB ring buffer bridges the SecLink receive callback (which fires
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asynchronously during `secLinkPoll()`) and the terminal widget's comm
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read interface (which is polled synchronously during the widget paint
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cycle).
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## Test Setup
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1. Start the SecLink proxy on the Linux host:
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```
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secproxy 2323 bbs.example.com 23
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```
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2. Configure 86Box with a COM port pointing at the proxy's listen port
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(TCP client mode, port 2323, no telnet negotiation).
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3. Run the terminal inside 86Box:
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```
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termdemo
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```
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## Dependencies
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All libraries are built into `lib/`:
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| Library | Purpose |
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|------------------|--------------------------------------|
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| `libdvx.a` | DVX windowed GUI and widget system |
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| `libseclink.a` | Secure serial link wrapper |
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| `libpacket.a` | HDLC framing and reliability |
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| `libsecurity.a` | DH key exchange and XTEA cipher |
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| `librs232.a` | ISR-driven UART serial driver |
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## Files
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```
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termdemo/
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termdemo.c terminal emulator program
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Makefile DJGPP cross-compilation build
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```
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## Build
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```
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make # builds bin/termdemo.exe (and dependency libs)
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make clean # removes objects and binary
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```
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