seed.c — Self-Growing Firmware

Source: https://github.com/Awis13/seed

You have access to a seed node — a minimal C firmware with an HTTP API that you can grow by writing and compiling new firmware on the device.

First steps

If the user hasn't given you a node address and token, ask them:

• Do they already have a seed node running? If so, get the IP and token.
• If not, offer to deploy one. All they need is a Linux machine with gcc:

# On the target machine (Pi, VPS, any Linux box):
curl -fsSL https://raw.githubusercontent.com/Awis13/seed/main/seeds/linux/seed.c -o seed.c
gcc -O2 -o seed seed.c
./seed 8080
# Token will be printed — give it to the agent

The seed binary is ~70KB, zero dependencies beyond libc.

Connecting

The node prints its address and token on startup. If you don't know them:

# The user will provide the address, or:
curl http://<ip>:8080/health          # no auth needed
curl http://<ip>:8080/skill           # full connection details + token

All requests except /health need: Authorization: Bearer <token>

What you can do

1. Discover the hardware

curl -H "Authorization: Bearer $TOKEN" http://$HOST/capabilities

Returns: arch, CPU, RAM, disk, temperature, GPIO, I2C, serial ports, USB devices, WiFi, Bluetooth, WireGuard — everything the node has.

2. Read the running firmware

curl -H "Authorization: Bearer $TOKEN" http://$HOST/firmware/source

Returns the C source code currently running on the node.

3. Write new firmware

curl -H "Authorization: Bearer $TOKEN" \
  -X POST --data-binary @new_firmware.c \
  http://$HOST/firmware/source

Upload C source code. The node saves it for compilation.

4. Compile on the device

curl -H "Authorization: Bearer $TOKEN" -X POST http://$HOST/firmware/build

The node runs gcc -O2 on itself. Check errors with GET /firmware/build/logs.

5. Apply (hot-swap)

curl -H "Authorization: Bearer $TOKEN" -X POST http://$HOST/firmware/apply

Atomic binary swap. 10-second watchdog — if the new firmware fails the health check, the old version is restored automatically.

API reference

Writing firmware

Constraints:

• C only, libc only — no external libraries
• gcc -O2 -o seed seed.c must compile with no extra flags
• Single-threaded, one request at a time
• Max request body: 64KB
• 3 failed applies -> /firmware/apply locks (POST /firmware/apply/reset to unlock)

Handler pattern:

if (strcmp(req.path, "/myendpoint") == 0
    && strcmp(req.method, "GET") == 0) {
    char resp[4096];
    snprintf(resp, sizeof(resp), "{\"key\":\"value\"}");
    json_resp(fd, 200, "OK", resp);
    goto done;
}

Available functions:

• json_resp(fd, code, status, json) — send JSON response
• text_resp(fd, code, status, text) — send plain text
• respond(fd, code, status, content_type, body, len) — send anything
• file_read(path, &len) — read file, returns malloc'd buffer
• file_write(path, data, len) — write file
• cmd_out(shell_cmd, buf, bufsize) — run command, capture output
• event_add(fmt, ...) — log event

Request struct: req.method, req.path, req.body (malloc'd, may be NULL), req.body_len, req.content_length. Path includes query string.

Auth is already checked before your handler. /health is always public.

Capabilities example

{
  "type": "seed", "version": "0.1.0", "seed": true,
  "hostname": "raspberrypi", "arch": "armv6l",
  "cpus": 1, "mem_mb": 512, "disk_mb": 14000,
  "temp_c": 42.3, "board_model": "Raspberry Pi Zero W Rev 1.1",
  "has_gcc": true,
  "net_interfaces": ["eth0", "wlan0", "usb0"],
  "serial_ports": ["/dev/ttyAMA0"],
  "i2c_buses": ["/dev/i2c-1"],
  "gpio_chips": ["/dev/gpiochip0"],
  "has_wifi": true, "has_bluetooth": true,
  "endpoints": ["/health", "/capabilities", "/config.md", ...]
}

Use this to decide what the node can do and what firmware to write.

Typical workflow

1. GET /health — is it alive?
2. GET /capabilities — what hardware does it have?
3. GET /firmware/source — read the current code
4. Write new firmware that adds the endpoints you need
5. POST /firmware/source — upload it
6. POST /firmware/build — compile
7. GET /firmware/build/logs — check for errors
8. POST /firmware/apply — deploy (auto-rollback on failure)
9. Test the new endpoints
10. Repeat — the grown firmware still has /firmware/*, so you can grow it again