dapp.py

# Copyright 2022 Cartesi Pte. Ltd.
#
# SPDX-License-Identifier: Apache-2.0
# Licensed under the Apache License, Version 2.0 (the "License"); you may not use
# this file except in compliance with the License. You may obtain a copy of the
# License at http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software distributed
# under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
# CONDITIONS OF ANY KIND, either express or implied. See the License for the
# specific language governing permissions and limitations under the License.

from os import environ
import traceback
import logging
import requests

import subprocess

logging.basicConfig(level="INFO")
logger = logging.getLogger(__name__)

rollup_server = environ["ROLLUP_HTTP_SERVER_URL"]
logger.info(f"HTTP rollup_server url is {rollup_server}")

FORTUNE_CMD = "/usr/games/fortune; exit 0"

def hex2str(hex):
    """
    Decodes a hex string into a regular string
    """
    return bytes.fromhex(hex[2:]).decode("utf-8")

def str2hex(str):
    """
    Encodes a string as a hex string
    """
    return "0x" + str.encode("utf-8").hex()

def handle_advance(data):
    logger.info(f"Received advance request data {data}")

    status = "accept"
    try:
        input = hex2str(data["payload"])
        logger.info(f"Received input: {input}")

        quote = subprocess.check_output(FORTUNE_CMD, shell=True, stderr=subprocess.STDOUT).decode()
        output = f"Received input: {input}. This was the quote {quote}"

        # Emits notice with result of calculation
        logger.info(f"Adding notice with payload: '{output}'")
        response = requests.post(rollup_server + "/notice", json={"payload": str2hex(str(output))})
        logger.info(f"Received notice status {response.status_code} body {response.content}")

    except Exception as e:
        status = "reject"
        msg = f"Error processing data {data}\n{traceback.format_exc()}"
        logger.error(msg)
        response = requests.post(rollup_server + "/report", json={"payload": str2hex(msg)})
        logger.info(f"Received report status {response.status_code} body {response.content}")

    return status

def handle_inspect(data):
    logger.info(f"Received inspect request data {data}")

    status = "accept"
    try:
        input = hex2str(data["payload"])
        logger.info(f"Received input: {input}")

        output = subprocess.check_output(FORTUNE_CMD, shell=True, stderr=subprocess.STDOUT).decode()

        # Emits notice with result of calculation
        logger.info(f"Adding report with payload: '{output}'")
        response = requests.post(rollup_server + "/report", json={"payload": str2hex(str(output))})
        logger.info(f"Received report status {response.status_code} body {response.content}")

    except Exception as e:
        status = "reject"
        msg = f"Error processing data {data}\n{traceback.format_exc()}"
        logger.error(msg)
        response = requests.post(rollup_server + "/report", json={"payload": str2hex(msg)})
        logger.info(f"Received report status {response.status_code} body {response.content}")

    return status

handlers = {
    "advance_state": handle_advance,
    "inspect_state": handle_inspect,
}

finish = {"status": "accept"}

while True:
    logger.info("Sending finish")
    response = requests.post(rollup_server + "/finish", json=finish)
    logger.info(f"Received finish status {response.status_code}")
    if response.status_code == 202:
        logger.info("No pending rollup request, trying again")
    else:
        rollup_request = response.json()
        data = rollup_request["data"]
        
        handler = handlers[rollup_request["request_type"]]
        finish["status"] = handler(rollup_request["data"])