monitor.py

#!/usr/bin/env python

# based on code by henryk ploetz
# https://hackaday.io/project/5301-reverse-engineering-a-low-cost-usb-co-monitor/log/17909-all-your-base-are-belong-to-us

import os, sys, fcntl, time, librato, yaml, socket

import requests

def callback_function(error, result):
    if error:
        print(error)
        return

    print(result)

def decrypt(key,  data):
    cstate = [0x48,  0x74,  0x65,  0x6D,  0x70,  0x39,  0x39,  0x65]
    shuffle = [2, 4, 0, 7, 1, 6, 5, 3]

    phase1 = [0] * 8
    for i, o in enumerate(shuffle):
        phase1[o] = data[i]

    phase2 = [0] * 8
    for i in range(8):
        phase2[i] = phase1[i] ^ key[i]

    phase3 = [0] * 8
    for i in range(8):
        phase3[i] = ( (phase2[i] >> 3) | (phase2[ (i-1+8)%8 ] << 5) ) & 0xff

    ctmp = [0] * 8
    for i in range(8):
        ctmp[i] = ( (cstate[i] >> 4) | (cstate[i]<<4) ) & 0xff

    out = [0] * 8
    for i in range(8):
        out[i] = (0x100 + phase3[i] - ctmp[i]) & 0xff

    return out

def hd(d):
    return " ".join("%02X" % e for e in d)

def now():
    return int(time.time())

def notifySlack(co2, config, upper_threshold):
    if ((not config) or (not "webhook" in config)):
        return
    webhookUrl = config["webhook"]
    channel = config["channel"] if "channel" in config else "#general"
    botName = config["botname"] if "botname" in config else "CO2bot"
    icon = config["icon"] if "icon" in config else ":robot_face:"

    if (co2 > upper_threshold):
        message = "Dude, you should open a window. We have *%dppm* in here." % co2
    else:
        message = "Ok, you can close the window now. We're down to *%dppm*." % co2
    try:
        payload = {
            'channel': channel,
            'username': botName,
            'text': message,
            'icon_emoji': icon
        }
        requests.post(webhookUrl, json=payload)
    except:
        print "Unexpected error:", sys.exc_info()[0]

def publish(client, prefix, co2, tmp):
    try:
        client.submit(prefix + ".co2", co2)
        client.submit(prefix + ".tmp", tmp)
    except:
        print "Unexpected error:", sys.exc_info()[0]

def config(config_file=None):
    """Get config from file; if no config_file is passed in as argument
        default to "config.yaml" in script dir"""

    if config_file is None:
        script_base_dir = os.path.dirname(os.path.realpath(sys.argv[0])) + "/"
        config_file = script_base_dir + "config.yaml"

    with open(config_file, 'r') as stream:
        return yaml.load(stream)

def client(config):
    return librato.connect(config["user"], config["token"])


if __name__ == "__main__":
    """main"""

    # use lock on socket to indicate that script is already running
    try:
        s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
        ## Create an abstract socket, by prefixing it with null.
        s.bind('\0postconnect_gateway_notify_lock')
    except socket.error, e:
        # if script is already running just exit silently
        sys.exit(0)

    key = [0xc4, 0xc6, 0xc0, 0x92, 0x40, 0x23, 0xdc, 0x96]
    fp = open(sys.argv[1], "a+b",  0)
    HIDIOCSFEATURE_9 = 0xC0094806
    set_report = "\x00" + "".join(chr(e) for e in key)
    fcntl.ioctl(fp, HIDIOCSFEATURE_9, set_report)

    values = {}
    stamp = now()
    notified = False

    try:
        config = config(config_file=sys.argv[2])
    except IndexError:
        config = config()

    client = client(config)

    while True:
        data = list(ord(e) for e in fp.read(8))
        decrypted = decrypt(key, data)
        if decrypted[4] != 0x0d or (sum(decrypted[:3]) & 0xff) != decrypted[3]:
            print hd(data), " => ", hd(decrypted),  "Checksum error"
        else:
            op = decrypted[0]
            val = decrypted[1] << 8 | decrypted[2]
            values[op] = val

            if (0x50 in values) and (0x42 in values):
                co2 = values[0x50]
                tmp = (values[0x42]/16.0-273.15)

                # check if it's a sensible value
                # (i.e. within the measuring range plus some margin)
                if (co2 > 5000 or co2 < 0):
                    continue

                print "CO2: %4i TMP: %3.1f" % (co2, tmp)
                if now() - stamp > 5:
                    print ">>>"
                    publish(client, config["prefix"], co2, tmp)

                    # publish to slack, if configured
                    if ("slack" in config):
                        upper_threshold = config["slack"]["upper_threshold"] if "upper_threshold" in config["slack"] else 800
                        lower_threshold = config["slack"]["lower_threshold"] if "lower_threshold" in config["slack"] else 600
                        if (co2 > upper_threshold) and (not notified):
                            notified = True
                            notifySlack(co2, config["slack"], upper_threshold)
                        elif (co2 < lower_threshold):
                            if (notified):
                                notifySlack(co2, config["slack"], upper_threshold)
                            notified = False

                    stamp = now()