dnsmasq rtmp device discovery

detect_cameras.py

#!/usr/bin/python
#
# Dynamically populate NGINX config with network cameras
# detected via DHCP leases table and DNSMasq
#

import os
import sys
import time

DHCP_LEASES_FILE   = '/tmp/dhcp.leases' # OpenWRT DNSMASQ
NGINX_CAMERAS_FILE = '/etc/nginx/cameras.conf' # This file will be included by nginx.conf

LOGIN_DETAILS = {
    'default': {'user': 'admin', 'password': 'password'}
    # Add MAC address for cameras with specific login details
}

SUPPORTED_CAMERAS = [
    {
        'name':             'Reolink',
        'mac_prefix':       'ec:71:db:',
        'stream_hi':        'rtmp://{host}/bcs/channel0_main.bcs?channel=0&stream=0&user={user}&password={password}',
        'stream_lo':        'rtmp://{host}/bcs/channel0_sub.bcs?channel=0&stream=1&user={user}&password={password}',
        'snapshot':         'http://{host}/cgi-bin/api.cgi?cmd=Snap&channel=0&rs=abc123&user={user}&password={password}',
    },
]

def reload_nginx():
    # Restart NGINX to start streaming the new cameras
    print()
    RESTART_COMMAND = 'docker container restart nginx'
    print(RESTART_COMMAND)
    os.system(RESTART_COMMAND)

def get_formatted(d, prop, **args):
    val = d.get(prop)
    if val:
        return val.format(**args)
    return None

def get_definition_for_mac(mac):
    mac_prefix = mac[:9]
    for cam_definition in SUPPORTED_CAMERAS:
        if mac_prefix == cam_definition['mac_prefix']:
            return cam_definition 
    return None

def make_camera_for_mac(mac, ip, name):
    definition = get_definition_for_mac(mac)
    if definition:
        print(f'Found camera {mac} @ {ip} ({name})')

        # Obtain login details for this specific camera, if available, otherwise use default
        login = LOGIN_DETAILS.get(mac, LOGIN_DETAILS['default'])
        
        # Obtain the streaming URLs
        fmt_args = dict(host=ip, user=login['user'], password=login['password'])
        stream_hi = get_formatted(definition, 'stream_hi', **fmt_args)
        stream_lo = get_formatted(definition, 'stream_lo', **fmt_args)
        snapshot  = get_formatted(definition, 'snapshot', **fmt_args)
        
        cam = {
            'mac': mac,
            'ip': ip,
            'name': name,
            'stream_hi': stream_hi,
            'stream_lo': stream_lo,
            'snapshot': snapshot
        }
        print(f"  stream hi: {cam['stream_hi']}")
        print(f"  stream lo: {cam['stream_lo']}")
        print()
        return cam
    return None

def get_cameras_from_current_leases(leases_file):
    cameras = []
    try:
        if os.path.isfile(leases_file):
            print(f'Read {leases_file}')
            with open(leases_file, 'r') as f:
                leases = f.readlines()

            # Scan the DHCP leases file to find any connected cameras
            for lease in leases:
                try:
                    # Example lease:
                    # '0 ec:71:db:ee:30:9b 192.168.4.251 Camera1 01:ec:71:db:ee:30:9b'
                    expiry, mac, ip, name, _ = lease.split(' ', maxsplit=5)
                    camera = make_camera_for_mac(mac, ip, name)
                    if camera:
                        cameras.append(camera)

                except Exception as e:
                    print(e)
                    continue
    except Exception as e:
        print(e)
    return cameras

def get_camera_from_args(action, mac, ip, name):
    if action == 'add':
        try:
            return make_camera_for_mac(mac, ip, name)
        except Exception as e:
            print(e)
            return None

def write_nginx_conf(conf_path, cameras):
    print()
    print(f'Update {conf_path}:')

    # Each line creates a new RTMP stream within nginx-rtmp.
    # 'pull' means the stream is pulling data from a remote source (as opposed to being pushed/published into nginx by a remote device)
    # 'static' means the stream will start pulling data from the camera immediately.
    lines = [
        f"pull {cam['stream_hi']} name={cam['name']} static;"
        for cam in cameras
    ]
    
    for ln in lines:
        print(ln)

    with open(NGINX_CAMERAS_FILE, 'w') as f:
        f.writelines(lines)

if __name__ == "__main__":

    # Hack: Let dnsmasq update the DHCP leases before continuing
    if len(sys.argv) > 1:
        time.sleep(2.0)

    cameras = get_cameras_from_current_leases(DHCP_LEASES_FILE)

    # # Optional: If called from dnsmasq (dhcp-script), add additional camera using arguments.
    # if len(sys.argv) > 1:
    #     camera = get_camera_from_args(*sys.argv)
    #     if camera:
    #         cameras.append(camera)
    
    write_nginx_conf(NGINX_CAMERAS_FILE, cameras)
    reload_nginx()