Initial commit

.gitignore

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+__pycache__
+.venv
+*.pyc
+config.yaml

README.md

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+# Schwarzschild
+
+A little tool that automatically updates the forwarding table in a fritz.box when a system goes down.

example_config.yaml

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+ip: 192.168.3.1
+user: schwarzschild
+pass: <pass>
+period: 10
+validate_paths_every: 10
+routes:
+  - name: main
+    paths:
+    - name: dodox-Y700-WIRED
+      ip: 192.168.7.150
+      forwards:
+        - name: haProxy
+          protocol: TCP
+          internal: 809
+          external: 80
+        - name: haProxy_ssl
+          protocol: TCP
+          internal: 4439
+          external: 443
+    - name: dodox-Y700
+      ip: 192.168.3.150
+      forwards:
+        - name: haProxy
+          protocol: TCP
+          internal: 809
+          external: 80
+        - name: haProxy_ssl
+          protocol: TCP
+          internal: 4439
+          external: 443
+    - name: ProjectHeimdall
+      ip: 192.168.3.250
+      forwards:
+        - name: haProxy
+          protocol: TCP
+          internal: 80
+          external: 80
+        - name: haProxy_ssl
+          protocol: TCP
+          internal: 443
+          external: 443

main.py

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+#!/usr/bin/env python3
+
+import traceback
+import sys
+import socket
+import os
+import yaml
+import time
+
+from ping3 import ping
+
+import fritzconnection.core.exceptions as exp
+from fritzconnection.cli import utils
+from fritzconnection import FritzConnection
+from fritzconnection.core.fritzconnection import (
+    FRITZ_IP_ADDRESS,
+    FRITZ_TCP_PORT,
+    FRITZ_ENV_USERNAME,
+    FRITZ_ENV_PASSWORD,
+)
+
+DRY = True
+
+def readPortmappings(fc):
+    num = fc.call_action("WANPPPConnection1", "GetPortMappingNumberOfEntries", )
+    portMappings = []
+    numi = num["NewPortMappingNumberOfEntries"]
+    for i in range(numi):
+        portMappings.append(fc.call_action("WANPPPConnection1", "GetGenericPortMappingEntry", NewPortMappingIndex=i))
+    return portMappings
+
+def findPortmapping(fc, extPort, intPort):
+    portmappings = readPortmappings(fc)
+    ip = readMyIP()
+    for m in portmappings:
+        if m["NewInternalClient"] == ip and m["NewInternalPort"] == int(intPort) and m["NewExternalPort"] == int(extPort):
+            return m
+    return None
+
+def printMappingHeader():
+    print('{:<20} {:<8} {:<20} {:<20} {:<15} {:<15}   {}\n'.format(
+        'Description', 'Protocol', 'Dest. Host', 'Dest. IP', 'Mapping', 'Lease Duration', 'Status'))
+
+def printMapping(m):
+    desc    = str(m['NewPortMappingDescription']) if m['NewPortMappingDescription'] else '-'
+    proto   = str(m['NewProtocol']) if m['NewProtocol'] else '-'
+    host    = str(m['NewInternalClient']) if m['NewInternalClient'] else '-'
+    extport = str(m['NewExternalPort']) if m['NewExternalPort'] else "?"
+    intport = str(m['NewInternalPort']) if m['NewInternalPort'] else "?"
+    lease   = str(m['NewLeaseDuration']) if m['NewLeaseDuration'] else "infinite"
+    status  = 'active' if m['NewEnabled'] else ''
+    ip      = host
+    mapping = extport + "->" + intport
+    try:
+        host = socket.gethostbyaddr(host)[0]
+    except:
+        pass
+
+    print(f'{desc:<20} {proto:<8} {host:<20} {ip:<20} {mapping:<15} {lease:<15}   {status}')
+
+def listPortmappings(fc):
+    print('Fritz Port Forwardings: \n')
+    printMappingHeader()
+
+    portmappings = readPortmappings(fc)
+    for m in portmappings: printMapping(m)
+    print()
+
+def readMyIP():
+    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+    s.connect(("8.8.8.8", 80))
+    return s.getsockname()[0]
+
+def addPortMapping(fc, extPort, intPort, name=None, protocol='TCP', active=True):
+    mapping = {
+        'NewRemoteHost': '0.0.0.0',
+        'NewExternalPort': extPort,
+        'NewProtocol': protocol,
+        'NewInternalPort': intPort,
+        'NewInternalClient': readMyIP(),
+        'NewEnabled': active,
+        'NewPortMappingDescription': name,
+        'NewLeaseDuration': 0
+    }
+    if DRY:
+        print('DRY', mapping)
+        return
+    fc.call_action("WANPPPConnection1", "AddPortMapping", **mapping )
+
+def deletePortMapping(fc, extPort, intPort, protocol='TCP', name=None):
+    addPortMapping(fc, extPort, intPort, name=name, protocol=protocol, active=False)
+
+def load_config():
+    with open('config.yaml', 'r') as f:
+        conf = yaml.safe_load(f)
+    return conf
+
+def make_con(ip, user, pw):
+    return FritzConnection(address=ip, user=user, password=pw, use_cache=True)
+
+def main():
+    conf = load_config()
+    fc = make_con(conf['ip'], conf['user'], conf['pass'])
+    loop(conf, fc)
+
+def loop(conf, fc):
+    period = conf['period']
+    active_paths = read_paths(conf, fc)
+    clock = 0
+    info('starting...')
+    while True:
+        begin = time.time()
+        active_paths, clock = cycle(active_paths, clock, conf, fc)
+        sleep = time.time() - begin + period
+        if sleep > 0:
+            time.sleep(sleep)
+
+def cycle(active_paths, clock, conf, fc):
+    if clock == -1 or (conf['validate_paths_every'] != 0 and clock >= conf['validate_paths_every']-1):
+        clock = 0
+        real_active_paths = read_paths(conf, fc)
+        diff = paths_diffs(active_paths, real_active_paths)
+        if diff:
+            active_paths = real_active_paths
+            alert(f'The paths configured in the router are different from what we expect based on our state. Were they changed manually? We will fix this.')
+        else:
+            info(f'Router paths validated.')
+    else:
+        clock += 1
+    new_paths = select_paths(conf, fc)
+    diff = paths_diffs(active_paths, new_paths)
+    if diff:
+        flush_paths(conf, fc, diff)
+        for route_name in diff:
+            old_path = active_paths[route_name]
+            new_path = new_paths[route_name]
+            alert(f'Route change: Switched from path {old_path} to path {new_path} for route {route_name}')
+        clock = -1 # force check next round
+    info(f'Routes ok:')
+    for route in conf['routes']:
+        print(f' -  {route["name"]} -> {new_paths[route["name"]]}')
+    return new_paths, clock
+
+def paths_diffs(old_paths, new_paths, verbose=False):
+    diffs = {}
+    for route_name in new_paths:
+        if route_name not in old_paths or old_paths[route_name] != new_paths[route_name]:
+            diffs[route_name] = new_paths[route_name]
+    return diffs
+
+def select_paths(conf, fc):
+    path_indices = {}
+    for route in conf['routes']:
+        for path in route['paths']:
+            if check_avail(path):
+                path_indices[route['name']] = path['name']
+                break
+        else:
+            # All paths are down
+            path_indices[route['name']] = None
+    return path_indices
+
+def read_paths(conf, fc):
+    ms = readPortmappings(fc)
+    path_indices = {}
+    for route in conf['routes']:
+        for path in route['paths']:
+            # Lets see if we have such a path active
+            fstFwd = path['forwards'][0]
+            found_map = False
+            for m in ms:
+                if m['NewEnabled'] and m['NewInternalClient'] == path['ip'] and m['NewPortMappingDescription'] == fstFwd['name'] and m['NewExternalPort'] == fstFwd['external'] and m['NewInternalPort'] == fstFwd['internal'] and m['NewProtocol'] == fstFwd['protocol'].upper():
+                    # This path is (at least partially) active
+                    path_indices[route['name']] = path['name']
+                    found_map = True
+                    break
+            if found_map:
+                break
+        else:
+            # All paths are down
+            path_indices[route['name']] = None
+            alert('We found no active path for route {route["name"]}.')
+    return path_indices
+
+def flush_paths(conf, fc, active_paths):
+    for route in conf['routes']:
+        if route['name'] not in active_paths:
+            continue
+        active_path = active_paths[route['name']]
+        make_active_path = None
+        for path in route['paths']:
+            if path['name'] == active_path:
+                if not make_active_path == None:
+                    alert(f'Illegal config for {route["name"]}: Has redundant path names.')
+                make_active_path = path
+            else:
+                flush_forwards(path, False, fc)
+        flush_forwards(make_active_path, True, fc)
+        if make_active_path==None:
+            alert(f'No active path for route {route["name"]}')
+
+def flush_forwards(path, make_active, fc):
+    for forward in path['forwards']:
+        addPortMapping(fc, forward['external'], forward['internal'], name=forward['name'], protocol=forward['protocol'], active=make_active)
+
+def check_avail(path):
+    ip = path['ip']
+    resp_time = ping(ip, timeout=3)
+    return resp_time!=None
+
+def alert(txt):
+    print('[!] '+txt)
+
+def info(txt):
+    print('[i] '+txt)
+
+if __name__=='__main__':
+    main()