├── .gitignore ├── COPYING ├── LICENSE ├── README.md ├── bin └── sftdyn ├── etc ├── sample.conf └── sftdyn.service ├── setup.py └── sftdyn ├── __init__.py ├── __main__.py ├── args.py ├── server.py └── util.py /.gitignore: -------------------------------------------------------------------------------- 1 | *.pyo 2 | __pycache__ 3 | *.pyc 4 | .*.swp 5 | ~* 6 | MANIFEST 7 | dist 8 | build 9 | -------------------------------------------------------------------------------- /COPYING: -------------------------------------------------------------------------------- 1 | Copyright (C) 2014 Michael Ensslin 2 | 3 | This program is free software: you can redistribute it and/or modify 4 | it under the terms of the GNU General Public License as published by 5 | the Free Software Foundation, either version 3 of the License, or 6 | (at your option) any later version. 7 | 8 | This program is distributed in the hope that it will be useful, 9 | but WITHOUT ANY WARRANTY; without even the implied warranty of 10 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 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If not, see . 649 | 650 | Also add information on how to contact you by electronic and paper mail. 651 | 652 | If the program does terminal interaction, make it output a short 653 | notice like this when it starts in an interactive mode: 654 | 655 | Copyright (C) 656 | This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. 657 | This is free software, and you are welcome to redistribute it 658 | under certain conditions; type `show c' for details. 659 | 660 | The hypothetical commands `show w' and `show c' should show the appropriate 661 | parts of the General Public License. Of course, your program's commands 662 | might be different; for a GUI interface, you would use an "about box". 663 | 664 | You should also get your employer (if you work as a programmer) or school, 665 | if any, to sign a "copyright disclaimer" for the program, if necessary. 666 | For more information on this, and how to apply and follow the GNU GPL, see 667 | . 668 | 669 | The GNU General Public License does not permit incorporating your program 670 | into proprietary programs. If your program is a subroutine library, you 671 | may consider it more useful to permit linking proprietary applications with 672 | the library. If this is what you want to do, use the GNU Lesser General 673 | Public License instead of this License. But first, please read 674 | . 675 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # sftdyn dynamic dns server 2 | 3 | `sftdyn` is a minimalistic dynamic DNS server that accepts update requests via `http` or `https` and forwards them to a locally running DNS server via `nsupdate -l`. 4 | You can use it to easily update IPs of hosts in a domain whose IPs are not static and change to unpredictable addresses. 5 | 6 | It lets you easily create a dyndns.org-like service, using your own DNS server, and can (probably) be used with your router at home. 7 | 8 | ## Operation 9 | 10 | * You have a domain, e.g. `sft.rofl`, and a subdomain for dynamic entries, e.g. `dyn.sft.rofl` 11 | * The device whose IP address you want to store submits a https request to the `sftdyn` server containing a secret token, in order to update `devicename.dyn.sft.rofl` 12 | * From this, the `sftdyn` server knows the request origin IP 13 | * From the secret token, `sftdyn` can associate a hostname to update its DNS record (`devicename.dyn.sft.rofl`) 14 | * The request therfore updated an IP in your zone 15 | 16 | 17 | ## Requirements 18 | 19 | * [Python >=3.5](https://www.python.org/) 20 | * [`aiohttp`](https://aiohttp.readthedocs.io/) 21 | 22 | 23 | ## Setup Guide 24 | 25 | `sftdyn` is for you if you host a DNS zone and can run a Python server so it updates the nameserver records. 26 | This guide assumes that you're using [BIND](https://en.wikipedia.org/wiki/BIND), your zone is `dyn.sft.rofl`, and your server's IP is `12.345.678.90`. 27 | Substitute the correct values for zone and IP as you use this guide. 28 | 29 | 30 | ### Nameserver 31 | 32 | `bind` has to be configured to serve the updatable zone. 33 | 34 | You probably have a zonefile for `sft.rofl` already. 35 | You need to delegate `dyn.sft.rofl` to the local nameserver. 36 | 37 | In the `sft.rofl` zone, add `NS records` to the new dynamic zone we're about to create: 38 | 39 | ``` 40 | # so the dyn.sft.rofl zone is delegated to the nameserver running sftdyn. 41 | # likely you need the same NS record as for the sft.rofl zone itself. 42 | dyn 30m IN NS yournameserver's_a_record 43 | ``` 44 | 45 | Now let's create the `dyn.sft.rofl` zone, where all the dynamic records will live. 46 | Somewhere in `named.conf`, add the new dynamic zone: 47 | 48 | ``` 49 | zone "dyn.sft.rofl" IN { 50 | type master; 51 | file "/etc/bind/dyn.sft.rofl.zone"; 52 | journal "/var/cache/bind/dyn.sft.rofl.zone.jnl"; 53 | update-policy local; 54 | }; 55 | ``` 56 | 57 | `/var/cache/bind` and `/etc/bind/dyn.sft.rofl.zone` must be writable for *bind*. 58 | 59 | Create the empty zone file 60 | 61 | ``` 62 | cp /etc/bind/db.empty /etc/bind/dyn.sft.rofl.zone 63 | ``` 64 | 65 | We also can define a hostname to send the IP update requests to within the `dyn.sft.rofl` zone, or even use `dyn.sft.rofl` itself. 66 | `@` means the zone name itself. 67 | 68 | ``` 69 | # within the dyn.sft.rofl zonefile, we set the IP for the dyn.sft.rofl host itself. 70 | # this is the ip of the nameserver itself, where sftdyn is running. 71 | # -> you can then send update requests to https://dyn.sft.rofl/... 72 | @ 10m IN A 12.345.678.90 73 | @ 10m IN AAAA some:ipv6::address 74 | ``` 75 | 76 | 77 | ### sftdyn server setup 78 | 79 | To install *sftdyn*, use `pip install sftdyn` or `./setup.py install`. 80 | 81 | Launch it with `python3 -m sftdyn [command-line options]`. 82 | 83 | Configuration is by command-line parameters and conf file. 84 | A sample conf file is provided in `etc/sample.conf`. 85 | If no conf file name is provided, `/etc/sftdyn/conf` is used. 86 | Hostnames/update keys are specified in the conf file. 87 | 88 | `sftdyn` _should_ run under the same user as your DNS server, or it _might_ 89 | not be able to update it properly. Alternatively, to run sftdyn as the user of 90 | your choice, see Advanced setup later in this article. 91 | 92 | 93 | #### systemd service 94 | 95 | To run `sftdyn` automatically, you can use a systemd service. 96 | 97 | The `sftdyn` distribution package should automatically install `sftdyn.service`. 98 | 99 | If you have to manually install it, use the example unit `etc/sftdyn.service` 100 | and copy it to `/etc/systemd/system/sftdyn.service` on the `sftdyn` host machine. 101 | 102 | Enable the launch on boot and also start `sftdyn` now: 103 | 104 | ``` 105 | sudo systemctl enable --now sftdyn.service 106 | ``` 107 | 108 | #### Unencrypted operation 109 | 110 | You _can_ use `sftdyn` in plain HTTP mode. 111 | Your average commercial dynamic DNS provider provides a HTTP interface, so most routers only support that. 112 | 113 | Somebody could grab your "secret url" with this and perform unintended updates of your record. 114 | 115 | 116 | #### Encrypted operation 117 | 118 | Because of the above reason, you _should_ use HTTPS to keep your update url token secret. 119 | For that, your server needs a X.509 key and certificate. 120 | You can create those with [let's encrypt](https://letsencrypt.org/), buy those somewhere, or create a self-signed one. 121 | 122 | ##### Reverse proxy 123 | 124 | Your server running `sftdyn` may already have a webserver (e.g. nginx) to handle other web requests. 125 | It may already have proper certificates setup (e.g. with letsencrypt) - which you can just reuse for sftdyn. 126 | 127 | If you have `nginx`, the following config block will redirect requests to `dyn.sft.rofl` to the `sftdyn` server. 128 | 129 | Remember to use the `X-Forwarded-For` header in the `sftdyn` config (in `get_ip`) as the client ip! 130 | 131 | ```nginx 132 | server { 133 | server_name dyn.sft.rofl; 134 | 135 | // ... 136 | 137 | location / { 138 | # with this line, nginx relays the request to sftdyn 139 | proxy_pass http://localhost:8080/; 140 | 141 | # remember the original ip - we need to extract it in get_ip 142 | # in the sftdyn config then! 143 | proxy_set_header X-Forwarded-For $remote_addr; 144 | proxy_set_header Host $host; 145 | } 146 | 147 | // ... 148 | } 149 | ``` 150 | 151 | Alternatively, you can add the location block with `location /dyn` or something to some existing server block. 152 | 153 | In any way, you can then submit requests to the regular https port since you send to nginx now. 154 | -> remove `:4443` in the client requests. 155 | 156 | 157 | ##### Let's Encrypt 158 | 159 | If you don't want to use a reverse proxy to terminate the tls connection, you can directly configure `sftdyn` to use the certificate. 160 | To use a certificate by [Let's Encrypt](https://letsencrypt.org/) directly in `sftdyn`: 161 | 162 | ``` 163 | # in sftdyn.conf: 164 | key = "/etc/letsencrypt/live/host.name.lol/privkey.pem" 165 | cert = "/etc/letsencrypt/live/host.name.lol/fullchain.pem" 166 | ``` 167 | 168 | Make sure the certificate is valid for the domain your `sftdyn` is getting requests for. 169 | 170 | A `https` request to `sftdyn` to update an IP will then be secure™ (e.g. with `curl`). 171 | 172 | 173 | ##### Self-signed certificate 174 | 175 | To generate `server.key` and a self-signed `server.crt` valid for 1337 days: 176 | 177 | ``` 178 | openssl genrsa -out server.key 4096 179 | openssl req -new -key server.key -out server.csr 180 | openssl x509 -req -days 1337 -in server.csr -signkey server.key -out server.crt 181 | rm server.csr 182 | ``` 183 | 184 | Make sure you enter your server's domain name for _Common Name_ (the hostname you'll use for querying `sftdyn` with clients. 185 | 186 | A `https` request to `sftdyn` to update an IP will then be more secure™ than a globally valid certificate like from Let's Encrypt, but you'll need to transfer the `server.crt` to the device performing the request (e.g. with `curl`). 187 | 188 | 189 | ### Client 190 | 191 | The client is the device whose IP we want to update in the dynamic zone. 192 | Common clients are your plastic router at home that changes it's DSL IP address from time to time. 193 | 194 | The client triggers the IP update at the `sftdyn` server, so your DNS then delivers the correct IP. 195 | 196 | #### Plastic router 197 | 198 | Cheap plastic routers often have built-in dynamic dns update support. 199 | Since `sftdyn` is not that well known, within the plastic router's web UI you need to select something like _user-defined provider_, and enter http://dyn.sft.rofl:8080/yourupdatekey as the update URL. 200 | Write random stuff as name/user name/password, since just the update URL is the secret alone (tested with my AVM Fritz!Box. YMMV). 201 | Most routers don't support HTTPS update requests (especially not with custom CA-cert, so you'll probably need HTTP. 202 | 203 | If you set up `sftdyn` with let's encrypt, https may work - just test it :) 204 | 205 | #### Request with `curl` 206 | 207 | If you want to update the external IP of some NAT gateway (like home router, ...), and you have a machine in that network which can use `curl`, choose this client method. 208 | 209 | If you use HTTPS with a let's encrypt certificate, `curl` will be happy to request with encryption 210 | 211 | If you use a self-signed certificate, `curl` will refuse to talk to the server (because it obviously can't trust it without knowing it). 212 | To make `curl` trust the self-signed certificate: 213 | - Copy `server.crt` to the client, and use `curl --cacert server.crt`. 214 | Alternatively, to let `curl` ignore the security problem and just accept whatever it gets: 215 | - Use `curl -k` to ignore the error (Warning: see the security considerations below). 216 | 217 | The result codes mean the following: 218 | 219 | | HTTP code | Text | Response interpretation | 220 | | ------------- | ------------- | ----------------------------------------------- | 221 | | 200 | OK | Update successful | 222 | | 200 | UPTODATE | Update unneccesary | 223 | | 403 | BADKEY | Unknown update key | 224 | | 500 | FAIL | Internal error (see the server log) | 225 | | 200 | _your ip_ | Returned if no association key is provided | 226 | 227 | ##### systemd timer 228 | 229 | `systemd` timers are like cronjobs. Use them to periodically run the update query. 230 | 231 | Create `/etc/systemd/system/sftdynupdate.timer`: 232 | ``` 233 | [Unit] 234 | Description=SFTdyn dns updater 235 | 236 | [Timer] 237 | OnCalendar=*:0/15 238 | Persistent=true 239 | 240 | [Install] 241 | WantedBy=timers.target 242 | ``` 243 | 244 | Create `/etc/systemd/system/sftdynupdate.service`: 245 | ``` 246 | [Unit] 247 | Description=SFTdyn name update 248 | 249 | [Service] 250 | Type=oneshot 251 | User=nobody 252 | ExecStart=/usr/bin/env curl -f -s --cacert /path/to/server.crt https://dyn.sft.rofl:4443/yoursecretupdatekey 253 | ``` 254 | 255 | Activate the timer firing with: 256 | 257 | ``` 258 | sudo systemctl enable --now sftdyn.timer 259 | ``` 260 | 261 | Verify the timer is scheduled: 262 | 263 | ``` 264 | sudo systemctl list-timers 265 | ``` 266 | 267 | To manually trigger the update (e.g. for testing purposes): 268 | 269 | ``` 270 | sudo systemctl start sftdyn.service 271 | ``` 272 | 273 | ##### Cronjob 274 | 275 | Cronjobs are the legacy variant to periodically run a task, you could do this like this: 276 | 277 | ``` 278 | */10 * * * * curl https://dyn.sft.rofl:4443/mysecretupdatekey 279 | ``` 280 | 281 | 282 | ### Advanced setup 283 | 284 | #### Pre-generated keyfile 285 | 286 | By default sftdyn uses a key auto-generated by bind, `/var/run/named/session.key`. 287 | The permissions of this file may be reset on startup, and could be too 288 | restrictive for sftdyn. 289 | 290 | If you see errors such as these in `journalctl -u sftdyn`, it may indicate a 291 | permission issue with the keyfile: 292 | ``` 293 | ; TSIG error with server: tsig indicates error 294 | update failed: NOTAUTH(BADSIG) 295 | ``` 296 | 297 | An alternative approach is to use a pre-generated keyfile dedicated to sftdyn, 298 | which lets you have more control over the file permissions. 299 | 300 | ##### Create a new key 301 | 302 | The example script below generates a keyfile in `/etc/bind/keys/sftdyn.key`, 303 | and changes the user/group ownership to `bind:sftdyn`. Modify as needed to 304 | best suit your specific setup. 305 | 306 | ```sh 307 | b=$(dnssec-keygen -a hmac-sha512 -b 512 -n USER -K /tmp foo) 308 | cat > /etc/bind/keys/sftdyn.key < you can write arbitrary python code in here! 5 | # 6 | # In "really complicated" setups you could redirect all calls to a database, 7 | # for example. 8 | 9 | 10 | # ---------------------------------------------------------------------------- 11 | # Listen on "port" (all interfaces) (default) 12 | # or "ip4address:port" 13 | # or "[ip6address]:port" 14 | http = "8080" 15 | #https = "4443" 16 | 17 | # Certificates for https, relative paths to this file possible. 18 | #key = "/etc/sftdyn/snakeoil.key" 19 | #cert = "/etc/sftdyn/snakeoil.crt" 20 | 21 | # ---------------------------------------------------------------------------- 22 | # Client hostname definitions. 23 | # 24 | # Map `querystring` => `hostname to update` 25 | # e.g. a request to "http://dyn.sft.rofl/example" will update "host.dyn.sft.rofl" 26 | # You should include a 'shared secret' in the url to prevent strangers 27 | # from updating your host's IP. 28 | CLIENTS = { 29 | # insecure simple example 30 | "example": "host.dyn.sft.rofl", 31 | # more secure variant 0 32 | "?hostname=myclient.dyn.sft.rofl&password=123456": "myclient.dyn.sft.rofl", 33 | # more secure variant 1 34 | "host=gnampf.dyn.sft.rofl,key=4bea92410b3146d0cfe": "gnampf.dyn.sft.rofl", 35 | # you can come up with anything you like for the client's 'secret' url... 36 | } 37 | 38 | # Alternatively, you could fetch the definitions from a file that contains 39 | # lines like this one: 40 | # host=gnampf.dyn.sft.rofl,key=4bea92410b3146d0cfe: gnampf.dyn.sft.rofl 41 | # This list would then be read at sftdyn's startup. 42 | # you can move the the file reading into the `get_host` function 43 | # to reload the file on every request, if needed. 44 | # 45 | #CLIENTS = dict() 46 | #with open("/etc/sftdyn/clientlist") as hdl: 47 | # for line in hdl: 48 | # query_key, host = line.split(":") 49 | # CLIENTS[query_key] = host.strip() 50 | # 51 | # the CLIENTS dict will be evaluated below in `get_host` 52 | # 53 | # Or, you can dynamically figure out whatever you want 54 | # in any of the functions below. 55 | 56 | # ---------------------------------------------------------------------------- 57 | # Custom nsupdate authentication key 58 | # 59 | # This option may be used to specify an authentication key for nsupdate, which 60 | # may be useful when the user running sftdyn doesn't have access to the key 61 | # auto-generated by bind. 62 | # 63 | # For more information, see the -k option of nsupdate(1). 64 | # 65 | #nskeyfile = "/etc/bind/keys/sftdyn.key" 66 | 67 | # ---------------------------------------------------------------------------- 68 | def get_ip(source_ip, headers, key): 69 | """ 70 | Custom IP conversion function. 71 | 72 | `source_ip` is the IP that sftdyn saw as peer. 73 | if sftdyn is behind a proxy, 74 | it'll see the proxy IP, i.e. `localhost` 75 | `headers` is the http header dict. 76 | in there may be `X-Real-IP`, which contains the real peer IP. 77 | `key` is the (unsanitized) URL query string. 78 | 79 | You can modify the client IP address here however you like. 80 | The returned IP will be the `new_ip` that is passed 81 | into `nsupdatecommands`, after `key` was looked up by `get_host` below 82 | where it was associated with a hostname. 83 | 84 | If this function is missing from your config file, 85 | by default it does `return source_ip`. 86 | """ 87 | 88 | # default: use the request source ip for updating the host address 89 | update_to = source_ip 90 | 91 | # If you use nginx as reverse proxy: 92 | #if 'X-Forwarded-For' in headers: 93 | # update_to = headers['X-Forwarded-For'] 94 | 95 | # When you want to ignore the source address, but rather want 96 | # to use a http header's value to update the dynamic host ip: 97 | #if 'X-Real-IP' in headers: 98 | # update_to = headers['X-Real-IP'] 99 | 100 | return update_to 101 | # ---------------------------------------------------------------------------- 102 | 103 | 104 | # ---------------------------------------------------------------------------- 105 | def get_host(querystring, ip): 106 | """ 107 | assign a "http query string" => "host to update" 108 | 109 | `querystring` is the part of the url after hostname and port without 110 | the leading /. 111 | `ip` is the target ip returned by the `get_ip` function above. 112 | 113 | returns the `hostname` that is then passed to `nsupdatecommands` below. 114 | """ 115 | 116 | # you may do database/ldap/... lookups here 117 | # to figure out the host to update. 118 | 119 | return CLIENTS.get(querystring) 120 | # ---------------------------------------------------------------------------- 121 | 122 | 123 | # ---------------------------------------------------------------------------- 124 | def nsupdatecommands(host, new_ip, headers): 125 | """ 126 | Return the lines fed into `nsupdate`'s stdin. 127 | 128 | `host` is the hostname returned by `get_host` function above. 129 | `new_ip` is the new IP returned by `get_ip` function above. 130 | `headers` are the http headers that sftdyn received with the request. 131 | 132 | Here you can, for example, customize the TTL (default 30s). 133 | """ 134 | 135 | import ipaddress 136 | new_ip = ipaddress.ip_address(new_ip) 137 | 138 | if isinstance(new_ip, ipaddress.IPv4Address): 139 | cmds = [ 140 | "update delete %s A" % host, 141 | "update add %s 30 A %s" % (host, new_ip), 142 | "send", 143 | ] 144 | 145 | else: 146 | cmds = [ 147 | "update delete %s AAAA" % host, 148 | "update add %s 30 AAAA %s" % (host, new_ip), 149 | "send", 150 | ] 151 | 152 | return cmds 153 | # ---------------------------------------------------------------------------- 154 | 155 | 156 | # vim: ft=python 157 | -------------------------------------------------------------------------------- /etc/sftdyn.service: -------------------------------------------------------------------------------- 1 | [Unit] 2 | Description=sft dynamic dns service 3 | After=network.target 4 | 5 | [Service] 6 | User=named 7 | ExecStart=/usr/bin/env python3 -u -m sftdyn -v 8 | Restart=on-failure 9 | 10 | [Install] 11 | WantedBy=multi-user.target 12 | -------------------------------------------------------------------------------- /setup.py: -------------------------------------------------------------------------------- 1 | #!/usr/bin/env python3 2 | from distutils.core import setup 3 | from sftdyn import VERSION 4 | from sys import version_info 5 | 6 | if version_info[0] < 3: 7 | print("use python3 to install sftdyn (e.g. pip3)") 8 | exit(1) 9 | 10 | setup( 11 | name="sftdyn", 12 | version=VERSION, 13 | description="HTTP(S)-based dynamic DNS updater server", 14 | long_description="dyndns.org-like service that accepts update requests " + 15 | "via HTTP(S) and forwards them to a locally running " + 16 | "DNS server via nsupdate -l.\n" + 17 | "Works with most routers.\n" + 18 | "Readme: " + 19 | "https://github.com/SFTtech/sftdyn/blob/master/README.md", 20 | author="Michael Ensslin", 21 | author_email="michael@ensslin.cc", 22 | url="https://github.com/SFTtech/sftdyn", 23 | license="GPL3+", 24 | packages=["sftdyn"], 25 | scripts=["bin/sftdyn"], 26 | data_files=[ 27 | ("/etc/sftdyn/", ["etc/sample.conf"]), 28 | ("/usr/lib/systemd/system/", ["etc/sftdyn.service"]), 29 | ], 30 | platforms=[ 31 | 'Linux', 32 | ], 33 | classifiers=[ 34 | ("License :: OSI Approved :: " 35 | "GNU General Public License v3 or later (GPLv3+)"), 36 | "Topic :: Internet :: WWW/HTTP", 37 | "Intended Audience :: Developers", 38 | "Environment :: Console", 39 | "Operating System :: POSIX :: Linux" 40 | ], 41 | ) 42 | -------------------------------------------------------------------------------- /sftdyn/__init__.py: -------------------------------------------------------------------------------- 1 | """ 2 | sftdyn is a simple dynamic dns server for http requests 3 | which then update dns records with nsupdate. 4 | """ 5 | 6 | import asyncio 7 | from logging import info 8 | 9 | 10 | from . import server 11 | from .args import parse_args 12 | from .util import log_setup 13 | 14 | 15 | VERSION = "0.10" 16 | 17 | 18 | def main(): 19 | """ 20 | launch sftdyn. 21 | """ 22 | 23 | args = parse_args(__doc__) 24 | 25 | log_setup(args.verbose - args.quiet) 26 | 27 | # the known ip associations 28 | # maps host => ip 29 | associations = dict() 30 | 31 | loop = asyncio.get_event_loop() 32 | loop.set_debug(args.debug) 33 | 34 | if args.http: 35 | http_server = server.Server(args.http, 36 | args.get_host, 37 | associations, 38 | args.get_ip, 39 | args.nsupdatecommands, 40 | nskeyfile=args.nskeyfile) 41 | info("starting http server at %s:%d" % args.http) 42 | loop.run_until_complete(http_server.listen(loop)) 43 | 44 | if args.https: 45 | https_server = server.Server(args.https, 46 | args.get_host, 47 | associations, 48 | args.get_ip, 49 | args.nsupdatecommands, 50 | nskeyfile=args.nskeyfile, 51 | tls=(args.cert, args.key)) 52 | info("starting https server at %s:%d" % args.https) 53 | loop.run_until_complete(https_server.listen(loop)) 54 | 55 | try: 56 | loop.run_forever() 57 | except KeyboardInterrupt: 58 | print("exiting...") 59 | loop.close() 60 | -------------------------------------------------------------------------------- /sftdyn/__main__.py: -------------------------------------------------------------------------------- 1 | """ 2 | Launch sftdyn. 3 | """ 4 | 5 | from . import main 6 | 7 | if __name__ == "__main__": 8 | main() 9 | -------------------------------------------------------------------------------- /sftdyn/args.py: -------------------------------------------------------------------------------- 1 | """ 2 | Argument parsing for all your configuration needs. 3 | """ 4 | 5 | import argparse 6 | import ipaddress 7 | import os 8 | from pathlib import Path 9 | from urllib.parse import urlparse 10 | 11 | 12 | def get_parser(intro): 13 | """ 14 | Create the argument parser. 15 | """ 16 | cmd = argparse.ArgumentParser(description=intro, 17 | epilog="SFT dynamic DNS updater HTTPS server") 18 | cmd.add_argument("conffile", type=str, nargs="?", 19 | default="/etc/sftdyn/conf", 20 | help="conf file, will be exec'd as python3") 21 | cmd.add_argument("-l", "--http", metavar="IP:PORT", 22 | help="Enable HTTP server") 23 | cmd.add_argument("-s", "--https", metavar="IP:PORT", 24 | help="Enable HTTPS server") 25 | cmd.add_argument("-c", "--cert", type=str, help="HTTPS X.509 cert file") 26 | cmd.add_argument("-k", "--key", type=str, help="HTTPS X.509 key file") 27 | cmd.add_argument("-i", "--interactive", action="store_true", 28 | help="launch a interactive session") 29 | cmd.add_argument("--nskeyfile", type=str, 30 | help="optional keyfile for nsupdate") 31 | cmd.add_argument("-d", "--debug", action="store_true", 32 | help="enable asyncio debugging") 33 | cmd.add_argument("-v", "--verbose", action="count", default=0, 34 | help="increase program verbosity") 35 | cmd.add_argument("-q", "--quiet", action="count", default=0, 36 | help="decrease program verbosity") 37 | 38 | return cmd 39 | 40 | 41 | def stringtoipport(txt): 42 | """ 43 | splits an IP:PORT string, as expected for --http and --https 44 | 45 | txt 46 | input string, either PORT or an IP4/6-address:port 47 | returns 48 | (ip, port) where ip is a string and port is an int 49 | """ 50 | 51 | # listen on any interface. 52 | defaultip = "" 53 | 54 | if isinstance(txt, int): 55 | return defaultip, txt 56 | 57 | elif txt.isnumeric(): 58 | return defaultip, int(txt) 59 | 60 | parsed = urlparse('//{}'.format(txt)) 61 | ip = ipaddress.ip_address(parsed.hostname) 62 | port = parsed.port 63 | 64 | return str(ip), int(port) 65 | 66 | 67 | def parse_args(intro): 68 | """ 69 | Parses the args, and returns the namespace. 70 | The config file is evaluated after the args and may replace its values. 71 | 72 | intro: info text displayed as program description. 73 | """ 74 | cmd = get_parser(intro) 75 | args = cmd.parse_args() 76 | 77 | # read the conffile 78 | if not os.path.isfile(args.conffile): 79 | cmd.error("Not a valid conf file: " + args.conffile) 80 | 81 | # execute the file so globals defined in it are added to args 82 | confdefs = dict() 83 | with open(args.conffile) as cfghdl: 84 | exec(cfghdl.read(), confdefs) 85 | vars(args).update(confdefs) 86 | 87 | if not hasattr(args, "get_host"): 88 | cmd.error("config file does not provide `get_host`" 89 | " function to look up client hostnames") 90 | 91 | if not hasattr(args, "get_ip"): 92 | setattr(args, 'get_ip', None) 93 | 94 | if not hasattr(args, "nsupdatecommands"): 95 | cmd.error("config file does not define the `nsupdatecommands` function") 96 | 97 | # check https IP:PORT string 98 | if args.https: 99 | try: 100 | args.https = stringtoipport(args.https) 101 | except ValueError: 102 | cmd.error("Invalid [IP:]PORT for --https: " + args.https) 103 | 104 | # check http IP:PORT string 105 | if args.http: 106 | try: 107 | args.http = stringtoipport(args.http) 108 | except ValueError: 109 | cmd.error("Invalid [IP:]PORT for --http: " + args.http) 110 | 111 | # check cert/key 112 | if args.https or args.cert or args.key: 113 | if not (args.https and args.cert and args.key): 114 | cmd.error("--https, --cert and --key need to be used together") 115 | 116 | conffolder = Path(args.conffile).parent 117 | # make cert paths relative to the conf file 118 | if not Path(args.cert).is_absolute(): 119 | args.cert = str(conffolder / args.cert) 120 | 121 | if not Path(args.key).is_absolute(): 122 | args.key = str(conffolder / args.key) 123 | 124 | return args 125 | -------------------------------------------------------------------------------- /sftdyn/server.py: -------------------------------------------------------------------------------- 1 | """ 2 | http(s) server implementation for sftdyn. 3 | """ 4 | 5 | 6 | import ssl 7 | import asyncio 8 | 9 | from logging import info, debug 10 | from aiohttp import web 11 | 12 | 13 | class Server: 14 | """ 15 | HTTP(S) server for DNS record update requests. 16 | """ 17 | 18 | def __init__(self, addr, get_host, associations, get_ip, 19 | nsupdatecommands, nskeyfile=None, tls=None): 20 | 21 | """ 22 | addr: (ip, port) to listen on 23 | get_host: function that provides hostname to update 24 | associations: {dnshostname: ipaddr} map to cache current dynamic ips 25 | get_ip: function that can update the ip to set, e.g. by headers 26 | nsupdatecommands: function to generate the `nsupdate` stdin, 27 | will be called with `host` and `new_ip` args. 28 | tls: (cerfilename, keyfilename) to use for the tls socket 29 | """ 30 | 31 | self.addr = addr 32 | self.get_host = get_host 33 | self.associations = associations 34 | self.get_ip = get_ip 35 | self.nsupdatecommands = nsupdatecommands 36 | self.nskeyfile = nskeyfile 37 | 38 | if tls: 39 | # create SSLContext for our TLS server 40 | self.sslcontext = ssl.create_default_context( 41 | purpose=ssl.Purpose.CLIENT_AUTH 42 | ) 43 | self.sslcontext.load_cert_chain(tls[0], tls[1]) 44 | else: 45 | self.sslcontext = None 46 | 47 | async def listen(self, loop): 48 | """ 49 | Let the server listen on the given event loop. 50 | """ 51 | 52 | server = web.Server(self.handler) 53 | await loop.create_server( 54 | server, 55 | self.addr[0], 56 | self.addr[1], 57 | ssl=self.sslcontext 58 | ) 59 | 60 | async def handler(self, request): 61 | """ 62 | Handler for a single request. 63 | """ 64 | 65 | if request.method != "GET": 66 | return web.Response(status=405) 67 | 68 | path = request.path_qs.lstrip('/') 69 | peername = request.transport.get_extra_info('peername') 70 | if peername is None: 71 | return web.Response(status=500) 72 | 73 | addr = peername[0] 74 | text, code = await self.handle_request(path, addr, request.headers) 75 | 76 | return web.Response(text=text, status=code) 77 | 78 | async def handle_request(self, key, ip, headers=None): 79 | """ 80 | the actual application-specific code 81 | 82 | key 83 | the path part of the client request URL, without the leading '/' 84 | ip 85 | the IP address of the client 86 | 87 | returns 88 | (status, httpcode) after examining the key 89 | """ 90 | 91 | if headers is None: 92 | headers = dict() 93 | 94 | # call to user-defined function 95 | if self.get_ip is not None: 96 | ip = self.get_ip(ip, headers, key) 97 | 98 | if not key: 99 | return ip, 200 100 | 101 | # call to user-defined function 102 | host = self.get_host(key, ip) 103 | if not host: 104 | return "BADKEY", 403 105 | 106 | if self.associations.get(host, None) == ip: 107 | return "UPTODATE", 200 108 | 109 | info("update request for %s => %s" % (host, ip)) 110 | 111 | # call to user-defined function 112 | cmdlist = self.nsupdatecommands(host, ip, headers) 113 | 114 | iter(cmdlist) # check if the generated updatecommand is iterable 115 | cmd = "\n".join(cmdlist) + "\n" 116 | 117 | nsupdate = ['nsupdate', '-l'] 118 | if self.nskeyfile: 119 | nsupdate.extend(['-k', self.nskeyfile]) 120 | 121 | debug('executing command: %s' % (nsupdate, )) 122 | proc = await asyncio.create_subprocess_exec( 123 | *nsupdate, 124 | stdin=asyncio.subprocess.PIPE 125 | ) 126 | proc.stdin.write(cmd.encode()) 127 | proc.stdin.close() 128 | await proc.wait() 129 | 130 | if proc.returncode == 0: 131 | self.associations[host] = ip 132 | return "OK", 200 133 | 134 | return "FAIL", 500 135 | -------------------------------------------------------------------------------- /sftdyn/util.py: -------------------------------------------------------------------------------- 1 | """ 2 | Various utility functions. 3 | """ 4 | 5 | import logging 6 | 7 | 8 | def log_setup(setting, default=1): 9 | """ 10 | Perform setup for the logger. 11 | Run before any logging.log thingy is called. 12 | 13 | if setting is 0: the default is used, which is WARNING. 14 | else: setting + default is used. 15 | """ 16 | 17 | levels = (logging.ERROR, logging.WARNING, logging.INFO, 18 | logging.DEBUG, logging.NOTSET) 19 | 20 | factor = clamp(default + setting, 0, len(levels) - 1) 21 | level = levels[factor] 22 | 23 | logging.basicConfig(level=level, format="[%(asctime)s] %(message)s") 24 | logging.error("loglevel: %s", logging.getLevelName(level)) 25 | logging.captureWarnings(True) 26 | 27 | 28 | def clamp(number, smallest, largest): 29 | """ return number but limit it to the inclusive given value range """ 30 | return max(smallest, min(number, largest)) 31 | --------------------------------------------------------------------------------