# coredhcp

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Fast, multithreaded, modular and extensible DHCP server written in Go

This is still a work-in-progress

## Example configuration

In CoreDHCP almost everything is implemented as a plugin. The order of plugins in the configuration matters: every request is evaluated calling each plugin in order, until one breaks the evaluation and responds to, or drops, the request.

The following configuration runs a DHCPv6-only server, listening on all the interfaces, using a custom server ID and DNS, and reading the leases from a text file.

```
server6:
    # this server will listen on all the available interfaces, on the default
    # DHCPv6 server port, and will join the default multicast groups. For more
    # control, see the `listen` directive in cmds/coredhcp/config.yml.example .
    plugins:
        - server_id: LL 00:de:ad:be:ef:00
        - file: "leases.txt"
        - dns: 8.8.8.8 8.8.4.4 2001:4860:4860::8888 2001:4860:4860::8844
```

For more complex examples, like how to listen on specific interfaces and
configure other plugins, see [config.yml.example](cmds/coredhcp/config.yml.example).

## Build and run

An example server is located under [cmds/coredhcp/](cmds/coredhcp/), so enter that
directory first. To build a server with a custom set of plugins, see the "Server
with custom plugins" section below.

Once you have a working configuration in `config.yml` (see [config.yml.example](cmds/coredhcp/config.yml.example)), you can build and run the server:
```
$ cd cmds/coredhcp
$ go build
$ sudo ./coredhcp
INFO[2019-01-05T22:28:07Z] Registering plugin "file"
INFO[2019-01-05T22:28:07Z] Registering plugin "server_id"
INFO[2019-01-05T22:28:07Z] Loading configuration
INFO[2019-01-05T22:28:07Z] Found plugin: `server_id` with 2 args, `[LL 00:de:ad:be:ef:00]`
INFO[2019-01-05T22:28:07Z] Found plugin: `file` with 1 args, `[leases.txt]`
INFO[2019-01-05T22:28:07Z] Loading plugins...
INFO[2019-01-05T22:28:07Z] Loading plugin `server_id`
INFO[2019-01-05T22:28:07Z] plugins/server_id: loading `server_id` plugin
INFO[2019-01-05T22:28:07Z] plugins/server_id: using ll 00:de:ad:be:ef:00
INFO[2019-01-05T22:28:07Z] Loading plugin `file`
INFO[2019-01-05T22:28:07Z] plugins/file: reading leases from leases.txt
INFO[2019-01-05T22:28:07Z] plugins/file: loaded 1 leases from leases.txt
INFO[2019-01-05T22:28:07Z] Starting DHCPv6 listener on [::]:547
INFO[2019-01-05T22:28:07Z] Waiting
2019/01/05 22:28:07 Server listening on [::]:547
2019/01/05 22:28:07 Ready to handle requests
...
```

Then try it with the local test client, that is located under
[cmds/client/](cmds/client):
```
$ cd cmds/client
$ go build
$ sudo ./client
INFO[2019-01-05T22:29:21Z] &{ReadTimeout:3s WriteTimeout:3s LocalAddr:[::1]:546 RemoteAddr:[::1]:547}
INFO[2019-01-05T22:29:21Z] DHCPv6Message
  messageType=SOLICIT
  transactionid=0x6d30ff
  options=[
    OptClientId{cid=DUID{type=DUID-LLT hwtype=Ethernet hwaddr=00:11:22:33:44:55}}
    OptRequestedOption{options=[DNS Recursive Name Server, Domain Search List]}
    OptElapsedTime{elapsedtime=0}
    OptIANA{IAID=[250 206 176 12], t1=3600, t2=5400, options=[]}
  ]
...
```

## Docker

There is a [Dockerfile](./Dockerfile) and a [docker-compose.yml](./docker-compose.yml).

Docker compose expects a configuration file under `/etc/coredhcp/config.yaml`, and it is
mapped to `./etc/coredhcp/config.yaml` when using `docker compose`. You can adjust the exported
volume in `docker-compose.yml` to point to a different configuration file on the host file system.

There is an example configuration file [config.yml.example](./cmds/coredhcp/config.yml.example)
that you can use as a starting point.

# Plugins

CoreDHCP is heavily based on plugins: even the core functionalities are
implemented as plugins. Therefore, knowing how to write one is the key to add
new features to CoreDHCP.

Core plugins can be found under the [plugins](/plugins/) directory. Additional
plugins can also be found in the
[coredhcp/plugins](https://github.com/coredhcp/plugins) repository.

## Server with custom plugins

To build a server with a custom set of plugins you can use the
[coredhcp-generator](/cmds/coredhcp-generator/) tool. Head there for
documentation on how to use it.

# How to write a plugin

The best way to learn is to read the comments and source code of the
[example plugin](plugins/example/), which guides you through the implementation
of a simple plugin that prints a packet every time it is received by the server.


# Authors

* [Andrea Barberio](https://github.com/insomniacslk)
* [Anatole Denis](https://github.com/natolumin)
* [Pablo Mazzini](https://github.com/pmazzini)