npm package: @fastify/proxy-addr
Description: Determine the address of a proxied request
Author: Douglas Christopher Wilson
Latest version: 5.1.0

# proxy-addr

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Determine the address of a proxied request.

Forked from https://github.com/jshttp/proxy-addr to address https://github.com/jshttp/forwarded/pull/9.

## Install

```sh
$ npm i @fastify/proxy-addr
```

## API

<!-- eslint-disable no-unused-vars -->

```js
const proxyaddr = require('@fastify/proxy-addr')
```

### proxyaddr(req, trust)

Return the address of the request, using the given `trust` parameter.

The `trust` argument is a function that returns `true` if you trust
the address, `false` if you don't. The closest untrusted address is
returned.

<!-- eslint-disable no-undef -->

```js
proxyaddr(req, function (addr) { return addr === '127.0.0.1' })
proxyaddr(req, function (addr, i) { return i < 1 })
```

The `trust` argument may also be a single IP address string or an
array of trusted addresses, as plain IP addresses, CIDR-formatted
strings, or IP/netmask strings.

<!-- eslint-disable no-undef -->

```js
proxyaddr(req, '127.0.0.1')
proxyaddr(req, ['127.0.0.0/8', '10.0.0.0/8'])
proxyaddr(req, ['127.0.0.0/255.0.0.0', '192.168.0.0/255.255.0.0'])
```

This module also supports IPv6. Your IPv6 addresses will be normalized
automatically (i.e. `fe80::00ed:1` equals `fe80:0:0:0:0:0:ed:1`).

<!-- eslint-disable no-undef -->

```js
proxyaddr(req, '::1')
proxyaddr(req, ['::1/128', 'fe80::/10'])
```

This module will automatically work with IPv4-mapped IPv6 addresses
as well to support node.js in IPv6-only mode. This means that you do
not have to specify both `::ffff:a00:1` and `10.0.0.1`.

As a convenience, this module also takes certain pre-defined names
in addition to IP addresses, which expand into IP addresses:

<!-- eslint-disable no-undef -->

```js
proxyaddr(req, 'loopback')
proxyaddr(req, ['loopback', 'fc00:ac:1ab5:fff::1/64'])
```

  * `loopback`: IPv4 and IPv6 loopback addresses (like `::1` and
    `127.0.0.1`).
  * `linklocal`: IPv4 and IPv6 link-local addresses (like
    `fe80::1:1:1:1` and `169.254.0.1`).
  * `uniquelocal`: IPv4 private addresses and IPv6 unique-local
    addresses (like `fc00:ac:1ab5:fff::1` and `192.168.0.1`).

When `trust` is specified as a function, it will be called for each
address to determine if it is a trusted address. The function is
given two arguments: `addr` and `i`, where `addr` is a string of
the address to check and `i` is a number that represents the distance
from the socket address.

### proxyaddr.all(req, [trust])

Return all the request addresses, optionally stopping at the
first untrusted. This array is ordered from closest to furthest
(i.e. `arr[0] === req.connection.remoteAddress`).

<!-- eslint-disable no-undef -->

```js
proxyaddr.all(req)
```

The optional `trust` argument takes the same arguments as `trust`
does in `proxyaddr(req, trust)`.

<!-- eslint-disable no-undef -->

```js
proxyaddr.all(req, 'loopback')
```

### proxyaddr.compile(val)

Compiles argument `val` into a `trust` function. This function takes
the same arguments as `trust` does in `proxyaddr(req, trust)` and
returns a function suitable for `proxyaddr(req, trust)`.

<!-- eslint-disable no-undef, no-unused-vars -->

```js
const trust = proxyaddr.compile('loopback')
const addr = proxyaddr(req, trust)
```

This function is meant to be optimized for use against every request.
It is recommended that a trust function be compiled up-front for the
trusted configuration and passed to proxyaddr(req, trust) for each request.

## Testing

```sh
$ npm test
```

## Benchmarks

```sh
$ npm run bench
```

## License

Licensed under [MIT](./LICENSE).