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/*!

* proxy-addr

* Copyright(c) 2014-2016 Douglas Christopher Wilson

* MIT Licensed

*/

'use strict'

/**

* Module exports.

* @public

*/

module.exports = proxyaddr

module.exports.all = alladdrs

module.exports.compile = compile

/**

* Module dependencies.

* @private

*/

var forwarded = require('forwarded')

var ipaddr = require('ipaddr.js')

/**

* Variables.

* @private

*/

var DIGIT_REGEXP = /^[0-9]+$/

var isip = ipaddr.isValid

var parseip = ipaddr.parse

/**

* Pre-defined IP ranges.

* @private

*/

var IP_RANGES = {

linklocal: ['169.254.0.0/16', 'fe80::/10'],

loopback: ['127.0.0.1/8', '::1/128'],

uniquelocal: ['10.0.0.0/8', '172.16.0.0/12', '192.168.0.0/16', 'fc00::/7']

}

/**

* Get all addresses in the request, optionally stopping

* at the first untrusted.

*

* @param {Object} request

* @param {Function|Array|String} [trust]

* @public

*/

function alladdrs (req, trust) {

// get addresses

var addrs = forwarded(req)

if (!trust) {

// Return all addresses

return addrs

}

if (typeof trust !== 'function') {

trust = compile(trust)

}

for (var i = 0; i < addrs.length - 1; i++) {

if (trust(addrs[i], i)) continue

addrs.length = i + 1

}

return addrs

}

/**

* Compile argument into trust function.

*

* @param {Array|String} val

* @private

*/

function compile (val) {

if (!val) {

throw new TypeError('argument is required')

}

var trust

if (typeof val === 'string') {

trust = [val]

} else if (Array.isArray(val)) {

trust = val.slice()

} else {

throw new TypeError('unsupported trust argument')

}

for (var i = 0; i < trust.length; i++) {

val = trust[i]

if (!Object.prototype.hasOwnProperty.call(IP_RANGES, val)) {

continue

}

// Splice in pre-defined range

val = IP_RANGES[val]

trust.splice.apply(trust, [i, 1].concat(val))

i += val.length - 1

}

return compileTrust(compileRangeSubnets(trust))

}

/**

* Compile `arr` elements into range subnets.

*

* @param {Array} arr

* @private

*/

function compileRangeSubnets (arr) {

var rangeSubnets = new Array(arr.length)

for (var i = 0; i < arr.length; i++) {

rangeSubnets[i] = parseipNotation(arr[i])

}

return rangeSubnets

}

/**

* Compile range subnet array into trust function.

*

* @param {Array} rangeSubnets

* @private

*/

function compileTrust (rangeSubnets) {

// Return optimized function based on length

var len = rangeSubnets.length

return len === 0

? trustNone

: len === 1

? trustSingle(rangeSubnets[0])

: trustMulti(rangeSubnets)

}

/**

* Parse IP notation string into range subnet.

*

* @param {String} note

* @private

*/

function parseipNotation (note) {

var pos = note.lastIndexOf('/')

var str = pos !== -1

? note.substring(0, pos)

: note

if (!isip(str)) {

throw new TypeError('invalid IP address: ' + str)

}

var ip = parseip(str)

if (pos === -1 && ip.kind() === 'ipv6' && ip.isIPv4MappedAddress()) {

// Store as IPv4

ip = ip.toIPv4Address()

}

var max = ip.kind() === 'ipv6'

? 128

: 32

var range = pos !== -1

? note.substring(pos + 1, note.length)

: null

if (range === null) {

range = max

} else if (DIGIT_REGEXP.test(range)) {

range = parseInt(range, 10)

} else if (ip.kind() === 'ipv4' && isip(range)) {

range = parseNetmask(range)

} else {

range = null

}

if (range <= 0 || range > max) {

throw new TypeError('invalid range on address: ' + note)

}

return [ip, range]

}

/**

* Parse netmask string into CIDR range.

*

* @param {String} netmask

* @private

*/

function parseNetmask (netmask) {

var ip = parseip(netmask)

var kind = ip.kind()

return kind === 'ipv4'

? ip.prefixLengthFromSubnetMask()

: null

}

/**

* Determine address of proxied request.

*

* @param {Object} request

* @param {Function|Array|String} trust

* @public

*/

function proxyaddr (req, trust) {

if (!req) {

throw new TypeError('req argument is required')

}

if (!trust) {

throw new TypeError('trust argument is required')

}

var addrs = alladdrs(req, trust)

var addr = addrs[addrs.length - 1]

return addr

}

/**

* Static trust function to trust nothing.

*

* @private

*/

function trustNone () {

return false

}

/**

* Compile trust function for multiple subnets.

*

* @param {Array} subnets

* @private

*/

function trustMulti (subnets) {

return function trust (addr) {

if (!isip(addr)) return false

var ip = parseip(addr)

if (ip.kind() === 'ipv6' && ip.isIPv4MappedAddress()) {

// Canonicalize IPv4-mapped candidates to IPv4 so a mapped address

// cannot bypass the cross-family guard via the same-family path

ip = ip.toIPv4Address()

}

var ipconv

var kind = ip.kind()

for (var i = 0; i < subnets.length; i++) {

var subnet = subnets[i]

var subnetip = subnet[0]

var subnetkind = subnetip.kind()

var subnetrange = subnet[1]

var trusted = ip

if (kind !== subnetkind) {

if (subnetkind === 'ipv4' && !ip.isIPv4MappedAddress()) {

// Incompatible IP addresses

continue

}

if (subnetkind !== 'ipv4' && !(subnetrange >= 96 && subnetip.isIPv4MappedAddress())) {

// IPv6 subnet only spans IPv4 when it is a mapped subnet whose

// prefix covers the ::ffff: marker; otherwise it must not match IPv4

continue

}

if (!ipconv) {

// Convert IP to match subnet IP kind

ipconv = subnetkind === 'ipv4'

? ip.toIPv4Address()

: ip.toIPv4MappedAddress()

}

trusted = ipconv

} else if (kind === 'ipv6' && subnetip.isIPv4MappedAddress()) {

// A native IPv6 candidate cannot match an IPv4-mapped subnet

continue

}

if (trusted.match(subnetip, subnetrange)) {

return true

}

}

return false

}

}

/**

* Compile trust function for single subnet.

*

* @param {Object} subnet

* @private

*/

function trustSingle (subnet) {

var subnetip = subnet[0]

var subnetkind = subnetip.kind()

var subnetisipv4 = subnetkind === 'ipv4'

var subnetrange = subnet[1]

return function trust (addr) {

if (!isip(addr)) return false

var ip = parseip(addr)

if (ip.kind() === 'ipv6' && ip.isIPv4MappedAddress()) {

// Canonicalize IPv4-mapped candidates to IPv4 so a mapped address

// cannot bypass the cross-family guard via the same-family path

ip = ip.toIPv4Address()

}

var kind = ip.kind()

if (kind !== subnetkind) {

if (subnetisipv4 && !ip.isIPv4MappedAddress()) {

// Incompatible IP addresses

return false

}

if (!subnetisipv4 && !(subnetrange >= 96 && subnetip.isIPv4MappedAddress())) {

// IPv6 subnet only spans IPv4 when it is a mapped subnet whose

// prefix covers the ::ffff: marker; otherwise it must not match IPv4

return false

}

// Convert IP to match subnet IP kind

ip = subnetisipv4

? ip.toIPv4Address()

: ip.toIPv4MappedAddress()

} else if (kind === 'ipv6' && subnetip.isIPv4MappedAddress()) {

// A native IPv6 candidate cannot match an IPv4-mapped subnet

return false

}

return ip.match(subnetip, subnetrange)

}

}