--- /dev/null
+'use strict'
+
+function formatHostname(hostname) {
+ // canonicalize the hostname, so that 'oogle.com' won't match 'google.com'
+ return hostname.replace(/^\.*/, '.').toLowerCase()
+}
+
+function parseNoProxyZone(zone) {
+ zone = zone.trim().toLowerCase()
+
+ var zoneParts = zone.split(':', 2)
+ , zoneHost = formatHostname(zoneParts[0])
+ , zonePort = zoneParts[1]
+ , hasPort = zone.indexOf(':') > -1
+
+ return {hostname: zoneHost, port: zonePort, hasPort: hasPort}
+}
+
+function uriInNoProxy(uri, noProxy) {
+ var port = uri.port || (uri.protocol === 'https:' ? '443' : '80')
+ , hostname = formatHostname(uri.hostname)
+ , noProxyList = noProxy.split(',')
+
+ // iterate through the noProxyList until it finds a match.
+ return noProxyList.map(parseNoProxyZone).some(function(noProxyZone) {
+ var isMatchedAt = hostname.indexOf(noProxyZone.hostname)
+ , hostnameMatched = (
+ isMatchedAt > -1 &&
+ (isMatchedAt === hostname.length - noProxyZone.hostname.length)
+ )
+
+ if (noProxyZone.hasPort) {
+ return (port === noProxyZone.port) && hostnameMatched
+ }
+
+ return hostnameMatched
+ })
+}
+
+function getProxyFromURI(uri) {
+ // Decide the proper request proxy to use based on the request URI object and the
+ // environmental variables (NO_PROXY, HTTP_PROXY, etc.)
+ // respect NO_PROXY environment variables (see: http://lynx.isc.org/current/breakout/lynx_help/keystrokes/environments.html)
+
+ var noProxy = process.env.NO_PROXY || process.env.no_proxy || ''
+
+ // if the noProxy is a wildcard then return null
+
+ if (noProxy === '*') {
+ return null
+ }
+
+ // if the noProxy is not empty and the uri is found return null
+
+ if (noProxy !== '' && uriInNoProxy(uri, noProxy)) {
+ return null
+ }
+
+ // Check for HTTP or HTTPS Proxy in environment Else default to null
+
+ if (uri.protocol === 'http:') {
+ return process.env.HTTP_PROXY ||
+ process.env.http_proxy || null
+ }
+
+ if (uri.protocol === 'https:') {
+ return process.env.HTTPS_PROXY ||
+ process.env.https_proxy ||
+ process.env.HTTP_PROXY ||
+ process.env.http_proxy || null
+ }
+
+ // if none of that works, return null
+ // (What uri protocol are you using then?)
+
+ return null
+}
+
+module.exports = getProxyFromURI