Add support for unix domain sockets (#109)

Author: fenichelar

README.md

@@ -28,9 +28,10 @@ const addresses = forwarded(req)
 ```
 
 Parse the `X-Forwarded-For` header from the request. Returns an array
-of the addresses, including the socket address for the `req`, in reverse
-order (i.e. index `0` is the socket address and the last index is the
-furthest address, typically the end-user).
+of the addresses, including the socket address for the `req` if present, in reverse
+order (i.e. index `0` is the socket address if present and the last index is the
+furthest address, typically the end-user). May return an empty array if no socket
+address (i.e. unix domain socket) and no `X-Forwarded-For` header.
 
 ## Testing
 

index.js

@@ -18,19 +18,23 @@ function forwarded (req) {
   const socketAddr = req.socket.remoteAddress
 
   if (!header || typeof header !== 'string') {
-    return [socketAddr]
+    return socketAddr ? [socketAddr] : []
   } else if (header.indexOf(',') === -1) {
     const remote = header.trim()
-    return (remote.length)
-      ? [socketAddr, remote]
-      : [socketAddr]
+    if (socketAddr) {
+      return (remote.length)
+        ? [socketAddr, remote]
+        : [socketAddr]
+    } else {
+      return (remote.length) ? [remote] : []
+    }
   } else {
     return parse(header, socketAddr)
   }
 }
 
 function parse (header, socketAddr) {
-  const result = [socketAddr]
+  const result = socketAddr ? [socketAddr] : []
 
   let end = header.length
   let start = end

test/test.js

@@ -138,6 +138,41 @@ test('should trim trailing OWS with tabs (HTAB)', function (t) {
   ])
 })
 
+test('should handle unix domain sockets without X-Forwarded-For header', function (t) {
+  t.plan(1)
+  const req = createReq(undefined)
+  t.assert.deepStrictEqual(forwarded(req), [])
+})
+
+test('should handle unix domain sockets with X-Forwarded-For header containing no addresses', function (t) {
+  t.plan(1)
+  const req = createReq(undefined, {
+    'x-forwarded-for': ' '
+  })
+  t.assert.deepStrictEqual(forwarded(req), [])
+})
+
+test('should handle unix domain sockets with X-Forwarded-For header containing one address', function (t) {
+  t.plan(1)
+  const req = createReq(undefined, {
+    'x-forwarded-for': '10.0.0.1'
+  })
+  t.assert.deepStrictEqual(forwarded(req), [
+    '10.0.0.1'
+  ])
+})
+
+test('should handle unix domain sockets with X-Forwarded-For header containing multiple addresses', function (t) {
+  t.plan(1)
+  const req = createReq(undefined, {
+    'x-forwarded-for': '10.0.0.2, 10.0.0.1'
+  })
+  t.assert.deepStrictEqual(forwarded(req), [
+    '10.0.0.1',
+    '10.0.0.2'
+  ])
+})
+
 function createReq (socketAddr, headers) {
   return {
     socket: {