http: append Cookie header values with semicolon

Previously, separate incoming Cookie headers would be concatenated
with a comma, which can cause confusion in userland code when it
comes to parsing the final Cookie header value. This commit
concatenates using a semicolon instead.

Fixes: https://github.com/nodejs/node/issues/11256
PR-URL: https://github.com/nodejs/node/pull/11259
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

lib/_http_incoming.js

@@ -194,6 +194,9 @@ function matchKnownFields(field) {
       case 'Set-Cookie':
       case 'set-cookie':
         return '\u0001';
+      case 'Cookie':
+      case 'cookie':
+        return '\u0002cookie';
       // The fields below are not used in _addHeaderLine(), but they are common
       // headers where we can avoid toLowerCase() if the mixed or lower case
       // versions match the first time through.
@@ -215,9 +218,6 @@ function matchKnownFields(field) {
       case 'Content-Encoding':
       case 'content-encoding':
         return '\u0000content-encoding';
-      case 'Cookie':
-      case 'cookie':
-        return '\u0000cookie';
       case 'Origin':
       case 'origin':
         return '\u0000origin';
@@ -263,18 +263,20 @@ function matchKnownFields(field) {
 //
 // Per RFC2616, section 4.2 it is acceptable to join multiple instances of the
 // same header with a ', ' if the header in question supports specification of
-// multiple values this way. If not, we declare the first instance the winner
-// and drop the second. Extended header fields (those beginning with 'x-') are
-// always joined.
+// multiple values this way. The one exception to this is the Cookie header,
+// which has multiple values joined with a '; ' instead. If a header's values
+// cannot be joined in either of these ways, we declare the first instance the
+// winner and drop the second. Extended header fields (those beginning with
+// 'x-') are always joined.
 IncomingMessage.prototype._addHeaderLine = _addHeaderLine;
 function _addHeaderLine(field, value, dest) {
   field = matchKnownFields(field);
   var flag = field.charCodeAt(0);
-  if (flag === 0) {
+  if (flag === 0 || flag === 2) {
     field = field.slice(1);
-    // Make comma-separated list
+    // Make a delimited list
     if (typeof dest[field] === 'string') {
-      dest[field] += ', ' + value;
+      dest[field] += (flag === 0 ? ', ' : '; ') + value;
     } else {
       dest[field] = value;
     }

test/parallel/test-http-incoming-matchKnownFields.js

@@ -6,9 +6,10 @@ const IncomingMessage = require('http').IncomingMessage;
 function checkDest(field, result, value) {
   const dest = {};
 
-  if (value) dest[field] = 'test';
   const incomingMessage = new IncomingMessage(field);
   // dest is changed by IncomingMessage._addHeaderLine
+  if (value)
+    incomingMessage._addHeaderLine(field, 'test', dest);
   incomingMessage._addHeaderLine(field, value, dest);
   assert.deepStrictEqual(dest, result);
 }
@@ -49,7 +50,7 @@ checkDest('age', {age: 'test'}, 'value');
 checkDest('Expires', {expires: undefined});
 checkDest('expires', {expires: 'test'}, 'value');
 checkDest('Set-Cookie', {'set-cookie': [undefined]});
-checkDest('set-cookie', {'set-cookie': [undefined]});
+checkDest('set-cookie', {'set-cookie': ['test', 'value']}, 'value');
 checkDest('Transfer-Encoding', {'transfer-encoding': undefined});
 checkDest('transfer-encoding', {'transfer-encoding': 'test, value'}, 'value');
 checkDest('Date', {date: undefined});
@@ -64,8 +65,8 @@ checkDest('Vary', {vary: undefined});
 checkDest('vary', {vary: 'test, value'}, 'value');
 checkDest('Content-Encoding', {'content-encoding': undefined}, undefined);
 checkDest('content-encoding', {'content-encoding': 'test, value'}, 'value');
-checkDest('Cookies', {cookies: undefined});
-checkDest('cookies', {cookies: 'test, value'}, 'value');
+checkDest('Cookie', {cookie: undefined});
+checkDest('cookie', {cookie: 'test; value'}, 'value');
 checkDest('Origin', {origin: undefined});
 checkDest('origin', {origin: 'test, value'}, 'value');
 checkDest('Upgrade', {upgrade: undefined});
@@ -88,3 +89,5 @@ checkDest('X-Forwarded-Host', {'x-forwarded-host': undefined});
 checkDest('x-forwarded-host', {'x-forwarded-host': 'test, value'}, 'value');
 checkDest('X-Forwarded-Proto', {'x-forwarded-proto': undefined});
 checkDest('x-forwarded-proto', {'x-forwarded-proto': 'test, value'}, 'value');
+checkDest('X-Foo', {'x-foo': undefined});
+checkDest('x-foo', {'x-foo': 'test, value'}, 'value');

test/parallel/test-http-server-multiheaders2.js

@@ -54,8 +54,10 @@ const srv = http.createServer(function(req, res) {
                        'foo', 'header parsed incorrectly: ' + header);
   });
   multipleAllowed.forEach(function(header) {
+    const sep = (header.toLowerCase() === 'cookie' ? '; ' : ', ');
     assert.strictEqual(req.headers[header.toLowerCase()],
-                       'foo, bar', 'header parsed incorrectly: ' + header);
+                       'foo' + sep + 'bar',
+                       'header parsed incorrectly: ' + header);
   });
 
   res.writeHead(200, {'Content-Type': 'text/plain'});