Embedding-CSP: Ports subsumption

third_party/WebKit/Source/core/frame/csp/CSPSource.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/frame/csp/CSPSource.h"
 
 #include "core/frame/UseCounter.h"
 #include "core/frame/csp/ContentSecurityPolicy.h"
 #include "platform/weborigin/KURL.h"
 #include "platform/weborigin/KnownPorts.h"
@@ skipping 114 matching lines @@
 }
 
 bool CSPSource::isSimilar(CSPSource* other) {
   bool schemesMatch =
       schemeMatches(other->m_scheme) || other->schemeMatches(m_scheme);
   if (!schemesMatch || isSchemeOnly() || other->isSchemeOnly())
     return schemesMatch;
   bool hostsMatch = (m_host == other->m_host) || hostMatches(other->m_host) ||
                     other->hostMatches(m_host);
   bool portsMatch = (other->m_portWildcard == HasWildcard) ||
-                    portMatches(other->m_port, other->m_scheme);
+                    portMatches(other->m_port, other->m_scheme) ||
+                    other->portMatches(m_port, m_scheme);
   bool pathsMatch = pathMatches(other->m_path) || other->pathMatches(m_path);
   if (hostsMatch && portsMatch && pathsMatch)
     return true;
 
   return false;
 }
 
 CSPSource* CSPSource::intersect(CSPSource* other) {
   if (!isSimilar(other))
     return nullptr;
 
   String scheme = other->schemeMatches(m_scheme) ? m_scheme : other->m_scheme;
   if (isSchemeOnly() || other->isSchemeOnly()) {
     CSPSource* stricter = isSchemeOnly() ? other : this;
     return new CSPSource(m_policy, scheme, stricter->m_host, stricter->m_port,
                          stricter->m_path, stricter->m_hostWildcard,
                          stricter->m_portWildcard);
   }
 
   String host = m_hostWildcard == NoWildcard ? m_host : other->m_host;
   String path = other->pathMatches(m_path) ? m_path : other->m_path;
-  int port = (other->m_portWildcard == HasWildcard || !other->m_port)
+  int port = (other->m_portWildcard == HasWildcard || !other->m_port ||
+              m_scheme.length() > other->m_scheme.length())

[amalika, 2016/12/06 09:29:13]

By this point, we know that A and B are similar, i.e. their schemes match. The
only case when one length could be greater than the other is if it is more
secure. So we want to pick that port.

[Mike West, 2016/12/06 13:41:09]

Can you spell this out, please? Reading `http` and `https` (or `ws` and `wss`)
is more verbose, but will be much clearer in a year when I've forgotten all
about the rationale for the length check here. :)

                  ? m_port
                  : other->m_port;
   WildcardDisposition hostWildcard =
       (m_hostWildcard == HasWildcard) ? other->m_hostWildcard : m_hostWildcard;
   WildcardDisposition portWildcard =
       (m_portWildcard == HasWildcard) ? other->m_portWildcard : m_portWildcard;
   return new CSPSource(m_policy, scheme, host, port, path, hostWildcard,
                        portWildcard);
 }
 
@@ skipping 20 matching lines @@
       return false;
   }
   return true;
 }
 
 DEFINE_TRACE(CSPSource) {
   visitor->trace(m_policy);
 }
 
 }  // namespace blink