Implement ContentSecurityPolicy on the browser-side.

content/common/content_security_policy/csp_source.cc

+// Copyright 2017 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 <sstream>
+
+#include "base/strings/string_util.h"
+#include "base/strings/utf_string_conversions.h"
+#include "content/common/content_security_policy/csp_context.h"
+#include "url/url_canon.h"
+#include "url/url_util.h"
+
+namespace content {
+
+namespace {
+
+bool DecodePath(const base::StringPiece& path, std::string* output) {
+  url::RawCanonOutputT<base::char16> unescaped;
+  url::DecodeURLEscapeSequences(path.data(), path.size(), &unescaped);
+  return base::UTF16ToUTF8(unescaped.data(), unescaped.length(), output);
+}
+
+int DefaultPortForScheme(const std::string& scheme) {
+  return url::DefaultPortForScheme(scheme.data(), scheme.size());
+}
+
+bool SourceAllowScheme(const CSPSource& source,
+                       const GURL& url,
+                       CSPContext* context) {
+  if (source.scheme.empty())
+    return context->ProtocolMatchesSelf(url);
+  if (source.scheme == url::kHttpScheme)
+    return url.SchemeIsHTTPOrHTTPS();
+  if (source.scheme == url::kWsScheme)
+    return url.SchemeIsWSOrWSS();
+  return url.SchemeIs(source.scheme);
+}
+
+bool SourceAllowHost(const CSPSource& source, const GURL& url) {
+  if (source.is_host_wildcard) {
+    if (source.host.empty())
+      return true;
+    // TODO(arthursonzogni): Chrome used to, incorrectly, match *.x.y to x.y.
+    // The renderer version of this function count how many times it happens.
+    // It might be useful to do it outside of blink too.
+    // See third_party/WebKit/Source/core/frame/csp/CSPSource.cpp
+    return base::EndsWith(url.host(), '.' + source.host,
+                          base::CompareCase::INSENSITIVE_ASCII);
+  } else
+    return url.host() == source.host;
+}
+
+bool SourceAllowPort(const CSPSource& source, const GURL& url) {
+  int url_port = url.EffectiveIntPort();
+
+  if (source.is_port_wildcard)
+    return true;
+
+  if (source.port == url::PORT_UNSPECIFIED)
+    return DefaultPortForScheme(url.scheme()) == url_port;
+
+  if (source.port == url_port)
+    return true;
+
+  if (source.port == 80 && url_port == 443)
+    return true;
+
+  return false;
+}
+
+bool SourceAllowPath(const CSPSource& source,
+                     const GURL& url,
+                     bool is_redirect) {
+  if (is_redirect)
+    return true;
+
+  if (source.path.empty() || url.path().empty())
+    return true;
+
+  std::string url_path;
+  if (!DecodePath(url.path(), &url_path)) {
+    // TODO(arthursonzogni): try to figure out if that could happen and how to
+    // handle it.
+    return false;
+  }
+
+  // If the path represents a directory.
+  if (base::EndsWith(source.path, "/", base::CompareCase::SENSITIVE))
+    return base::StartsWith(url_path, source.path,
+                            base::CompareCase::SENSITIVE);
+
+  // The path represents a file.
+  return source.path == url_path;
+}
+
+}  // namespace
+
+CSPSource::CSPSource()
+    : scheme(),
+      host(),
+      is_host_wildcard(false),
+      port(url::PORT_UNSPECIFIED),
+      is_port_wildcard(false),
+      path() {}
+
+CSPSource::CSPSource(const std::string& scheme,
+                     const std::string& host,
+                     bool is_host_wildcard,
+                     int port,
+                     bool is_port_wildcard,
+                     const std::string& path)
+    : scheme(scheme),
+      host(host),
+      is_host_wildcard(is_host_wildcard),
+      port(port),
+      is_port_wildcard(is_port_wildcard),
+      path(path) {
+  DCHECK(!HasPort() || HasHost());  // port => host
+  DCHECK(!HasPath() || HasHost());  // path => host
+  DCHECK(!is_port_wildcard || port == url::PORT_UNSPECIFIED);
+}
+
+CSPSource::CSPSource(const CSPSource& source) = default;
+CSPSource::~CSPSource() = default;
+
+// static
+bool CSPSource::Allow(const CSPSource& source,
+                      const GURL& url,
+                      CSPContext* context,
+                      bool is_redirect) {
+  if (source.IsSchemeOnly())
+    return SourceAllowScheme(source, url, context);
+
+  return SourceAllowScheme(source, url, context) &&
+         SourceAllowHost(source, url) && SourceAllowPort(source, url) &&
+         SourceAllowPath(source, url, is_redirect);
+}
+
+std::string CSPSource::ToString() const {
+  // scheme
+  if (IsSchemeOnly())
+    return scheme + ":";
+
+  std::stringstream text;
+  if (!scheme.empty())
+    text << scheme << "://";
+
+  // host
+  if (is_host_wildcard) {
+    if (host.empty())
+      text << "*";
+    else
+      text << "*." << host;
+  } else {
+    text << host;
+  }
+
+  // port
+  if (is_port_wildcard)
+    text << ":*";
+  if (port != url::PORT_UNSPECIFIED)
+    text << ":" << port;
+
+  // path
+  text << path;
+
+  return text.str();
+}
+
+bool CSPSource::IsSchemeOnly() const {
+  return !HasHost();
+}
+
+bool CSPSource::HasPort() const {
+  return port != url::PORT_UNSPECIFIED || is_port_wildcard;
+}
+
+bool CSPSource::HasHost() const {
+  return !host.empty() || is_host_wildcard;
+}
+
+bool CSPSource::HasPath() const {
+  return !path.empty();
+}
+
+}  // namespace content