Introduce WebSocketDeflateParameters.

net/websockets/websocket_basic_handshake_stream.cc

Index: net/websockets/websocket_basic_handshake_stream.cc
diff --git a/net/websockets/websocket_basic_handshake_stream.cc b/net/websockets/websocket_basic_handshake_stream.cc
index da64386a463de3d54143d0eddd7b38ff2dd2c7c4..cdb432edf4f767b042d719a0c85deb6ad7987d84 100644
--- a/net/websockets/websocket_basic_handshake_stream.cc
+++ b/net/websockets/websocket_basic_handshake_stream.cc
@@ -35,6 +35,7 @@
 #include "net/socket/client_socket_handle.h"
 #include "net/socket/websocket_transport_client_socket_pool.h"
 #include "net/websockets/websocket_basic_stream.h"
+#include "net/websockets/websocket_deflate_parameters.h"
 #include "net/websockets/websocket_deflate_predictor.h"
 #include "net/websockets/websocket_deflate_predictor_impl.h"
 #include "net/websockets/websocket_deflate_stream.h"
@@ -57,14 +58,8 @@ const char kConnectionErrorStatusLine[] = "HTTP/1.1 503 Connection Error";
 // TODO(ricea): If more extensions are added, replace this with a more general
 // mechanism.
 struct WebSocketExtensionParams {
-  WebSocketExtensionParams()
-      : deflate_enabled(false),
-        client_window_bits(15),
-        deflate_mode(WebSocketDeflater::TAKE_OVER_CONTEXT) {}
-
-  bool deflate_enabled;
-  int client_window_bits;
-  WebSocketDeflater::ContextTakeOverMode deflate_mode;
+  bool deflate_enabled = false;
+  WebSocketDeflateParameters deflate_parameters;
 };
 
 namespace {
@@ -235,73 +230,6 @@ bool ValidateSubProtocol(
   return true;
 }
 
-bool DeflateError(std::string* message, const base::StringPiece& piece) {
-  *message = "Error in permessage-deflate: ";
-  piece.AppendToString(message);
-  return false;
-}
-
-bool ValidatePerMessageDeflateExtension(const WebSocketExtension& extension,
-                                        std::string* failure_message,
-                                        WebSocketExtensionParams* params) {
-  static const char kClientPrefix[] = "client_";
-  static const char kServerPrefix[] = "server_";
-  static const char kNoContextTakeover[] = "no_context_takeover";
-  static const char kMaxWindowBits[] = "max_window_bits";
-  const size_t kPrefixLen = arraysize(kClientPrefix) - 1;
-  static_assert(kPrefixLen == arraysize(kServerPrefix) - 1,
-                "the strings server and client must be the same length");
-  typedef std::vector<WebSocketExtension::Parameter> ParameterVector;
-
-  DCHECK_EQ("permessage-deflate", extension.name());
-  const ParameterVector& parameters = extension.parameters();
-  std::set<std::string> seen_names;
-  for (ParameterVector::const_iterator it = parameters.begin();
-       it != parameters.end(); ++it) {
-    const std::string& name = it->name();
-    if (seen_names.count(name) != 0) {
-      return DeflateError(
-          failure_message,
-          "Received duplicate permessage-deflate extension parameter " + name);
-    }
-    seen_names.insert(name);
-    const std::string client_or_server(name, 0, kPrefixLen);
-    const bool is_client = (client_or_server == kClientPrefix);
-    if (!is_client && client_or_server != kServerPrefix) {
-      return DeflateError(
-          failure_message,
-          "Received an unexpected permessage-deflate extension parameter");
-    }
-    const std::string rest(name, kPrefixLen);
-    if (rest == kNoContextTakeover) {
-      if (it->HasValue()) {
-        return DeflateError(failure_message,
-                            "Received invalid " + name + " parameter");
-      }
-      if (is_client)
-        params->deflate_mode = WebSocketDeflater::DO_NOT_TAKE_OVER_CONTEXT;
-    } else if (rest == kMaxWindowBits) {
-      if (!it->HasValue())
-        return DeflateError(failure_message, name + " must have value");
-      int bits = 0;
-      if (!base::StringToInt(it->value(), &bits) || bits < 8 || bits > 15 ||
-          it->value()[0] == '0' ||
-          it->value().find_first_not_of("0123456789") != std::string::npos) {
-        return DeflateError(failure_message,
-                            "Received invalid " + name + " parameter");
-      }
-      if (is_client)
-        params->client_window_bits = bits;
-    } else {
-      return DeflateError(
-          failure_message,
-          "Received an unexpected permessage-deflate extension parameter");
-    }
-  }
-  params->deflate_enabled = true;
-  return true;
-}
-
 bool ValidateExtensions(const HttpResponseHeaders* headers,
                         std::string* accepted_extensions_descriptor,
                         std::string* failure_message,
@@ -332,11 +260,16 @@ bool ValidateExtensions(const HttpResponseHeaders* headers,
           return false;
         }
         seen_permessage_deflate = true;
-
-        if (!ValidatePerMessageDeflateExtension(extension, failure_message,
-                                                params)) {
+        auto& deflate_parameters = params->deflate_parameters;
+        if (!deflate_parameters.Initialize(extension, failure_message) ||
+            !deflate_parameters.IsValidAsResponse(failure_message)) {
+          *failure_message = "Error in permessage-deflate: " + *failure_message;
           return false;
         }
+        // Note that we don't have to check the request-response compatibility
+        // here because we send a request compatible with any valid responses.
+        // TODO(yhirano): Place a DCHECK here.
+
         header_values.push_back(header_value);
       } else {
         *failure_message = "Found an unsupported extension '" +
@@ -347,6 +280,7 @@ bool ValidateExtensions(const HttpResponseHeaders* headers,
     }
   }
   *accepted_extensions_descriptor = base::JoinString(header_values, ", ");
+  params->deflate_enabled = seen_permessage_deflate;
   return true;
 }
 
@@ -531,15 +465,13 @@ scoped_ptr<WebSocketStream> WebSocketBasicHandshakeStream::Upgrade() {
   if (extension_params_->deflate_enabled) {
     UMA_HISTOGRAM_ENUMERATION(
         "Net.WebSocket.DeflateMode",
-        extension_params_->deflate_mode,
+        extension_params_->deflate_parameters.client_context_take_over_mode(),
         WebSocketDeflater::NUM_CONTEXT_TAKEOVER_MODE_TYPES);
 
-    return scoped_ptr<WebSocketStream>(
-        new WebSocketDeflateStream(basic_stream.Pass(),
-                                   extension_params_->deflate_mode,
-                                   extension_params_->client_window_bits,
-                                   scoped_ptr<WebSocketDeflatePredictor>(
-                                       new WebSocketDeflatePredictorImpl)));
+    return scoped_ptr<WebSocketStream>(new WebSocketDeflateStream(
+        basic_stream.Pass(), extension_params_->deflate_parameters,
+        scoped_ptr<WebSocketDeflatePredictor>(
+            new WebSocketDeflatePredictorImpl)));
   } else {
     return basic_stream.Pass();
   }