Add basic permessage-deflate, pass entire Autobahn

src/WebSocketExtensions.h

@@ -0,0 +1,176 @@
+/*
+ * Copyright 2018 Alex Hultman and contributors.
+
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+
+ *     http://www.apache.org/licenses/LICENSE-2.0
+
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef WEBSOCKETEXTENSIONS_H
+#define WEBSOCKETEXTENSIONS_H
+
+#include <string_view>
+
+namespace uWS {
+
+enum Options : unsigned int {
+    NO_OPTIONS = 0,
+    PERMESSAGE_DEFLATE = 1,
+    SERVER_NO_CONTEXT_TAKEOVER = 2, // remove this
+    CLIENT_NO_CONTEXT_TAKEOVER = 4, // remove this
+    NO_DELAY = 8,
+    SLIDING_DEFLATE_WINDOW = 16
+};
+
+template <bool isServer>
+class ExtensionsNegotiator {
+protected:
+    int options;
+public:
+    ExtensionsNegotiator(int wantedOptions);
+    std::string generateOffer();
+    void readOffer(std::string_view offer);
+    int getNegotiatedOptions();
+};
+
+enum ExtensionTokens {
+    TOK_PERMESSAGE_DEFLATE = 1838,
+    TOK_SERVER_NO_CONTEXT_TAKEOVER = 2807,
+    TOK_CLIENT_NO_CONTEXT_TAKEOVER = 2783,
+    TOK_SERVER_MAX_WINDOW_BITS = 2372,
+    TOK_CLIENT_MAX_WINDOW_BITS = 2348
+};
+
+class ExtensionsParser {
+private:
+    int *lastInteger = nullptr;
+
+public:
+    bool perMessageDeflate = false;
+    bool serverNoContextTakeover = false;
+    bool clientNoContextTakeover = false;
+    int serverMaxWindowBits = 0;
+    int clientMaxWindowBits = 0;
+
+    int getToken(const char *&in, const char *stop);
+    ExtensionsParser(const char *data, size_t length);
+};
+
+int ExtensionsParser::getToken(const char *&in, const char *stop) {
+    while (!isalnum(*in) && in != stop) {
+        in++;
+    }
+
+    int hashedToken = 0;
+    while (isalnum(*in) || *in == '-' || *in == '_') {
+        if (isdigit(*in)) {
+            hashedToken = hashedToken * 10 - (*in - '0');
+        } else {
+            hashedToken += *in;
+        }
+        in++;
+    }
+    return hashedToken;
+}
+
+ExtensionsParser::ExtensionsParser(const char *data, size_t length) {
+    const char *stop = data + length;
+    int token = 1;
+    for (; token && token != TOK_PERMESSAGE_DEFLATE; token = getToken(data, stop));
+
+    perMessageDeflate = (token == TOK_PERMESSAGE_DEFLATE);
+    while ((token = getToken(data, stop))) {
+        switch (token) {
+        case TOK_PERMESSAGE_DEFLATE:
+            return;
+        case TOK_SERVER_NO_CONTEXT_TAKEOVER:
+            serverNoContextTakeover = true;
+            break;
+        case TOK_CLIENT_NO_CONTEXT_TAKEOVER:
+            clientNoContextTakeover = true;
+            break;
+        case TOK_SERVER_MAX_WINDOW_BITS:
+            serverMaxWindowBits = 1;
+            lastInteger = &serverMaxWindowBits;
+            break;
+        case TOK_CLIENT_MAX_WINDOW_BITS:
+            clientMaxWindowBits = 1;
+            lastInteger = &clientMaxWindowBits;
+            break;
+        default:
+            if (token < 0 && lastInteger) {
+                *lastInteger = -token;
+            }
+            break;
+        }
+    }
+}
+
+template <bool isServer>
+ExtensionsNegotiator<isServer>::ExtensionsNegotiator(int wantedOptions) {
+    options = wantedOptions;
+}
+
+template <bool isServer>
+std::string ExtensionsNegotiator<isServer>::generateOffer() {
+    std::string extensionsOffer;
+    if (options & Options::PERMESSAGE_DEFLATE) {
+        extensionsOffer += "permessage-deflate";
+
+        if (options & Options::CLIENT_NO_CONTEXT_TAKEOVER) {
+            extensionsOffer += "; client_no_context_takeover";
+        }
+
+        // we do not support accepting this yet
+        // todo: if we agree on this, do not allocate a compressor
+        // per socket!
+
+        // It is RECOMMENDED that a server supports the
+        // "server_no_context_takeover" extension parameter in an extension
+        // negotiation offer.
+        if (options & Options::SERVER_NO_CONTEXT_TAKEOVER) {
+            //extensionsOffer += "; server_no_context_takeover";
+        }
+    }
+
+    return extensionsOffer;
+}
+
+template <bool isServer>
+void ExtensionsNegotiator<isServer>::readOffer(std::string_view offer) {
+    if (isServer) {
+        ExtensionsParser extensionsParser(offer.data(), offer.length());
+        if ((options & PERMESSAGE_DEFLATE) && extensionsParser.perMessageDeflate) {
+            if (extensionsParser.clientNoContextTakeover || (options & CLIENT_NO_CONTEXT_TAKEOVER)) {
+                options |= CLIENT_NO_CONTEXT_TAKEOVER;
+            }
+
+            if (extensionsParser.serverNoContextTakeover) {
+                options |= SERVER_NO_CONTEXT_TAKEOVER;
+            } else {
+                options &= ~SERVER_NO_CONTEXT_TAKEOVER;
+            }
+        } else {
+            options &= ~PERMESSAGE_DEFLATE;
+        }
+    } else {
+        // todo!
+    }
+}
+
+template <bool isServer>
+int ExtensionsNegotiator<isServer>::getNegotiatedOptions() {
+    return options;
+}
+
+}
+
+#endif // WEBSOCKETEXTENSIONS_H