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WebSocketExtensions.h
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169 lines (143 loc) · 5.18 KB
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/*
* Authored by Alex Hultman, 2018-2019.
* Intellectual property of third-party.
* 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 UWS_WEBSOCKETEXTENSIONS_H
#define UWS_WEBSOCKETEXTENSIONS_H
#include <climits>
#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
};
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
};
struct 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) {
while (in != stop && !isalnum(*in)) {
in++;
}
/* Don't care more than this for now */
static_assert(SHRT_MIN > INT_MIN, "Integer overflow fix is invalid for this platform, report this as a bug!");
int hashedToken = 0;
while (in != stop && (isalnum(*in) || *in == '-' || *in == '_')) {
if (isdigit(*in)) {
/* This check is a quick and incorrect fix for integer overflow
* in oss-fuzz but we don't care as it doesn't matter either way */
if (hashedToken > SHRT_MIN && hashedToken < SHRT_MAX) {
hashedToken = hashedToken * 10 - (*in - '0');
}
} else {
hashedToken += *in;
}
in++;
}
return hashedToken;
}
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>
struct ExtensionsNegotiator {
protected:
int options;
public:
ExtensionsNegotiator(int wantedOptions) {
options = wantedOptions;
}
std::string generateOffer() {
std::string extensionsOffer;
if (options & Options::PERMESSAGE_DEFLATE) {
extensionsOffer += "permessage-deflate";
if (options & Options::CLIENT_NO_CONTEXT_TAKEOVER) {
extensionsOffer += "; client_no_context_takeover";
}
/* It is questionable sending this improves anything */
/*if (options & Options::SERVER_NO_CONTEXT_TAKEOVER) {
extensionsOffer += "; server_no_context_takeover";
}*/
}
return extensionsOffer;
}
void 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;
}
/* We leave this option for us to read even if the client did not send it */
if (extensionsParser.serverNoContextTakeover) {
options |= SERVER_NO_CONTEXT_TAKEOVER;
}/* else {
options &= ~SERVER_NO_CONTEXT_TAKEOVER;
}*/
} else {
options &= ~PERMESSAGE_DEFLATE;
}
} else {
// todo!
}
}
int getNegotiatedOptions() {
return options;
}
};
}
#endif // UWS_WEBSOCKETEXTENSIONS_H