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// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/websockets/websocket_extension_parser.h"
#include "base/check_op.h"
#include "net/http/http_util.h"
namespace net {
namespace {
class WebSocketExtensionParser {
public:
WebSocketExtensionParser() = default;
~WebSocketExtensionParser() = default;
WebSocketExtensionParser(const WebSocketExtensionParser&) = delete;
WebSocketExtensionParser& operator=(const WebSocketExtensionParser&) = delete;
std::vector<WebSocketExtension> Parse(std::string_view data) {
std::vector<WebSocketExtension> extensions;
remaining_ = data;
bool failed = false;
do {
WebSocketExtension extension;
if (!ConsumeExtension(&extension)) {
failed = true;
break;
}
extensions.push_back(extension);
ConsumeSpaces();
} while (ConsumeIfMatch(','));
if (!failed && remaining_.empty()) {
return extensions;
}
return {};
}
private:
[[nodiscard]] bool Consume(char c) {
ConsumeSpaces();
if (remaining_.empty() || c != remaining_.front()) {
return false;
}
remaining_.remove_prefix(1);
return true;
}
[[nodiscard]] bool ConsumeExtension(WebSocketExtension* extension) {
std::string_view name;
if (!ConsumeToken(&name)) {
return false;
}
*extension = WebSocketExtension(std::string(name));
while (ConsumeIfMatch(';')) {
WebSocketExtension::Parameter parameter((std::string()));
if (!ConsumeExtensionParameter(¶meter)) {
return false;
}
extension->Add(parameter);
}
return true;
}
[[nodiscard]] bool ConsumeExtensionParameter(
WebSocketExtension::Parameter* parameter) {
std::string_view name;
if (!ConsumeToken(&name)) {
return false;
}
if (!ConsumeIfMatch('=')) {
*parameter = WebSocketExtension::Parameter(std::string(name));
return true;
}
std::string value_string;
if (Lookahead('\"')) {
if (!ConsumeQuotedToken(&value_string)) {
return false;
}
} else {
std::string_view value;
if (!ConsumeToken(&value)) {
return false;
}
value_string = std::string(value);
}
*parameter = WebSocketExtension::Parameter(std::string(name), value_string);
return true;
}
[[nodiscard]] bool ConsumeToken(std::string_view* token) {
ConsumeSpaces();
size_t count = 0;
while (count < remaining_.size() &&
HttpUtil::IsTokenChar(remaining_[count])) {
++count;
}
if (count == 0) {
return false;
}
*token = remaining_.substr(0, count);
remaining_.remove_prefix(count);
return true;
}
[[nodiscard]] bool ConsumeQuotedToken(std::string* token) {
if (!Consume('"')) {
return false;
}
*token = "";
while (!remaining_.empty() && remaining_.front() != '"') {
if (remaining_.front() == '\\') {
remaining_.remove_prefix(1);
if (remaining_.empty()) {
return false;
}
}
if (!HttpUtil::IsTokenChar(remaining_.front())) {
return false;
}
*token += remaining_.front();
remaining_.remove_prefix(1);
}
if (remaining_.empty()) {
return false;
}
DCHECK_EQ(remaining_.front(), '"');
remaining_.remove_prefix(1);
return !token->empty();
}
void ConsumeSpaces() {
while (!remaining_.empty() &&
(remaining_.front() == ' ' || remaining_.front() == '\t')) {
remaining_.remove_prefix(1);
}
}
[[nodiscard]] bool Lookahead(char c) {
std::string_view saved = remaining_;
bool result = Consume(c);
remaining_ = saved;
return result;
}
[[nodiscard]] bool ConsumeIfMatch(char c) {
std::string_view saved = remaining_;
if (!Consume(c)) {
remaining_ = saved;
return false;
}
return true;
}
// Unprocessed part of the input string.
std::string_view remaining_;
};
} // namespace
std::vector<WebSocketExtension> ParseWebSocketExtensions(
std::string_view data) {
WebSocketExtensionParser parser;
return parser.Parse(data);
}
} // namespace net
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