| /** @file |
| |
| A plugin to parse Link headers from an origin server's response and initiate H2 Server Push for preload links. |
| |
| @section license License |
| |
| Licensed to the Apache Software Foundation (ASF) under one |
| or more contributor license agreements. See the NOTICE file |
| distributed with this work for additional information |
| regarding copyright ownership. The ASF licenses this file |
| to you 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. |
| */ |
| |
| #include <iostream> |
| #include <regex> |
| #include <set> |
| #include <sstream> |
| #include <ts/ts.h> |
| #include "tscpp/api/GlobalPlugin.h" |
| #include "tscpp/api/RemapPlugin.h" |
| #include "tscpp/api/TransactionPlugin.h" |
| |
| #define PLUGIN_NAME "server_push_preload" |
| #define PRELOAD_PARAM "rel=preload" |
| #define NOPUSH_OPTION "nopush" |
| |
| using namespace std; |
| using namespace atscppapi; |
| |
| static regex linkRegexp("<([^>]+)>;(.+)"); |
| |
| namespace |
| { |
| GlobalPlugin *globalPlugin; |
| RemapPlugin *remapPlugin; |
| } // namespace |
| |
| class ServerPushTransaction : public TransactionPlugin |
| { |
| public: |
| explicit ServerPushTransaction(Transaction &transaction) : TransactionPlugin(transaction) |
| { |
| TransactionPlugin::registerHook(HOOK_SEND_RESPONSE_HEADERS); |
| } |
| |
| void |
| handleSendResponseHeaders(Transaction &transaction) override |
| { |
| serverPush(transaction); |
| transaction.resume(); |
| } |
| |
| void |
| serverPush(Transaction &transaction) |
| { |
| TSHttpTxn txnp = static_cast<TSHttpTxn>(transaction.getAtsHandle()); |
| if (TSHttpTxnClientProtocolStackContains(txnp, "h2") == nullptr) { |
| return; |
| } |
| |
| ClientRequest &request = transaction.getClientRequest(); |
| Response &response = transaction.getClientResponse(); |
| Headers &headers = response.getHeaders(); |
| |
| const Url &clientUrl = request.getPristineUrl(); |
| |
| for (header_field_iterator it = headers.find("Link"); it != headers.end(); it.nextDup()) { |
| HeaderField field = *it; |
| |
| for (header_field_value_iterator hit = field.begin(); hit != field.end(); ++hit) { |
| const string &link = *hit; |
| |
| TSDebug(PLUGIN_NAME, "Parsing link header: %s", link.c_str()); |
| smatch matches; |
| |
| if (regex_search(link, matches, linkRegexp)) { |
| string url = matches[1].str(); |
| TSDebug(PLUGIN_NAME, "Found link header match: %s", url.c_str()); |
| |
| set<string> params = split(matches[2].str(), ';'); |
| auto preload = params.find(PRELOAD_PARAM); |
| if (preload == params.end()) { |
| continue; |
| } |
| |
| auto noPush = params.find(NOPUSH_OPTION); |
| if (noPush != params.end()) { |
| TSDebug(PLUGIN_NAME, "Skipping nopush link: %s", link.c_str()); |
| continue; |
| } |
| |
| Request request(url); |
| Url &linkUrl = request.getUrl(); |
| |
| if (linkUrl.getHost().empty()) { |
| linkUrl.setHost(clientUrl.getHost()); |
| linkUrl.setScheme(clientUrl.getScheme()); |
| } |
| if (0 != clientUrl.getPort()) { |
| linkUrl.setPort(clientUrl.getPort()); |
| } |
| string lu = linkUrl.getUrlString(); |
| TSDebug(PLUGIN_NAME, "Push preloaded content: %s", lu.c_str()); |
| TSHttpTxnServerPush(txnp, lu.c_str(), lu.length()); |
| } else { |
| TSDebug(PLUGIN_NAME, "No match found for link header: %s", link.c_str()); |
| } |
| } |
| } |
| } |
| |
| set<string> |
| split(const string ¶ms, char delim) |
| { |
| stringstream ss(params); |
| string s; |
| set<string> tokens; |
| while (getline(ss, s, delim)) { |
| s.erase(find_if(s.rbegin(), s.rend(), [](unsigned char c) { return !std::isspace(c); }).base(), s.end()); // trim left |
| s.erase(s.begin(), find_if(s.begin(), s.end(), [](unsigned char c) { return !std::isspace(c); })); // trim right |
| tokens.insert(s); |
| } |
| return tokens; |
| } |
| }; |
| |
| class ServerPushRemap : public RemapPlugin |
| { |
| public: |
| explicit ServerPushRemap(void **instance_handle) : RemapPlugin(instance_handle) {} |
| |
| Result |
| doRemap(const Url &map_from_url, const Url &map_to_url, Transaction &transaction, bool &redirect) override |
| { |
| transaction.addPlugin(new ServerPushTransaction(transaction)); |
| return RESULT_DID_REMAP; |
| } |
| }; |
| |
| class ServerPushGlobal : public GlobalPlugin |
| { |
| public: |
| ServerPushGlobal() { GlobalPlugin::registerHook(HOOK_READ_REQUEST_HEADERS_PRE_REMAP); } |
| |
| void |
| handleReadRequestHeadersPreRemap(Transaction &transaction) override |
| { |
| transaction.addPlugin(new ServerPushTransaction(transaction)); |
| transaction.resume(); |
| } |
| }; |
| |
| void |
| TSPluginInit(int argc ATSCPPAPI_UNUSED, const char *argv[] ATSCPPAPI_UNUSED) |
| { |
| TSDebug(PLUGIN_NAME, "Init"); |
| if (!RegisterGlobalPlugin("ServerPushPreloadPlugin", PLUGIN_NAME, "dev@trafficserver.apache.org")) { |
| return; |
| } |
| globalPlugin = new ServerPushGlobal(); |
| } |
| |
| TSReturnCode |
| TSRemapNewInstance(int argc ATSCPPAPI_UNUSED, char *argv[] ATSCPPAPI_UNUSED, void **instance_handle, char *errbuf ATSCPPAPI_UNUSED, |
| int errbuf_size ATSCPPAPI_UNUSED) |
| { |
| TSDebug(PLUGIN_NAME, "New Instance"); |
| remapPlugin = new ServerPushRemap(instance_handle); |
| return TS_SUCCESS; |
| } |