Optimize plugins with redirection functions (#1776)

Note: after this submission, users who use the SecureSSLRedirector plugin and the SlashRemover plugin should add the following line to the configuration file:
   {
      "name": "drogon::plugin::Redirector",
      "dependencies": [],
      "config": {
      }
   }
 and add the plugin name "drogon::plugin::Redirector" to the dependencies list of the SecureSSLRedirector plugin and the SlashRemover plugin.

CMakeLists.txt

@@ -268,6 +268,7 @@ set(DROGON_SOURCES
     lib/src/RateLimiter.cc
     lib/src/RealIpResolver.cc
     lib/src/SecureSSLRedirector.cc
+    lib/src/Redirector.cc
     lib/src/SessionManager.cc
     lib/src/SlashRemover.cc
     lib/src/SlidingWindowRateLimiter.cc
@@ -710,6 +711,7 @@ install(FILES ${DROGON_MONITORING_HEADERS}
 
 set(DROGON_PLUGIN_HEADERS
     lib/inc/drogon/plugins/Plugin.h
+    lib/inc/drogon/plugins/Redirector.h
     lib/inc/drogon/plugins/SecureSSLRedirector.h
     lib/inc/drogon/plugins/AccessLogger.h
     lib/inc/drogon/plugins/RealIpResolver.h

lib/inc/drogon/HttpRequest.h

@@ -416,6 +416,7 @@ class DROGON_EXPORT HttpRequest
 
     /// Set the path of the request
     virtual void setPath(const std::string &path) = 0;
+    virtual void setPath(std::string &&path) = 0;
 
     /**
      * @brief The default behavior is to encode the value of setPath

lib/inc/drogon/plugins/Redirector.h

@@ -0,0 +1,119 @@
+/**
+ *  @file Redirector.h
+ *  @author An Tao
+ *
+ *  Copyright 2018, An Tao.  All rights reserved.
+ *  https://github.com/an-tao/drogon
+ *  Use of this source code is governed by a MIT license
+ *  that can be found in the License file.
+ *
+ *  Drogon
+ *
+ */
+
+#pragma once
+
+#include <drogon/plugins/Plugin.h>
+#include <drogon/HttpRequest.h>
+#include <vector>
+
+namespace drogon
+{
+namespace plugin
+{
+/**
+ * @brief The RedirectorHandler is a function object that can be registered to
+ * the Redirector plugin. It is used to redirect requests to proper URLs. Users
+ * can modify the protocol, host and path of the request. If a false value is
+ * returned, the request will be considered as invalid and a 404 response will
+ * be sent to the client.
+ */
+using RedirectorHandler =
+    std::function<bool(const drogon::HttpRequestPtr &,
+                       std::string &,  //"http://" or "https://"
+                       std::string &,  // host
+                       bool &)>;       // path changed or not
+/**
+ * @brief The PathRewriteHandler is a function object that can be registered to
+ * the Redirector plugin. It is used to rewrite the path of the request. The
+ * Redirector plugin will call all registered PathRewriteHandlers in the order
+ * of registration. If one or more handlers return true, the request will be
+ * redirected to the new path.
+ */
+using PathRewriteHandler = std::function<bool(const drogon::HttpRequestPtr &)>;
+
+/**
+ * @brief The ForwardHandler is a function object that can be registered to the
+ * Redirector plugin. It is used to forward the request to next processing steps
+ * in the framework. The Redirector plugin will call all registered
+ * ForwardHandlers in the order of registration. Users can use this handler to
+ * change the request path or any other part of the request.
+ */
+using ForwardHandler = std::function<void(const drogon::HttpRequestPtr &)>;
+
+/**
+ * @brief This plugin is used to redirect requests to proper URLs. It is a
+ * helper plugin for other plugins, e.g. SlashRemover.
+ * Users can register a handler to this plugin to redirect requests. All
+ * handlers will be called in the order of registration.
+ * The json configuration is as follows:
+ *
+ * @code
+   {
+      "name": "drogon::plugin::Redirector",
+      "dependencies": [],
+      "config": {
+      }
+   }
+   @endcode
+ *
+ */
+class DROGON_EXPORT Redirector : public drogon::Plugin<Redirector>,
+                                 public std::enable_shared_from_this<Redirector>
+{
+  public:
+    Redirector()
+    {
+    }
+
+    void initAndStart(const Json::Value &config) override;
+    void shutdown() override;
+
+    void registerRedirectHandler(RedirectorHandler &&handler)
+    {
+        handlers_.emplace_back(std::move(handler));
+    }
+
+    void registerRedirectHandler(const RedirectorHandler &handler)
+    {
+        handlers_.emplace_back(handler);
+    }
+
+    void registerPathRewriteHandler(PathRewriteHandler &&handler)
+    {
+        pathRewriteHandlers_.emplace_back(std::move(handler));
+    }
+
+    void registerPathRewriteHandler(const PathRewriteHandler &handler)
+    {
+        pathRewriteHandlers_.emplace_back(handler);
+    }
+
+    void registerForwardHandler(ForwardHandler &&handler)
+    {
+        forwardHandlers_.emplace_back(std::move(handler));
+    }
+
+    void registerForwardHandler(const ForwardHandler &handler)
+    {
+        forwardHandlers_.emplace_back(handler);
+    }
+
+  private:
+    std::vector<RedirectorHandler> handlers_;
+    std::vector<PathRewriteHandler> pathRewriteHandlers_;
+    std::vector<ForwardHandler> forwardHandlers_;
+};
+
+}  // namespace plugin
+}  // namespace drogon

lib/inc/drogon/plugins/SecureSSLRedirector.h

@@ -25,7 +25,7 @@ namespace plugin
  * @code
    {
       "name": "drogon::plugin::SecureSSLRedirector",
-      "dependencies": [],
+      "dependencies": ["drogon::plugin::Redirector"],
       "config": {
             "ssl_redirect_exempt": ["^/.*\\.jpg", ...],
             "secure_ssl_host": "localhost:8849"
@@ -64,8 +64,12 @@ class DROGON_EXPORT SecureSSLRedirector
     void shutdown() override;
 
   private:
-    HttpResponsePtr redirectingAdvice(const HttpRequestPtr &) const;
-    HttpResponsePtr redirectToSSL(const HttpRequestPtr &) const;
+    bool redirectingAdvice(const HttpRequestPtr &,
+                           std::string &,
+                           std::string &) const;
+    bool redirectToSSL(const HttpRequestPtr &,
+                       std::string &,
+                       std::string &) const;
 
     std::regex exemptPegex_;
     bool regexFlag_{false};

lib/inc/drogon/plugins/SlashRemover.h

@@ -27,7 +27,7 @@ namespace drogon::plugin
  * @code
   {
      "name": "drogon::plugin::SlashRemover",
-     "dependencies": [],
+     "dependencies": ["drogon::plugin::Redirector"],
      "config": {
         // If true, it removes all trailing slashes, e.g.
 ///home// -> ///home

lib/src/HttpRequestImpl.h

@@ -159,6 +159,11 @@ class HttpRequestImpl : public HttpRequest
         path_ = path;
     }
 
+    void setPath(std::string &&path) override
+    {
+        path_ = std::move(path);
+    }
+
     void setPathEncode(bool pathEncode) override
     {
         pathEncode_ = pathEncode;

lib/src/Redirector.cc

@@ -0,0 +1,87 @@
+/**
+ *
+ *  @file Redirector.cc
+ *  An Tao
+ *
+ *  Copyright 2018, An Tao.  All rights reserved.
+ *  https://github.com/an-tao/drogon
+ *  Use of this source code is governed by a MIT license
+ *  that can be found in the License file.
+ *
+ *  Drogon
+ *
+ */
+
+#include <drogon/drogon.h>
+#include <drogon/plugins/Redirector.h>
+
+using namespace drogon;
+using namespace drogon::plugin;
+
+void Redirector::initAndStart(const Json::Value &config)
+{
+    auto weakPtr = std::weak_ptr<Redirector>(shared_from_this());
+    drogon::app().registerSyncAdvice(
+        [weakPtr](const HttpRequestPtr &req) -> HttpResponsePtr {
+            auto thisPtr = weakPtr.lock();
+            if (!thisPtr)
+            {
+                return HttpResponsePtr{};
+            }
+            std::string protocol, host;
+            bool pathChanged{false};
+            for (auto &handler : thisPtr->handlers_)
+            {
+                if (!handler(req, protocol, host, pathChanged))
+                {
+                    return HttpResponse::newNotFoundResponse();
+                }
+            }
+            for (auto &handler : thisPtr->pathRewriteHandlers_)
+            {
+                pathChanged |= handler(req);
+            }
+            if (!protocol.empty() || !host.empty() || pathChanged)
+            {
+                std::string url;
+                if (protocol.empty())
+                {
+                    if (!host.empty())
+                    {
+                        url = req->isOnSecureConnection() ? "https://"
+                                                          : "http://";
+                        url.append(host);
+                    }
+                }
+                else
+                {
+                    url = std::move(protocol);
+                    if (!host.empty())
+                    {
+                        url.append(host);
+                    }
+                    else
+                    {
+                        url.append(req->getHeader("host"));
+                    }
+                }
+                url.append(req->path());
+                auto &query = req->query();
+                if (!query.empty())
+                {
+                    url.append("?").append(query);
+                }
+                return HttpResponse::newRedirectionResponse(url);
+            }
+            for (auto &handler : thisPtr->forwardHandlers_)
+            {
+                handler(req);
+            }
+            return HttpResponsePtr{};
+        });
+}
+
+void Redirector::shutdown()
+{
+    LOG_TRACE << "Redirector plugin is shutdown!";
+}

lib/src/SecureSSLRedirector.cc

@@ -5,6 +5,7 @@
  */
 #include <drogon/drogon.h>
 #include <drogon/plugins/SecureSSLRedirector.h>
+#include <drogon/plugins/Redirector.h>
 #include <string>
 
 using namespace drogon;
@@ -42,14 +43,24 @@ void SecureSSLRedirector::initAndStart(const Json::Value &config)
     }
     secureHost_ = config.get("secure_ssl_host", "").asString();
     std::weak_ptr<SecureSSLRedirector> weakPtr = shared_from_this();
-    app().registerSyncAdvice([weakPtr](const HttpRequestPtr &req) {
-        auto thisPtr = weakPtr.lock();
-        if (!thisPtr)
-        {
-            return HttpResponsePtr{};
-        }
-        return thisPtr->redirectingAdvice(req);
-    });
+    auto redirector = drogon::app().getPlugin<Redirector>();
+    if (!redirector)
+    {
+        LOG_ERROR << "Redirector plugin is not found!";
+        return;
+    }
+    redirector->registerRedirectHandler(
+        [weakPtr](const drogon::HttpRequestPtr &req,
+                  std::string &protocol,
+                  std::string &host,
+                  bool &) -> bool {
+            auto thisPtr = weakPtr.lock();
+            if (!thisPtr)
+            {
+                return false;
+            }
+            return thisPtr->redirectingAdvice(req, protocol, host);
+        });
 }
 
 void SecureSSLRedirector::shutdown()
@@ -57,60 +68,58 @@ void SecureSSLRedirector::shutdown()
     /// Shutdown the plugin
 }
 
-HttpResponsePtr SecureSSLRedirector::redirectingAdvice(
-    const HttpRequestPtr &req) const
+bool SecureSSLRedirector::redirectingAdvice(const HttpRequestPtr &req,
+                                            std::string &protocol,
+                                            std::string &host) const
 {
-    if (req->isOnSecureConnection())
+    if (req->isOnSecureConnection() || protocol == "https://")
     {
-        return HttpResponsePtr{};
+        return true;
     }
     else if (regexFlag_)
     {
         std::smatch regexResult;
         if (std::regex_match(req->path(), regexResult, exemptPegex_))
         {
-            return HttpResponsePtr{};
+            return true;
         }
         else
         {
-            return redirectToSSL(req);
+            return redirectToSSL(req, protocol, host);
         }
     }
     else
     {
-        return redirectToSSL(req);
+        return redirectToSSL(req, protocol, host);
     }
 }
 
-HttpResponsePtr SecureSSLRedirector::redirectToSSL(
-    const HttpRequestPtr &req) const
+bool SecureSSLRedirector::redirectToSSL(const HttpRequestPtr &req,
+                                        std::string &protocol,
+                                        std::string &host) const
 {
     if (!secureHost_.empty())
     {
-        static std::string urlPrefix{"https://" + secureHost_};
-        std::string query{urlPrefix + req->path()};
-        if (!req->query().empty())
-        {
-            query += "?" + req->query();
-        }
-        return HttpResponse::newRedirectionResponse(query);
+        host = secureHost_;
+        protocol = "https://";
+        return true;
     }
-    else
+    else if (host.empty())
     {
-        const auto &host = req->getHeader("host");
-        if (!host.empty())
+        const auto &reqHost = req->getHeader("host");
+        if (!reqHost.empty())
         {
-            std::string query{"https://" + host};
-            query += req->path();
-            if (!req->query().empty())
-            {
-                query += "?" + req->query();
-            }
-            return HttpResponse::newRedirectionResponse(query);
+            protocol = "https://";
+            return true;
         }
         else
         {
-            return HttpResponse::newNotFoundResponse();
+            return false;
         }
     }
+    else
+    {
+        protocol = "https://";
+        return true;
+    }
 }

lib/src/SlashRemover.cc

@@ -1,11 +1,13 @@
-#include "drogon/plugins/SlashRemover.h"
-#include "drogon/HttpAppFramework.h"
+#include <drogon/plugins/SlashRemover.h>
+#include <drogon/plugins/Redirector.h>
+#include <drogon/HttpAppFramework.h>
 #include "drogon/utils/FunctionTraits.h"
 #include <functional>
 #include <string>
+#include <regex>
 
 using namespace drogon;
-using namespace plugin;
+using namespace drogon::plugin;
 using std::string;
 
 #define TRAILING_SLASH_REGEX ".+\\/$"
@@ -64,6 +66,31 @@ static inline void removeExcessiveSlashes(string& url)
     removeDuplicateSlashes(url);
 }
 
+static inline bool handleReq(const drogon::HttpRequestPtr& req, int removeMode)
+{
+    static const std::regex regex(regexes[removeMode - 1]);
+    if (std::regex_match(req->path(), regex))
+    {
+        string newPath = req->path();
+        switch (removeMode)
+        {
+            case trailing:
+                removeTrailingSlashes(newPath);
+                break;
+            case duplicate:
+                removeDuplicateSlashes(newPath);
+                break;
+            case both:
+            default:
+                removeExcessiveSlashes(newPath);
+                break;
+        }
+        req->setPath(std::move(newPath));
+        return true;
+    }
+    return false;
+}
+
 void SlashRemover::initAndStart(const Json::Value& config)
 {
     trailingSlashes_ = config.get("remove_trailing_slashes", true).asBool();
@@ -73,33 +100,23 @@ void SlashRemover::initAndStart(const Json::Value& config)
         (trailingSlashes_ * trailing) | (duplicateSlashes_ * duplicate);
     if (!removeMode)
         return;
-    app().registerHandlerViaRegex(
-        regexes[removeMode - 1],
-        [removeMode,
-         this](const HttpRequestPtr& req,
-               std::function<void(const HttpResponsePtr&)>&& callback) {
-            string newPath = req->path();
-            switch (removeMode)
-            {
-                case trailing:
-                    removeTrailingSlashes(newPath);
-                    break;
-                case duplicate:
-                    removeDuplicateSlashes(newPath);
-                    break;
-                case both:
-                default:
-                    removeExcessiveSlashes(newPath);
-                    break;
-            }
-            if (redirect_)
-                callback(HttpResponse::newRedirectionResponse(newPath));
-            else
-            {
-                req->setPath(newPath);
-                app().forward(req, std::move(callback));
-            }
-        });
+    auto redirector = app().getPlugin<Redirector>();
+    if (!redirector)
+    {
+        LOG_ERROR << "Redirector plugin is not found!";
+        return;
+    }
+    auto func = [removeMode](const HttpRequestPtr& req) -> bool {
+        return handleReq(req, removeMode);
+    };
+    if (redirect_)
+    {
+        redirector->registerPathRewriteHandler(std::move(func));
+    }
+    else
+    {
+        redirector->registerForwardHandler(std::move(func));
+    }
 }
 
 void SlashRemover::shutdown()