first commit

ext/crow/middleware.h

@@ -0,0 +1,174 @@
+#pragma once
+#include <boost/algorithm/string/trim.hpp>
+#include "http_request.h"
+#include "http_response.h"
+
+namespace crow
+{
+    // Any middleware requires following 3 members:
+
+    // struct context;
+    //      storing data for the middleware; can be read from another middleware or handlers
+
+    // before_handle
+    //      called before handling the request.
+    //      if res.end() is called, the operation is halted. 
+    //      (still call after_handle of this middleware)
+    //      2 signatures:
+    //      void before_handle(request& req, response& res, context& ctx)
+    //          if you only need to access this middlewares context.
+    //      template <typename AllContext>
+    //      void before_handle(request& req, response& res, context& ctx, AllContext& all_ctx)
+    //          you can access another middlewares' context by calling `all_ctx.template get<MW>()'
+    //          ctx == all_ctx.template get<CurrentMiddleware>()
+
+    // after_handle
+    //      called after handling the request.
+    //      void after_handle(request& req, response& res, context& ctx)
+    //      template <typename AllContext>
+    //      void after_handle(request& req, response& res, context& ctx, AllContext& all_ctx)
+
+    struct CookieParser
+    {
+        struct context
+        {
+            std::unordered_map<std::string, std::string> jar;
+            std::unordered_map<std::string, std::string> cookies_to_add;
+
+            std::string get_cookie(const std::string& key)
+            {
+                if (jar.count(key))
+                    return jar[key];
+                return {};
+            }
+
+            void set_cookie(const std::string& key, const std::string& value)
+            {
+                cookies_to_add.emplace(key, value);
+            }
+        };
+
+        void before_handle(request& req, response& res, context& ctx)
+        {
+            int count = req.headers.count("Cookie");
+            if (!count)
+                return;
+            if (count > 1)
+            {
+                res.code = 400;
+                res.end();
+                return;
+            }
+            std::string cookies = req.get_header_value("Cookie");
+            size_t pos = 0;
+            while(pos < cookies.size())
+            {
+                size_t pos_equal = cookies.find('=', pos);
+                if (pos_equal == cookies.npos)
+                    break;
+                std::string name = cookies.substr(pos, pos_equal-pos);
+                boost::trim(name);
+                pos = pos_equal+1;
+                while(pos < cookies.size() && cookies[pos] == ' ') pos++;
+                if (pos == cookies.size())
+                    break;
+
+                std::string value;
+
+                if (cookies[pos] == '"')
+                {
+                    int dquote_meet_count = 0;
+                    pos ++;
+                    size_t pos_dquote = pos-1;
+                    do
+                    {
+                        pos_dquote = cookies.find('"', pos_dquote+1);
+                        dquote_meet_count ++;
+                    } while(pos_dquote < cookies.size() && cookies[pos_dquote-1] == '\\');
+                    if (pos_dquote == cookies.npos)
+                        break;
+
+                    if (dquote_meet_count == 1)
+                        value = cookies.substr(pos, pos_dquote - pos);
+                    else
+                    {
+                        value.clear();
+                        value.reserve(pos_dquote-pos);
+                        for(size_t p = pos; p < pos_dquote; p++)
+                        {
+                            // FIXME minimal escaping
+                            if (cookies[p] == '\\' && p + 1 < pos_dquote)
+                            {
+                                p++;
+                                if (cookies[p] == '\\' || cookies[p] == '"')
+                                    value += cookies[p];
+                                else
+                                {
+                                    value += '\\';
+                                    value += cookies[p];
+                                }
+                            }
+                            else
+                                value += cookies[p];
+                        }
+                    }
+
+                    ctx.jar.emplace(std::move(name), std::move(value));
+                    pos = cookies.find(";", pos_dquote+1);
+                    if (pos == cookies.npos)
+                        break;
+                    pos++;
+                    while(pos < cookies.size() && cookies[pos] == ' ') pos++;
+                    if (pos == cookies.size())
+                        break;
+                }
+                else
+                {
+                    size_t pos_semicolon = cookies.find(';', pos);
+                    value = cookies.substr(pos, pos_semicolon - pos);
+                    boost::trim(value);
+                    ctx.jar.emplace(std::move(name), std::move(value));
+                    pos = pos_semicolon;
+                    if (pos == cookies.npos)
+                        break;
+                    pos ++;
+                    while(pos < cookies.size() && cookies[pos] == ' ') pos++;
+                    if (pos == cookies.size())
+                        break;
+                }
+            }
+        }
+
+        void after_handle(request& req, response& res, context& ctx)
+        {
+            for(auto& cookie:ctx.cookies_to_add)
+            {
+                res.add_header("Set-Cookie", cookie.first + "=" + cookie.second);
+            }
+        }
+    };
+
+    /*
+    App<CookieParser, AnotherJarMW> app;
+    A B C
+    A::context
+        int aa;
+
+    ctx1 : public A::context
+    ctx2 : public ctx1, public B::context
+    ctx3 : public ctx2, public C::context
+
+    C depends on A
+
+    C::handle
+        context.aaa
+
+    App::context : private CookieParser::contetx, ... 
+    {
+        jar
+
+    }
+
+    SimpleApp
+    */
+}