http_response.h

#pragma once
#include <string>
#include <unordered_map>
#include <ios>
#include <fstream>
#include <sstream>
// S_ISREG is not defined for windows
// This defines it like suggested in https://stackoverflow.com/a/62371749
#if defined(_MSC_VER)
#define _CRT_INTERNAL_NONSTDC_NAMES 1
#endif
#include <sys/stat.h>
#if !defined(S_ISREG) && defined(S_IFMT) && defined(S_IFREG)
#define S_ISREG(m) (((m) & S_IFMT) == S_IFREG)
#endif
 
#include "crow/http_request.h"
#include "crow/ci_map.h"
#include "crow/socket_adaptors.h"
#include "crow/logging.h"
#include "crow/mime_types.h"
#include "crow/returnable.h"
 
 
namespace crow
{
    template<typename Adaptor, typename Handler, typename... Middlewares>
    class Connection;
 
    namespace websocket
    {
        template<typename Adaptor, typename Handler>
        class Connection;
    }
 
    class Router;
 
    /// HTTP response
    struct response
    {
        template<typename Adaptor, typename Handler, typename... Middlewares>
        friend class crow::Connection;
 
        template<typename Adaptor, typename Handler>
        friend class websocket::Connection;
 
        friend class Router;
 
        int code{200};    ///< The Status code for the response.
        std::string body; ///< The actual payload containing the response data.
        ci_map headers;   ///< HTTP headers.
 
#ifdef CROW_ENABLE_COMPRESSION
        bool compressed = true; ///< If compression is enabled and this is false, the individual response will not be compressed.
#endif
        bool skip_body = false;            ///< Whether this is a response to a HEAD request.
        bool manual_length_header = false; ///< Whether Crow should automatically add a "Content-Length" header.
 
        /// Set the value of an existing header in the response.
        void set_header(std::string key, std::string value)
        {
            headers.erase(key);
            headers.emplace(std::move(key), std::move(value));
        }
 
        /// Add a new header to the response.
        void add_header(std::string key, std::string value)
        {
            headers.emplace(std::move(key), std::move(value));
        }
 
        const std::string& get_header_value(const std::string& key)
        {
            return crow::get_header_value(headers, key);
        }
 
        // naive validation of a mime-type string
        static bool validate_mime_type(const std::string& candidate) noexcept
        {
            // Here we simply check that the candidate type starts with
            // a valid parent type, and has at least one character afterwards.
            std::array<std::string, 10> valid_parent_types = {
              "application/", "audio/", "font/", "example/",
              "image/", "message/", "model/", "multipart/",
              "text/", "video/"};
            for (const std::string& parent : valid_parent_types)
            {
                // ensure the candidate is *longer* than the parent,
                // to avoid unnecessary string comparison and to
                // reject zero-length subtypes.
                if (candidate.size() <= parent.size())
                {
                    continue;
                }
                // strncmp is used rather than substr to avoid allocation,
                // but a string_view approach would be better if Crow
                // migrates to C++17.
                if (strncmp(parent.c_str(), candidate.c_str(), parent.size()) == 0)
                {
                    return true;
                }
            }
            return false;
        }
 
        // Find the mime type from the content type either by lookup,
        // or by the content type itself, if it is a valid a mime type.
        // Defaults to text/plain.
        static std::string get_mime_type(const std::string& contentType)
        {
            const auto mimeTypeIterator = mime_types.find(contentType);
            if (mimeTypeIterator != mime_types.end())
            {
                return mimeTypeIterator->second;
            }
            else if (validate_mime_type(contentType))
            {
                return contentType;
            }
            else
            {
                CROW_LOG_WARNING << "Unable to interpret mime type for content type '" << contentType << "'. Defaulting to text/plain.";
                return "text/plain";
            }
        }
 
 
        // clang-format off
        response() {}
        explicit response(int code_) : code(code_) {}
        response(std::string body_) : body(std::move(body_)) {}
        response(int code_, std::string body_) : code(code_), body(std::move(body_)) {}
        // clang-format on
        response(returnable&& value)
        {
            body = value.dump();
            set_header("Content-Type", value.content_type);
        }
        response(returnable& value)
        {
            body = value.dump();
            set_header("Content-Type", value.content_type);
        }
        response(int code_, returnable& value):
          code(code_)
        {
            body = value.dump();
            set_header("Content-Type", value.content_type);
        }
        response(int code_, returnable&& value):
          code(code_), body(value.dump())
        {
            set_header("Content-Type", std::move(value.content_type));
        }
 
        response(response&& r)
        {
            *this = std::move(r);
        }
 
        response(std::string contentType, std::string body_):
          body(std::move(body_))
        {
            set_header("Content-Type", get_mime_type(contentType));
        }
 
        response(int code_, std::string contentType, std::string body_):
          code(code_), body(std::move(body_))
        {
            set_header("Content-Type", get_mime_type(contentType));
        }
 
        response& operator=(const response& r) = delete;
 
        response& operator=(response&& r) noexcept
        {
            body = std::move(r.body);
            code = r.code;
            headers = std::move(r.headers);
            completed_ = r.completed_;
            file_info = std::move(r.file_info);
            return *this;
        }
 
        /// Check if the response has completed (whether response.end() has been called)
        bool is_completed() const noexcept
        {
            return completed_;
        }
 
        void clear()
        {
            body.clear();
            code = 200;
            headers.clear();
            completed_ = false;
            file_info = static_file_info{};
        }
 
        /// Return a "Temporary Redirect" response.
 
        ///
        /// Location can either be a route or a full URL.
        void redirect(const std::string& location)
        {
            code = 307;
            set_header("Location", location);
        }
 
        /// Return a "Permanent Redirect" response.
 
        ///
        /// Location can either be a route or a full URL.
        void redirect_perm(const std::string& location)
        {
            code = 308;
            set_header("Location", location);
        }
 
        /// Return a "Found (Moved Temporarily)" response.
 
        ///
        /// Location can either be a route or a full URL.
        void moved(const std::string& location)
        {
            code = 302;
            set_header("Location", location);
        }
 
        /// Return a "Moved Permanently" response.
 
        ///
        /// Location can either be a route or a full URL.
        void moved_perm(const std::string& location)
        {
            code = 301;
            set_header("Location", location);
        }
 
        void write(const std::string& body_part)
        {
            body += body_part;
        }
 
        /// Set the response completion flag and call the handler (to send the response).
        void end()
        {
            if (!completed_)
            {
                completed_ = true;
                if (skip_body)
                {
                    set_header("Content-Length", std::to_string(body.size()));
                    body = "";
                    manual_length_header = true;
                }
                if (complete_request_handler_)
                {
                    complete_request_handler_();
                    manual_length_header = false;
                    skip_body = false;
                }
            }
        }
 
        /// Same as end() except it adds a body part right before ending.
        void end(const std::string& body_part)
        {
            body += body_part;
            end();
        }
 
        /// Check if the connection is still alive (usually by checking the socket status).
        bool is_alive()
        {
            return is_alive_helper_ && is_alive_helper_();
        }
 
        /// Check whether the response has a static file defined.
        bool is_static_type()
        {
            return file_info.path.size();
        }
 
        /// This constains metadata (coming from the `stat` command) related to any static files associated with this response.
 
        ///
        /// Either a static file or a string body can be returned as 1 response.
        struct static_file_info
        {
            std::string path = "";
            struct stat statbuf;
            int statResult;
        };
 
        /// Return a static file as the response body, the content_type may be specified explicitly.
        void set_static_file_info(std::string path, std::string content_type = "")
        {
            utility::sanitize_filename(path);
            set_static_file_info_unsafe(path, content_type);
        }
 
        /// Return a static file as the response body without sanitizing the path (use set_static_file_info instead),
        /// the content_type may be specified explicitly.
        void set_static_file_info_unsafe(std::string path, std::string content_type = "")
        {
            file_info.path = path;
            file_info.statResult = stat(file_info.path.c_str(), &file_info.statbuf);
#ifdef CROW_ENABLE_COMPRESSION
            compressed = false;
#endif
            if (file_info.statResult == 0 && S_ISREG(file_info.statbuf.st_mode))
            {
                code = 200;
                this->add_header("Content-Length", std::to_string(file_info.statbuf.st_size));
 
                if (content_type.empty())
                {
                    std::size_t last_dot = path.find_last_of('.');
                    std::string extension = path.substr(last_dot + 1);
 
                    if (!extension.empty())
                    {
                        this->add_header("Content-Type", get_mime_type(extension));
                    }
                }
                else
                {
                    this->add_header("Content-Type", content_type);
                }
            }
            else
            {
                code = 404;
                file_info.path.clear();
            }
        }
 
    private:
        void write_header_into_buffer(std::vector<asio::const_buffer>& buffers, std::string& content_length_buffer, bool add_keep_alive, const std::string& server_name)
        {
            // TODO(EDev): HTTP version in status codes should be dynamic
            // Keep in sync with common.h/status
            static std::unordered_map<int, std::string> statusCodes = {
              {status::CONTINUE, "HTTP/1.1 100 Continue\r\n"},
              {status::SWITCHING_PROTOCOLS, "HTTP/1.1 101 Switching Protocols\r\n"},
 
              {status::OK, "HTTP/1.1 200 OK\r\n"},
              {status::CREATED, "HTTP/1.1 201 Created\r\n"},
              {status::ACCEPTED, "HTTP/1.1 202 Accepted\r\n"},
              {status::NON_AUTHORITATIVE_INFORMATION, "HTTP/1.1 203 Non-Authoritative Information\r\n"},
              {status::NO_CONTENT, "HTTP/1.1 204 No Content\r\n"},
              {status::RESET_CONTENT, "HTTP/1.1 205 Reset Content\r\n"},
              {status::PARTIAL_CONTENT, "HTTP/1.1 206 Partial Content\r\n"},
 
              {status::MULTIPLE_CHOICES, "HTTP/1.1 300 Multiple Choices\r\n"},
              {status::MOVED_PERMANENTLY, "HTTP/1.1 301 Moved Permanently\r\n"},
              {status::FOUND, "HTTP/1.1 302 Found\r\n"},
              {status::SEE_OTHER, "HTTP/1.1 303 See Other\r\n"},
              {status::NOT_MODIFIED, "HTTP/1.1 304 Not Modified\r\n"},
              {status::TEMPORARY_REDIRECT, "HTTP/1.1 307 Temporary Redirect\r\n"},
              {status::PERMANENT_REDIRECT, "HTTP/1.1 308 Permanent Redirect\r\n"},
 
              {status::BAD_REQUEST, "HTTP/1.1 400 Bad Request\r\n"},
              {status::UNAUTHORIZED, "HTTP/1.1 401 Unauthorized\r\n"},
              {status::FORBIDDEN, "HTTP/1.1 403 Forbidden\r\n"},
              {status::NOT_FOUND, "HTTP/1.1 404 Not Found\r\n"},
              {status::METHOD_NOT_ALLOWED, "HTTP/1.1 405 Method Not Allowed\r\n"},
              {status::NOT_ACCEPTABLE, "HTTP/1.1 406 Not Acceptable\r\n"},
              {status::PROXY_AUTHENTICATION_REQUIRED, "HTTP/1.1 407 Proxy Authentication Required\r\n"},
              {status::CONFLICT, "HTTP/1.1 409 Conflict\r\n"},
              {status::GONE, "HTTP/1.1 410 Gone\r\n"},
              {status::PAYLOAD_TOO_LARGE, "HTTP/1.1 413 Payload Too Large\r\n"},
              {status::UNSUPPORTED_MEDIA_TYPE, "HTTP/1.1 415 Unsupported Media Type\r\n"},
              {status::RANGE_NOT_SATISFIABLE, "HTTP/1.1 416 Range Not Satisfiable\r\n"},
              {status::EXPECTATION_FAILED, "HTTP/1.1 417 Expectation Failed\r\n"},
              {status::PRECONDITION_REQUIRED, "HTTP/1.1 428 Precondition Required\r\n"},
              {status::TOO_MANY_REQUESTS, "HTTP/1.1 429 Too Many Requests\r\n"},
              {status::UNAVAILABLE_FOR_LEGAL_REASONS, "HTTP/1.1 451 Unavailable For Legal Reasons\r\n"},
 
              {status::INTERNAL_SERVER_ERROR, "HTTP/1.1 500 Internal Server Error\r\n"},
              {status::NOT_IMPLEMENTED, "HTTP/1.1 501 Not Implemented\r\n"},
              {status::BAD_GATEWAY, "HTTP/1.1 502 Bad Gateway\r\n"},
              {status::SERVICE_UNAVAILABLE, "HTTP/1.1 503 Service Unavailable\r\n"},
              {status::GATEWAY_TIMEOUT, "HTTP/1.1 504 Gateway Timeout\r\n"},
              {status::VARIANT_ALSO_NEGOTIATES, "HTTP/1.1 506 Variant Also Negotiates\r\n"},
            };
 
            static const std::string seperator = ": ";
 
            buffers.clear();
            buffers.reserve(4 * (headers.size() + 5) + 3);
 
            if (!statusCodes.count(code))
            {
                CROW_LOG_WARNING << this << " status code "
                                 << "(" << code << ")"
                                 << " not defined, returning 500 instead";
                code = 500;
            }
 
            auto& status = statusCodes.find(code)->second;
            buffers.emplace_back(status.data(), status.size());
 
            if (code >= 400 && body.empty())
                body = statusCodes[code].substr(9);
 
            for (auto& kv : headers)
            {
                buffers.emplace_back(kv.first.data(), kv.first.size());
                buffers.emplace_back(seperator.data(), seperator.size());
                buffers.emplace_back(kv.second.data(), kv.second.size());
                buffers.emplace_back(crlf.data(), crlf.size());
            }
 
            if (!manual_length_header && !headers.count("content-length"))
            {
                content_length_buffer = std::to_string(body.size());
                static std::string content_length_tag = "Content-Length: ";
                buffers.emplace_back(content_length_tag.data(), content_length_tag.size());
                buffers.emplace_back(content_length_buffer.data(), content_length_buffer.size());
                buffers.emplace_back(crlf.data(), crlf.size());
            }
            if (!headers.count("server") && !server_name.empty())
            {
                static std::string server_tag = "Server: ";
                buffers.emplace_back(server_tag.data(), server_tag.size());
                buffers.emplace_back(server_name.data(), server_name.size());
                buffers.emplace_back(crlf.data(), crlf.size());
            }
            /*if (!headers.count("date"))
            {
                static std::string date_tag = "Date: ";
                date_str_ = get_cached_date_str();
                buffers.emplace_back(date_tag.data(), date_tag.size());
                buffers.emplace_back(date_str_.data(), date_str_.size());
                buffers.emplace_back(crlf.data(), crlf.size());
            }*/
            if (add_keep_alive)
            {
                static std::string keep_alive_tag = "Connection: Keep-Alive";
                buffers.emplace_back(keep_alive_tag.data(), keep_alive_tag.size());
                buffers.emplace_back(crlf.data(), crlf.size());
            }
 
            buffers.emplace_back(crlf.data(), crlf.size());
        }
 
        bool completed_{};
        std::function<void()> complete_request_handler_;
        std::function<bool()> is_alive_helper_;
        static_file_info file_info;
    };
} // namespace crow