apewer-dotnet/Apewer/Web/WebUtility.cs

using Apewer.Models;
using Apewer.Source;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.IO;
using System.Net;
using System.Text;

#if NETFX
using System.Web;
#endif

#if NETCORE
using Microsoft.AspNetCore.Http;
#endif

namespace Apewer.Web
{

    /// <summary></summary>
    public static class WebUtility
    {

        /// <summary>按 & 拆分多个参数。</summary>
        public static StringPairs ParseParameters(string query, bool decode = true)
        {
            var input = query;
            var list = new StringPairs();
            if (!string.IsNullOrEmpty(input))
            {
                if (input[0] == '?') input = input.Substring(1);
                var args = input.Split('&');
                foreach (var arg in args)
                {
                    var equals = arg.IndexOf("=");
                    var left = equals < 0 ? arg : arg.Substring(0, equals);
                    var right = equals < 0 ? "" : arg.Substring(equals + 1);
                    if (decode)
                    {
                        left = TextUtility.DecodeUrl(left);
                        right = TextUtility.DecodeUrl(right);
                    }
                    list.Add(left, right);
                }
            }
            return list;
        }

        /// <summary>获取 URL 查询段，不存在的段为 NULL 值。可要求解码。</summary>
        public static string GetSegmental(Uri url, int index = 3, bool decode = false)
        {
            try
            {
                if (url == null) return null;
                if (index < 0) return null;
                var sus = url.AbsolutePath.Split('/');
                if (sus.Length > index)
                {
                    var result = sus[index];
                    if (decode) result = TextUtility.DecodeUrl(result);
                    return result;
                }
            }
            catch { }
            return null;
        }

        /// <summary>获取参数并解码，可要求修剪参数值。</summary>
        public static string GetParameter(string encoded, bool trim, params string[] names)
        {
            if (string.IsNullOrEmpty(encoded)) return null;
            if (names == null || names.Length < 1) return null;

            // Names 转为小写，加强适配。
            var lowerNames = new List<string>(names.Length);
            foreach (var name in names)
            {
                var lower = TextUtility.ToLower(name);
                if (string.IsNullOrEmpty(lower)) continue;
                lowerNames.Add(lower);
            }
            if (lowerNames.Count < 1) return null;

            // 分参数对比。
            var parameters = ParseParameters(encoded);
            var matched = false;
            foreach (var parameter in parameters)
            {
                var left = parameter.Key;
                var right = parameter.Value;
                if (trim) right = TextUtility.ToLower(right);
                var lowerLeft = TextUtility.ToLower(left);
                if (lowerNames.Contains(right))
                {
                    matched = true;
                    if (!string.IsNullOrEmpty(right)) return right;
                }
            }

            return matched ? "" : null;
        }

        /// <summary>获取参数并解码，默认不修剪参数值。</summary>
        public static string GetParameter(string encoded, params string[] names) => GetParameter(encoded, false, names);

        /// <summary>指定可能的参数名，从 URL 中获取参数值并解码，默认不修剪参数值。</summary>
        public static string GetParameter(Uri url, params string[] names) => url == null ? null : GetParameter(url.Query, false, names);

        /// <summary>获取参数，默认不修剪参数值。</summary>
        public static string GetParameter(List<KeyValuePair<string, string>> parameters, params string[] names) => GetParameter(parameters, false, names);

        /// <summary>指定可能的参数名，从 URL 中获取参数值并解码，可要求修剪参数值。</summary>
        public static string GetParameter(Uri url, bool trim, params string[] names) => url == null ? null : GetParameter(url.Query, trim, names);

        /// <summary>获取参数，可要求修剪参数值。</summary>
        public static string GetParameter(List<KeyValuePair<string, string>> parameters, bool trim, params string[] names)
        {
            if (parameters == null || parameters.Count < 1) return null;
            if (names == null || names.Length < 1) return null;

            var lowerNames = new List<string>(names.Length);
            foreach (var name in names)
            {
                var lower = TextUtility.ToLower(name);
                if (string.IsNullOrEmpty(lower)) continue;
                lowerNames.Add(lower);
            }

            foreach (var parameter in parameters)
            {
                var lowerKey = TextUtility.ToLower(parameter.Key);
                if (lowerNames.Contains(lowerKey))
                {
                    var value = parameter.Value;
                    if (trim) value = TextUtility.ToLower(value);
                    if (!string.IsNullOrEmpty(value)) return value;
                }
            }
            return null;
        }

        /// <summary>修剪 IP 地址，去除无效的部分。</summary>
        public static string TrimIP(string text)
        {
            var trimmed = TextUtility.Trim(text);
            if (string.IsNullOrEmpty(trimmed)) return "";

            var ip = TextUtility.Trim(trimmed.Split(':')[0]);
            return NetworkUtility.IsIP(ip) ? ip : "";
        }

        private static string GetClientIP(string directIP, StringPairs headers)
        {
            // 获取直连 IP。
            var ip = directIP;

            if (NetworkUtility.FromLAN(ip)) // 直连 IP 来自内网。
            {
                // 请求可能由内网服务器反向代理，检测 Forwarded IP，取最后一个 IP。
                foreach (var header in headers)
                {
                    if (header.Key != "x-forwarded-for") continue;

                    var fips = new List<string>();
                    var split = header.Value.Split(',', ' ');
                    foreach (var para in split)
                    {
                        var fip = TrimIP(para);
                        if (!string.IsNullOrEmpty(fip)) fips.Add(fip);
                    }
                    if (fips.Count > 0) return fips[fips.Count - 1];
                    break;
                }
            }
            else // 直连 IP 来自公网。
            {
                // 请求可能由阿里云 CDN 反向代理，检测 Ali-CDN-Real-IP。
                foreach (var header in headers)
                {
                    if (header.Key != "ali-cdn-real-ip") continue;

                    var alicdn_ip = TrimIP(header.Value);
                    if (!string.IsNullOrEmpty(alicdn_ip)) return alicdn_ip;
                    break;
                }
            }

            return ip;
        }

        /// <summary>请求来自于可信客户端。</summary>
        public static bool FromTrusted(string clientIP, params string[] addresses)
        {
            var cip = TrimIP(clientIP);
            if (!NetworkUtility.IsIP(cip)) return false;

            // 解析可信地址。
            if (addresses == null) return false;
            foreach (var address in addresses)
            {
                if (NetworkUtility.IsIP(address))
                {
                    if (address == cip) return true;
                    continue;
                }

                var tip = NetworkUtility.Resolve(address);
                if (NetworkUtility.IsIP(tip))
                {
                    if (tip == cip) return true;
                }
            }

            return false;
        }

        /// <summary>获取 HTTP 方法。</summary>
        public static Network.HttpMethod GetMethod(string method)
        {
            if (!string.IsNullOrEmpty(method))
            {
                var upper = TextUtility.ToUpper(method);
                if (upper.Contains("OPTIONS")) return Network.HttpMethod.OPTIONS;
                else if (upper.Contains("POST")) return Network.HttpMethod.POST;
                else if (upper.Contains("GET")) return Network.HttpMethod.GET;
                else if (upper.Contains("CONNECT")) return Network.HttpMethod.CONNECT;
                else if (upper.Contains("DELETE")) return Network.HttpMethod.DELETE;
                else if (upper.Contains("HEAD")) return Network.HttpMethod.HEAD;
                else if (upper.Contains("PATCH")) return Network.HttpMethod.PATCH;
                else if (upper.Contains("PUT")) return Network.HttpMethod.PUT;
                else if (upper.Contains("TRACE")) return Network.HttpMethod.TRACE;
            }
            return Network.HttpMethod.NULL;
        }

        /// <summary>获取 X-Forwarded-For，不存在时返回 NULL 值。</summary>
        public static string GetForwardedIP(StringPairs headers)
        {
            if (headers == null) return "";
            var value = headers.GetValue("x-forwarded-for", true);
            if (string.IsNullOrEmpty(value)) return "";

            var split = value.Split(',');
            var ips = new List<string>();
            foreach (var para in split)
            {
                var ip = TrimIP(para);
                if (string.IsNullOrEmpty(ip)) continue;
                ips.Add(ip);
            }
            if (ips.Count > 0) return string.Join(", ", ips.ToArray());

            return "";
        }

        /// <summary>获取 User Agent。</summary>
        public static string GetUserAgent(StringPairs headers) => headers == null ? null : headers.GetValue("user-agent");

        /// <summary>获取查询字符串。</summary>
        public static string QueryString(ApiRequest request, string name)
        {
            if (request == null) return null;
            if (request.Parameters == null) return null;
            if (string.IsNullOrEmpty(name)) return null;

            return request.Parameters.GetValue(name, true);
        }

        /// <summary>获取表单。</summary>
        public static string Form(ApiRequest request, string name)
        {
            if (request == null) return null;
            if (string.IsNullOrEmpty(request.PostText)) return null;
            if (string.IsNullOrEmpty(name)) return null;

            var ps = ParseParameters(request.PostText, true);
            return ps.GetValue(name, true);
        }

        #region ApiController

        /// <summary>以 POST 转移请求到其它 URL。</summary>
        public static string Transfer(ApiController controller, string url, string application = null, string function = null)
        {
            if (controller == null || controller.Request == null || controller.Response == null) return "ApiControllser 无效。";
            if (url.IsEmpty()) return "ApiController 无效。";

            var s = Json.NewObject();
            s.SetProperty("random", TextUtility.NewGuid());
            s.SetProperty("application", application.IsEmpty() ? controller.Request.Application : application);
            s.SetProperty("function", function.IsEmpty() ? controller.Request.Function : function);
            s.SetProperty("data", controller.Request.Data);
            s.SetProperty("session", controller.Request.Session);
            s.SetProperty("ticket", controller.Request.Ticket);
            s.SetProperty("page", controller.Request.Page);

            var c = new Network.HttpClient();
            c.Request.Url = url;
            c.Request.Method = Network.HttpMethod.POST;
            // TODO 设置 Request 的 Cookies。
            c.Request.Data = s.ToString().GetBytes();

            var e = c.Send();
            if (e != null) return e.Message;

            // TODO 解析 Response 的 Cookies。
            var r = Json.Parse(c.Response.Data.GetString());

            if (r == null || !r.Available)
            {
                controller.Response.Error("请求失败。");
                return "请求失败。";
            }

            if (r["status"] != "ok")
            {
                controller.Response.Error(r["message"]);
                return r["message"];
            }

            controller.Response.Data.Reset(r.GetProperty("data"));
            return null;
        }

        /// <summary>创建新控制器实例并运行。</summary>
        /// <typeparam name="T">新控制器的类型。</typeparam>
        /// <param name="current">当前控制器。</param>
        public static T Run<T>(ApiController current) where T : ApiController, new()
        {
            if (current == null) return null;
            var target = new T();
            target.Request = current.Request;
            target.Response = current.Response;
            target.AfterInitialized?.Invoke();
            return target;
        }

        /// <summary>创建新控制器实例并运行。</summary>
        /// <param name="current">当前控制器。</param>
        /// <param name="controller">新控制器的类型。</param>
        public static ApiController Run(ApiController current, Type controller)
        {
            if (current == null || controller == null) return null;
            if (!RuntimeUtility.IsInherits(controller, typeof(ApiController))) return null;
            var target = ApiProcessor.CreateController(controller);
            if (target == null) return null;
            target.Request = current.Request;
            target.Response = current.Response;
            target.AfterInitialized?.Invoke();
            return target;
        }

        #endregion

        #region ApiRequest

        /// <summary>获取 URL 查询段，不存在的段为 NULL 值。可要求解码。</summary>
        public static string GetSegmentalUrl(ApiRequest request, int index = 3, bool decode = false)
        {
            return request == null ? null : GetSegmental(request.Url, index, decode);
        }

        /// <summary>获取参数，指定可能的参数名，从 URL 中获取参数时将解码，默认不修剪参数值。</summary>
        public static string GetParameter(ApiRequest request, params string[] names) => GetParameter(request, false, names);

        /// <summary>获取参数，指定可能的参数名，从 URL 中获取参数时将解码，可要求修剪参数值。</summary>
        public static string GetParameter(ApiRequest request, bool trim, params string[] names)
        {
            if (request == null) return null;
            if (names == null || names.Length < 1) return null;

            var dedupNames = new List<string>(names.Length);
            var lowerNames = new List<string>(names.Length);
            foreach (var name in names)
            {
                if (string.IsNullOrEmpty(name)) continue;
                if (dedupNames.Contains(name)) continue;
                else dedupNames.Add(name);

                var lower = TextUtility.ToLower(name);
                if (lowerNames.Contains(lower)) continue;
                else lowerNames.Add(lower);
            }

            var matched = false;

            // POST 优先。
            var data = request.Data;
            if (data != null && data.IsObject)
            {
                var properties = data.GetProperties();
                if (properties != null)
                {
                    // Json 区分大小写，先全字匹配。
                    foreach (var property in properties)
                    {
                        if (!property.IsProperty) continue;
                        var name = property.Name;
                        if (!dedupNames.Contains(name)) continue;
                        var value = property.Value;
                        if (value == null) continue;
                        matched = true;
                        var text = value.ToString();
                        if (trim) text = TextUtility.Trim(text);
                        if (!string.IsNullOrEmpty(text)) return text;
                    }

                    // 以小写模糊匹配。
                    foreach (var property in properties)
                    {
                        if (!property.IsProperty) continue;
                        var name = TextUtility.ToLower(property.Name);
                        if (!lowerNames.Contains(name)) continue;
                        var value = property.Value;
                        if (value == null) continue;
                        matched = true;
                        var text = value.ToString();
                        if (trim) text = TextUtility.Trim(text);
                        if (!string.IsNullOrEmpty(text)) return text;
                    }
                }
            }

            // 从已解析的 Get 参数中搜索。
            if (request.Parameters != null)
            {
                var value = GetParameter(request.Parameters, trim, names);
                if (!string.IsNullOrEmpty(value)) return value;
                if (value != null) matched = true;
            }

            return matched ? "" : null;
        }

        #endregion

        #region ApiResponse

        /// <summary>设置响应。</summary>
        public static string Respond(ApiResponse response, Json data, bool lower = true)
        {
            if (response == null) return "Response 对象无效。";

            if (data != null)
            {
                if (lower) data = Json.ToLower(data);
                response.Data.Reset(data);
            }

            return null;
        }

        /// <summary>设置响应，当发生错误时设置响应。返回错误信息。</summary>
        public static string Respond(ApiResponse response, IList list, bool lower = true, int depth = -1, bool force = false)
        {
            if (response == null) return "Response 对象无效。";

            if (list == null)
            {
                var error = "列表对象无效。";
                response.Error(error);
                return error;
            }

            var json = Json.Parse(list, lower, depth, force);
            if (json == null || !json.Available)
            {
                var error = "列表无法序列化。";
                response.Error(error);
                return error;
            }

            if (response.Data == null) response.Data = Json.NewObject();
            response.Data.SetProperty("count", list.Count);
            response.Data.SetProperty("list", Json.Parse(list, lower, depth, force));
            return null;
        }

        /// <summary>设置响应，当发生错误时设置响应。返回错误信息。</summary>
        public static string Respond(ApiResponse response, Record record, bool lower = true)
        {
            if (response == null) return "Response 对象无效。";

            if (record == null)
            {
                var error = "记录无效。";
                response.Error(error);
                return error;
            }

            var json = Json.Parse(record, lower);
            if (json == null || !json.Available)
            {
                var error = "记录无法序列化。";
                response.Error(error);
                return error;
            }

            if (response.Data == null) response.Data = Json.NewObject();
            response.Data.Reset(json);
            return null;
        }

        /// <summary>设置 status 为 error，并设置 message 的内容。</summary>
        public static void SetError(ApiResponse response, string message = "未知错误。")
        {
            if (response == null) return;
            response.Type = ApiFormat.Json;
            response.Status = "error";
            response.Message = message ?? TextUtility.EmptyString;
        }

        /// <summary>设置 status 为 error，并设置 message 的内容。</summary>
        public static void SetError(ApiResponse response, Exception exception)
        {
            if (response == null) return;
            response.Exception = exception;
            response.Type = ApiFormat.Json;
            response.Status = "error";
            try
            {
                response.Message = exception == null ? "无效异常。" : exception.Message;
                response.Data.Reset(Json.NewObject());
                response.Data["message"] = exception.Message;
                response.Data["helplink"] = exception.HelpLink;
                response.Data["source"] = exception.Source;
                response.Data["stacktrace"] = Json.Parse(exception.StackTrace.Split('\n'), true);
            }
            catch { }
        }

        /// <summary>输出 UTF-8 文本。</summary>
        public static void SetText(ApiResponse response, string content, string type = "text/plain; charset=utf-8")
        {
            if (response == null) return;
            response.Type = ApiFormat.Text;
            response.TextString = content;
            response.TextType = type ?? "text/plain; charset=utf-8";
        }

        /// <summary>输出字节数组。</summary>
        public static void SetBinary(ApiResponse response, byte[] content, string type = "application/octet-stream")
        {
            if (response == null) return;
            response.Type = ApiFormat.Binary;
            response.BinaryStream = null;
            response.BinaryBytes = content;
            response.BinaryPath = null;
            response.BinaryType = type ?? "application/octet-stream";
        }

        /// <summary>输出二进制。</summary>
        public static void SetBinary(ApiResponse response, Stream content, string type = "application/octet-stream")
        {
            if (response == null) return;
            response.Type = ApiFormat.Binary;
            response.BinaryStream = content;
            response.BinaryBytes = null;
            response.BinaryPath = null;
            response.BinaryType = type ?? "application/octet-stream";
        }

        /// <summary>输出二进制。</summary>
        public static void SetBinary(ApiResponse response, string path, string type = "application/octet-stream")
        {
            if (response == null) return;
            response.Type = ApiFormat.Binary;
            response.BinaryStream = null;
            response.BinaryBytes = null;
            response.BinaryPath = path;
            response.BinaryType = type ?? "application/octet-stream";
        }

        /// <summary>输出文件。</summary>
        public static void SetFile(ApiResponse response, Stream stream, string name, string type = "application/octet-stream")
        {
            if (response == null) return;
            response.Type = ApiFormat.File;
            response.FileStream = stream;
            response.FileName = name;
            response.FileType = type ?? "application/octet-stream";
        }

        /// <summary>重定向。</summary>
        public static void SetRedirect(ApiResponse response, string url)
        {
            if (response == null) return;
            response.Type = ApiFormat.Redirect;
            response.RedirectUrl = url;
        }

        #endregion

        #region Application & Path

        /// <summary>获取程序目录的路径。</summary>
        public static string AppDirectory
        {
            get
            {
                // AppDomain.CurrentDomain.BaseDirectory
                // AppDomain.CurrentDomain.SetupInformation.ApplicationBase
                return AppDomain.CurrentDomain.BaseDirectory;
            }
        }

        /// <summary>MapPath。</summary>
        public static string MapPath(params string[] names)
        {
            var list = new List<string>();
            if (names != null)
            {
                var invalid = StorageUtility.InvalidPathChars;
                foreach (var name in names)
                {
                    if (string.IsNullOrEmpty(name)) continue;
                    var split = name.Split('/', '\\');
                    foreach (var s in split)
                    {
                        var sb = new StringBuilder();
                        foreach (var c in s)
                        {
                            if (Array.IndexOf(invalid, "c") < 0) sb.Append(c);
                        }
                        var t = sb.ToString();
                        if (!string.IsNullOrEmpty(t)) list.Add(t);
                    }
                }
            }
            return list.Count > 1 ? StorageUtility.CombinePath(list.ToArray()) : list[0];
        }

        #endregion

        #region Request - GetMethod

        /// <summary>获取 HTTP 方法。</summary>
        public static Network.HttpMethod GetMethod(HttpListenerRequest request)
        {
            if (request == null) return Network.HttpMethod.NULL;
            return GetMethod(request.HttpMethod);
        }

#if NETFX || NETCORE

        /// <summary>获取 HTTP 方法。</summary>
        public static Network.HttpMethod GetMethod(HttpRequest request)
        {
            if (request == null) return Network.HttpMethod.NULL;
#if NETFX
            return GetMethod(request.HttpMethod);
#else
            return GetMethod(request.Method);
#endif
        }

#endif

        #endregion

        #region Request - Client IP

        /// <summary>获取直连端的 IP。</summary>
        public static string GetDirectIP(HttpListenerRequest request)
        {
            if (request == null) return null;
            var ip = request.UserHostAddress;
            return TrimIP(ip);
        }

        /// <summary>获取客户端 IP。</summary>
        public static string GetClientIP(HttpListenerRequest request)
        {
            if (request == null) return null;
            var headers = GetHeaders(request, true);
            var directIP = GetDirectIP(request);
            return GetClientIP(directIP, headers);
        }

#if NETFX || NETCORE

        /// <summary>获取直连端的 IP。</summary>
        public static string GetDirectIP(HttpRequest request)
        {
            if (request == null) return null;
#if NETFX
            var ip = request.UserHostAddress;
#else
            if (request.HttpContext == null || request.HttpContext.Connection == null) return null;
            var ip = request.HttpContext.Connection.RemoteIpAddress.ToString();
#endif
            return TrimIP(ip);
        }

        /// <summary>获取客户端 IP。</summary>
        public static string GetClientIP(HttpRequest request)
        {
            if (request == null) return null;
            var headers = GetHeaders(request, true);
            var directIP = GetDirectIP(request);
            return GetClientIP(directIP, headers);
        }

#endif

        #endregion

        #region Request - URL

        /// <summary>获取请求的 URL，失败时返回 NULL 值。</summary>
        public static Uri GetUrl(HttpListenerRequest request)
        {
            if (request == null) return null;
            return request.Url;
        }

#if NETFX || NETCORE

        /// <summary>获取请求的 URL，失败时返回 NULL 值。</summary>
        public static Uri GetUrl(HttpRequest request)
        {
            if (request == null) return null;
#if NETFX
            return request.Url;
#else
            var context = request.HttpContext;
            if (context == null) return null;

            var https = request.IsHttps;
            var port = context.Connection.LocalPort;
            var query = request.QueryString == null ? null : request.QueryString.Value;

            var sb = new StringBuilder();
            sb.Append(https ? "https://" : "http://");
            sb.Append(request.Host.Host ?? "");
            if ((https && port != 443) || (!https && port != 80))
            {
                sb.Append(":");
                sb.Append(port);
            }
            sb.Append(request.Path);
            if (!string.IsNullOrEmpty(query))
            {
                sb.Append("?");
                sb.Append(query);
            }

            var url = sb.ToString();
            var uri = new Uri(url);
            return uri;
#endif
        }

#endif

        #endregion

        #region Request - Parameters

        /// <summary>解析 URL 的查询字符串，获取所有已解码的参数。</summary>
        public static StringPairs ParseUrlParameters(HttpListenerRequest request)
        {
            if (request == null) return new StringPairs();
            if (request.Url == null) return new StringPairs();
            return ParseParameters(request.Url.Query);
        }

#if NETFX || NETCORE

        /// <summary>解析 URL 的查询字符串，获取所有已解码的参数。</summary>
        public static StringPairs ParseUrlParameters(HttpRequest request)
        {
            if (request == null) return new StringPairs();
#if NETFX
            if (request.Url == null) return new StringPairs();
            return ParseParameters(request.Url.Query);
#else
            var list = new StringPairs();
            if (request.Query == null) return list;

            var keys = request.Query.Keys;
            list.Capacity = keys.Count;
            foreach (var key in keys)
            {
                list.Add(new KeyValuePair<string, string>(key, request.Query[key]));
            }
            list.Capacity = list.Count;
            return list;
#endif
        }

#endif

        #endregion

        #region Request - Headers

        /// <summary>获取 HTTP 头。</summary>
        public static StringPairs GetHeaders(HttpListenerRequest request, bool lowerKey = false)
        {
            var sp = new StringPairs();
            if (request != null && request.Headers != null)
            {
                foreach (var key in request.Headers.AllKeys)
                {
                    try
                    {
                        var v = request.Headers[key];
                        if (string.IsNullOrEmpty(v)) continue;
                        var k = lowerKey ? key.ToLower() : key;
                        sp.Add(k, v);
                    }
                    catch { }
                }
            }
            return sp;
        }

        /// <summary>获取 User Agent。</summary>
        public static string GetUserAgent(HttpListenerRequest request) => GetUserAgent(GetHeaders(request));

#if NETFX || NETCORE

        /// <summary>获取 HTTP 头。</summary>
        public static StringPairs GetHeaders(HttpRequest request, bool lowerKey = false)
        {
            var sp = new StringPairs();
            if (request != null && request.Headers != null)
            {
#if NETFX
                foreach (var key in request.Headers.AllKeys)
#else
                foreach (var key in request.Headers.Keys)
#endif
                {
                    try
                    {
                        var v = request.Headers[key];
                        if (string.IsNullOrEmpty(v)) continue;
                        var k = lowerKey ? key.ToLower() : key;
                        sp.Add(k, v);
                    }
                    catch { }
                }
            }
            return sp;
        }

        /// <summary>获取 X-Forwarded-For。</summary>
        public static string GetForwardedIP(HttpRequest request) => GetForwardedIP(GetHeaders(request));

        /// <summary>获取 User Agent。</summary>
        public static string GetUserAgent(HttpRequest request) => GetUserAgent(GetHeaders(request));

#endif

        #endregion

        #region Response - Redirect

        /// <summary>将客户端重新定向到新 URL。</summary>
        /// <remarks>响应 302 状态。</remarks>
        public static void Redirect(HttpListenerResponse response, string url)
        {
            if (response == null) return;
            try { response.Redirect(url); } catch { }
        }

#if NETFX

        /// <summary>将客户端重新定向到新 URL。</summary>
        /// <remarks>响应 302 状态。</remarks>
        public static void Redirect(HttpResponse response, string url)
        {
            if (response == null) return;
            try { response.Redirect(url, true); } catch { }
        }

#endif

#if NETCORE

        /// <summary>将客户端重新定向到新 URL。</summary>
        /// <remarks>默认响应 302 状态。可指定 permanent = true 以响应 301 状态。</remarks>
        public static void Redirect(HttpResponse response, string url, bool permanent = false)
        {
            if (response == null) return;
            try { response.Redirect(url, permanent); } catch { }
        }

#endif

        #endregion

        #region Response - Stop

        /// <summary>停止并关闭响应流。可指定向发送缓冲区的数据。</summary>
        public static void Stop(HttpListenerResponse response, bool flush = true)
        {
            if (response == null) return;
            try { if (flush) response.OutputStream.Flush(); } catch { }
            try { response.Close(); } catch { }
        }

#if NETFX || NETCORE

        /// <summary>停止并关闭响应流。可指定向发送缓冲区的数据。</summary>
        public static void Stop(HttpResponse response, bool flush = true)
        {
            if (response == null) return;
#if NETFX
            try { if (flush) response.Flush(); } catch { }
            try { response.Close(); } catch { }
            // try { response.End(); } catch { }
#endif
        }

#endif

        #endregion

        #region Response - Headers

        /// <summary>从 Response 头中移除 Server 和 X-Powered-By 属性。</summary>
        public static void RemoveServer(HttpListenerResponse response)
        {
            if (response == null) return;
            var keys = new List<string>(response.Headers.AllKeys);
            if (keys.Contains("Server")) response.Headers.Remove("Server");
            if (keys.Contains("X-Powered-By")) response.Headers.Remove("X-Powered-By");
        }

        /// <summary>添加 Header 属性，返回错误信息。</summary>
        public static string AddHeader(HttpListenerResponse response, string name, string value)
        {
            if (response == null || string.IsNullOrEmpty(name) || string.IsNullOrEmpty(value)) return "参数无效。";
            try
            {
                response.AddHeader(name, value);
                return null;
            }
            catch (Exception ex) { return ex.Message; }
        }

        /// <summary>添加多个 Headers 属性。</summary>
        public static void AddHeaders(HttpListenerResponse response, StringPairs headers)
        {
            if (response == null || headers == null) return;
            foreach (var key in headers.GetAllKeys())
            {
                var values = headers.GetValues(key);
                foreach (var value in values) AddHeader(response, key, value);
            }
        }

#if NETFX || NETCORE

        /// <summary>从 Response 头中移除 Server 和 X-Powered-By 属性。</summary>
        public static void RemoveServer(HttpResponse response)
        {
            if (response == null) return;
#if NETFX
            var keys = new List<string>(response.Headers.AllKeys);
#else
            var keys = new List<string>(response.Headers.Keys);
#endif
            if (keys.Contains("Server")) response.Headers.Remove("Server");
            if (keys.Contains("X-Powered-By")) response.Headers.Remove("X-Powered-By");
        }

        /// <summary>添加 Header 属性，返回错误信息。</summary>
        public static string AddHeader(HttpResponse response, string name, string value)
        {
            if (response == null || string.IsNullOrEmpty(name) || string.IsNullOrEmpty(value)) return "参数无效。";
            try
            {
#if NET20
                response.AddHeader(name, value);
#else
                response.Headers.Add(name, value);
#endif
                return null;
            }
            catch (Exception ex) { return ex.Message; }
        }

        /// <summary>添加多个 Headers 属性。</summary>
        public static void AddHeaders(HttpResponse response, StringPairs headers)
        {
            if (response == null || headers == null) return;
            foreach (var key in headers.GetAllKeys())
            {
                var values = headers.GetValues(key);
                foreach (var value in values) AddHeader(response, key, value);
            }
        }

#endif

        #endregion

        #region Response - Cache Control

        /// <summary>设置缓存时间，单位为秒，最大为 2592000 秒（30 天）。</summary>
        public static void SetCacheControl(HttpListenerResponse response, int seconds = 0)
        {
            if (response == null) return;
            var s = seconds;
            if (s < 0) s = 0;
            if (s > 2592000) s = 2592000;
            if (s > 0)
            {
                AddHeader(response, "Cache-Control", $"public, max-age={s}, s-maxage={s}");
            }
            else
            {
                AddHeader(response, "Cache-Control", "no-cache, no-store, must-revalidate");
                AddHeader(response, "Pragma", "no-cache");
            }
        }

#if NETFX || NETCORE

        /// <summary>设置缓存时间，单位为秒，最大为 2592000 秒（30 天）。</summary>
        public static void SetCacheControl(HttpResponse response, int seconds = 0)
        {
            if (response == null) return;
            var s = seconds;
            if (s < 0) s = 0;
            if (s > 2592000) s = 2592000;
#if NETFX
            if (s > 0)
            {
                response.CacheControl = "public";
                response.Cache.SetCacheability(HttpCacheability.Public);
                response.Cache.SetMaxAge(TimeSpan.FromSeconds(seconds));
                response.Cache.SetProxyMaxAge(TimeSpan.FromSeconds(seconds));
                response.Cache.SetRevalidation(HttpCacheRevalidation.AllCaches);
            }
            else
            {
                var minutes = s < 60 ? 0 : (s / 60);
                response.CacheControl = "no-cache";
                response.Cache.SetCacheability(HttpCacheability.NoCache);
                response.Cache.SetNoStore();
                AddHeader(response, "Pragma", "no-cache");
            }
#else
            if (s > 0)
            {
                AddHeader(response, "Cache-Control", $"public, max-age={s}, s-maxage={s}");
            }
            else
            {
                AddHeader(response, "Cache-Control", "no-cache, no-store, must-revalidate");
                AddHeader(response, "Pragma", "no-cache");
            }
#endif
        }

#endif

        #endregion

        #region Cookies

        // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Set-Cookie
        // https://developer.mozilla.org/zh-CN/docs/Web/HTTP/Headers/Set-Cookie

        // <cookie-name> 可以是除了控制字符 (CTLs)、空格 (spaces) 或制表符 (tab)之外的任何 US-ASCII 字符。
        // 同时不能包含以下分隔字符： ( ) < > @ , ; : \ " /  [ ] ? = { }.

        // <cookie-value> 是可选的，如果存在的话，那么需要包含在双引号里面。
        // 支持除了控制字符（CTLs）、空格（whitespace）、双引号（double quotes）、逗号（comma）、分号（semicolon）以及反斜线（backslash）之外的任意 US-ASCII 字符。

        // 关于编码：许多应用会对 cookie 值按照URL编码（URL encoding）规则进行编码，但是按照 RFC 规范，这不是必须的。
        // 不过满足规范中对于 <cookie-value> 所允许使用的字符的要求是有用的。

        /// <summary>获取 Cookies。</summary>
        public static StringPairs GetCookies(HttpListenerRequest request)
        {
            var sp = new StringPairs();
            if (request != null && request.Cookies != null)
            {
                for (var i = 0; i < request.Cookies.Count; i++)
                {
                    try
                    {
                        var cookie = request.Cookies[i];
                        var key = cookie.Name;
                        var value = cookie.Value ?? "";
                        sp.Add(new KeyValuePair<string, string>(key, value));
                    }
                    catch { }
                }
            }
            return sp;
        }

        /// <summary>设置响应的 Cookies。</summary>
        public static string SetCookies(HttpListenerResponse response, IEnumerable<KeyValuePair<string, string>> cookies)
        {
            // experimentation_subject_id
            if (cookies == null) return "参数 Response 无效。";
            foreach (var kvp in cookies)
            {
                var error = SetCookie(response, kvp.Key, kvp.Value);
                if (error.NotEmpty()) return error;
            }
            return null;
        }

        /// <summary>设置响应的 Cookie。</summary>
        public static string SetCookie(HttpListenerResponse response, string key, string value)
        {
            if (response == null) return null;
            var k = key.SafeTrim();
            var v = value.SafeTrim();
            if (k.IsEmpty()) return "参数 Key 无效。";

            try
            {
                var cookie = new Cookie(k, v);
                var now = DateTime.Now;
                cookie.Expires = v.IsEmpty() ? now.AddDays(-1) : now.AddYears(1);
                response.SetCookie(cookie);
                return null;
            }
            catch (Exception ex)
            {
                return ex.Message;
            }
        }

#if NETFX || NETCORE

        /// <summary>获取 Cookies。</summary>
        public static StringPairs GetCookies(HttpRequest request)
        {
            var sp = new StringPairs();
            if (request != null && request.Cookies != null)
            {
#if NETFX
                foreach (var key in request.Cookies.AllKeys)
                {
                    try
                    {
                        var cookie = request.Cookies[key];
                        var value = cookie.Value ?? "";
                        sp.Add(new KeyValuePair<string, string>(key, value));
                    }
                    catch { }
                }
#else
                foreach (var key in request.Cookies.Keys)
                {
                    try
                    {
                        var value = request.Cookies[key] ?? "";
                        sp.Add(new KeyValuePair<string, string>(key, value));
                    }
                    catch { }
                }
#endif
            }
            return sp;
        }

        /// <summary>设置响应的 Cookies。</summary>
        public static string SetCookies(HttpResponse response, IEnumerable<KeyValuePair<string, string>> cookies)
        {
            // experimentation_subject_id
            if (cookies == null) return "参数 Response 无效。";
            foreach (var kvp in cookies)
            {
                var error = SetCookie(response, kvp.Key, kvp.Value);
                if (error.NotEmpty()) return error;
            }
            return null;
        }

        /// <summary>设置响应的 Cookie。</summary>
        public static string SetCookie(HttpResponse response, string key, string value)
        {
            if (response == null) return null;
            var k = key.SafeTrim();
            var v = value.SafeTrim();
            if (k.IsEmpty()) return "参数 Key 无效。";

            try
            {
#if NETFX
                var cookie = new HttpCookie(k, v);
                var now = DateTime.Now;
                cookie.Expires = v.IsEmpty() ? now.AddDays(-1) : now.AddYears(1);
                response.SetCookie(cookie);

#else
                // var options = new CookieOptions();
                // response.Cookies.Append(key, value, options);
                response.Cookies.Append(key, value);
#endif
                return null;
            }
            catch (Exception ex)
            {
                return ex.Message;
            }
        }

#endif

        #endregion

    }

}