HTTPDNS域名解析场景下如何使用Cookie？-阿里云开发者社区

1. Cookie

由于HTTP协议是无状态的，为了维护服务端和客户端的会话状态，客户端可存储服务端返回的Cookie，之后请求中可携带Cookie标识状态。

客户端根据服务端返回的携带Set-Cookie的HTTP Header来创建一个Cookie，Set-Cookie为字符串，主要字段如下：

Set-Cookie: [name1=value1, name2=value2;],[expires=date;],[path=path;],[domain=domain;]

Cookie信息为形如name=value的字符串；
expires，Cookie过期时间；
domain，Cookie适用域名；
path，请求资源URL中必须存在指定的路径时，才会发送该Cookie。

2. Cookie存储策略

基于iOS平台说明服务端Set-Cookie配置和客户端Cookie存储策略。

2.1 准备工作

访问域名test.com，假定HTTPDNS域名解析结果为201.87.1.125；
Web服务器设置Cookie如下，domain字段待定：

"Set-Cookie" = "name1=value1; expires=Wed, 15-Nov-17 15:41:02 GMT; path=/"

客户端发送普通HTTP请求：

- (void)connectToUrlString:(NSString *)urlString {
    NSURL *url = [NSURL URLWithString:urlString];
    NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
    configuration.requestCachePolicy = NSURLRequestReloadIgnoringLocalCacheData;
    NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    NSURLSessionTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
        if (error) {
            NSLog(@"error: %@", error);
        } else {
            NSLog(@"response: %@", response);
            NSLog(@"data: %@", [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
        }
    }];
    [task resume];
}

客户端使用HTTPDNS服务发送HTTP请求：

- (void)connectToUrlStringUsingHTTPDNS:(NSString *)urlString {
    NSURL *url = [NSURL URLWithString:urlString];
    NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
    configuration.requestCachePolicy = NSURLRequestReloadIgnoringLocalCacheData;
    NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    NSString *ip = [[HttpDnsService sharedInstance] getIpByHostAsync:url.host];
    if (ip) {
      NSLog(@"Get IP(%@) for host(%@) from HTTPDNS Successfully!", ip, url.host);
      NSRange hostFirstRange = [urlString rangeOfString:url.host];
      if (hostFirstRange.location != NSNotFound) {
        NSString * newUrlString = [urlString stringByReplacingCharactersInRange:hostFirstRange withString:ip];
        request.URL = [NSURL URLWithString:newUrlString];
        [request setValue:url.host forHTTPHeaderField:@"host"];
      }
    }
    NSURLSessionTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
        if (error) {
            NSLog(@"error: %@", error);
        } else {
            NSLog(@"response: %@", response);
            NSLog(@"data: %@", [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
        }
    }];
    [task resume];
}

查询本App存储全部Cookie：

NSHTTPCookieStorage *cookieStorage = [NSHTTPCookieStorage sharedHTTPCookieStorage];
for (NSHTTPCookie *cookie in [cookieStorage cookies]) {
    NSLog(@"cookie: %@", cookie);
}

查询本App存储指定URL对应适配Cookie：

NSHTTPCookieStorage *cookieStorage = [NSHTTPCookieStorage sharedHTTPCookieStorage];
NSDictionary *cookiesDic = [NSHTTPCookie requestHeaderFieldsWithCookies:[cookieStorage cookiesForURL:url]];

2.2 指定domain的Cookie

服务端配置Set-Cookie如下，domain设置为.test.com，

"Set-Cookie" = "name1=value1; expires=Wed, 15-Nov-17 15:41:02 GMT; path=/; domain=.test.com"

客户端调用[self connectToUrlString:@"http://test.com"];发送HTTP请求后查询本地Cookie如下；再次访问时，HTTP头部自动添加该Cookie并发送到服务端。

name1 = value1;
expires = Wed, 15-Nov-17 15:41:02 GMT;
path = /;
domain = .test.com;

客户端调用[self connectToUrlStringUsingHTTPDNS:@"http://test.com"];，使用HTTPDNS服务发送HTTP请求，客户端同样收到上述domain为.test.com的Cookie，iOS网络库关于Cookie的默认存储策略为NSHTTPCookieAcceptPolicyOnlyFromMainDocumentDomain，domain与URL无法匹配时（使用HTTPDNS服务发送HTTP请求时，原生URL.host被替换为IP地址），该Cookie不会存储，因此再次发送请求时无法使用Cookie。

2.3 未指定domain的Cookie

若服务端配置Set-Cookie的domain不配置，

"Set-Cookie" = "name1=value1; expires=Wed, 15-Nov-17 15:41:02 GMT; path=/;

客户端发送HTTP请求返回Cookie如下，domain字段为空。

name1 = value1;
expires = Wed, 15-Nov-17 15:41:02 GMT;
path = /;

iOS网络库存储该Cookie时，自动填充Cookie的domain字段为HTTP请求的URL.host，即普通HTTP请求存储Cookie如下：

name1 = value1;
expires = Wed, 15-Nov-17 15:41:02 GMT;
path = /;
domain = .test.com;

使用HTTPDNS访问的Cookie存储如下，再次使用HTTPDNS进行HTTP请求时，网络库默认Cookie匹配规则可以匹配到该Cookie。（此场景下使用HTTPDNS服务发送HTTP请求，虽然默认Cookie匹配规则可正确匹配Cookie，但是该场景依赖服务端Cookie的配置，为了安全性，通常服务端返回Set-Cookie的domain字段不为空。）

name1 = value1;
expires = Wed, 15-Nov-17 15:41:02 GMT;
path = /;
domain = 201.87.1.125;

3. 适配策略

适配目的是在使用HTTPDNS服务，可以像通用HTTP请求对Cookie进行存储、匹配和发送，这就需要自行管理使用HTTPDNS服务的HTTP请求的Cookie。

存储，收到服务端返回的HTTP Header Set-Cookie，可以正确解析并存储；
匹配，发送HTTP请求前，可正确搜索匹配Cookie；
发送，将匹配的Cookie放入HTTP请求中发送到服务端。

3.1 iOS适配

根据苹果文档说明，按照以下方式可以改变Cookie接受策略，文档说明默认策略为NSHTTPCookieAcceptPolicyAlways，经测试发现默认策略其实为NSHTTPCookieAcceptPolicyOnlyFromMainDocumentDomain；使用以下方式手动将策略修改为NSHTTPCookieAcceptPolicyAlways，测试发现Accept Cookie Always没有生效，原因需要进一步确定。

NSHTTPCookieStorage *cookieStorage = [NSHTTPCookieStorage sharedHTTPCookieStorage];
[cookieStorage setCookieAcceptPolicy:NSHTTPCookieAcceptPolicyAlways];

实现了简单的HTTPDNS专用的HTTPDNSCookieManager（【注意】此处仅提供Cookie管理的示例，Cookie管理细节如生命周期、匹配规则等不涉及，如有需要可参考RFC 2965），适用于使用HTTPDNS服务的HTTP请求，
HTTPDNSCookieManager.h

#ifndef HTTPDNSCookieManager_h
#define HTTPDNSCookieManager_h

// URL匹配Cookie规则
typedef BOOL (^HTTPDNSCookieFilter)(NSHTTPCookie *, NSURL *);

@interface HTTPDNSCookieManager : NSObject

+ (instancetype)sharedInstance;

/**
 指定URL匹配Cookie策略

 @param filter 匹配器
 */
- (void)setCookieFilter:(HTTPDNSCookieFilter)filter;

/**
 处理HTTP Reponse携带的Cookie并存储

 @param headerFields HTTP Header Fields
 @param URL 根据匹配策略获取查找URL关联的Cookie
 @return 返回添加到存储的Cookie
 */
- (NSArray<NSHTTPCookie *> *)handleHeaderFields:(NSDictionary *)headerFields forURL:(NSURL *)URL;

/**
 匹配本地Cookie存储，获取对应URL的request cookie字符串

 @param URL 根据匹配策略指定查找URL关联的Cookie
 @return 返回对应URL的request Cookie字符串
 */
- (NSString *)getRequestCookieHeaderForURL:(NSURL *)URL;

/**
 删除存储cookie

 @param URL 根据匹配策略查找URL关联的cookie
 @return 返回成功删除cookie数
 */
- (NSInteger)deleteCookieForURL:(NSURL *)URL;

@end

#endif /* HTTPDNSCookieManager_h */

HTTPDNSCookieManager.m

#import <Foundation/Foundation.h>
#import "HTTPDNSCookieManager.h"

@implementation HTTPDNSCookieManager
{
    HTTPDNSCookieFilter cookieFilter;
}

- (instancetype)init {
    if (self = [super init]) {
        /**
            此处设置的Cookie和URL匹配策略比较简单，检查URL.host是否包含Cookie的domain字段
            通过调用setCookieFilter接口设定Cookie匹配策略，
            比如可以设定Cookie的domain字段和URL.host的后缀匹配 | URL是否符合Cookie的path设定
            细节匹配规则可参考RFC 2965 3.3节
         */
        cookieFilter = ^BOOL(NSHTTPCookie *cookie, NSURL *URL) {
            if ([URL.host containsString:cookie.domain]) {
                return YES;
            }
            return NO;
        };
    }
    return self;
}

+ (instancetype)sharedInstance {
    static id singletonInstance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        if (!singletonInstance) {
            singletonInstance = [[super allocWithZone:NULL] init];
        }
    });
    return singletonInstance;
}

+ (id)allocWithZone:(struct _NSZone *)zone {
    return [self sharedInstance];
}

- (id)copyWithZone:(struct _NSZone *)zone {
    return self;
}

- (void)setCookieFilter:(HTTPDNSCookieFilter)filter {
    if (filter != nil) {
        cookieFilter = filter;
    }
}

- (NSArray<NSHTTPCookie *> *)handleHeaderFields:(NSDictionary *)headerFields forURL:(NSURL *)URL {
    NSArray *cookieArray = [NSHTTPCookie cookiesWithResponseHeaderFields:headerFields forURL:URL];
    if (cookieArray != nil) {
        NSHTTPCookieStorage *cookieStorage = [NSHTTPCookieStorage sharedHTTPCookieStorage];
        for (NSHTTPCookie *cookie in cookieArray) {
            if (cookieFilter(cookie, URL)) {
                NSLog(@"Add a cookie: %@", cookie);
                [cookieStorage setCookie:cookie];
            }
        }
    }
    return cookieArray;
}

- (NSString *)getRequestCookieHeaderForURL:(NSURL *)URL {
    NSArray *cookieArray = [self searchAppropriateCookies:URL];
    if (cookieArray != nil && cookieArray.count > 0) {
        NSDictionary *cookieDic = [NSHTTPCookie requestHeaderFieldsWithCookies:cookieArray];
        if ([cookieDic objectForKey:@"Cookie"]) {
            return cookieDic[@"Cookie"];
        }
    }
    return nil;
}

- (NSArray *)searchAppropriateCookies:(NSURL *)URL {
    NSMutableArray *cookieArray = [NSMutableArray array];
    NSHTTPCookieStorage *cookieStorage = [NSHTTPCookieStorage sharedHTTPCookieStorage];
    for (NSHTTPCookie *cookie in [cookieStorage cookies]) {
        if (cookieFilter(cookie, URL)) {
            NSLog(@"Search an appropriate cookie: %@", cookie);
            [cookieArray addObject:cookie];
        }
    }
    return cookieArray;
}

- (NSInteger)deleteCookieForURL:(NSURL *)URL {
    int delCount = 0;
    NSHTTPCookieStorage *cookieStorage = [NSHTTPCookieStorage sharedHTTPCookieStorage];
    for (NSHTTPCookie *cookie in [cookieStorage cookies]) {
        if (cookieFilter(cookie, URL)) {
            NSLog(@"Delete a cookie: %@", cookie);
            [cookieStorage deleteCookie:cookie];
            delCount++;
        }
    }
    return delCount;
}

@end

使用HTTPDNS处理Cookie示例（使用上述默认简单匹配策略）：

- (void)connectToUrlStringUsingHTTPDNS:(NSString *)urlString {
    NSURL *url = [NSURL URLWithString:urlString];
    NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
    configuration.requestCachePolicy = NSURLRequestReloadIgnoringLocalCacheData;
    NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    NSString *ip = [[HttpDnsService sharedInstance] getIpByHostAsync:url.host];
    if (ip) {
        NSLog(@"Get IP(%@) for host(%@) from HTTPDNS Successfully!", ip, url.host);
        NSRange hostFirstRange = [urlString rangeOfString:url.host];
        if (hostFirstRange.location != NSNotFound) {
            NSString *newUrlString = [urlString stringByReplacingCharactersInRange:hostFirstRange withString:ip];
            NSLog(@"New URL: %@", newUrlString);
            request.URL = [NSURL URLWithString:newUrlString];
            [request setValue:url.host forHTTPHeaderField:@"host"];
            // 匹配合适Cookie添加到request中，这里传入的是原生URL
            [request setValue:[[HTTPDNSCookieManager sharedInstance] getRequestCookieHeaderForURL:url] forHTTPHeaderField:@"Cookie"];
            // 删除Cookie
            [[HTTPDNSCookieManager sharedInstance] deleteCookieForURL:url];
        }
    }
    NSURLSessionTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
        if (error) {
            NSLog(@"error: %@", error);
        } else {
            NSLog(@"response: %@", response);
            NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)response;
            // 解析HTTP Response Header，存储cookie
            [[HTTPDNSCookieManager sharedInstance] handleHeaderFields:[httpResponse allHeaderFields] forURL:url];
            NSLog(@"data: %@", [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
            NSHTTPCookieStorage *cookieStorage = [NSHTTPCookieStorage sharedHTTPCookieStorage];
        }
    }];
    [task resume];
}

3.2 Android适配

使用如下方式HTTPDNS解析"http://test.com" 域名进行访问，

String urlStr = "http://test.com";
// HTTPDNS解析"test.com"域名，发HTTP请求访问
new DownloadWebPageTask().execute(urlStr);

private class DownloadWebPageTask extends AsyncTask<String, Void, String> {

        @Override
        protected String doInBackground(String... params) {
            try {
                return downloadUrl(params[0]);
            } catch (IOException e) {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(String result) {
            if (result != null) {
                Log.e(TAG, "Get response: " + result);
            } else {
                Log.e(TAG, "Get response error.");
            }
        }
    }

    private String downloadUrl(String urlStr) throws IOException {
        try {
            URL url = new URL(urlStr);
            conn = (HttpURLConnection) url.openConnection();
            String ip = httpDnsService.getIpByHostAsync(urlStr);
            if (urlStr.equals(url2)) {
                ip = IP;
            }
            if (ip != null) {
                Log.d(TAG, "Get IP: " + ip + " for host: " + url.getHost() + " from HTTPDNS successfully!");
                String newUrlStr = urlStr.replaceFirst(url.getHost(), ip);
                conn = (HttpURLConnection) new URL(newUrlStr).openConnection();
                conn.setRequestProperty("Host", url.getHost());
            }
            conn.setConnectTimeout(1000 * 15);
            int responseCode = conn.getResponseCode();
            if (responseCode == 200) {
                Log.i(TAG, "Reponse code is 200.");
                dis = new DataInputStream(conn.getInputStream());
                int len;
                byte[] buff = new byte[4096];
                StringBuilder response = new StringBuilder();
                while ((len = dis.read(buff)) != -1) {
                    response.append(new String(buff, 0, len));
                }
                return response.toString();
            } else {
                Log.e(TAG, "Response code is " + responseCode);
                return null;
            }
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }
        return null;
    }

CookieManager配置如下：

/**
 *  配置cookie manager
 */
private void setCookieHandler() {
    /**
     *  指定cookie存储policy
     *  系统已定义策略有：
     *  CookiePolicy.ACCEPT_ALL，存储全部cookie
     *  CookiePolicy.ACCEPT_NONE，不存储cookie
     *  CookiePolicy.ACCEPT_ORIGINAL_SERVER，按照RFC 2965 3.3节标准域名匹配存储cookie
     * */
    cookieManager.setCookiePolicy(new CookiePolicy() {
        @Override
        public boolean shouldAccept(URI uri, HttpCookie cookie) {
            // 为方便测试，此处都返回true，存储全部cookie
            Log.i(TAG, "Uri: " + uri.toString() + ", cookie: " + cookie.toString() + ", domain: " + cookie.getDomain());
            return true;
        }
    });
    CookieHandler.setDefault(cookieManager);  }

使用CookieManager管理App的Cookie缓存，当对应Cookie满足策略存储到本地时，针对使用HTTPDNS域名解析进行HTTP访问的场景，不用修改即可完成适配。
基于HTTPDNS访问http://test.com，获取到Cookie如下，shouldAccept()返回true后网络库自动缓存该Cookie；

name1 = value1;
expires = Wed, 15-Nov-17 15:41:02 GMT;
path = /;
domain = .test.com;

Cookie存储时，该Cookie直接和访问的URL（http://201.87.1.125）相关联，并且Cookie的domain为test.com；所以，再次使用HTTPDNS服务防伪URL(http://201.87.1.125)时，系统可自动获取到该Cookie。Cookie存储后可按照下面代码测试，基于域名/IP的URL查询缓存Cookie，都可以正确获取该Cookie，因此使用HTTPDNS服务时可自动完成适配。

String url1 = "http://test.com";
String url2 = "http://201.87.1.125";
CookieStore cookieStore = cookieManager.getCookieStore();
try {
    Log.e(TAG, "store cookie is " + cookieStore.get(new URI(url1)));
    Log.e(TAG, "store cookie is " + cookieStore.get(new URI(url2)));
} catch (URISyntaxException e) {
    e.printStackTrace();
}

HTTPDNS域名解析场景下如何使用Cookie？

1. Cookie

2. Cookie存储策略

2.1 准备工作

2.2 指定domain的Cookie

2.3 未指定domain的Cookie

3. 适配策略

3.1 iOS适配

3.2 Android适配

DNS最佳实践

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