單IP多HTTPS域名場景下的解決方案__最佳實踐_HTTPDNS-阿裏雲

1. NSStreamEventOpenCompleted：連接已打開。
2. NSStreamEventHasBytesAvailable：響應頭部已下載完整，body中字節可讀。
3. NSStreamEventErrorOccurred：連接發生錯誤。
4. NSStreamEventEndEncountered：連接結束。

- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode {
    if (eventCode == NSStreamEventHasBytesAvailable) {
        CFReadStreamRef readStream = (__bridge_retained CFReadStreamRef) aStream;
        CFHTTPMessageRef message = (CFHTTPMessageRef) CFReadStreamCopyProperty(readStream, kCFStreamPropertyHTTPResponseHeader);
        if (CFHTTPMessageIsHeaderComplete(message)) {
            // 以防response的header信息不完整
            UInt8 buffer[16 * 1024];
            UInt8 *buf = NULL;
            unsigned long length = 0;
            NSInputStream *inputstream = (NSInputStream *) aStream;
            NSNumber *alreadyAdded = objc_getAssociatedObject(aStream, kAnchorAlreadyAdded);
            if (!alreadyAdded || ![alreadyAdded boolValue]) {
                objc_setAssociatedObject(aStream, kAnchorAlreadyAdded, [NSNumber numberWithBool:YES], OBJC_ASSOCIATION_COPY);
                // 通知client已收到response，隻通知一次
                NSDictionary *headDict = (__bridge NSDictionary *) (CFHTTPMessageCopyAllHeaderFields(message));
                CFStringRef httpVersion = CFHTTPMessageCopyVersion(message);
                // 獲取響應頭部的狀態碼
                CFIndex myErrCode = CFHTTPMessageGetResponseStatusCode(message);
                NSHTTPURLResponse *response = [[NSHTTPURLResponse alloc] initWithURL:curRequest.URL statusCode:myErrCode HTTPVersion:(__bridge NSString *) httpVersion headerFields:headDict];
                [self.client URLProtocol:self didReceiveResponse:response cacheStoragePolicy:NSURLCacheStorageNotAllowed];
                // 驗證證書
                SecTrustRef trust = (__bridge SecTrustRef) [aStream propertyForKey:(__bridge NSString *) kCFStreamPropertySSLPeerTrust];
                SecTrustResultType res = kSecTrustResultInvalid;
                NSMutableArray *policies = [NSMutableArray array];
                NSString *domain = [[curRequest allHTTPHeaderFields] valueForKey:@"host"];
                if (domain) {
                    [policies addObject:(__bridge_transfer id) SecPolicyCreateSSL(true, (__bridge CFStringRef) domain)];
                } else {
                    [policies addObject:(__bridge_transfer id) SecPolicyCreateBasicX509()];
                }
                /*
                 * 綁定校驗策略到服務端的證書上
                 */
                SecTrustSetPolicies(trust, (__bridge CFArrayRef) policies);
                if (SecTrustEvaluate(trust, &res) != errSecSuccess) {
                    [aStream removeFromRunLoop:curRunLoop forMode:NSRunLoopCommonModes];
                    [aStream setDelegate:nil];
                    [aStream close];
                    [self.client URLProtocol:self didFailWithError:[[NSError alloc] initWithDomain:@"can not evaluate the server trust" code:-1 userInfo:nil]];
                }
                if (res != kSecTrustResultProceed && res != kSecTrustResultUnspecified) {
                    /* 證書驗證不通過，關閉input stream */
                    [aStream removeFromRunLoop:curRunLoop forMode:NSRunLoopCommonModes];
                    [aStream setDelegate:nil];
                    [aStream close];
                    [self.client URLProtocol:self didFailWithError:[[NSError alloc] initWithDomain:@"fail to evaluate the server trust" code:-1 userInfo:nil]];
                } else {
                    // 證書通過，返回數據
                    if (![inputstream getBuffer:&buf length:&length]) {
                        NSInteger amount = [inputstream read:buffer maxLength:sizeof(buffer)];
                        buf = buffer;
                        length = amount;
                    }
                    NSData *data = [[NSData alloc] initWithBytes:buf length:length];
                    [self.client URLProtocol:self didLoadData:data];
                }
            } else {
                // 證書已驗證過，返回數據
                if (![inputstream getBuffer:&buf length:&length]) {
                    NSInteger amount = [inputstream read:buffer maxLength:sizeof(buffer)];
                    buf = buffer;
                    length = amount;
                }
                NSData *data = [[NSData alloc] initWithBytes:buf length:length];
                [self.client URLProtocol:self didLoadData:data];
            }
        }
    } else if (eventCode == NSStreamEventErrorOccurred) {
        [aStream removeFromRunLoop:curRunLoop forMode:NSRunLoopCommonModes];
        [aStream setDelegate:nil];
        [aStream close];
        // 通知client發生錯誤了
        [self.client URLProtocol:self didFailWithError:[aStream streamError]];
    } else if (eventCode == NSStreamEventEndEncountered) {
        [self handleResponse];
    }
}
- (void)handleResponse {
    // 獲取響應頭部信息
    CFReadStreamRef readStream = (__bridge_retained CFReadStreamRef) inputStream;
    CFHTTPMessageRef message = (CFHTTPMessageRef) CFReadStreamCopyProperty(readStream, kCFStreamPropertyHTTPResponseHeader);
    if (CFHTTPMessageIsHeaderComplete(message)) {
        // 確保response頭部信息完整
        NSDictionary *headDict = (__bridge NSDictionary *) (CFHTTPMessageCopyAllHeaderFields(message));
        // 獲取響應頭部的狀態碼
        CFIndex myErrCode = CFHTTPMessageGetResponseStatusCode(message);
        // 把當前請求關閉
        [inputStream removeFromRunLoop:curRunLoop forMode:NSRunLoopCommonModes];
        [inputStream setDelegate:nil];
        [inputStream close];
        if (myErrCode >= 200 && myErrCode < 300) {
            // 返回碼為2xx，直接通知client
            [self.client URLProtocolDidFinishLoading:self];
        } else if (myErrCode >= 300 && myErrCode < 400) {
            // 返回碼為3xx，需要重定向請求，繼續訪問重定向頁麵
            NSString *location = headDict[@"Location"];
            NSURL *url = [[NSURL alloc] initWithString:location];
            curRequest = [[NSMutableURLRequest alloc] initWithURL:url];
            /***********重定向通知client處理或內部處理*************/
            // client處理
            // NSURLResponse* response = [[NSURLResponse alloc] initWithURL:curRequest.URL MIMEType:headDict[@"Content-Type"] expectedContentLength:[headDict[@"Content-Length"] integerValue] textEncodingName:@"UTF8"];
            // [self.client URLProtocol:self wasRedirectedToRequest:curRequest redirectResponse:response];
            // 內部處理，將url中的host通過HTTPDNS轉換為IP，不能在startLoading線程中進行同步網絡請求，會被阻塞
            NSString *ip = [[HttpDnsService sharedInstance] getIpByHostAsync:url.host];
            if (ip) {
                NSLog(@"Get IP from HTTPDNS Successfully!");
                NSRange hostFirstRange = [location rangeOfString:url.host];
                if (NSNotFound != hostFirstRange.location) {
                    NSString *newUrl = [location stringByReplacingCharactersInRange:hostFirstRange withString:ip];
                    curRequest = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:newUrl]];
                    [curRequest setValue:url.host forHTTPHeaderField:@"host"];
                }
            }
            [self startRequest];
        } else {
            // 其他情況，直接返回響應信息給client
            [self.client URLProtocolDidFinishLoading:self];
        }
    } else {
        // 頭部信息不完整，關閉inputstream，通知client
        [inputStream removeFromRunLoop:curRunLoop forMode:NSRunLoopCommonModes];
        [inputStream setDelegate:nil];
        [inputStream close];
        [self.client URLProtocolDidFinishLoading:self];
    }
}

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