get ip by safe dns source when hijacked

Author: YangSen-qn

QiniuSDK/Http/Dns/QNDnsPrefetch.m

@@ -355,6 +355,15 @@ - (void)checkWhetherCachedDnsValid{
     }
 }
 
+- (void)invalidNetworkAddressOfHost:(NSString *)host {
+    if (host == nil || host.length == 0) {
+        return;
+    }
+    @synchronized (self) {
+        [self.addressDictionary removeObjectForKey:host];
+    }
+}
+
 - (void)clearDnsCache:(NSError *__autoreleasing  _Nullable *)error {
     [self clearDnsMemoryCache];
     [self clearDnsDiskCache:error];
@@ -366,6 +375,9 @@ - (NSString *)prefetchHostBySafeDns:(NSString *)host error:(NSError * __autorele
     if (host == nil) {
         return nil;
     }
+    
+    [self invalidNetworkAddressOfHost:host];
+    
     NSError *err = nil;
     NSArray *nextFetchHosts = @[host];
     nextFetchHosts = [self preFetchHosts:nextFetchHosts dns:self.customDns error:&err];

QiniuSDK/Http/Request/QNHttpRegionRequest.m

@@ -9,6 +9,7 @@
 #import "QNDefine.h"
 #import "QNLogUtil.h"
 #import "QNAsyncRun.h"
+#import "QNDnsPrefetch.h"
 #import "QNUploadRequestState.h"
 #import "QNHttpRegionRequest.h"
 #import "QNConfiguration.h"
@@ -160,13 +161,15 @@ - (void)performRequest:(id <QNUploadServer>)server
         [self.requestMetrics addMetricsList:metrics];
 
         BOOL hijacked = metrics.lastObject.isMaybeHijacked || metrics.lastObject.isForsureHijacked;
-        if (hijacked) {
+        BOOL isSafeDnsSource = kQNIsDnsSourceCustom(metrics.lastObject.syncDnsSource) || kQNIsDnsSourceDoh(metrics.lastObject.syncDnsSource) || kQNIsDnsSourceDnsPod(metrics.lastObject.syncDnsSource);
+        BOOL hijackedAndNeedRetry = hijacked && isSafeDnsSource;
+        if (hijackedAndNeedRetry) {
             [self.region updateIpListFormHost:server.host];
         }
 
         if ((shouldRetry(responseInfo, response)
             && self.config.allowBackupHost
-            && responseInfo.couldRegionRetry) || hijacked) {
+            && responseInfo.couldRegionRetry) || hijackedAndNeedRetry) {
 
             id <QNUploadServer> newServer = [self getNextServer:responseInfo];
             if (newServer) {