Added the feature to config the status code and content type checking logic, do not hard-coded 200-400

SDWebImage/Core/SDWebImageDownloader.m

@@ -349,6 +349,14 @@ static void * SDWebImageDownloaderContext = &SDWebImageDownloaderContext;
         operation.minimumProgressInterval = MIN(MAX(self.config.minimumProgressInterval, 0), 1);
     }
     
+    if ([operation respondsToSelector:@selector(setAcceptableStatusCodes:)]) {
+        operation.acceptableStatusCodes = self.config.acceptableStatusCodes;
+    }
+    
+    if ([operation respondsToSelector:@selector(setAcceptableContentTypes:)]) {
+        operation.acceptableContentTypes = self.config.acceptableContentTypes;
+    }
+    
     if (options & SDWebImageDownloaderHighPriority) {
         operation.queuePriority = NSOperationQueuePriorityHigh;
     } else if (options & SDWebImageDownloaderLowPriority) {

SDWebImage/Core/SDWebImageDownloaderConfig.h

@@ -95,4 +95,19 @@ typedef NS_ENUM(NSInteger, SDWebImageDownloaderExecutionOrder) {
  */
 @property (nonatomic, copy, nullable) NSString *password;
 
+/**
+ * Set the acceptable HTTP Response status code. The status code which beyond the range will mark the download operation failed.
+ * For example, if we config [200, 400) but server response is 503, the download will fail with error code `SDWebImageErrorInvalidDownloadStatusCode`.
+ * Defaults to [200,400). Nil means no validation at all.
+ */
+@property (nonatomic, copy, nullable) NSIndexSet *acceptableStatusCodes;
+
+/**
+ * Set the acceptable HTTP Response content type. The content type beyond the set will mark the download operation failed.
+ * For example, if we config ["image/png"] but server response is "application/json", the download will fail with error code `SDWebImageErrorInvalidDownloadContentType`.
+ * Normally you don't need this for image format detection because we use image's data file signature magic bytes: https://en.wikipedia.org/wiki/List_of_file_signatures
+ * Defaults to nil. Nil means no validation at all.
+ */
+@property (nonatomic, copy, nullable) NSSet<NSString *> *acceptableContentTypes;
+
 @end

SDWebImage/Core/SDWebImageDownloaderConfig.m

@@ -26,6 +26,7 @@ static SDWebImageDownloaderConfig * _defaultDownloaderConfig;
         _maxConcurrentDownloads = 6;
         _downloadTimeout = 15.0;
         _executionOrder = SDWebImageDownloaderFIFOExecutionOrder;
+        _acceptableStatusCodes = [NSIndexSet indexSetWithIndexesInRange:NSMakeRange(200, 100)];
     }
     return self;
 }
@@ -41,6 +42,8 @@ static SDWebImageDownloaderConfig * _defaultDownloaderConfig;
     config.urlCredential = self.urlCredential;
     config.username = self.username;
     config.password = self.password;
+    config.acceptableStatusCodes = self.acceptableStatusCodes;
+    config.acceptableContentTypes = self.acceptableContentTypes;
     
     return config;
 }

SDWebImage/Core/SDWebImageDownloaderOperation.h

@@ -37,8 +37,12 @@
 @optional
 @property (strong, nonatomic, readonly, nullable) NSURLSessionTask *dataTask;
 @property (strong, nonatomic, readonly, nullable) NSURLSessionTaskMetrics *metrics API_AVAILABLE(macosx(10.12), ios(10.0), watchos(3.0), tvos(10.0));
+
+// These operation-level config was inherited from downloader. See `SDWebImageDownloaderConfig` for documentation.
 @property (strong, nonatomic, nullable) NSURLCredential *credential;
 @property (assign, nonatomic) double minimumProgressInterval;
+@property (copy, nonatomic, nullable) NSIndexSet *acceptableStatusCodes;
+@property (copy, nonatomic, nullable) NSSet<NSString *> *acceptableContentTypes;
 
 @end
 
@@ -85,6 +89,21 @@
  */
 @property (assign, nonatomic) double minimumProgressInterval;
 
+/**
+ * Set the acceptable HTTP Response status code. The status code which beyond the range will mark the download operation failed.
+ * For example, if we config [200, 400) but server response is 503, the download will fail with error code `SDWebImageErrorInvalidDownloadStatusCode`.
+ * Defaults to [200,400). Nil means no validation at all.
+ */
+@property (copy, nonatomic, nullable) NSIndexSet *acceptableStatusCodes;
+
+/**
+ * Set the acceptable HTTP Response content type. The content type beyond the set will mark the download operation failed.
+ * For example, if we config ["image/png"] but server response is "application/json", the download will fail with error code `SDWebImageErrorInvalidDownloadContentType`.
+ * Normally you don't need this for image format detection because we use image's data file signature magic bytes: https://en.wikipedia.org/wiki/List_of_file_signatures
+ * Defaults to nil. Nil means no validation at all.
+ */
+@property (copy, nonatomic, nullable) NSSet<NSString *> *acceptableContentTypes;
+
 /**
  * The options for the receiver.
  */

SDWebImage/Core/SDWebImageDownloaderOperation.m

@@ -332,18 +332,37 @@ didReceiveResponse:(NSURLResponse *)response
     self.expectedSize = expected;
     self.response = response;
     
-    NSInteger statusCode = [response respondsToSelector:@selector(statusCode)] ? ((NSHTTPURLResponse *)response).statusCode : 200;
+    // Check status code valid (defaults [200,400))
-    // Status code should between [200,400)
+    NSInteger statusCode = [response isKindOfClass:NSHTTPURLResponse.class] ? ((NSHTTPURLResponse *)response).statusCode : 0;
-    BOOL statusCodeValid = statusCode >= 200 && statusCode < 400;
+    BOOL statusCodeValid = YES;
+    if (valid && statusCode > 0 && self.acceptableStatusCodes) {
+        statusCodeValid = [self.acceptableStatusCodes containsIndex:statusCode];
+    }
     if (!statusCodeValid) {
         valid = NO;
-        self.responseError = [NSError errorWithDomain:SDWebImageErrorDomain code:SDWebImageErrorInvalidDownloadStatusCode userInfo:@{NSLocalizedDescriptionKey : @"Download marked as failed because response status code is not in 200-400", SDWebImageErrorDownloadStatusCodeKey : @(statusCode)}];
+        self.responseError = [NSError errorWithDomain:SDWebImageErrorDomain
+                                                 code:SDWebImageErrorInvalidDownloadStatusCode
+                                             userInfo:@{NSLocalizedDescriptionKey: [NSString stringWithFormat:@"Download marked as failed because of invalid response status code %ld", (long)statusCode], SDWebImageErrorDownloadStatusCodeKey: @(statusCode)}];
+    }
+    // Check content type valid (defaults nil)
+    NSString *contentType = [response isKindOfClass:NSHTTPURLResponse.class] ? ((NSHTTPURLResponse *)response).MIMEType : nil;
+    BOOL contentTypeValid = YES;
+    if (valid && contentType.length > 0 && self.acceptableContentTypes) {
+        contentTypeValid = [self.acceptableContentTypes containsObject:contentType];
+    }
+    if (!contentTypeValid) {
+        valid = NO;
+        self.responseError = [NSError errorWithDomain:SDWebImageErrorDomain
+                                                 code:SDWebImageErrorInvalidDownloadContentType
+                                             userInfo:@{NSLocalizedDescriptionKey: [NSString stringWithFormat:@"Download marked as failed because of invalid response content type %@", contentType], SDWebImageErrorDownloadContentTypeKey: contentType}];
     }
     //'304 Not Modified' is an exceptional one
     //URLSession current behavior will return 200 status code when the server respond 304 and URLCache hit. But this is not a standard behavior and we just add a check
-    if (statusCode == 304 && !self.cachedData) {
+    if (valid && statusCode == 304 && !self.cachedData) {
         valid = NO;
-        self.responseError = [NSError errorWithDomain:SDWebImageErrorDomain code:SDWebImageErrorCacheNotModified userInfo:@{NSLocalizedDescriptionKey : @"Download response status code is 304 not modified and ignored"}];
+        self.responseError = [NSError errorWithDomain:SDWebImageErrorDomain
+                                                 code:SDWebImageErrorCacheNotModified
+                                             userInfo:@{NSLocalizedDescriptionKey: @"Download response status code is 304 not modified and ignored"}];
     }
     
     if (valid) {

SDWebImage/Core/SDWebImageError.h

@@ -13,6 +13,8 @@ FOUNDATION_EXPORT NSErrorDomain const _Nonnull SDWebImageErrorDomain;
 
 /// The HTTP status code for invalid download response (NSNumber *)
 FOUNDATION_EXPORT NSErrorUserInfoKey const _Nonnull SDWebImageErrorDownloadStatusCodeKey;
+/// The HTTP MIME content type for invalid download response (NSString *)
+FOUNDATION_EXPORT NSErrorUserInfoKey const _Nonnull SDWebImageErrorDownloadContentTypeKey;
 
 /// SDWebImage error domain and codes
 typedef NS_ERROR_ENUM(SDWebImageErrorDomain, SDWebImageError) {
@@ -24,4 +26,5 @@ typedef NS_ERROR_ENUM(SDWebImageErrorDomain, SDWebImageError) {
     SDWebImageErrorInvalidDownloadStatusCode = 2001, // The image download response a invalid status code. You can check the status code in error's userInfo under `SDWebImageErrorDownloadStatusCodeKey`
     SDWebImageErrorCancelled = 2002, // The image loading operation is cancelled before finished, during either async disk cache query, or waiting before actual network request. For actual network request error, check `NSURLErrorDomain` error domain and code.
     SDWebImageErrorInvalidDownloadResponse = 2003, // When using response modifier, the modified download response is nil and marked as failed.
+    SDWebImageErrorInvalidDownloadContentType = 2004, // The image download response a invalid content type. You can check the MIME content type in error's userInfo under `SDWebImageErrorDownloadContentTypeKey`
 };

SDWebImage/Core/SDWebImageError.m

@@ -11,3 +11,4 @@
 
 NSErrorDomain const _Nonnull SDWebImageErrorDomain = @"SDWebImageErrorDomain";
 NSErrorUserInfoKey const _Nonnull SDWebImageErrorDownloadStatusCodeKey = @"SDWebImageErrorDownloadStatusCodeKey";
+NSErrorUserInfoKey const _Nonnull SDWebImageErrorDownloadContentTypeKey = @"SDWebImageErrorDownloadContentTypeKey";