Index: src/OFData.h
==================================================================
--- src/OFData.h
+++ src/OFData.h
@@ -21,10 +21,14 @@
 
 OF_ASSUME_NONNULL_BEGIN
 
 @class OFString;
 @class OFURL;
+
+enum {
+	OF_DATA_SEARCH_BACKWARDS = 1
+};
 
 /*!
  * @class OFData OFData.h ObjFW/OFData.h
  *
  * @brief A class for storing arbitrary data in an array.
@@ -277,10 +281,27 @@
  * @param index The number of the item to return
  * @return The specified item of the OFData
  */
 - (const void *)itemAtIndex: (size_t)index OF_RETURNS_INNER_POINTER;
 
+/*!
+ * @brief Returns the range of the data.
+ *
+ * @param data The data to search for
+ * @param options Options modifying search behavior.@n
+ *		  Possible values are:
+ *		  Value                      | Description
+ *		  ---------------------------|-----------------------------
+ *		  `OF_DATA_SEARCH_BACKWARDS` | Search backwards in the data
+ * @param range The range in which to search
+ * @return The range of the first occurrence of the data or a range with
+ *	   `OF_NOT_FOUND` as start position if it was not found.
+ */
+- (of_range_t)rangeOfData: (OFData *)data
+		  options: (int)options
+		    range: (of_range_t)range;
+
 #ifdef OF_HAVE_FILES
 /*!
  * @brief Writes the OFData into the specified file.
  *
  * @param path The path of the file to write to

Index: src/OFData.m
==================================================================
--- src/OFData.m
+++ src/OFData.m
@@ -540,10 +540,53 @@
 
 - (OFString *)stringByBase64Encoding
 {
 	return of_base64_encode(_items, _count * _itemSize);
 }
+
+- (of_range_t)rangeOfData: (OFData *)data
+		  options: (int)options
+		    range: (of_range_t)range
+{
+	const char *search;
+	size_t searchLength;
+
+	if (range.length > SIZE_MAX - range.location ||
+	    range.location + range.length > _count)
+		@throw [OFOutOfRangeException exception];
+
+	if (data == nil || [data itemSize] != _itemSize)
+		@throw [OFInvalidArgumentException exception];
+
+	if ((searchLength = [data count]) == 0)
+		return of_range(0, 0);
+
+	if (searchLength > range.length)
+		return of_range(OF_NOT_FOUND, 0);
+
+	search = [data items];
+
+	if (options & OF_DATA_SEARCH_BACKWARDS) {
+		for (size_t i = range.length - searchLength;; i--) {
+			if (memcmp(_items + i * _itemSize, search,
+			    searchLength * _itemSize) == 0)
+				return of_range(i, searchLength);
+
+			/* No match and we're at the last item */
+			if (i == 0)
+				break;
+		}
+	} else {
+		for (size_t i = range.location;
+		    i <= range.length - searchLength; i++)
+			if (memcmp(_items + i * _itemSize, search,
+			    searchLength * _itemSize) == 0)
+				return of_range(i, searchLength);
+	}
+
+	return of_range(OF_NOT_FOUND, 0);
+}
 
 #ifdef OF_HAVE_FILES
 - (void)writeToFile: (OFString *)path
 {
 	OFFile *file = [[OFFile alloc] initWithPath: path

Index: src/OFString.h
==================================================================
--- src/OFString.h
+++ src/OFString.h
@@ -960,11 +960,11 @@
 
 /*!
  * @brief Returns the range of the string.
  *
  * @param string The string to search
- * @param options Options modifying search behaviour.@n
+ * @param options Options modifying search behavior.@n
  *		  Possible values are:
  *		  Value                        | Description
  *		  -----------------------------|-------------------------------
  *		  `OF_STRING_SEARCH_BACKWARDS` | Search backwards in the string
  * @return The range of the first occurrence of the string or a range with

Index: tests/OFDataTests.m
==================================================================
--- tests/OFDataTests.m
+++ tests/OFDataTests.m
@@ -21,10 +21,11 @@
 
 #import "OFData.h"
 #import "OFString.h"
 #import "OFAutoreleasePool.h"
 
+#import "OFInvalidArgumentException.h"
 #import "OFOutOfRangeException.h"
 
 #import "TestsAppDelegate.h"
 
 static OFString *module = @"OFData";
@@ -35,10 +36,11 @@
 {
 	OFAutoreleasePool *pool = [[OFAutoreleasePool alloc] init];
 	OFMutableData *mutable;
 	OFData *immutable;
 	void *raw[2];
+	of_range_t range;
 
 	TEST(@"+[dataWithItemSize:]",
 	    (mutable = [OFMutableData dataWithItemSize: 4096]))
 
 	OFObject *tmp = [[[OFObject alloc] init] autorelease];
@@ -94,10 +96,69 @@
 	TEST(@"-[insertItems:atIndex:count:]",
 	    R([mutable insertItems: "bc"
 			   atIndex: 1
 			     count: 2]) && [mutable count] == 5 &&
 	    memcmp([mutable items], "abcde", 5) == 0)
+
+	immutable = [OFData dataWithItems: "aaabaccdacaabb"
+				 itemSize: 2
+				    count: 7];
+	TEST(@"-[rangeOfString:options:range:]",
+	    R(range = [immutable rangeOfData: [OFData dataWithItems: "aa"
+							   itemSize: 2
+							      count: 1]
+				     options: 0
+				       range: of_range(0, 7)]) &&
+	    range.location == 0 && range.length == 1 &&
+	    R(range = [immutable rangeOfData: [OFData dataWithItems: "aa"
+							   itemSize: 2
+							      count: 1]
+				     options: OF_DATA_SEARCH_BACKWARDS
+				       range: of_range(0, 7)]) &&
+	    range.location == 5 && range.length == 1 &&
+	    R(range = [immutable rangeOfData: [OFData dataWithItems: "ac"
+							   itemSize: 2
+							      count: 1]
+				     options: 0
+				       range: of_range(0, 7)]) &&
+	    range.location == 2 && range.length == 1 &&
+	    R(range = [immutable rangeOfData: [OFData dataWithItems: "aabb"
+							   itemSize: 2
+							      count: 2]
+				     options: 0
+				       range: of_range(0, 7)]) &&
+	    range.location == 5 && range.length == 2 &&
+	    R(range = [immutable rangeOfData: [OFData dataWithItems: "aa"
+							   itemSize: 2
+							      count: 1]
+				     options: 0
+				       range: of_range(1, 6)]) &&
+	    range.location == 5 && range.length == 1 &&
+	    R(range = [immutable rangeOfData: [OFData dataWithItems: "aa"
+							   itemSize: 2
+							      count: 1]
+				     options: OF_DATA_SEARCH_BACKWARDS
+				       range: of_range(0, 5)]) &&
+	    range.location == 0 && range.length == 1)
+
+	EXPECT_EXCEPTION(
+	    @"-[rangeOfString:options:range:] failing on different itemSize",
+	    OFInvalidArgumentException,
+	    [immutable rangeOfData: [OFData dataWithItems: "aaa"
+						 itemSize: 3
+						    count: 1]
+			   options: 0
+			     range: of_range(0, 1)])
+
+	EXPECT_EXCEPTION(
+	    @"-[rangeOfString:options:range:] failing on out of range",
+	    OFOutOfRangeException,
+	    [immutable rangeOfData: [OFData dataWithItems: ""
+						 itemSize: 2
+						    count: 0]
+			   options: 0
+			     range: of_range(8, 1)])
 
 	TEST(@"-[MD5Hash]", [[mutable MD5Hash] isEqual: [@"abcde" MD5Hash]])
 
 	TEST(@"-[RIPEMD160Hash]", [[mutable RIPEMD160Hash]
 	    isEqual: [@"abcde" RIPEMD160Hash]])