Parse expires / max-age headers

@@ -109,6 +109,8 @@ static NSString *permanentCacheFolder = @"PermanentStore";
 	if ([request isResponseCompressed]) {
 		[responseHeaders removeObjectForKey:@"Content-Encoding"];
 	}
+	// We use this special key to help expire the request when we get a max-age header
+	[responseHeaders setObject:[NSDate date] forKey:@"X-ASIHTTPRequest-Fetch-date"];
 	[responseHeaders writeToFile:metadataPath atomically:NO];
 	
 	if ([request responseData]) {
@@ -182,12 +184,38 @@ static NSString *permanentCacheFolder = @"PermanentStore";
 	if (!dataPath) {
 		return NO;
 	}
+	// If the Etag or Last-Modified date are different from the one we have, fetch the document again
 	NSArray *headersToCompare = [NSArray arrayWithObjects:@"etag",@"last-modified",nil];
 	for (NSString *header in headersToCompare) {
 		if (![[[self class] responseHeader:header fromHeaders:[request responseHeaders]] isEqualToString:[[self class] responseHeader:header fromHeaders:cachedHeaders]]) {
 			return NO;
 		}
 	}
+	if (![self shouldRespectCacheControlHeaders]) {
+		return YES;
+	}
+	// Look for an Expires header to see if the content is out of data
+	NSString *expires = [[self class] responseHeader:@"expires" fromHeaders:cachedHeaders];
+	if (expires) {
+		if ([[ASIHTTPRequest dateFromRFC1123String:expires] timeIntervalSinceNow] < 0) {
+			return NO;
+		}
+	}
+	// Look for a max-age header
+	NSString *cacheControl = [[[self class] responseHeader:@"cache-control" fromHeaders:cachedHeaders] lowercaseString];
+	if (cacheControl) {
+		NSScanner *scanner = [NSScanner scannerWithString:cacheControl];
+		if ([scanner scanString:@"max-age" intoString:NULL]) {
+			[scanner scanString:@"=" intoString:NULL];
+			NSTimeInterval maxAge = 0;
+			[scanner scanDouble:&maxAge];
+			NSDate *fetchDate = [[cachedHeaders objectForKey:@"X-ASIHTTPRequest-Fetch-date"] dateValue];
+			NSDate *expiryDate = [fetchDate addTimeInterval:maxAge];
+			if ([expiryDate timeIntervalSinceNow] < 0) {
+				return NO;
+			}
+		}
+	}
 	return YES;
 }
 

@@ -702,6 +702,9 @@ extern unsigned long const ASIWWANBandwidthThrottleAmount;
 // And also by ASIS3Request
 + (NSString *)base64forData:(NSData *)theData;
 
+// Returns a date from a string in RFC1123 format
++ (NSDate *)dateFromRFC1123String:(NSString *)string;
+
 #pragma mark ===
 
 @property (retain) NSString *username;

@@ -23,7 +23,7 @@
 
 
 // Automatically set on build
-NSString *ASIHTTPRequestVersion = @"v1.6.2-12 2010-05-03";
+NSString *ASIHTTPRequestVersion = @"v1.6.2-13 2010-05-03";
 
 NSString* const NetworkRequestErrorDomain = @"ASIHTTPRequestErrorDomain";
 
@@ -3780,6 +3780,25 @@ static id <ASICacheDelegate> defaultCache = nil;
     return [[[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding] autorelease];
 }
 
+// Based on hints from http://stackoverflow.com/questions/1850824/parsing-a-rfc-822-date-with-nsdateformatter
++ (NSDate *)dateFromRFC1123String:(NSString *)string
+{
+	NSDateFormatter *formatter = [[[NSDateFormatter alloc] init] autorelease];
+	[formatter setLocale:[[[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"] autorelease]];
+	// Does the string include a week day?
+	NSString *day = @"";
+	if ([string rangeOfString:@","].location != NSNotFound) {
+		day = @"EEE, ";
+	}
+	// Does the string include seconds?
+	NSString *seconds = @"";
+	if ([[string componentsSeparatedByString:@":"] count] == 3) {
+		seconds = @":ss";
+	}
+	[formatter setDateFormat:[NSString stringWithFormat:@"%@dd MMM yyyy HH:mm%@ z",day,seconds]];
+	return [formatter dateFromString:string];
+}
+
 #pragma mark ===
 
 @synthesize username;

@@ -1579,5 +1579,25 @@
 	[[self responseData] appendData:data];
 }
 
+- (void)testRFC1123DateParsing
+{
+	unsigned dateUnits = NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit | NSWeekdayCalendarUnit;
+	NSCalendar *calendar = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease];
+	[calendar setTimeZone:[NSTimeZone timeZoneWithAbbreviation:@"GMT"]];
+	NSString *dateString = @"Thu, 19 Nov 1981 08:52:01 GMT";
+	NSDate *date = [ASIHTTPRequest dateFromRFC1123String:dateString];
+	NSDateComponents *components = [calendar components:dateUnits fromDate:date];
+	NSLog(@"%i",[components weekday]);
+	BOOL success = ([components year] == 1981 && [components month] == 11 && [components day] == 19 && [components weekday] == 5 && [components hour] == 8 && [components minute] == 52 && [components second] == 1);
+	GHAssertTrue(success,@"Failed to parse an RFC1123 date correctly");
+
+	dateString = @"4 May 2010 00:59 CET";
+	date = [ASIHTTPRequest dateFromRFC1123String:dateString];
+	components = [calendar components:dateUnits fromDate:date];
+	success = ([components year] == 2010 && [components month] == 5 && [components day] == 3 && [components hour] == 23 && [components minute] == 59);
+	GHAssertTrue(success,@"Failed to parse an RFC1123 date correctly");
+
+}
+
 @synthesize responseData;
 @end
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