515 lines
17 KiB
Objective-C
515 lines
17 KiB
Objective-C
//
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// ASIDownloadCache.m
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// Part of ASIHTTPRequest -> http://allseeing-i.com/ASIHTTPRequest
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//
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// Created by Ben Copsey on 01/05/2010.
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// Copyright 2010 All-Seeing Interactive. All rights reserved.
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//
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#import "ASIDownloadCache.h"
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#import "ASIHTTPRequest.h"
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#import <CommonCrypto/CommonHMAC.h>
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static ASIDownloadCache *sharedCache = nil;
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static NSString *sessionCacheFolder = @"SessionStore";
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static NSString *permanentCacheFolder = @"PermanentStore";
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static NSArray *fileExtensionsToHandleAsHTML = nil;
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@interface ASIDownloadCache ()
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+ (NSString *)keyForURL:(NSURL *)url;
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- (NSString *)pathToFile:(NSString *)file;
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@end
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@implementation ASIDownloadCache
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+ (void)initialize
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{
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if (self == [ASIDownloadCache class]) {
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// Obviously this is not an exhaustive list, but hopefully these are the most commonly used and this will 'just work' for the widest range of people
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// I imagine many web developers probably use url rewriting anyway
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fileExtensionsToHandleAsHTML = [[NSArray alloc] initWithObjects:@"asp",@"aspx",@"jsp",@"php",@"rb",@"py",@"pl",@"cgi", nil];
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}
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}
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- (id)init
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{
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self = [super init];
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[self setShouldRespectCacheControlHeaders:YES];
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[self setDefaultCachePolicy:ASIUseDefaultCachePolicy];
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[self setAccessLock:[[[NSRecursiveLock alloc] init] autorelease]];
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return self;
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}
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+ (id)sharedCache
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{
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if (!sharedCache) {
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@synchronized(self) {
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if (!sharedCache) {
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sharedCache = [[self alloc] init];
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[sharedCache setStoragePath:[[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:@"ASIHTTPRequestCache"]];
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}
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}
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}
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return sharedCache;
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}
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- (void)dealloc
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{
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[storagePath release];
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[accessLock release];
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[super dealloc];
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}
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- (NSString *)storagePath
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{
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[[self accessLock] lock];
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NSString *p = [[storagePath retain] autorelease];
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[[self accessLock] unlock];
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return p;
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}
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- (void)setStoragePath:(NSString *)path
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{
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[[self accessLock] lock];
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[self clearCachedResponsesForStoragePolicy:ASICacheForSessionDurationCacheStoragePolicy];
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[storagePath release];
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storagePath = [path retain];
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NSFileManager *fileManager = [[[NSFileManager alloc] init] autorelease];
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BOOL isDirectory = NO;
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NSArray *directories = [NSArray arrayWithObjects:path,[path stringByAppendingPathComponent:sessionCacheFolder],[path stringByAppendingPathComponent:permanentCacheFolder],nil];
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for (NSString *directory in directories) {
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BOOL exists = [fileManager fileExistsAtPath:directory isDirectory:&isDirectory];
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if (exists && !isDirectory) {
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[[self accessLock] unlock];
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[NSException raise:@"FileExistsAtCachePath" format:@"Cannot create a directory for the cache at '%@', because a file already exists",directory];
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} else if (!exists) {
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[fileManager createDirectoryAtPath:directory withIntermediateDirectories:NO attributes:nil error:nil];
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if (![fileManager fileExistsAtPath:directory]) {
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[[self accessLock] unlock];
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[NSException raise:@"FailedToCreateCacheDirectory" format:@"Failed to create a directory for the cache at '%@'",directory];
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}
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}
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}
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[self clearCachedResponsesForStoragePolicy:ASICacheForSessionDurationCacheStoragePolicy];
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[[self accessLock] unlock];
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}
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- (void)updateExpiryForRequest:(ASIHTTPRequest *)request maxAge:(NSTimeInterval)maxAge
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{
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NSString *headerPath = [self pathToStoreCachedResponseHeadersForRequest:request];
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NSMutableDictionary *cachedHeaders = [NSMutableDictionary dictionaryWithContentsOfFile:headerPath];
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if (!cachedHeaders) {
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return;
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}
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NSDate *expires = [self expiryDateForRequest:request maxAge:maxAge];
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if (!expires) {
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return;
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}
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[cachedHeaders setObject:[NSNumber numberWithDouble:[expires timeIntervalSince1970]] forKey:@"X-ASIHTTPRequest-Expires"];
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[cachedHeaders writeToFile:headerPath atomically:NO];
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}
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- (NSDate *)expiryDateForRequest:(ASIHTTPRequest *)request maxAge:(NSTimeInterval)maxAge
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{
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return [ASIHTTPRequest expiryDateForRequest:request maxAge:maxAge];
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}
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- (void)storeResponseForRequest:(ASIHTTPRequest *)request maxAge:(NSTimeInterval)maxAge
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{
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[[self accessLock] lock];
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if ([request error] || ![request responseHeaders] || ([request cachePolicy] & ASIDoNotWriteToCacheCachePolicy)) {
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[[self accessLock] unlock];
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return;
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}
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// We only cache 200/OK or redirect reponses (redirect responses are cached so the cache works better with no internet connection)
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int responseCode = [request responseStatusCode];
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if (responseCode != 200 && responseCode != 301 && responseCode != 302 && responseCode != 303 && responseCode != 307) {
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[[self accessLock] unlock];
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return;
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}
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if ([self shouldRespectCacheControlHeaders] && ![[self class] serverAllowsResponseCachingForRequest:request]) {
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[[self accessLock] unlock];
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return;
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}
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NSString *headerPath = [self pathToStoreCachedResponseHeadersForRequest:request];
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NSString *dataPath = [self pathToStoreCachedResponseDataForRequest:request];
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NSMutableDictionary *responseHeaders = [NSMutableDictionary dictionaryWithDictionary:[request responseHeaders]];
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if ([request isResponseCompressed]) {
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[responseHeaders removeObjectForKey:@"Content-Encoding"];
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}
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// Create a special 'X-ASIHTTPRequest-Expires' header
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// This is what we use for deciding if cached data is current, rather than parsing the expires / max-age headers individually each time
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// We store this as a timestamp to make reading it easier as NSDateFormatter is quite expensive
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NSDate *expires = [self expiryDateForRequest:request maxAge:maxAge];
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if (expires) {
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[responseHeaders setObject:[NSNumber numberWithDouble:[expires timeIntervalSince1970]] forKey:@"X-ASIHTTPRequest-Expires"];
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}
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// Store the response code in a custom header so we can reuse it later
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// We'll change 304/Not Modified to 200/OK because this is likely to be us updating the cached headers with a conditional GET
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int statusCode = [request responseStatusCode];
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if (statusCode == 304) {
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statusCode = 200;
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}
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[responseHeaders setObject:[NSNumber numberWithInt:statusCode] forKey:@"X-ASIHTTPRequest-Response-Status-Code"];
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[responseHeaders writeToFile:headerPath atomically:NO];
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if ([request responseData]) {
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[[request responseData] writeToFile:dataPath atomically:NO];
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} else if ([request downloadDestinationPath] && ![[request downloadDestinationPath] isEqualToString:dataPath]) {
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NSError *error = nil;
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NSFileManager* manager = [[NSFileManager alloc] init];
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if ([manager fileExistsAtPath:dataPath]) {
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[manager removeItemAtPath:dataPath error:&error];
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}
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[manager copyItemAtPath:[request downloadDestinationPath] toPath:dataPath error:&error];
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[manager release];
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}
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[[self accessLock] unlock];
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}
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- (NSDictionary *)cachedResponseHeadersForURL:(NSURL *)url
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{
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NSString *path = [self pathToCachedResponseHeadersForURL:url];
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if (path) {
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return [NSDictionary dictionaryWithContentsOfFile:path];
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}
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return nil;
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}
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- (NSData *)cachedResponseDataForURL:(NSURL *)url
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{
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NSString *path = [self pathToCachedResponseDataForURL:url];
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if (path) {
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return [NSData dataWithContentsOfFile:path];
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}
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return nil;
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}
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- (NSString *)pathToCachedResponseDataForURL:(NSURL *)url
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{
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// Grab the file extension, if there is one. We do this so we can save the cached response with the same file extension - this is important if you want to display locally cached data in a web view
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NSString *extension = [[url path] pathExtension];
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// If the url doesn't have an extension, we'll add one so a webview can read it when locally cached
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// If the url has the extension of a common web scripting language, we'll change the extension on the cached path to html for the same reason
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if (![extension length] || [[[self class] fileExtensionsToHandleAsHTML] containsObject:[extension lowercaseString]]) {
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extension = @"html";
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}
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return [self pathToFile:[[[self class] keyForURL:url] stringByAppendingPathExtension:extension]];
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}
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+ (NSArray *)fileExtensionsToHandleAsHTML
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{
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return fileExtensionsToHandleAsHTML;
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}
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- (NSString *)pathToCachedResponseHeadersForURL:(NSURL *)url
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{
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return [self pathToFile:[[[self class] keyForURL:url] stringByAppendingPathExtension:@"cachedheaders"]];
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}
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- (NSString *)pathToFile:(NSString *)file
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{
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[[self accessLock] lock];
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if (![self storagePath]) {
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[[self accessLock] unlock];
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return nil;
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}
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NSFileManager *fileManager = [[[NSFileManager alloc] init] autorelease];
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// Look in the session store
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NSString *dataPath = [[[self storagePath] stringByAppendingPathComponent:sessionCacheFolder] stringByAppendingPathComponent:file];
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if ([fileManager fileExistsAtPath:dataPath]) {
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[[self accessLock] unlock];
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return dataPath;
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}
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// Look in the permanent store
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dataPath = [[[self storagePath] stringByAppendingPathComponent:permanentCacheFolder] stringByAppendingPathComponent:file];
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if ([fileManager fileExistsAtPath:dataPath]) {
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[[self accessLock] unlock];
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return dataPath;
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}
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[[self accessLock] unlock];
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return nil;
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}
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- (NSString *)pathToStoreCachedResponseDataForRequest:(ASIHTTPRequest *)request
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{
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[[self accessLock] lock];
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if (![self storagePath]) {
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[[self accessLock] unlock];
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return nil;
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}
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NSString *path = [[self storagePath] stringByAppendingPathComponent:([request cacheStoragePolicy] == ASICacheForSessionDurationCacheStoragePolicy ? sessionCacheFolder : permanentCacheFolder)];
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// Grab the file extension, if there is one. We do this so we can save the cached response with the same file extension - this is important if you want to display locally cached data in a web view
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NSString *extension = [[[request url] path] pathExtension];
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// If the url doesn't have an extension, we'll add one so a webview can read it when locally cached
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// If the url has the extension of a common web scripting language, we'll change the extension on the cached path to html for the same reason
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if (![extension length] || [[[self class] fileExtensionsToHandleAsHTML] containsObject:[extension lowercaseString]]) {
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extension = @"html";
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}
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path = [path stringByAppendingPathComponent:[[[self class] keyForURL:[request url]] stringByAppendingPathExtension:extension]];
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[[self accessLock] unlock];
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return path;
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}
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- (NSString *)pathToStoreCachedResponseHeadersForRequest:(ASIHTTPRequest *)request
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{
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[[self accessLock] lock];
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if (![self storagePath]) {
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[[self accessLock] unlock];
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return nil;
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}
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NSString *path = [[self storagePath] stringByAppendingPathComponent:([request cacheStoragePolicy] == ASICacheForSessionDurationCacheStoragePolicy ? sessionCacheFolder : permanentCacheFolder)];
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path = [path stringByAppendingPathComponent:[[[self class] keyForURL:[request url]] stringByAppendingPathExtension:@"cachedheaders"]];
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[[self accessLock] unlock];
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return path;
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}
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- (void)removeCachedDataForURL:(NSURL *)url
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{
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[[self accessLock] lock];
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if (![self storagePath]) {
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[[self accessLock] unlock];
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return;
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}
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NSFileManager *fileManager = [[[NSFileManager alloc] init] autorelease];
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NSString *path = [self pathToCachedResponseHeadersForURL:url];
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if (path) {
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[fileManager removeItemAtPath:path error:NULL];
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}
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path = [self pathToCachedResponseDataForURL:url];
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if (path) {
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[fileManager removeItemAtPath:path error:NULL];
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}
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[[self accessLock] unlock];
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}
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- (void)removeCachedDataForRequest:(ASIHTTPRequest *)request
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{
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[self removeCachedDataForURL:[request url]];
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}
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- (BOOL)isCachedDataCurrentForRequest:(ASIHTTPRequest *)request
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{
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[[self accessLock] lock];
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if (![self storagePath]) {
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[[self accessLock] unlock];
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return NO;
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}
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NSDictionary *cachedHeaders = [self cachedResponseHeadersForURL:[request url]];
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if (!cachedHeaders) {
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[[self accessLock] unlock];
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return NO;
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}
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NSString *dataPath = [self pathToCachedResponseDataForURL:[request url]];
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if (!dataPath) {
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[[self accessLock] unlock];
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return NO;
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}
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// New content is not different
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if ([request responseStatusCode] == 304) {
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[[self accessLock] unlock];
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return YES;
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}
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// If we already have response headers for this request, check to see if the new content is different
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// We check [request complete] so that we don't end up comparing response headers from a redirection with these
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if ([request responseHeaders] && [request complete]) {
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// If the Etag or Last-Modified date are different from the one we have, we'll have to fetch this resource again
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NSArray *headersToCompare = [NSArray arrayWithObjects:@"Etag",@"Last-Modified",nil];
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for (NSString *header in headersToCompare) {
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if (![[[request responseHeaders] objectForKey:header] isEqualToString:[cachedHeaders objectForKey:header]]) {
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[[self accessLock] unlock];
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return NO;
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}
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}
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}
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if ([self shouldRespectCacheControlHeaders]) {
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// Look for X-ASIHTTPRequest-Expires header to see if the content is out of date
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NSNumber *expires = [cachedHeaders objectForKey:@"X-ASIHTTPRequest-Expires"];
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if (expires) {
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if ([[NSDate dateWithTimeIntervalSince1970:[expires doubleValue]] timeIntervalSinceNow] >= 0) {
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[[self accessLock] unlock];
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return YES;
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}
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}
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// No explicit expiration time sent by the server
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[[self accessLock] unlock];
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return NO;
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}
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[[self accessLock] unlock];
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return YES;
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}
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- (ASICachePolicy)defaultCachePolicy
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{
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[[self accessLock] lock];
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ASICachePolicy cp = defaultCachePolicy;
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[[self accessLock] unlock];
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return cp;
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}
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- (void)setDefaultCachePolicy:(ASICachePolicy)cachePolicy
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{
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[[self accessLock] lock];
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if (!cachePolicy) {
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defaultCachePolicy = ASIAskServerIfModifiedWhenStaleCachePolicy;
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} else {
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defaultCachePolicy = cachePolicy;
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}
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[[self accessLock] unlock];
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}
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- (void)clearCachedResponsesForStoragePolicy:(ASICacheStoragePolicy)storagePolicy
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{
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[[self accessLock] lock];
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if (![self storagePath]) {
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[[self accessLock] unlock];
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return;
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}
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NSString *path = [[self storagePath] stringByAppendingPathComponent:(storagePolicy == ASICacheForSessionDurationCacheStoragePolicy ? sessionCacheFolder : permanentCacheFolder)];
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NSFileManager *fileManager = [[[NSFileManager alloc] init] autorelease];
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BOOL isDirectory = NO;
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BOOL exists = [fileManager fileExistsAtPath:path isDirectory:&isDirectory];
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if (!exists || !isDirectory) {
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[[self accessLock] unlock];
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return;
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}
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NSError *error = nil;
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NSArray *cacheFiles = [fileManager contentsOfDirectoryAtPath:path error:&error];
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if (error) {
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[[self accessLock] unlock];
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[NSException raise:@"FailedToTraverseCacheDirectory" format:@"Listing cache directory failed at path '%@'",path];
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}
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for (NSString *file in cacheFiles) {
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[fileManager removeItemAtPath:[path stringByAppendingPathComponent:file] error:&error];
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if (error) {
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[[self accessLock] unlock];
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[NSException raise:@"FailedToRemoveCacheFile" format:@"Failed to remove cached data at path '%@'",path];
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}
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}
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[[self accessLock] unlock];
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}
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+ (BOOL)serverAllowsResponseCachingForRequest:(ASIHTTPRequest *)request
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{
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NSString *cacheControl = [[[request responseHeaders] objectForKey:@"Cache-Control"] lowercaseString];
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if (cacheControl) {
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if ([cacheControl isEqualToString:@"no-cache"] || [cacheControl isEqualToString:@"no-store"]) {
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return NO;
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}
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}
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NSString *pragma = [[[request responseHeaders] objectForKey:@"Pragma"] lowercaseString];
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if (pragma) {
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if ([pragma isEqualToString:@"no-cache"]) {
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return NO;
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}
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}
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return YES;
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}
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+ (NSString *)keyForURL:(NSURL *)url
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{
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NSString *urlString = [url absoluteString];
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if ([urlString length] == 0) {
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return nil;
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}
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// Strip trailing slashes so http://allseeing-i.com/ASIHTTPRequest/ is cached the same as http://allseeing-i.com/ASIHTTPRequest
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if ([[urlString substringFromIndex:[urlString length]-1] isEqualToString:@"/"]) {
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urlString = [urlString substringToIndex:[urlString length]-1];
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}
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// Borrowed from: http://stackoverflow.com/questions/652300/using-md5-hash-on-a-string-in-cocoa
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const char *cStr = [urlString UTF8String];
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unsigned char result[16];
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CC_MD5(cStr, (CC_LONG)strlen(cStr), result);
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return [NSString stringWithFormat:@"%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",result[0], result[1], result[2], result[3], result[4], result[5], result[6], result[7],result[8], result[9], result[10], result[11],result[12], result[13], result[14], result[15]];
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}
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- (BOOL)canUseCachedDataForRequest:(ASIHTTPRequest *)request
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{
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// Ensure the request is allowed to read from the cache
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if ([request cachePolicy] & ASIDoNotReadFromCacheCachePolicy) {
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return NO;
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// If we don't want to load the request whatever happens, always pretend we have cached data even if we don't
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} else if ([request cachePolicy] & ASIDontLoadCachePolicy) {
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return YES;
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}
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NSDictionary *headers = [self cachedResponseHeadersForURL:[request url]];
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if (!headers) {
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return NO;
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}
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NSString *dataPath = [self pathToCachedResponseDataForURL:[request url]];
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if (!dataPath) {
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return NO;
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}
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// If we get here, we have cached data
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// If we have cached data, we can use it
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if ([request cachePolicy] & ASIOnlyLoadIfNotCachedCachePolicy) {
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return YES;
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// If we want to fallback to the cache after an error
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} else if ([request complete] && [request cachePolicy] & ASIFallbackToCacheIfLoadFailsCachePolicy) {
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return YES;
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// If we have cached data that is current, we can use it
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} else if ([request cachePolicy] & ASIAskServerIfModifiedWhenStaleCachePolicy) {
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if ([self isCachedDataCurrentForRequest:request]) {
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return YES;
|
|
}
|
|
|
|
// If we've got headers from a conditional GET and the cached data is still current, we can use it
|
|
} else if ([request cachePolicy] & ASIAskServerIfModifiedCachePolicy) {
|
|
if (![request responseHeaders]) {
|
|
return NO;
|
|
} else if ([self isCachedDataCurrentForRequest:request]) {
|
|
return YES;
|
|
}
|
|
}
|
|
return NO;
|
|
}
|
|
|
|
@synthesize storagePath;
|
|
@synthesize defaultCachePolicy;
|
|
@synthesize accessLock;
|
|
@synthesize shouldRespectCacheControlHeaders;
|
|
@end
|