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executable file 515 lines (438 sloc) 17.761 kb
//
// ASIDownloadCache.m
// Part of ASIHTTPRequest -> http://allseeing-i.com/ASIHTTPRequest
//
// Created by Ben Copsey on 01/05/2010.
// Copyright 2010 All-Seeing Interactive. All rights reserved.
//
#import "ASIDownloadCache.h"
#import "ASIHTTPRequest.h"
#import <CommonCrypto/CommonHMAC.h>
static ASIDownloadCache *sharedCache = nil;
static NSString *sessionCacheFolder = @"SessionStore";
static NSString *permanentCacheFolder = @"PermanentStore";
static NSArray *fileExtensionsToHandleAsHTML = nil;
@interface ASIDownloadCache ()
+ (NSString *)keyForURL:(NSURL *)url;
- (NSString *)pathToFile:(NSString *)file;
@end
@implementation ASIDownloadCache
+ (void)initialize
{
if (self == [ASIDownloadCache class]) {
// 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
// I imagine many web developers probably use url rewriting anyway
fileExtensionsToHandleAsHTML = [[NSArray alloc] initWithObjects:@"asp",@"aspx",@"jsp",@"php",@"rb",@"py",@"pl",@"cgi", nil];
}
}
- (id)init
{
self = [super init];
[self setShouldRespectCacheControlHeaders:YES];
[self setDefaultCachePolicy:ASIUseDefaultCachePolicy];
[self setAccessLock:[[[NSRecursiveLock alloc] init] autorelease]];
return self;
}
+ (id)sharedCache
{
if (!sharedCache) {
@synchronized(self) {
if (!sharedCache) {
sharedCache = [[self alloc] init];
[sharedCache setStoragePath:[[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:@"ASIHTTPRequestCache"]];
}
}
}
return sharedCache;
}
- (void)dealloc
{
[storagePath release];
[accessLock release];
[super dealloc];
}
- (NSString *)storagePath
{
[[self accessLock] lock];
NSString *p = [[storagePath retain] autorelease];
[[self accessLock] unlock];
return p;
}
- (void)setStoragePath:(NSString *)path
{
[[self accessLock] lock];
[self clearCachedResponsesForStoragePolicy:ASICacheForSessionDurationCacheStoragePolicy];
[storagePath release];
storagePath = [path retain];
NSFileManager *fileManager = [[[NSFileManager alloc] init] autorelease];
BOOL isDirectory = NO;
NSArray *directories = [NSArray arrayWithObjects:path,[path stringByAppendingPathComponent:sessionCacheFolder],[path stringByAppendingPathComponent:permanentCacheFolder],nil];
for (NSString *directory in directories) {
BOOL exists = [fileManager fileExistsAtPath:directory isDirectory:&isDirectory];
if (exists && !isDirectory) {
[[self accessLock] unlock];
[NSException raise:@"FileExistsAtCachePath" format:@"Cannot create a directory for the cache at '%@', because a file already exists",directory];
} else if (!exists) {
[fileManager createDirectoryAtPath:directory withIntermediateDirectories:NO attributes:nil error:nil];
if (![fileManager fileExistsAtPath:directory]) {
[[self accessLock] unlock];
[NSException raise:@"FailedToCreateCacheDirectory" format:@"Failed to create a directory for the cache at '%@'",directory];
}
}
}
[self clearCachedResponsesForStoragePolicy:ASICacheForSessionDurationCacheStoragePolicy];
[[self accessLock] unlock];
}
- (void)updateExpiryForRequest:(ASIHTTPRequest *)request maxAge:(NSTimeInterval)maxAge
{
NSString *headerPath = [self pathToStoreCachedResponseHeadersForRequest:request];
NSMutableDictionary *cachedHeaders = [NSMutableDictionary dictionaryWithContentsOfFile:headerPath];
if (!cachedHeaders) {
return;
}
NSDate *expires = [self expiryDateForRequest:request maxAge:maxAge];
if (!expires) {
return;
}
[cachedHeaders setObject:[NSNumber numberWithDouble:[expires timeIntervalSince1970]] forKey:@"X-ASIHTTPRequest-Expires"];
[cachedHeaders writeToFile:headerPath atomically:NO];
}
- (NSDate *)expiryDateForRequest:(ASIHTTPRequest *)request maxAge:(NSTimeInterval)maxAge
{
return [ASIHTTPRequest expiryDateForRequest:request maxAge:maxAge];
}
- (void)storeResponseForRequest:(ASIHTTPRequest *)request maxAge:(NSTimeInterval)maxAge
{
[[self accessLock] lock];
if ([request error] || ![request responseHeaders] || ([request cachePolicy] & ASIDoNotWriteToCacheCachePolicy)) {
[[self accessLock] unlock];
return;
}
// We only cache 200/OK or redirect reponses (redirect responses are cached so the cache works better with no internet connection)
int responseCode = [request responseStatusCode];
if (responseCode != 200 && responseCode != 301 && responseCode != 302 && responseCode != 303 && responseCode != 307) {
[[self accessLock] unlock];
return;
}
if ([self shouldRespectCacheControlHeaders] && ![[self class] serverAllowsResponseCachingForRequest:request]) {
[[self accessLock] unlock];
return;
}
NSString *headerPath = [self pathToStoreCachedResponseHeadersForRequest:request];
NSString *dataPath = [self pathToStoreCachedResponseDataForRequest:request];
NSMutableDictionary *responseHeaders = [NSMutableDictionary dictionaryWithDictionary:[request responseHeaders]];
if ([request isResponseCompressed]) {
[responseHeaders removeObjectForKey:@"Content-Encoding"];
}
// Create a special 'X-ASIHTTPRequest-Expires' header
// This is what we use for deciding if cached data is current, rather than parsing the expires / max-age headers individually each time
// We store this as a timestamp to make reading it easier as NSDateFormatter is quite expensive
NSDate *expires = [self expiryDateForRequest:request maxAge:maxAge];
if (expires) {
[responseHeaders setObject:[NSNumber numberWithDouble:[expires timeIntervalSince1970]] forKey:@"X-ASIHTTPRequest-Expires"];
}
// Store the response code in a custom header so we can reuse it later
// We'll change 304/Not Modified to 200/OK because this is likely to be us updating the cached headers with a conditional GET
int statusCode = [request responseStatusCode];
if (statusCode == 304) {
statusCode = 200;
}
[responseHeaders setObject:[NSNumber numberWithInt:statusCode] forKey:@"X-ASIHTTPRequest-Response-Status-Code"];
[responseHeaders writeToFile:headerPath atomically:NO];
if ([request responseData]) {
[[request responseData] writeToFile:dataPath atomically:NO];
} else if ([request downloadDestinationPath] && ![[request downloadDestinationPath] isEqualToString:dataPath]) {
NSError *error = nil;
NSFileManager* manager = [[NSFileManager alloc] init];
if ([manager fileExistsAtPath:dataPath]) {
[manager removeItemAtPath:dataPath error:&error];
}
[manager copyItemAtPath:[request downloadDestinationPath] toPath:dataPath error:&error];
[manager release];
}
[[self accessLock] unlock];
}
- (NSDictionary *)cachedResponseHeadersForURL:(NSURL *)url
{
NSString *path = [self pathToCachedResponseHeadersForURL:url];
if (path) {
return [NSDictionary dictionaryWithContentsOfFile:path];
}
return nil;
}
- (NSData *)cachedResponseDataForURL:(NSURL *)url
{
NSString *path = [self pathToCachedResponseDataForURL:url];
if (path) {
return [NSData dataWithContentsOfFile:path];
}
return nil;
}
- (NSString *)pathToCachedResponseDataForURL:(NSURL *)url
{
// 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
NSString *extension = [[url path] pathExtension];
// If the url doesn't have an extension, we'll add one so a webview can read it when locally cached
// 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
if (![extension length] || [[[self class] fileExtensionsToHandleAsHTML] containsObject:[extension lowercaseString]]) {
extension = @"html";
}
return [self pathToFile:[[[self class] keyForURL:url] stringByAppendingPathExtension:extension]];
}
+ (NSArray *)fileExtensionsToHandleAsHTML
{
return fileExtensionsToHandleAsHTML;
}
- (NSString *)pathToCachedResponseHeadersForURL:(NSURL *)url
{
return [self pathToFile:[[[self class] keyForURL:url] stringByAppendingPathExtension:@"cachedheaders"]];
}
- (NSString *)pathToFile:(NSString *)file
{
[[self accessLock] lock];
if (![self storagePath]) {
[[self accessLock] unlock];
return nil;
}
NSFileManager *fileManager = [[[NSFileManager alloc] init] autorelease];
// Look in the session store
NSString *dataPath = [[[self storagePath] stringByAppendingPathComponent:sessionCacheFolder] stringByAppendingPathComponent:file];
if ([fileManager fileExistsAtPath:dataPath]) {
[[self accessLock] unlock];
return dataPath;
}
// Look in the permanent store
dataPath = [[[self storagePath] stringByAppendingPathComponent:permanentCacheFolder] stringByAppendingPathComponent:file];
if ([fileManager fileExistsAtPath:dataPath]) {
[[self accessLock] unlock];
return dataPath;
}
[[self accessLock] unlock];
return nil;
}
- (NSString *)pathToStoreCachedResponseDataForRequest:(ASIHTTPRequest *)request
{
[[self accessLock] lock];
if (![self storagePath]) {
[[self accessLock] unlock];
return nil;
}
NSString *path = [[self storagePath] stringByAppendingPathComponent:([request cacheStoragePolicy] == ASICacheForSessionDurationCacheStoragePolicy ? sessionCacheFolder : permanentCacheFolder)];
// 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
NSString *extension = [[[request url] path] pathExtension];
// If the url doesn't have an extension, we'll add one so a webview can read it when locally cached
// 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
if (![extension length] || [[[self class] fileExtensionsToHandleAsHTML] containsObject:[extension lowercaseString]]) {
extension = @"html";
}
path = [path stringByAppendingPathComponent:[[[self class] keyForURL:[request url]] stringByAppendingPathExtension:extension]];
[[self accessLock] unlock];
return path;
}
- (NSString *)pathToStoreCachedResponseHeadersForRequest:(ASIHTTPRequest *)request
{
[[self accessLock] lock];
if (![self storagePath]) {
[[self accessLock] unlock];
return nil;
}
NSString *path = [[self storagePath] stringByAppendingPathComponent:([request cacheStoragePolicy] == ASICacheForSessionDurationCacheStoragePolicy ? sessionCacheFolder : permanentCacheFolder)];
path = [path stringByAppendingPathComponent:[[[self class] keyForURL:[request url]] stringByAppendingPathExtension:@"cachedheaders"]];
[[self accessLock] unlock];
return path;
}
- (void)removeCachedDataForURL:(NSURL *)url
{
[[self accessLock] lock];
if (![self storagePath]) {
[[self accessLock] unlock];
return;
}
NSFileManager *fileManager = [[[NSFileManager alloc] init] autorelease];
NSString *path = [self pathToCachedResponseHeadersForURL:url];
if (path) {
[fileManager removeItemAtPath:path error:NULL];
}
path = [self pathToCachedResponseDataForURL:url];
if (path) {
[fileManager removeItemAtPath:path error:NULL];
}
[[self accessLock] unlock];
}
- (void)removeCachedDataForRequest:(ASIHTTPRequest *)request
{
[self removeCachedDataForURL:[request url]];
}
- (BOOL)isCachedDataCurrentForRequest:(ASIHTTPRequest *)request
{
[[self accessLock] lock];
if (![self storagePath]) {
[[self accessLock] unlock];
return NO;
}
NSDictionary *cachedHeaders = [self cachedResponseHeadersForURL:[request url]];
if (!cachedHeaders) {
[[self accessLock] unlock];
return NO;
}
NSString *dataPath = [self pathToCachedResponseDataForURL:[request url]];
if (!dataPath) {
[[self accessLock] unlock];
return NO;
}
// New content is not different
if ([request responseStatusCode] == 304) {
[[self accessLock] unlock];
return YES;
}
// If we already have response headers for this request, check to see if the new content is different
// We check [request complete] so that we don't end up comparing response headers from a redirection with these
if ([request responseHeaders] && [request complete]) {
// If the Etag or Last-Modified date are different from the one we have, we'll have to fetch this resource again
NSArray *headersToCompare = [NSArray arrayWithObjects:@"Etag",@"Last-Modified",nil];
for (NSString *header in headersToCompare) {
if (![[[request responseHeaders] objectForKey:header] isEqualToString:[cachedHeaders objectForKey:header]]) {
[[self accessLock] unlock];
return NO;
}
}
}
if ([self shouldRespectCacheControlHeaders]) {
// Look for X-ASIHTTPRequest-Expires header to see if the content is out of date
NSNumber *expires = [cachedHeaders objectForKey:@"X-ASIHTTPRequest-Expires"];
if (expires) {
if ([[NSDate dateWithTimeIntervalSince1970:[expires doubleValue]] timeIntervalSinceNow] >= 0) {
[[self accessLock] unlock];
return YES;
}
}
// No explicit expiration time sent by the server
[[self accessLock] unlock];
return NO;
}
[[self accessLock] unlock];
return YES;
}
- (ASICachePolicy)defaultCachePolicy
{
[[self accessLock] lock];
ASICachePolicy cp = defaultCachePolicy;
[[self accessLock] unlock];
return cp;
}
- (void)setDefaultCachePolicy:(ASICachePolicy)cachePolicy
{
[[self accessLock] lock];
if (!cachePolicy) {
defaultCachePolicy = ASIAskServerIfModifiedWhenStaleCachePolicy;
} else {
defaultCachePolicy = cachePolicy;
}
[[self accessLock] unlock];
}
- (void)clearCachedResponsesForStoragePolicy:(ASICacheStoragePolicy)storagePolicy
{
[[self accessLock] lock];
if (![self storagePath]) {
[[self accessLock] unlock];
return;
}
NSString *path = [[self storagePath] stringByAppendingPathComponent:(storagePolicy == ASICacheForSessionDurationCacheStoragePolicy ? sessionCacheFolder : permanentCacheFolder)];
NSFileManager *fileManager = [[[NSFileManager alloc] init] autorelease];
BOOL isDirectory = NO;
BOOL exists = [fileManager fileExistsAtPath:path isDirectory:&isDirectory];
if (!exists || !isDirectory) {
[[self accessLock] unlock];
return;
}
NSError *error = nil;
NSArray *cacheFiles = [fileManager contentsOfDirectoryAtPath:path error:&error];
if (error) {
[[self accessLock] unlock];
[NSException raise:@"FailedToTraverseCacheDirectory" format:@"Listing cache directory failed at path '%@'",path];
}
for (NSString *file in cacheFiles) {
[fileManager removeItemAtPath:[path stringByAppendingPathComponent:file] error:&error];
if (error) {
[[self accessLock] unlock];
[NSException raise:@"FailedToRemoveCacheFile" format:@"Failed to remove cached data at path '%@'",path];
}
}
[[self accessLock] unlock];
}
+ (BOOL)serverAllowsResponseCachingForRequest:(ASIHTTPRequest *)request
{
NSString *cacheControl = [[[request responseHeaders] objectForKey:@"Cache-Control"] lowercaseString];
if (cacheControl) {
if ([cacheControl isEqualToString:@"no-cache"] || [cacheControl isEqualToString:@"no-store"]) {
return NO;
}
}
NSString *pragma = [[[request responseHeaders] objectForKey:@"Pragma"] lowercaseString];
if (pragma) {
if ([pragma isEqualToString:@"no-cache"]) {
return NO;
}
}
return YES;
}
+ (NSString *)keyForURL:(NSURL *)url
{
NSString *urlString = [url absoluteString];
if ([urlString length] == 0) {
return nil;
}
// Strip trailing slashes so http://allseeing-i.com/ASIHTTPRequest/ is cached the same as http://allseeing-i.com/ASIHTTPRequest
if ([[urlString substringFromIndex:[urlString length]-1] isEqualToString:@"/"]) {
urlString = [urlString substringToIndex:[urlString length]-1];
}
// Borrowed from: http://stackoverflow.com/questions/652300/using-md5-hash-on-a-string-in-cocoa
const char *cStr = [urlString UTF8String];
unsigned char result[16];
CC_MD5(cStr, (CC_LONG)strlen(cStr), result);
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]];
}
- (BOOL)canUseCachedDataForRequest:(ASIHTTPRequest *)request
{
// Ensure the request is allowed to read from the cache
if ([request cachePolicy] & ASIDoNotReadFromCacheCachePolicy) {
return NO;
// If we don't want to load the request whatever happens, always pretend we have cached data even if we don't
} else if ([request cachePolicy] & ASIDontLoadCachePolicy) {
return YES;
}
NSDictionary *headers = [self cachedResponseHeadersForURL:[request url]];
if (!headers) {
return NO;
}
NSString *dataPath = [self pathToCachedResponseDataForURL:[request url]];
if (!dataPath) {
return NO;
}
// If we get here, we have cached data
// If we have cached data, we can use it
if ([request cachePolicy] & ASIOnlyLoadIfNotCachedCachePolicy) {
return YES;
// If we want to fallback to the cache after an error
} else if ([request complete] && [request cachePolicy] & ASIFallbackToCacheIfLoadFailsCachePolicy) {
return YES;
// If we have cached data that is current, we can use it
} else if ([request cachePolicy] & ASIAskServerIfModifiedWhenStaleCachePolicy) {
if ([self isCachedDataCurrentForRequest:request]) {
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
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