TrustURLSessionCache.m   [plain text]

/*
* Copyright (c) 2020 Apple Inc. All Rights Reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this
* file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
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* @APPLE_LICENSE_HEADER_END@
*
*/

#import <Foundation/Foundation.h>
#import <CFNetwork/CFNSURLConnection.h>
#include <Security/SecInternalReleasePriv.h>
#include <utilities/debugging.h>

#include "trust/trustd/TrustURLSessionDelegate.h"
#include "trust/trustd/TrustURLSessionCache.h"

#define MAX_CACHED_SESSIONS 20
const NSString *TrustdUserAgent = @"com.apple.trustd/2.1";

static NSTimeInterval TrustURLSessionGetResourceTimeout(void) {
return (NSTimeInterval)3.0;
}

@interface TrustURLSessionCache()
@property TrustURLSessionDelegate *delegate;
@property NSMutableDictionary <NSData *, NSURLSession *>* _clientSessionMap;
@property NSMutableArray <NSData *>* _clientLRUList;
@end

@implementation TrustURLSessionCache

- (instancetype)initWithDelegate:(TrustURLSessionDelegate *)delegate
{
if (self = [super init]) {
self.delegate = delegate;
self._clientSessionMap = [NSMutableDictionary dictionaryWithCapacity:MAX_CACHED_SESSIONS];
self._clientLRUList = [NSMutableArray arrayWithCapacity:(MAX_CACHED_SESSIONS + 1)];
}
return self;
}

- (NSURLSession *)createSessionForAuditToken:(NSData *)auditToken
{
NSURLSessionConfiguration *config = [NSURLSessionConfiguration ephemeralSessionConfiguration];
config.timeoutIntervalForResource = TrustURLSessionGetResourceTimeout();
config.HTTPAdditionalHeaders = @{@"User-Agent" : TrustdUserAgent};
config._sourceApplicationAuditTokenData = auditToken;

NSOperationQueue *queue = [[NSOperationQueue alloc] init];

NSURLSession *session = [NSURLSession sessionWithConfiguration:config delegate:self.delegate delegateQueue:queue];
return session;
}

- (NSURLSession *)sessionForAuditToken:(NSData *)auditToken
{
@synchronized (self._clientLRUList) {
NSURLSession *result = [self._clientSessionMap objectForKey:auditToken];
if (result) {
/* insert the client to the front of the LRU list */
[self._clientLRUList removeObject:auditToken];
[self._clientLRUList insertObject:auditToken atIndex:0];
secdebug("http", "re-using session for %@", auditToken);
return result;
}
/* Cache miss: create new session */
result = [self createSessionForAuditToken:auditToken];
[self._clientLRUList insertObject:auditToken atIndex:0];
[self._clientSessionMap setObject:result forKey:auditToken];
secdebug("http", "creating session for %@", auditToken);
if (self._clientLRUList.count > MAX_CACHED_SESSIONS) {
/* close the excess NSURLSession and remove it from our cache */
NSData *removeToken = [self._clientLRUList objectAtIndex:(self._clientLRUList.count - 1)];
NSURLSession *removeSession = [self._clientSessionMap objectForKey:removeToken];
[removeSession finishTasksAndInvalidate];
[self._clientSessionMap removeObjectForKey:removeToken];
[self._clientLRUList removeLastObject];
secdebug("http", "removing session for %@", removeToken);
}
return result;
}
}

@end