keychain/ot/OctagonStateMachineHelpers.m

   1 /*
   2  * Copyright (c) 2018 Apple Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #if OCTAGON
  25
  26 #import "keychain/ot/OTStates.h"
  27 #import "keychain/ot/ObjCImprovements.h"
  28 #import "keychain/ot/OTDefines.h"
  29 #import "keychain/ot/OTConstants.h"
  30 #import "keychain/categories/NSError+UsefulConstructors.h"
  31
  32 OctagonState* const OctagonStateMachineNotStarted = (OctagonState*) @"not_started";
  33 OctagonState* const OctagonStateMachineHalted = (OctagonState*) @"halted";
  34
  35 @implementation OctagonStateTransitionOperation : CKKSResultOperation
  36 - (instancetype)initIntending:(OctagonState*)intendedState
  37                    errorState:(OctagonState*)errorState
  38 {
  39     if((self = [super init])) {
  40         _nextState = errorState;
  41         _intendedState = intendedState;
  42     }
  43     return self;
  44 }
  45
  46 - (NSString*)description
  47 {
  48     return [NSString stringWithFormat:@"<OctagonStateTransitionOperation(%@): intended:%@ actual:%@>", self.name, self.intendedState, self.nextState];
  49 }
  50
  51 + (instancetype)named:(NSString*)name
  52             intending:(OctagonState*)intendedState
  53            errorState:(OctagonState*)errorState
  54               timeout:(dispatch_time_t)timeout
  55   withBlockTakingSelf:(void(^)(OctagonStateTransitionOperation* op))block
  56 {
  57     OctagonStateTransitionOperation* op = [[self alloc] initIntending:intendedState
  58                                                            errorState:errorState];
  59     WEAKIFY(op);
  60     [op addExecutionBlock:^{
  61         STRONGIFY(op);
  62         block(op);
  63     }];
  64     op.name = name;
  65     [op timeout:timeout];
  66     return op;
  67 }
  68
  69 + (instancetype)named:(NSString*)name
  70              entering:(OctagonState*)intendedState
  71 {
  72     OctagonStateTransitionOperation* op = [[self alloc] initIntending:intendedState
  73                                                            errorState:intendedState];
  74     op.name = name;
  75     return op;
  76 }
  77 @end
  78
  79 @interface OctagonStateTransitionRequest ()
  80 @property dispatch_queue_t queue;
  81 @property bool timeoutCanOccur;
  82 @end
  83
  84 @implementation OctagonStateTransitionRequest
  85
  86 - (instancetype)init:(NSString*)name
  87         sourceStates:(NSSet<OctagonState*>*)sourceStates
  88          serialQueue:(dispatch_queue_t)queue
  89              timeout:(dispatch_time_t)timeout
  90         transitionOp:(CKKSResultOperation<OctagonStateTransitionOperationProtocol>*)transitionOp
  91 {
  92     if((self = [super init])) {
  93         _name = name;
  94         _sourceStates = sourceStates;
  95         _queue = queue;
  96
  97         _timeoutCanOccur = true;
  98         _transitionOperation = transitionOp;
  99     }
 100
 101     [self timeout:timeout];
 102
 103     return self;
 104 }
 105
 106 - (NSString*)description
 107 {
 108     return [NSString stringWithFormat:@"<OctagonStateTransitionRequest: %@ %@ %@>", self.name, self.transitionOperation, self.sourceStates];
 109 }
 110
 111 - (CKKSResultOperation<OctagonStateTransitionOperationProtocol>* _Nullable)_onqueueStart
 112 {
 113     dispatch_assert_queue(self.queue);
 114
 115     if(self.timeoutCanOccur) {
 116         self.timeoutCanOccur = false;
 117         return self.transitionOperation;
 118     } else {
 119         return nil;
 120     }
 121 }
 122
 123 - (instancetype)timeout:(dispatch_time_t)timeout
 124 {
 125     WEAKIFY(self);
 126     dispatch_after(dispatch_time(DISPATCH_TIME_NOW, timeout), self.queue, ^{
 127         STRONGIFY(self);
 128         if(self.timeoutCanOccur) {
 129             self.timeoutCanOccur = false;
 130
 131             // The operation will only realize it's finished once added to any operation queue. Fake one up.
 132             [self.transitionOperation timeout:0*NSEC_PER_SEC];
 133             [[[NSOperationQueue alloc] init] addOperation:self.transitionOperation];
 134         }
 135     });
 136
 137     return self;
 138 }
 139
 140 @end
 141
 142 #endif // OCTAGON