keychain/ckks/RateLimiter.h

   1 /*
   2  * Copyright (c) 2017 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 #ifndef RateLimiter_h
  25 #define RateLimiter_h
  26
  27 #import <Foundation/Foundation.h>
  28
  29 @interface RateLimiter : NSObject <NSSecureCoding>
  30
  31 @property (readonly, nonatomic, nonnull) NSDictionary *config;
  32 @property (readonly, nonatomic) NSUInteger stateSize;
  33 @property (readonly, nonatomic, nullable) NSString *assetType;
  34
  35 typedef NS_ENUM(NSInteger, RateLimiterBadness) {
  36     RateLimiterBadnessClear = 0,            // everything is fine, process right now
  37     RateLimiterBadnessCongested,
  38     RateLimiterBadnessSeverelyCongested,
  39     RateLimiterBadnessGridlocked,
  40     RateLimiterBadnessOverloaded,           // everything is on fire, go away
  41 };
  42
  43 - (instancetype _Nullable)initWithConfig:(NSDictionary * _Nonnull)config;
  44 - (instancetype _Nullable)initWithPlistFromURL:(NSURL * _Nonnull)url;
  45 - (instancetype _Nullable)initWithAssetType:(NSString * _Nonnull)type;  // Not implemented yet
  46 - (instancetype _Nullable)initWithCoder:(NSCoder * _Nonnull)coder;
  47 - (instancetype _Nullable)init NS_UNAVAILABLE;
  48
  49 /*!
  50  * @brief Find out whether objects may be processed or must wait.
  51  * @param obj The object being judged.
  52  * @param time Current time.
  53  * @param limitTime Assigned okay-to-process time. Nil when object may be processed immediately.
  54  * @return RateLimiterBadness enum value indicating current congestion situation, or to signal
  55  *
  56  * judge:at: will set the limitTime object to nil in case of 0 badness. For badnesses 1-4 the time object will indicate when it is okay to send the entry.
  57  * At badness 5 judge:at: has determined there is too much activity so the caller should hold off altogether. The limitTime object will indicate when
  58  * this overloaded state will end.
  59  */
  60 - (NSInteger)judge:(id _Nonnull)obj at:(NSDate * _Nonnull)time limitTime:(NSDate * _Nullable __autoreleasing * _Nonnull)limitTime;
  61
  62 - (void)reset;
  63 - (NSString * _Nonnull)diagnostics;
  64 + (BOOL)supportsSecureCoding;
  65
  66 // TODO:
  67 // implement config loading from MobileAsset
  68
  69 @end
  70
  71 #endif /* RateLimiter_h */
  72
  73 /* Annotated example plist
  74
  75 <?xml version="1.0" encoding="UTF-8"?>
  76 <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
  77 <plist version="1.0">
  78 <dict>
  79     <key>general</key>
  80     <dict>
  81         <!-- Total item limit -->
  82         <key>maxStateSize</key>
  83         <integer>250</integer>
  84         <!-- Throw away items after this many seconds -->
  85         <key>maxItemAge</key>
  86         <integer>3600</integer>
  87         <!-- Ignore everybody for this many seconds -->
  88         <key>overloadDuration</key>
  89         <integer>1800</integer>
  90         <!-- Printable string for logs -->
  91         <key>name</key>
  92         <string>CKKS</string>
  93         <!-- Load config stored in this MobileAsset (ignored if inited with config or plist directly) -->
  94         <key>MAType</key>
  95         <string></string>
  96         <!-- Use this property for AWD's topWriters metric -->
  97         <key>topOffendersPropertyIndex</key>
  98         <integer></integer>
  99     </dict>
 100     <!-- Each property you want to ratelimit on must have its own group dictionary -->
 101     <key>groups</key>
 102     <array>
 103         <dict>
 104             <!-- The first group must be for the global bucket. It behaves identically otherwise -->
 105             <key>property</key>
 106             <string>global</string>
 107             <key>capacity</key>
 108             <integer>20</integer>
 109             <key>rate</key>
 110             <integer>30</integer>
 111             <key>badness</key>
 112             <integer>1</integer>
 113         </dict>
 114         <dict>
 115             <!-- Your object must respond to this selector that takes no arguments by returning an NSString * -->
 116             <key>property</key>
 117             <string>UUID</string>
 118             <!-- Buckets of this type hold at most this many tokens -->
 119             <key>capacity</key>
 120             <integer>3</integer>
 121             <!-- Tokens replenish at 1 every this many seconds -->
 122             <key>rate</key>
 123             <integer>600</integer>
 124             <!-- Max of all empty bucket badnesses is returned to caller. See RateLimiterBadness enum -->
 125             <key>badness</key>
 126             <integer>3</integer>
 127         </dict>
 128     </array>
 129 </dict>
 130 </plist>
 131
 132 */