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 #import <Foundation/Foundation.h>
  25
  26 NS_ASSUME_NONNULL_BEGIN
  27
  28 @interface RateLimiter : NSObject <NSSecureCoding>
  29
  30 @property (readonly, nonatomic) NSDictionary* config;
  31 @property (readonly, nonatomic) NSUInteger stateSize;
  32 @property (readonly, nonatomic, nullable) NSString* assetType;
  33
  34 typedef NS_ENUM(NSInteger, RateLimiterBadness) {
  35     RateLimiterBadnessClear = 0,  // everything is fine, process right now
  36     RateLimiterBadnessCongested,
  37     RateLimiterBadnessSeverelyCongested,
  38     RateLimiterBadnessGridlocked,
  39     RateLimiterBadnessOverloaded,  // everything is on fire, go away
  40 };
  41
  42 - (instancetype _Nullable)initWithConfig:(NSDictionary*)config;
  43 - (instancetype _Nullable)initWithCoder:(NSCoder*)coder;
  44 - (instancetype _Nullable)init NS_UNAVAILABLE;
  45
  46 /*!
  47  * @brief Find out whether objects may be processed or must wait.
  48  * @param obj The object being judged.
  49  * @param time Current time.
  50  * @param limitTime Assigned okay-to-process time. Nil when object may be processed immediately.
  51  * @return RateLimiterBadness enum value indicating current congestion situation, or to signal
  52  *
  53  * 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.
  54  * 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
  55  * this overloaded state will end.
  56  */
  57 - (RateLimiterBadness)judge:(id)obj at:(NSDate*)time limitTime:(NSDate* _Nonnull __autoreleasing* _Nonnull)limitTime;
  58
  59 - (void)reset;
  60 - (NSString*)diagnostics;
  61 + (BOOL)supportsSecureCoding;
  62
  63 // TODO:
  64 // implement config loading from MobileAsset
  65
  66 @end
  67
  68 NS_ASSUME_NONNULL_END
  69
  70 /* Annotated example plist
  71
  72 <?xml version="1.0" encoding="UTF-8"?>
  73 <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
  74 <plist version="1.0">
  75 <dict>
  76     <key>general</key>
  77     <dict>
  78         <!-- Total item limit -->
  79         <key>maxStateSize</key>
  80         <integer>250</integer>
  81         <!-- Throw away items after this many seconds -->
  82         <key>maxItemAge</key>
  83         <integer>3600</integer>
  84         <!-- Ignore everybody for this many seconds -->
  85         <key>overloadDuration</key>
  86         <integer>1800</integer>
  87         <!-- Printable string for logs -->
  88         <key>name</key>
  89         <string>CKKS</string>
  90         <!-- Load config stored in this MobileAsset (ignored if inited with config or plist directly) -->
  91         <key>MAType</key>
  92         <string></string>
  93     </dict>
  94     <!-- Each property you want to ratelimit on must have its own group dictionary -->
  95     <key>groups</key>
  96     <array>
  97         <dict>
  98             <!-- The first group must be for the global bucket. It behaves identically otherwise -->
  99             <key>property</key>
 100             <string>global</string>
 101             <key>capacity</key>
 102             <integer>20</integer>
 103             <key>rate</key>
 104             <integer>30</integer>
 105             <key>badness</key>
 106             <integer>1</integer>
 107         </dict>
 108         <dict>
 109             <!-- Your object must respond to this selector that takes no arguments by returning an NSString * -->
 110             <key>property</key>
 111             <string>UUID</string>
 112             <!-- Buckets of this type hold at most this many tokens -->
 113             <key>capacity</key>
 114             <integer>3</integer>
 115             <!-- Tokens replenish at 1 every this many seconds -->
 116             <key>rate</key>
 117             <integer>600</integer>
 118             <!-- Max of all empty bucket badnesses is returned to caller. See RateLimiterBadness enum -->
 119             <key>badness</key>
 120             <integer>3</integer>
 121         </dict>
 122     </array>
 123 </dict>
 124 </plist>
 125
 126 */