Fixed issue with NetAssociations not being accounted for offsetAverage calculation. Added new NetworkClock factory method.

Author: pivotal-tomasz-rybakiewicz

Code/NetAssociation.h

@@ -58,7 +58,7 @@
 /**
  Returns Net Association statistics.
  
- Returned stats are: leap_indicator, version_number, protocol_mode, stratum, poll interval, precision_exp, root_delay, dispersion, reference_ID
+ Returned stats are: server, leap_indicator, version_number, protocol_mode, stratum, poll interval, precision_exp, root_delay, dispersion, reference_ID
  
  @return NSDictionary with receiver stats.
  */

Code/NetAssociation.m

@@ -241,7 +241,7 @@ - (NSData *) createPacket {
     struct timeval  now;
 	gettimeofday(&now, NULL);
 
-	ntpClientSendTime.fullSeconds = now.tv_sec + JAN_1970;
+	ntpClientSendTime.fullSeconds = (uint32_t) now.tv_sec + JAN_1970;
 	ntpClientSendTime.partSeconds = uSec2Frac(now.tv_usec);
 
     wireData[10] = htonl(now.tv_sec + JAN_1970);                            // Transmit Timestamp
@@ -343,7 +343,7 @@ - (BOOL) onUdpSocket:(AsyncUdpSocket *)sender didReceiveData:(NSData *)data
     struct timeval          arrival_time;
 	gettimeofday(&arrival_time, NULL);
 
-    ntpClientRecvTime.fullSeconds = arrival_time.tv_sec + JAN_1970;     // Transmit Timestamp coarse
+    ntpClientRecvTime.fullSeconds = (uint32_t) arrival_time.tv_sec + JAN_1970;     // Transmit Timestamp coarse
 	ntpClientRecvTime.partSeconds = uSec2Frac(arrival_time.tv_usec);    // Transmit Timestamp fine
 
     uint32_t                hostData[12];
@@ -480,7 +480,7 @@ - (NSString *) description {
 
 - (NSDictionary*)stats {
     NSMutableDictionary *stats = [NSMutableDictionary dictionary];
-    
+    stats[@"server"] = server;
     stats[@"leap_indicator"] = @(li);
     stats[@"version_number:"] = @(vn);
     stats[@"protocol_mode"] = @(mode);

Code/NetworkClock.h

@@ -11,6 +11,30 @@
 /**
  The NetworkClock is a singleton class which will provide the best estimate of the difference in time
  between the device's system clock and the time returned by a collection of time servers.
+ 
+ NetworkClock can be initialized with NTP hosts file:
+
+    [[NetworkClock clockWithNTPHostsFile:[[NSBundle mainBundle] pathForResource:@"ntp.hosts" ofType:@""]];
+    NSDate *networkTime = [[NetworkClock sharedInstance] networkTime];
+ 
+     // ------ ntp.hosts file ------
+     time.apple.com
+     192.168.123.12 alwaystrust
+     #ignored line
+     // --- (END) ntp.hosts file ---
+ 
+ Or it can be initialized with NTP hosts array:
+ 
+    [[NetworkClock clockWithNTPHosts:@[
+        @"time.apple.com",
+        @"192.168.123.12 alwaystrust"   // 'alwaystrust' flag ignores dispersion and stratum check for this NTP server
+    ]];
+    NSDate *networkTime = [[NetworkClock sharedInstance] networkTime];
+ 
+ Invoking [NetworkClock sharedInstance] before either [NetworkClock clockWithNTPHostsFile:] or [NetworkClock clockWithNTPHosts:] is equavilent to:
+ 
+    [[NetworkClock clockWithNTPHostsFile:[[NSBundle mainBundle] pathForResource:@"ntp.hosts" ofType:@""]];
+ 
  */
 @interface NetworkClock : NSObject
 
@@ -30,7 +54,7 @@
  
  @param instance The new shared instance.
  */
-+ (void)setSharedInstance:(NetworkClock*)instance;
++ (void)setSharedInstance:(NetworkClock *)instance;
 
 ///-------------------------------------
 /// @name Initializing an Network Clock
@@ -42,7 +66,17 @@
  @param filePath The full path to NTP hosts file with wich to initialize `NetAssociation` objects.
  @return A new `NetworkClock` object initialized with the given hosts file.
  */
-+ (instancetype)clockNTPHostsFile:(NSString*)filePath;
++ (instancetype)clockWithNTPHostsFile:(NSString *)filePath;
+
+
+/**
+ Creates and returns a new `NetworkClock` object initialized with a list of `NetAssociation` objects that was in turn initialized with the given NTP hosts array.
+ 
+ @param ntpHosts The NSArray of NSString NTP hosts with wich to initialize `NetAssociation` objects.
+ @return A new `NetworkClock` object initialized with the given hosts array.
+ */
+
++ (instancetype)clockWithNTPHosts:(NSArray *)ntpHosts;
 
 /**
  Intializes the receiver with the given Hosts File path.
@@ -52,7 +86,17 @@
  @param filePath The full path to hosts file with wich to initialize the receiver.
  @return The receiver, initialized with the given hosts file.
  */
-- (id)initWithNTPHostsFile:(NSString*)filePath;
+- (id)initWithNTPHostsFile:(NSString *)filePath;
+
+/**
+ Intializes the receiver with the given Hosts array.
+ 
+ If the `sharedInstnace` instance is `nil`, the receive will be set as the `sharedInstnace`.
+ 
+ @param ntpHosts The NSArray of NSString NTP hosts with wich to initialize `NetAssociation` objects.
+ @return The receiver, initialized with the given hosts array.
+ */
+- (id)initWithNTPHosts:(NSArray *)ntpHosts;
 
 ///-------------------------------------
 /// @name Requesting Network Time

Code/NetworkClock.m

@@ -32,20 +32,24 @@ @implementation NetworkClock
 
 + (instancetype) sharedInstance {
     if (nil == sharedInstance) {
-        return [NetworkClock clockNTPHostsFile:kDefaultNTPHostsFile];
+        return [NetworkClock clockWithNTPHostsFile:kDefaultNTPHostsFile];
     }
     return sharedInstance;
 }
 
-+ (void)setSharedInstance:(NetworkClock*)instance {
++ (void)setSharedInstance:(NetworkClock *)instance {
     sharedInstance = instance;
 }
 
-+ (instancetype)clockNTPHostsFile:(NSString*)filePath {
++ (instancetype)clockWithNTPHostsFile:(NSString *)filePath {
     return [[NetworkClock alloc] initWithNTPHostsFile:filePath];
 }
 
-- (id)initWithNTPHostsFile:(NSString*)filePath {
++ (instancetype)clockWithNTPHosts:(NSArray *)ntpHosts {
+    return [[NetworkClock alloc] initWithNTPHosts:ntpHosts];
+}
+
+- (id)initWithNTPHostsFile:(NSString *)filePath {
     self = [super init];
     if (self) {
         [self setupSortDescriptors];
@@ -60,6 +64,21 @@ - (id)initWithNTPHostsFile:(NSString*)filePath {
     return self;
 }
 
+- (id)initWithNTPHosts:(NSArray *)ntpHosts {
+    self = [super init];
+    if (self) {
+        [self setupSortDescriptors];
+        [self setupTimeAssociationsFromArray:ntpHosts];
+        [self subscribeToAppBackgroundNotifications];
+        [self subscribeToTimeAssociationNotifications];
+
+        if (nil == sharedInstance) {
+            [NetworkClock setSharedInstance:self];
+        }
+    }
+    return self;
+}
+
 #pragma mark - Setup methods
 
 - (void)setupSortDescriptors {
@@ -68,7 +87,7 @@ - (void)setupSortDescriptors {
     self.sortDescriptors = @[self.dispersionSortDescriptor];
 }
 
-- (void)setupTimeAssociationsFromFile:(NSString*)filePath {
+- (void)setupTimeAssociationsFromFile:(NSString *)filePath {
     NSArray *ntpDomains = [self loadDomainNamesFromFile:filePath];
     NSDictionary *hostAddresses = [self resolveDomainAddressesFromArray:ntpDomains];
 
@@ -83,6 +102,20 @@ - (void)setupTimeAssociationsFromFile:(NSString*)filePath {
     }
 }
 
+- (void)setupTimeAssociationsFromArray:(NSArray *)ntpHosts {
+    NSDictionary *hostAddresses = [self resolveDomainAddressesFromArray:ntpHosts];
+    
+    // start an 'association' (network clock object) for each address.
+    self.timeAssociations = [NSMutableArray arrayWithCapacity:48];
+    for (NSString *server in [hostAddresses allKeys]) {
+        NSString *ipAddress = hostAddresses[server][@"address"];
+        NetAssociation *timeAssociation = [NetAssociation associationWithServerIpAddress:ipAddress];
+        timeAssociation.alwaysTrust = [hostAddresses[server][@"alwaystrust"] boolValue];
+        [self.timeAssociations addObject:timeAssociation];
+        [timeAssociation enable]; // starts are randomized internally
+    }
+}
+
 - (void)subscribeToAppBackgroundNotifications {
     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationBack:)
 												 name:UIApplicationDidEnterBackgroundNotification
@@ -128,7 +161,7 @@ - (void) finishAssociations {
 }
 
 
-- (NSArray*)loadDomainNamesFromFile:(NSString*)filePath {
+- (NSArray *)loadDomainNamesFromFile:(NSString *)filePath {
     NSString *fileData = [[NSString alloc] initWithData:[[NSFileManager defaultManager]
                                                          contentsAtPath:filePath]
                                                encoding:NSUTF8StringEncoding];
@@ -138,7 +171,7 @@ - (NSArray*)loadDomainNamesFromFile:(NSString*)filePath {
 
 // for each NTP service domain name in the 'ntp.hosts' file : "0.pool.ntp.org" etc
 // resolve the IP address of the named host : "0.pool.ntp.org" --> [123.45.67.89], ...
-- (NSDictionary*)resolveDomainAddressesFromArray:(NSArray*)domains {
+- (NSDictionary *)resolveDomainAddressesFromArray:(NSArray *)domains {
     NSMutableDictionary *hostAddresses = [NSMutableDictionary dictionaryWithCapacity:48];
 
     for (NSString * ntpDomainName in domains) {
@@ -159,7 +192,7 @@ - (NSDictionary*)resolveDomainAddressesFromArray:(NSArray*)domains {
         }
 
         if (!CFHostStartInfoResolution (ntpHostName, kCFHostAddresses, &nameError)) {
-            LogInProduction(@"CFHostStartInfoResolution error %li", nameError.error);
+            LogInProduction(@"CFHostStartInfoResolution error %i", (int)nameError.error);
             CFRelease(ntpHostName);
             continue;                                           // couldn't start resolution ...
         }
@@ -233,7 +266,9 @@ - (void) offsetAverage {
     short usefulCount = 0;
 
     for (NetAssociation * timeAssociation in sortedArray) {
-        if (timeAssociation.trusty) {
+        BOOL isValidOffset = (timeAssociation.offset < -0.0000001 || 0.0000001 < timeAssociation.offset);
+        BOOL isTrusty = (timeAssociation.alwaysTrust && timeAssociation.trusty);
+        if (isValidOffset && isTrusty) {
             usefulCount++;
             self.timeIntervalSinceDeviceTime += timeAssociation.offset;
         }

Examples/ntpDemo/ntpDemo/AppDelegate.m

@@ -12,7 +12,13 @@
 @implementation AppDelegate
 
 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
-    [NetworkClock clockNTPHostsFile:[[NSBundle mainBundle] pathForResource:@"ntp.hosts" ofType:@""]];
+    [NetworkClock clockWithNTPHostsFile:[[NSBundle mainBundle] pathForResource:@"ntp.hosts" ofType:@""]];
+    
+    // Alternatively:
+//    [NetworkClock clockWithNTPHosts:@[
+//        @"time.apple.com",
+//        @"south-america.pool.ntp.org alwaystrust"
+//    ]];
     return YES;
 }
 

README.mdown

@@ -4,17 +4,84 @@ This project is a mirror of the iOS-ntp project hosted on [Google code](http://c
 
 ### Notes
 
-The structure of this project may need some cleaning up and modernisation but it is ARC compatible and runs fine on Xcode 4.6.2.
+The structure of this project may need some cleaning up and modernisation but it is ARC compatible and runs fine on Xcode 5.0.2.
 
 It probably neeeds to be worked around a newer version of Cocoa Async Socket https://github.com/mattsoftware/CocoaAsyncSocket
 
-### Running the project
 
-    git clone git://github.com/jessedc/iOS-ntp.git ios-ntp
-    cd ios-ntp
-    git submodule sync
-    git submodule update --init
-    open ntpA.xcodeproj
+### Install using CocoaPods
+
+##### Podspec
+```
+platform :ios, '6.0'
+pod 'iOS-ntp', :git => 'https://github.com/tomaszrybakiewicz/iOS-ntp'
+```
+
+### Examples
+
+
+##### AppDelegate.m
+
+	#import "AppDelegate.h"
+	#import <iOS-ntp/NetworkClock.h>
+	
+	@implementation AppDelegate
+	
+	- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
+	-
+	    [NetworkClock clockWithNTPHosts:@[
+	        @"time.apple.com",
+	        @"south-america.pool.ntp.org alwaystrust"
+	    ]];
+	    
+	    return YES;
+	}
+	
+	@end
+
+##### RootViewController.m
+
+	#import "ViewController.h"
+	#import <iOS-ntp/NetworkClock.h>
+	
+	@implementation ViewController
+	
+	- (void)viewDidLoad {
+	    [super viewDidLoad];
+	    [self updateTime];
+	    [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(updateTime) userInfo:nil repeats:YES];
+	}
+	
+	- (void)updateTime {
+	    NSDate *systemTime = [NSDate date];
+	    NSDate *networkTime = [[NetworkClock sharedInstance] networkTime];
+	    NSTimeInterval difference = [networkTime timeIntervalSinceDate:systemTime];
+	    
+	    NSLog(@"system:  %@", systemTime);
+		NSLog(@"network: %@", networkTime);
+		NSLog(@"difference: %5.3f sec", difference);
+	}
+	
+	@end
+
+
+Example iOS application can be found in Examples folder.
+
+```
+$ cd Examples/ntpDemo/
+$ pod install
+$ open ntpDemo.xcworkspace
+```
+
+### Running the library project
+
+```
+$ git clone [email protected]:tomaszrybakiewicz/iOS-ntp.git ios-ntp_git
+$ cd ios-ntp_git
+$ git submodule sync
+$ git submodule update --init
+$ open iOS-ntp.xcodeproj
+```
 
 ## Original README
 

iOS-ntp.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name      = 'iOS-ntp'
-  s.version   = '0.2.0'
+  s.version   = '0.2.1'
   s.summary   = 'This project is a mirror of the iOS-ntp project hosted on [Google code](http://code.google.com/p/ios-ntp/) by Gavin Eadie'
   s.homepage  = 'http://code.google.com/p/ios-ntp/'
   s.author    = { 'Gavin Eadie' => '' }