/*
    File:       main.m

    Contains:   Trivial test program for the SimplePing class.

    Written by: DTS

    Copyright:  Copyright (c) 2010-2012 Apple Inc. All Rights Reserved.

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*/

#include "SimplePing.h"

#include <sys/socket.h>
#include <netdb.h>

#pragma mark * Utilities

static NSString * DisplayAddressForAddress(NSData * address)
    // Returns a dotted decimal string for the specified address (a (struct sockaddr) 
    // within the address NSData).
{
    int         err;
    NSString *  result;
    char        hostStr[NI_MAXHOST];
    
    result = nil;
    
    if (address != nil) {
        err = getnameinfo([address bytes], (socklen_t) [address length], hostStr, sizeof(hostStr), NULL, 0, NI_NUMERICHOST);
        if (err == 0) {
            result = [NSString stringWithCString:hostStr encoding:NSASCIIStringEncoding];
            assert(result != nil);
        }
    }

    return result;
}

#pragma mark * Main

@interface Main : NSObject <SimplePingDelegate>

- (void)runWithHostName:(NSString *)hostName;

@end

@interface Main ()

@property (nonatomic, strong, readwrite) SimplePing *   pinger;
@property (nonatomic, strong, readwrite) NSTimer *      sendTimer;

@end

@implementation Main

@synthesize pinger    = _pinger;
@synthesize sendTimer = _sendTimer;

- (void)dealloc
{
    [self->_pinger stop];
    [self->_sendTimer invalidate];
}

- (NSString *)shortErrorFromError:(NSError *)error
    // Given an NSError, returns a short error string that we can print, handling 
    // some special cases along the way.
{
    NSString *      result;
    NSNumber *      failureNum;
    int             failure;
    const char *    failureStr;
    
    assert(error != nil);
    
    result = nil;
    
    // Handle DNS errors as a special case.
    
    if ( [[error domain] isEqual:(NSString *)kCFErrorDomainCFNetwork] && ([error code] == kCFHostErrorUnknown) ) {
        failureNum = [[error userInfo] objectForKey:(id)kCFGetAddrInfoFailureKey];
        if ( [failureNum isKindOfClass:[NSNumber class]] ) {
            failure = [failureNum intValue];
            if (failure != 0) {
                failureStr = gai_strerror(failure);
                if (failureStr != NULL) {
                    result = [NSString stringWithUTF8String:failureStr];
                    assert(result != nil);
                }
            }
        }
    }
    
    // Otherwise try various properties of the error object.
    
    if (result == nil) {
        result = [error localizedFailureReason];
    }
    if (result == nil) {
        result = [error localizedDescription];
    }
    if (result == nil) {
        result = [error description];
    }
    assert(result != nil);
    return result;
}

- (void)runWithHostName:(NSString *)hostName
    // The Objective-C 'main' for this program.  It creates a SimplePing object 
    // and runs the runloop sending pings and printing the results.
{
    assert(self.pinger == nil);
    
    self.pinger = [SimplePing simplePingWithHostName:hostName];
    assert(self.pinger != nil);
    
    self.pinger.delegate = self;
    [self.pinger start];
    
    do {
        [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
    } while (self.pinger != nil);
}

- (void)sendPing
    // Called to send a ping, both directly (as soon as the SimplePing object starts up) 
    // and via a timer (to continue sending pings periodically).
{
    assert(self.pinger != nil);
    [self.pinger sendPingWithData:nil];
}

- (void)simplePing:(SimplePing *)pinger didStartWithAddress:(NSData *)address
    // A SimplePing delegate callback method.  We respond to the startup by sending a 
    // ping immediately and starting a timer to continue sending them every second.
{
    #pragma unused(pinger)
    assert(pinger == self.pinger);
    assert(address != nil);

    NSLog(@"pinging %@", DisplayAddressForAddress(address));

    // Send the first ping straight away.
    
    [self sendPing];

    // And start a timer to send the subsequent pings.
    
    assert(self.sendTimer == nil);
    self.sendTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(sendPing) userInfo:nil repeats:YES];
}

- (void)simplePing:(SimplePing *)pinger didFailWithError:(NSError *)error
    // A SimplePing delegate callback method.  We shut down our timer and the 
    // SimplePing object itself, which causes the runloop code to exit.
{
    #pragma unused(pinger)
    assert(pinger == self.pinger);
    #pragma unused(error)
    NSLog(@"failed: %@", [self shortErrorFromError:error]);

    [self.sendTimer invalidate];
    self.sendTimer = nil;

    // No need to call -stop.  The pinger will stop itself in this case.
    // We do however want to nil out pinger so that the runloop stops.

    self.pinger = nil;
}

- (void)simplePing:(SimplePing *)pinger didSendPacket:(NSData *)packet
    // A SimplePing delegate callback method.  We just log the send.
{
    #pragma unused(pinger)
    assert(pinger == self.pinger);
    #pragma unused(packet)
    NSLog(@"#%u sent", (unsigned int) OSSwapBigToHostInt16(((const ICMPHeader *) [packet bytes])->sequenceNumber) );
}

- (void)simplePing:(SimplePing *)pinger didFailToSendPacket:(NSData *)packet error:(NSError *)error
    // A SimplePing delegate callback method.  We just log the failure.
{
    #pragma unused(pinger)
    assert(pinger == self.pinger);
    #pragma unused(packet)
    #pragma unused(error)
    NSLog(@"#%u send failed: %@", (unsigned int) OSSwapBigToHostInt16(((const ICMPHeader *) [packet bytes])->sequenceNumber), [self shortErrorFromError:error]);
}

- (void)simplePing:(SimplePing *)pinger didReceivePingResponsePacket:(NSData *)packet
    // A SimplePing delegate callback method.  We just log the reception of a ping response.
{
    #pragma unused(pinger)
    assert(pinger == self.pinger);
    #pragma unused(packet)
    NSLog(@"#%u received", (unsigned int) OSSwapBigToHostInt16([SimplePing icmpInPacket:packet]->sequenceNumber) );
}

- (void)simplePing:(SimplePing *)pinger didReceiveUnexpectedPacket:(NSData *)packet
    // A SimplePing delegate callback method.  We just log the receive.
{
    const ICMPHeader *  icmpPtr;
    
    #pragma unused(pinger)
    assert(pinger == self.pinger);
    #pragma unused(packet)
    
    icmpPtr = [SimplePing icmpInPacket:packet];
    if (icmpPtr != NULL) {
        NSLog(@"#%u unexpected ICMP type=%u, code=%u, identifier=%u", (unsigned int) OSSwapBigToHostInt16(icmpPtr->sequenceNumber), (unsigned int) icmpPtr->type, (unsigned int) icmpPtr->code, (unsigned int) OSSwapBigToHostInt16(icmpPtr->identifier) );
    } else {
        NSLog(@"unexpected packet size=%zu", (size_t) [packet length]);
    }
}

@end

int main(int argc, char* argv[])
{
    Main *              mainObj;
    
    @autoreleasepool {
        if (argc == 2) {
            mainObj = [[Main alloc] init];
            assert(mainObj != nil);
            
            [mainObj runWithHostName:[NSString stringWithUTF8String:argv[1]]];
        } else {
            fprintf(stderr, "usage: %s host\n", getprogname());
        }
    }

    // On success we loop forever in -runWithHostName:, so the only way to 
    // get here is if something went wrong.
    
    return EXIT_FAILURE;
}