/*

File: PortMapper.m

Abstract: Objective-C class implementation using Bonjour port mapping

Version: 1.0

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*/

#import "PortMapper.h"

#import <dns_sd.h>

#import <sys/types.h>

#import <sys/socket.h>

#import <net/if.h>

#import <netinet/in.h>

#import <ifaddrs.h>

#ifndef Log

#define ENABLE_LOGGING 0                            /* Change value to 1 to enable logging. */

#define Log   if(!ENABLE_LOGGING) ; else NSLog

#endif

NSString* const PortMapperChangedNotification = @"PortMapperChanged";

/** Converts a raw IPv4 address to an NSString in dotted-quad notation */

static NSString* StringFromIPv4Addr( UInt32 ipv4Addr )

{

    if( ipv4Addr != 0 ) {

        const UInt8* addrBytes = (const UInt8*)&ipv4Addr;

        return [NSString stringWithFormat: @"%u.%u.%u.%u",

                (unsigned)addrBytes[0],(unsigned)addrBytes[1],

                (unsigned)addrBytes[2],(unsigned)addrBytes[3]];

    } else

        return nil;

}    

@interface PortMapper ()

// Redeclare these properties as settable, internally:

@property (readwrite) SInt32 error;

@property (readwrite) UInt32 rawPublicAddress;

@property (copy) NSString* publicAddress;

@property (readwrite) unsigned short publicPort;

// Private getter:

@property (readonly) void* _service;

- (void) priv_disconnect;

@end

@implementation PortMapper

- (id) initWithPort: (UInt16)port

{

    self = [super init];

    if (self != nil) {

        _port = port;

        _mapTCP = YES;

    }

    return self;

}

- (void) dealloc

{

    if( _service )

        [self priv_disconnect];

    [super dealloc];

}

- (void) finalize

{

    if( _service )

        [self priv_disconnect];

    [super finalize];

}

@synthesize publicAddress=_publicAddress, rawPublicAddress=_rawPublicAddress,

            publicPort=_publicPort, error=_error, _service=_service,

            mapTCP=_mapTCP, mapUDP=_mapUDP,

            desiredPublicPort=_desiredPublicPort;

- (BOOL) isMapped

{

    return _rawPublicAddress && _rawPublicAddress != [[self class] rawLocalAddress];

}

/** Called whenever the port mapping changes (see comment for callback, below.) */

- (void) priv_portMapStatus: (DNSServiceErrorType)errorCode 

              publicAddress: (UInt32)rawPublicAddress

                 publicPort: (UInt16)publicPort

{

    if( errorCode ) {

        Log(@"Port-mapping callback got error %i",errorCode);

    } else {

        if( publicPort == 0 && _desiredPublicPort != 0 ) {

            Log(@"Port-mapping callback reported no mapping available");

            errorCode = kDNSServiceErr_NATPortMappingUnsupported;

        }

    }

    if( errorCode != self.error )

        self.error = errorCode;

    if( rawPublicAddress != self.rawPublicAddress ) {

        self.rawPublicAddress = rawPublicAddress;

        self.publicAddress = StringFromIPv4Addr(rawPublicAddress);

    }

    if( publicPort != self.publicPort )

        self.publicPort = publicPort;

    if( ! errorCode ) {

        Log(@"PortMapper: Got %@ :%hu (mapped=%i)", self.publicAddress,self.publicPort,self.isMapped);

    }

    [[NSNotificationCenter defaultCenter] postNotificationName: PortMapperChangedNotification

                                                        object: self];

}

/** Asynchronous callback from DNSServiceNATPortMappingCreate.

    This is invoked whenever the status of the port mapping changes.

    All it does is dispatch to the object's priv_portMapStatus:publicAddress:publicPort: method. */

static void portMapCallback (

                      DNSServiceRef                    sdRef,

                      DNSServiceFlags                  flags,

                      uint32_t                         interfaceIndex,

                      DNSServiceErrorType              errorCode,

                      uint32_t                         publicAddress,    /* four byte IPv4 address in network byte order */

                      DNSServiceProtocol               protocol,

                      uint16_t                         privatePort,

                      uint16_t                         publicPort,       /* may be different than the requested port */

                      uint32_t                         ttl,              /* may be different than the requested ttl */

                      void                             *context

                      )

{

    NSAutoreleasePool *pool = [NSAutoreleasePool new];

    @try{

        [(PortMapper*)context priv_portMapStatus: errorCode 

                                   publicAddress: publicAddress

                                      publicPort: ntohs(publicPort)];  // port #s in network byte order!

    }@catch( id x ) {

        NSLog(@"PortMapper caught exception: %@",x);

    }

    [pool drain];

}

/** CFSocket callback, informing us that _socket has data available, which means

    that the DNS service has an incoming result to be processed. This will end up invoking

    the portMapCallback. */

static void serviceCallback(CFSocketRef s, 

                            CFSocketCallBackType type,

                            CFDataRef address, const void *data, void *clientCallBackInfo)

{

    PortMapper *mapper = (PortMapper*)clientCallBackInfo;

    DNSServiceRef service = mapper._service;

    DNSServiceErrorType err = DNSServiceProcessResult(service);

    if( err ) {

        // An error here means the socket has failed and should be closed.

        [mapper priv_portMapStatus: err publicAddress: 0 publicPort: 0];

        [mapper priv_disconnect];

    }

}

- (BOOL) open

{

    NSAssert(!_service,@"Already open");

    // Create the DNSService:

    DNSServiceProtocol protocol = 0;

    if( _mapTCP ) protocol |= kDNSServiceProtocol_TCP;

    if( _mapUDP ) protocol |= kDNSServiceProtocol_UDP;

    self.error = DNSServiceNATPortMappingCreate((DNSServiceRef*)&_service, 

                                         0 /*flags*/, 

                                         0 /*interfaceIndex*/, 

                                         protocol,

                                         htons(_port),

                                         htons(_desiredPublicPort),

                                         0 /*ttl*/,

                                         &portMapCallback, 

                                         self);

    if( _error ) {

        Log(@"Error %i creating port mapping",_error);

        return NO;

    }

    // Wrap a CFSocket around the service's socket:

    CFSocketContext ctxt = { 0, self, CFRetain, CFRelease, NULL };

    _socket = CFSocketCreateWithNative(NULL, 

                                       DNSServiceRefSockFD(_service), 

                                       kCFSocketReadCallBack, 

                                       &serviceCallback, &ctxt);

    if( _socket ) {

        CFSocketSetSocketFlags(_socket, CFSocketGetSocketFlags(_socket) & ~kCFSocketCloseOnInvalidate);

        // Attach the socket to the runloop so the serviceCallback will be invoked:

        _socketSource = CFSocketCreateRunLoopSource(NULL, _socket, 0);

        if( _socketSource )

            CFRunLoopAddSource(CFRunLoopGetCurrent(), _socketSource, kCFRunLoopCommonModes);

    }

    if( _socketSource ) {

        Log(@"Opening PortMapper");

        return YES;

    } else {

        Log(@"Failed to open PortMapper");

        [self close];

        _error = kDNSServiceErr_Unknown;

        return NO;

    }

}

- (BOOL) waitTillOpened

{

    if( ! _socketSource )

        if( ! [self open] )

            return NO;

    // Run the runloop until there's either an error or a result:

    while( _error==0 && _publicAddress==nil )

        if( ! [[NSRunLoop currentRunLoop] runMode: NSDefaultRunLoopMode

                                       beforeDate: [NSDate distantFuture]] )

            break;

    return (_error==0);

}

// Close down, but _without_ clearing the 'error' property

- (void) priv_disconnect

{

    if( _socketSource ) {

        CFRunLoopSourceInvalidate(_socketSource);

        CFRelease(_socketSource);

        _socketSource = NULL;

    }

    if( _socket ) {

        CFSocketInvalidate(_socket);

        CFRelease(_socket);

        _socket = NULL;

    }

    if( _service ) {

        Log(@"Deleting port mapping");

        DNSServiceRefDeallocate(_service);

        _service = NULL;

        self.rawPublicAddress = 0;

        self.publicAddress = nil;

        self.publicPort = 0;

    }

}

- (void) close

{

    [self priv_disconnect];

    self.error = 0;

}

#pragma mark -

#pragma mark UTILITY CLASS METHODS:

+ (UInt32) rawLocalAddress

{

    // getifaddrs returns a linked list of interface entries;

    // find the first active non-loopback interface with IPv4:

    UInt32 address = 0;

    struct ifaddrs *interfaces;

    if( getifaddrs(&interfaces) == 0 ) {

        struct ifaddrs *interface;

        for( interface=interfaces; interface; interface=interface->ifa_next ) {

            if( (interface->ifa_flags & IFF_UP) && ! (interface->ifa_flags & IFF_LOOPBACK) ) {

                const struct sockaddr_in *addr = (const struct sockaddr_in*) interface->ifa_addr;

                if( addr && addr->sin_family==AF_INET ) {

                    address = addr->sin_addr.s_addr;

                    break;

                }

            }

        }

        freeifaddrs(interfaces);

    }

    return address;

}

+ (NSString*) localAddress

{

    return StringFromIPv4Addr( [self rawLocalAddress] );

}

// Private IP address ranges. See RFC 3330.

static const struct {UInt32 mask, value;} const kPrivateRanges[] = {

    {0xFF000000, 0x00000000},       //   0.x.x.x (hosts on "this" network)

    {0xFF000000, 0x0A000000},       //  10.x.x.x (private address range)

    {0xFF000000, 0x7F000000},       // 127.x.x.x (loopback)

    {0xFFFF0000, 0xA9FE0000},       // 169.254.x.x (link-local self-configured addresses)

    {0xFFF00000, 0xAC100000},       // 172.(16-31).x.x (private address range)

    {0xFFFF0000, 0xC0A80000},       // 192.168.x.x (private address range)

    {0,0}

};

+ (BOOL) localAddressIsPrivate

{

    UInt32 address = ntohl([self rawLocalAddress]);

    int i;

    for( i=0; kPrivateRanges[i].mask; i++ )

        if( (address & kPrivateRanges[i].mask) == kPrivateRanges[i].value )

            return YES;

    return NO;

}

+ (NSString*) findPublicAddress

{

    // To find our public IP address, open a PortMapper with no port or protocols.

    // This will cause the DNSService to look up our public address without creating a mapping.

    NSString *addr = nil;

    PortMapper *mapper = [[self alloc] initWithPort: 0];

    mapper.mapTCP = mapper.mapUDP = NO;

    if( [mapper waitTillOpened] )

        addr = mapper.publicAddress;

    [mapper close];

    [mapper release];

    return addr;

}

@end