ComputersOnNetwork

I’m writing a program which uses AppleScript to issue commands to a remote computer. I want to be able to find all of the computers on a network which support this. How would I do that? If you don’t know how to do that, then can you tell me how to find all of the computers or devices connected to a network. Any help will be greatly appreciated.

check this out-> http://developer.apple.com/documentation/Cocoa/Conceptual/NetServices/

I was able to get this to work by finding all of the computers on the network using eppc (Apple Remote Events) by using the NSNetServiceBrowser class. Thanks for your help.

It would be nice if you could post your solution once you get it working. I’m sure it will be useful info!!

This code finds all of the computers on the network with Apple Remote Events (eppc) enabled and puts it into an NSTableView called remoteHostTableView.

@interface Controller : NSObject

{ NSMutableArray *remoteHosts; NSNetServiceBrowser *serviceBrowser; IBOutlet NSTableView *remoteHostTableView; }

@end

#import “Controller.h”

@implementation Controller

(void)awakeFromNib { remoteHosts = [[NSMutableArray alloc] init]; serviceBrowser = [[NSNetServiceBrowser alloc] init]; [serviceBrowser setDelegate:self]; [serviceBrowser searchForServicesOfType:@”_eppc._tcp.” inDomain:@””]; }

// NSNetServiceBrowser delegate methods

(void)netServiceBrowser:(NSNetServiceBrowser *)aNetServiceBrowser didFindService:(NSNetService *)aNetService moreComing:(BOOL)moreComing {
[remoteHosts addObject:aNetService];

[aNetService setDelegate:self]; [aNetService resolve];

if (!moreComing) { [remoteHostTableView reloadData]; } }
(void)netServiceBrowser:(NSNetServiceBrowser *)aNetServiceBrowser didRemoveService:(NSNetService *)aNetService moreComing:(BOOL)moreComing {
[remoteHosts removeObject:aNetService];

if (!moreComing) { [remoteHostTableView reloadData]; } }

// NSNetService delegate methods

(void)netService:(NSNetService *)sender didNotResolve:(NSDictionary *)errorDict { NSLog( @”Couldn’t resolve %@”, [sender name] ); }
(void)netServiceDidResolveAddress:(NSNetService *)sender { NSLog( @”Successfully resolved %@.”, [sender name] ); }
(void)netServiceWillResolve:(NSNetService *)sender { NSLog( @”Attempting to resolve %@…”, [sender name] ); }

// data source methods

(int)numberOfRowsInTableView:(NSTableView *)aTableView { return [remoteHosts count]; }
(id)tableView:(NSTableView *)aTableView objectValueForTableColumn:(NSTableColumn *)aTableColumn row:(int)rowIndex { return remoteHosts objectAtIndex:rowIndex] name]; }

@end

I have a new problem now. I’m trying to find the IP Address of the [[NSNetService after it is resolved so I can use it to tell the remote computer to do things in AppleScript using of machine. If you do [aNetService addresses], it returns an array of addresses, each is an NSData object. I’m just going to use the first address to attempt to make a connection. The problem is I can’t convert the NSData object into the format that I need it in which is something like 192.168.1.1.

The sockaddr_in structure that the NSData object encapsulates is defined in the netinet/in.h header and there are some convenience methods for handling it in the arpa/inet.h header (both of these are found in /usr/include/). Anyway, without further ado, a quick (as in entirely untested) category on NSData to extract the relevant bits would look something like this: NSData+Extras.h

#import <Foundation/Foundation.h>

@interface NSData (Extras)

(struct sockaddr_in)sockAddrStruct;
(NSString*)ipAddress;
(unsigned short)port; @end

NSData+Extras.m

#import “NSData+Extras.h” #import “sys/socket.h” #import “netinet/in.h” #import “arpa/inet.h”

@implementation NSData (Extras)

(struct sockaddr_in)sockAddrStruct { return (struct sockaddr_in)[self bytes]; }
(NSString*)ipAddress { return [NSString stringWithCString:inet_ntoa([self sockAddrStruct].sin_addr)]; }
(unsigned short)port { return ntohs([self sockAddrStruct].sin_port); } @end

Edited the above code to add ntohs() around the return value of the port method. This recently bit me on a new Intel machine.

Since addresses could be either IPv4 or IPv6 I’d rather do something like

NSString *addressString = nil; struct sockaddr *address; unsigned int port = 0;

address = (struct sockaddr *) [data bytes];

switch( address->sa_family ) { case AF_INET: { struct sockaddr_in *ip4; char dest[INET_ADDRSTRLEN];

ip4 = (struct sockaddr_in *) address;

addressString = [NSString stringWithFormat: @"%s", inet_ntop(AF_INET, &ip4->sin_addr, dest, sizeof dest)];
port = ntohs(ip4->sin_port);   }   break;

case AF_INET6: { struct sockaddr_in6 *ip6; char dest[INET6_ADDRSTRLEN];

ip6 = (struct sockaddr_in6 *) address;

addressString = [NSString stringWithFormat: @"%s",  inet_ntop(AF_INET6, &ip6->sin6_addr, dest, sizeof dest)];
port = ntohs(ip6->sin6_port);   }   break;

default: NSLog(@”Unknown family”); break; }

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