SMJobBlessXPC/SMJobBlessApp/SMJobBlessAppController.m

/*
 
    File: SMJobBlessAppController.m
Abstract: The main application controller. When the application has finished
launching, the helper tool will be installed.
 Version: 1.2

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*/

#import <ServiceManagement/ServiceManagement.h>
#import <Security/Authorization.h>
#import "SMJobBlessAppController.h"


@interface SMJobBlessAppController ()

@property (nonatomic, assign) IBOutlet NSTextField* textField;

- (BOOL)blessHelperWithLabel:(NSString *)label error:(NSError **)error;

@end


@implementation SMJobBlessAppController

@synthesize textField=_textField;

- (void)appendLog:(NSString *)log {
    self.textField.stringValue = [self.textField.stringValue stringByAppendingFormat:@"\n%@", log];
}

- (void)applicationDidFinishLaunching:(NSNotification *)notification {
	NSError *error = nil;
	if (![self blessHelperWithLabel:@"com.apple.bsd.SMJobBlessHelper" error:&error]) {
        [self appendLog:[NSString stringWithFormat:@"Failed to bless helper. Error: %@", error]];
        return;
    }
    
    self.textField.stringValue = @"Helper available.";
    
    xpc_connection_t connection = xpc_connection_create_mach_service("com.apple.bsd.SMJobBlessHelper", NULL, XPC_CONNECTION_MACH_SERVICE_PRIVILEGED);
    
    if (!connection) {
        [self appendLog:@"Failed to create XPC connection."];
        return;
    }
    
    xpc_connection_set_event_handler(connection, ^(xpc_object_t event) {
        xpc_type_t type = xpc_get_type(event);
        
        if (type == XPC_TYPE_ERROR) {
            
            if (event == XPC_ERROR_CONNECTION_INTERRUPTED) {
                [self appendLog:@"XPC connection interupted."];
                
            } else if (event == XPC_ERROR_CONNECTION_INVALID) {
                [self appendLog:@"XPC connection invalid, releasing."];
                xpc_release(connection);
                
            } else {
                [self appendLog:@"Unexpected XPC connection error."];
            }
            
        } else {
            [self appendLog:@"Unexpected XPC connection event."];
        }
    });
    
    xpc_connection_resume(connection);
    
    xpc_object_t message = xpc_dictionary_create(NULL, NULL, 0);
    const char* request = "Hi there, helper service.";
    xpc_dictionary_set_string(message, "request", request);
    
    [self appendLog:[NSString stringWithFormat:@"Sending request: %s", request]];
    
    xpc_connection_send_message_with_reply(connection, message, dispatch_get_main_queue(), ^(xpc_object_t event) {
        const char* response = xpc_dictionary_get_string(event, "reply");
        [self appendLog:[NSString stringWithFormat:@"Received response: %s.", response]];
    });
}

- (BOOL)blessHelperWithLabel:(NSString *)label
                       error:(NSError **)error {
    
	BOOL result = NO;

	AuthorizationItem authItem		= { kSMRightBlessPrivilegedHelper, 0, NULL, 0 };
	AuthorizationRights authRights	= { 1, &authItem };
	AuthorizationFlags flags		=	kAuthorizationFlagDefaults				| 
										kAuthorizationFlagInteractionAllowed	|
										kAuthorizationFlagPreAuthorize			|
										kAuthorizationFlagExtendRights;

	AuthorizationRef authRef = NULL;
	
	/* Obtain the right to install privileged helper tools (kSMRightBlessPrivilegedHelper). */
	OSStatus status = AuthorizationCreate(&authRights, kAuthorizationEmptyEnvironment, flags, &authRef);
	if (status != errAuthorizationSuccess) {
        [self appendLog:[NSString stringWithFormat:@"Failed to create AuthorizationRef. Error code: %ld", status]];
        
	} else {
		/* This does all the work of verifying the helper tool against the application
		 * and vice-versa. Once verification has passed, the embedded launchd.plist
		 * is extracted and placed in /Library/LaunchDaemons and then loaded. The
		 * executable is placed in /Library/PrivilegedHelperTools.
		 */
		result = SMJobBless(kSMDomainSystemLaunchd, (CFStringRef)label, authRef, (CFErrorRef *)error);
	}
	
	return result;
}

@end