BLAuthentication.m

//  ====================================================================== 	//
//  BLAuthentication.h														//
//  																		//
//  Last Modified on Tuesday April 24 2001									//
//  Copyright 2001 Ben Lachman												//
//																			//
//	Thanks to Brian R. Hill <http://personalpages.tds.net/~brian_hill/>		//
//  ====================================================================== 	//

#import "BLAuthentication.h"
#import <Security/AuthorizationTags.h>
#include <sys/stat.h>

OSStatus AuthorizationExecuteWithPrivilegesStdErrAndPid (
                                                         AuthorizationRef authorization, 
                                                         const char *pathToTool, 
                                                         AuthorizationFlags options, 
                                                         char * const *arguments, 
                                                         FILE **communicationsPipe,
                                                         FILE **errPipe,
                                                         pid_t* processid
                                                         )
{
    [[NSFileManager defaultManager] changeCurrentDirectoryPath: @"/tmp/"];
    
    char stderrpath[] = "/tmp/AuthorizationExecuteWithPrivilegesStdErrXXXXXXX.err" ;
	const char* commandtemplate = "echo $$; \"$@\" 2>%s" ;
    if (communicationsPipe == errPipe) {
        commandtemplate = "echo $$; \"$@\" 2>1";
    } else if (errPipe == 0) {
        commandtemplate = "echo $$; \"$@\"";
    }
	char command[1024];
	char ** args = nil;
	OSStatus result;
	int argcount = 0;
	int i;
	int stderrfd = 0;
	FILE* commPipe = 0;
	
	/* Create temporary file for stderr */
    
    if (errPipe) {
        stderrfd = mkstemps (stderrpath, strlen(".err")); 
        
        /* create a pipe on that path */ 
        close(stderrfd); unlink(stderrpath);
        if (mkfifo(stderrpath,S_IRWXU | S_IRWXG) != 0) {
            fprintf(stderr,"Error mkfifo:%d\n",errno);
            return errAuthorizationInternal;
        }
        
        if (stderrfd < 0)
            return errAuthorizationInternal;
    }
    
	/* Create command to be executed */
    if( arguments)
        for (argcount = 0; arguments[argcount] != 0; ++argcount) {}	
	args = (char**)malloc (sizeof(char*)*(argcount + 5));
	args[0] = "-c";
	snprintf (command, sizeof (command), commandtemplate, stderrpath);
	args[1] = command;
	args[2] = "";
	args[3] = (char*)pathToTool;
	for (i = 0; i < argcount; ++i) {
		args[i+4] = arguments[i];
	}
	args[argcount+4] = 0;
    
    /* for debugging: log the executed command */
	/* printf ("Exec:\n%s", "/bin/sh"); for (i = 0; args[i] != 0; ++i) { printf (" \"%s\"", args[i]); } printf ("\n"); */
    
	/* Execute command */
	result = AuthorizationExecuteWithPrivileges( 
                                                authorization, "/bin/sh",  options, args, &commPipe );
	if (result != noErr) {
		unlink (stderrpath);
        free( args);
		return result;
	}
	
    [NSThread sleepForTimeInterval: 0.2];
    
	/* Read the first line of stdout => it's the pid */
	{
		int stdoutfd = fileno (commPipe);
		char pidnum[1024];
		pid_t pid = 0;
		int i = 0;
		char ch = 0;
		while ((read(stdoutfd, &ch, sizeof(ch)) == 1) && (ch != '\n') && (i < sizeof(pidnum))) {
			pidnum[i++] = ch;
		}
		pidnum[i] = 0;
		if (ch != '\n') {
			// we shouldn't get there
			unlink (stderrpath);
			return errAuthorizationInternal;
		}
		sscanf(pidnum, "%d", &pid);
		if (processid) {
			*processid = pid;
		}
	}
	
	if (errPipe) {
        stderrfd = open(stderrpath, O_RDONLY, 0);
        *errPipe = fdopen(stderrfd, "r");
        /* Now it's safe to unlink the stderr file, as the opened handle will be still valid */
        unlink (stderrpath);
	} else {
		unlink(stderrpath);
	}
	if (communicationsPipe) {
		*communicationsPipe = commPipe;
	} else {
		fclose (commPipe);
	}
    
    [[NSFileManager defaultManager] removeItemAtPath: [[[NSFileManager defaultManager] currentDirectoryPath] stringByAppendingPathComponent: @"1"] error: nil];
    
    if( args)
        free( args);
    
	return noErr;
}


@implementation BLAuthentication

// returns an instace of itself, creating one if needed
+ sharedInstance {
    static id sharedTask = nil;
    if(sharedTask==nil) {
        sharedTask = [[BLAuthentication alloc] init];
    }
    return sharedTask;
}

// initializes the super class and sets authorizationRef to NULL 
- (id)init {
    self = [super init];
    authorizationRef = NULL;
    return self;
}

// deauthenticates the user and deallocates memory
- (void)dealloc {
    [self deauthenticate];
    
    [super dealloc];
}

//============================================================================
//	- (BOOL)isAuthenticated:(NSArray *)forCommands
//============================================================================
// Find outs if the user has the appropriate authorization rights for the 
// commands listed in (NSArray *)forCommands.
// This should be called each time you need to know whether the user
// is authorized, since the AuthorizationRef can be invalidated elsewhere, or
// may expire after a short period of time.
//
- (BOOL)isAuthenticated:(NSArray *)forCommands {
	AuthorizationRights rights;
	AuthorizationRights *authorizedRights;
	AuthorizationFlags flags;
	
	int numItems = [forCommands count];
	AuthorizationItem *items = malloc( sizeof(AuthorizationItem) * numItems );
	char paths[20][128]; // only handles upto 20 commands with paths upto 128 characters in length
	
	OSStatus err = 0;
	BOOL authorized = NO;
	int i = 0;

	if(authorizationRef==NULL) {
		rights.count=0;
		rights.items = NULL;
		
		flags = kAuthorizationFlagDefaults;
		
		err = AuthorizationCreate(&rights, kAuthorizationEmptyEnvironment, flags, &authorizationRef);
	}
    	
	if( numItems < 1 )
    {
        free( items);
		return authorized;
	}

	while( i < numItems && i < 20 ) {
		 [[forCommands objectAtIndex:i] getCString:paths[i]];
		
		items[i].name = kAuthorizationRightExecute;
		items[i].value = paths[i];
		items[i].valueLength = [[forCommands objectAtIndex:i] cStringLength];
		items[i].flags = 0;
		
		i++;
	}
	
    rights.count = numItems;
    rights.items = items;
    
    flags = kAuthorizationFlagExtendRights;
    
    err = AuthorizationCopyRights(authorizationRef, &rights, kAuthorizationEmptyEnvironment, flags, &authorizedRights);

    authorized = (errAuthorizationSuccess==err);

	if(authorized)
		AuthorizationFreeItemSet(authorizedRights);
	
    if( items)
        free(items);
	
    return authorized;
}

//============================================================================
//	- (void)deauthenticate
//============================================================================
// Deauthenticates the user by freeing their authorization.
//
- (void)deauthenticate {
    if(authorizationRef) {
        AuthorizationFree(authorizationRef, kAuthorizationFlagDestroyRights);
        authorizationRef = NULL;
        [[NSNotificationCenter defaultCenter]postNotificationName:BLDeauthenticatedNotification object:self];
    }
}

//============================================================================
//	- (BOOL)fetchPassword:(NSArray *)forCommands
//============================================================================
// Adds rights for commands specified in (NSArray *)forCommands.
// Commands should be passed as a NSString comtaining the path to the executable. 
// Returns YES if rights were gained
//
- (BOOL)fetchPassword:(NSArray *)forCommands {
	AuthorizationRights rights;
	AuthorizationRights *authorizedRights;
	AuthorizationFlags flags;
	
	int numItems = [forCommands count];
	AuthorizationItem *items = malloc( sizeof(AuthorizationItem) * numItems );
	char paths[20][128];
	
	OSStatus err = 0;
	BOOL authorized = NO;
	int i = 0;
	
	if( numItems < 1 )
    {
        free( items);
		return authorized;
	}
    
	while( i < numItems && i < 20 ) {
		[[forCommands objectAtIndex:i] getCString:paths[i]];
		
		items[i].name = kAuthorizationRightExecute;
		items[i].value = paths[i];
		items[i].valueLength = [[forCommands objectAtIndex:i] cStringLength];
		items[i].flags = 0;
		
		i++;
	}
	
	rights.count = numItems;
	rights.items = items;
	
	flags = kAuthorizationFlagInteractionAllowed | kAuthorizationFlagExtendRights;
	
	err = AuthorizationCopyRights(authorizationRef, &rights, kAuthorizationEmptyEnvironment, flags, &authorizedRights);
	
	authorized = (errAuthorizationSuccess == err);
	
	if(authorized) {
		AuthorizationFreeItemSet(authorizedRights);
		[[NSNotificationCenter defaultCenter] postNotificationName:BLAuthenticatedNotification object:self];
	}                                                    

	free(items);
	
	return authorized;
}

//============================================================================
//	- (BOOL)authenticate:(NSArray *)forCommands
//============================================================================
// Authenticates the commands in the array (NSArray *)forCommands by calling 
// fetchPassword.
//
- (BOOL)authenticate:(NSArray *)forCommands {
	if( ![self isAuthenticated:forCommands] ) {
        [self fetchPassword:forCommands];
	}
	
	return [self isAuthenticated:forCommands];
}


//============================================================================
//	- (int)getPID:(NSString *)forProcess
//============================================================================
// Retrieves the PID (process ID) for the process specified in 
// (NSString *)forProcess.
// The more specific forProcess is the better your accuracy will be, esp. when 
// multiple versions of the process exist. 
//
- (int)getPID:(NSString *)forProcess {
	FILE* outpipe = NULL;
	NSMutableData* outputData = [NSMutableData data];
	
	NSString *commandOutput = nil;
	NSString *scannerOutput = nil;
	NSString *popenArgs = [[NSString alloc] initWithFormat:@"/bin/ps -axwwopid,command | grep \"%@\"",forProcess];
	NSScanner *outputScanner = nil;
	NSScanner *intScanner = nil;
	int pid = 0;
	int len = 0;
    
    outpipe = popen([popenArgs UTF8String],"r");

	[popenArgs release];

	if(!outpipe) {
        NSLog(@"Error opening pipe: %@",forProcess);
        NSBeep();
        return 0;
    }
	
	NSMutableData* tempData = [[NSMutableData alloc] initWithLength:512];
	
	do {
        [tempData setLength:512];
        len = fread([tempData mutableBytes],1,512,outpipe);
        if( len > 0 ) {
            [tempData setLength:len];
            [outputData appendData:tempData];        
		}
	} while(len==512);
    
	[tempData release];

	pclose(outpipe);
	
	commandOutput = [[NSString alloc] initWithData:outputData encoding:NSASCIIStringEncoding];    
	
	if( [commandOutput length] > 0 ) {
		outputScanner = [NSScanner scannerWithString:commandOutput];
		
		[commandOutput release];
		
		[outputScanner setCharactersToBeSkipped:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
		
		[outputScanner scanUpToString:forProcess intoString:&scannerOutput];
		
		if( [scannerOutput rangeOfString:@"grep"].length != 0 ) {
			return 0;
		}
		
		intScanner = [NSScanner scannerWithString:scannerOutput];
		
		[intScanner scanInt:&pid];
		
		if( pid ) {
			return pid;
		}
		else {
			return 0;
		}
	}
	else {
		[commandOutput release];

		return 0;
	}
}


//============================================================================
//	-(void)executeCommand:(NSString *)pathToCommand withArgs:(NSArray *)arguments
//============================================================================
// Executes command in (NSString *)pathToCommand with the arguments listed in
// (NSArray *)arguments as root.
// pathToCommand should be a string contain the path to the command 
// (eg., /usr/bin/more), arguments should be an array of strings each containing
// a single argument.
//
-(BOOL)executeCommand:(NSString *)pathToCommand withArgs:(NSArray *)arguments
{
    #ifdef MACAPPSTORE
    NSTask *task = [NSTask launchedTaskWithLaunchPath: pathToCommand arguments: arguments];
    [task waitUntilExit];
    return YES;
    #else
	char* args[30]; // can only handle 30 arguments to a given command
	OSStatus err = 0;
	int i = 0;
	pid_t processid;
    
	if(![self authenticate:[NSArray arrayWithObject:pathToCommand]])
		return NO;
	
	if( arguments == nil || [arguments count] < 1)
    {
        err = AuthorizationExecuteWithPrivilegesStdErrAndPid(   authorizationRef, 
                                                             [pathToCommand UTF8String], 
                                                             kAuthorizationFlagDefaults, 
                                                             nil, 
                                                             nil,
                                                             nil,
                                                             &processid);
        
//		err = AuthorizationExecuteWithPrivileges(authorizationRef, [pathToCommand UTF8String], 0, NULL, NULL);
	}
	else
	{
		while( i < [arguments count] && i < 19)
		{
			args[i] = (char*)[[arguments objectAtIndex:i] cString];
			i++;
		}
		args[i] = NULL;
        
        err = AuthorizationExecuteWithPrivilegesStdErrAndPid(   authorizationRef, 
                                                             [pathToCommand UTF8String], 
                                                             kAuthorizationFlagDefaults, 
                                                             args, 
                                                             nil,
                                                             nil,
                                                             &processid);
        
//		err = AuthorizationExecuteWithPrivileges(authorizationRef,
//												[pathToCommand UTF8String],
//												0, args, NULL);
	}
	
    if( err != 0)
	{
		NSBeep();
		NSLog(@"Error %d in AuthorizationExecuteWithPrivileges",(int)err);
		return NO;
	}
	else
	{
        pid_t waitResult;
		int junkStatus;
        
        do
        {
			waitResult = waitpid( processid, &junkStatus, 0);
		}
        while((waitResult < 0) && (errno == EINTR));
        
		return YES;
	}
    #endif
}


//============================================================================
//	- (void)killProcess:(NSString *)commandFromPS
//============================================================================
// Finds and kills the process specified in (NSString *)commandFromPS using ps 
// and kill. (by pid)
// The more specific (ie., closer to matching the actual listing in ps) 
// commandFromPS is the better your accuracy will be, esp. when multiple 
// versions of the process exist.
//
- (BOOL)killProcess:(NSString *)commandFromPS {
	NSString *pid;

	if( ![self isAuthenticated:[NSArray arrayWithObject:commandFromPS]] ) {
		[self authenticate:[NSArray arrayWithObject:commandFromPS]];
	}
	
	pid = [NSString stringWithFormat:@"%d",[self getPID:commandFromPS]];
	
	if( [pid intValue] > 0 ) {
		[self executeCommand:@"/bin/kill" withArgs:[NSArray arrayWithObject:pid]];
		return YES;
	}
	else {
		NSBeep();
		NSLog(@"Error killing process %@, invalid PID.",pid);
		return NO;
	}
}	
@end

// BLAuthentication sends these notifications are sent when the user  
// becomes authenticated or deauthenticated.

// Sample notification observer:
/*
    [[NSNotificationCenter defaultCenter] addObserver:self
                                        selector:@selector(userAuthenticated:)
                                        name:BLAuthenticatedNotification
                                        object:[BLAuthentication sharedInstance]];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                        selector:@selector(userDeauthenticated:)
                                        name:BLDeauthenticatedNotification
                                        object:[BLAuthentication sharedInstance]];
*/