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    Length: 5717 (0x1655)
    Types: TextFile
    Notes: UNIX file
    Names: »passwd.c«

└─⟦f27320a65⟧ Bits:30001972 Commodore 900 hard disk image with partial source code
    └─⟦f4b8d8c84⟧ UNIX Filesystem
        └─ ⟦this⟧ »cmd/passwd.c« 

TextFile

/*
 * Rec'd from Lauren Weinstein, 7-16-84.
 * Passwd - set login password
 * for a user.
 */

#include <stdio.h>
#include <ctype.h>
#include <sys/types.h>
#include <pwd.h>
#include <signal.h>
#include <errno.h>

#define	NSALT	64		/* Size of salt character set */
#define	NSALTC	2		/* Number of characters in salt */
#define	NPASSC	32		/* Maximum characters copied into pass. buf */
#define	AWRITE	2		/* Access for write */
#define	NLOKOUT	7		/* Maximum number of lockout attempts */
#define	NPWCHAR	256		/* Number of characters in passwd file line */

char	notrich[] = "\
Password is too easily broken\n\
Try again: \
";
char	pfile[] = "/etc/passwd";
char	tmpfile[] = "/tmp/passwd";

char	salttab[NSALT] =
	"./abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

char	pwline[NPWCHAR];

FILE	*lockopen();
char	*crypt();
int	cleanup();
time_t	time();

int	tmpflag;		/* Says tempfile is open */

main(argc, argv)
char *argv[];
{
	register struct passwd *pwp;
	register char *pass, *name;
	char passbuf[NPASSC+1];
	int myuid;
	extern char *getpass();

	if (signal(SIGINT, SIG_IGN) != SIG_IGN)
		signal(SIGINT, cleanup);
	if (signal(SIGHUP, SIG_IGN) != SIG_IGN)
		signal(SIGHUP, cleanup);
	myuid = getuid();

	umask(077);  /* mask out file access by other users */

	if (argc > 1) {
		if (argc != 2)
			usage();
		if ((pwp = getpwnam(argv[1])) == NULL)
			perr("%s: bad user name\n", argv[1]);
		if (myuid!=0 && pwp->pw_uid!=myuid)
			perr("%s: not allowed to change password\n", argv[1]);
		name = argv[1];  /* get name for change */
	} else {
	        if ((pwp = getpwuid(myuid)) == NULL)
		   perr("Error on /etc/passwd\n");
		name = pwp->pw_name;  /* changing our own name */
	}
	if (myuid!=0 && pwp->pw_passwd[0]!='\0') {
		if ((pass = getpass("Old password: ")) == NULL)
			exit(1);
		if (!checkpass(pwp->pw_passwd, pass))
			perr("Sorry\n");
	}
	if ((pass = getpass("New password: ")) == NULL)
	   exit(1);
	if (pass[0] != 0 || (pass[0] == 0 && getuid() != 0))
	   while (!richenough(pass) || !strcmp(pass, pwp->pw_name))
	      if ((pass = getpass(notrich)) == NULL)
		 exit(1);
	strncpy(passbuf, pass, NPASSC);
	if ((pass = getpass("Verification: ")) == NULL) 
	   exit(1);
	if (strncmp(pass, passbuf, NPASSC) != 0)
	   perr("No match: password not changed\n");
	setpass(name, pass);
}

/*
 * Tests to see if a password is rich enough
 * (i.e. not too easy to break by exhaustion).
 * A password must be 4 characters if the alphabet
 * is rich enough and 6 characters if it is in a
 * single case.  Perhaps the dictionary should
 * be searched as well for more security-conscious
 * systems.  We also check (above) to make sure
 * that the selected password is not the same as the username!
 */
richenough(passwd)
char *passwd;
{
	register char *cp;
	register int uflag=0, lflag=0, oflag=0;
	register int l;

	for (cp = passwd; *cp != '\0'; cp++) {
		if (islower(*cp))
			lflag = 1;
		else if (isupper(*cp))
			uflag = 1;
		else
			oflag = 1;
	}
	l = cp-passwd;
	if (l < 4)
		return (0);
	if (oflag==0 && lflag^uflag && l<6)
		return (0);
	return (1);
}

/*
 * Check the passwd in the password file (`rpass')
 * against the typed-in (`tpass') password.
 */
checkpass(rpass, tpass)
register char *rpass, *tpass;
{
	char salt[3];

	salt[0] = rpass[0];
	salt[1] = rpass[1];
	return (strcmp(crypt(tpass, salt), rpass) == 0);
}

/*
 * Set password for specified name.
 */
setpass(name, passwd)
char *name, *passwd;
{
	char salt[NSALTC+1];
	char namebuff[NPWCHAR];  /* name buffer */
	time_t xtime;
	register char *p1, *p2;
	register int c;
	register FILE *pwf;
	register FILE *tf;

	/*
	 * Generate the salt for crypt.
	 */
	time(&xtime);
	srand((int)xtime);
	salt[0] = salttab[rand()%NSALT];
	salt[1] = salttab[rand()%NSALT];
	salt[2] = '\0';
	if (*passwd != '\0')
		passwd = crypt(passwd, salt);
	/*
	 * Copy password file to tempfile
	 * looking for slot to change.
	 * The format of a passwd entry is:
	 * name:password:uid:...
	 */
	if ((pwf = fopen(pfile, "r")) == NULL)
		perr("Cannot open %s\n", pfile);
	tf = lockopen(tmpfile);
	while (fgets(pwline, NPWCHAR, pwf) != NULL) {
		strcpy(namebuff, pwline);  /* copy line */
		p1 = namebuff;		
		while (*p1 != '\0')
			if (*p1++ == ':')
				break;	
		*--p1 = '\0';  /* null terminate user name */
					
		p1 = pwline;
		while (*p1 != '\0')
			if (*p1++ == ':')
				break;
		p2 = p1;
		while (*p2 != '\0')
	 	        if (*p2++ == ':')
			        break;

		if (!strcmp(namebuff, name)) {  /* check for name match */
			*p1 = '\0';
			fputs(pwline, tf);
			fputs(passwd, tf);
			putc(':', tf);
			fputs(p2, tf);
			break;
		}
		fputs(pwline, tf);
	}
	while ((c = getc(pwf)) != EOF)  /* copy rest of file */
		putc(c, tf);
	fclose(pwf);
	/*
	 * Copy tempfile back to password
	 * file -- this runs protected
	 * from interrupts.
	 */
	signal(SIGINT, SIG_IGN);
	signal(SIGHUP, SIG_IGN);
	signal(SIGQUIT, SIG_IGN);
	if ((pwf = fopen(pfile, "w")) == NULL)
		perr("Cannot create %s\n", pfile);
	fflush(tf);
	rewind(tf);
	while ((c = getc(tf)) != EOF)
		putc(c, pwf);
	fflush(pwf);
	unlink(tmpfile);  
}

/*
 * Open the tempfile waiting
 * for the tempfile to come free.
 */
FILE *
lockopen(file)
char *file;
{
	register int n;
	register FILE *fp;
	extern int errno;

	for (n=NLOKOUT; n>0; n--)
		if (access(file, AWRITE)<0 && errno==ENOENT) {
			if ((fp=fopen(file, "w")) == NULL
			||  (fp=freopen(file, "r+w", fp)) == NULL)
				perr("Cannot create tempfile\n");
			tmpflag = 1;
			return (fp);
		}
	perr("Tempfile busy, try again later\n");
}

/*
 * Cleanup the tempfile.
 */
cleanup()
{
	if (tmpflag)
		unlink(tmpfile);
	exit (1);
}

/*
 * Error routines
 */
usage()
{
	perr("Usage: passwd [name]\n");
}

perr(x)
{
	fprintf(stderr, "%r", &x);
	exit(1);
}