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/* passwd.c - change password on an account
* Initially written for Linux by Peter Orbaek <poe@daimi.aau.dk>
* Currently maintained at ftp://ftp.daimi.aau.dk/pub/linux/poe/
*/
/* Hacked by Alvaro Martinez Echevarria, alvaro@enano.etsit.upm.es,
to allow peaceful coexistence with yp. Nov 94. */
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <unistd.h>
#include <termios.h>
#include <pwd.h>
#include <ctype.h>
#include <time.h>
#include <string.h>
extern int is_local(char *);
#define ascii_to_bin(c) ((c)>='a'?(c-59):(c)>='A'?((c)-53):(c)-'.')
#define bin_to_ascii(c) ((c)>=38?((c)-38+'a'):(c)>=12?((c)-12+'A'):(c)+'.')
#define MAX_LENGTH 1024
int
main(argc, argv)
int argc;
char *argv[];
{
struct passwd *pe;
uid_t gotuid = getuid();
char *pwdstr, *cryptstr;
char pwdstr1[10];
int ucase, lcase, other;
char *p, *q, *user;
time_t tm;
char salt[2];
FILE *fd_in, *fd_out;
char line[MAX_LENGTH];
int error=0;
int r;
umask(022);
if(argc > 2) {
puts("Too many arguments");
exit(1);
} else if(argc == 2) {
if(gotuid) {
puts("Only root can change the password for others");
exit(1);
}
user = argv[1];
} else {
if (!(user = getlogin())) {
if (!(pe = getpwuid( getuid() ))) {
puts("Cannot find login name");
exit(1);
} else
user = pe->pw_name;
}
}
if(!(pe = getpwnam(user))) {
puts("Can't find username anywhere. Are you really a user?");
exit(1);
}
if (!(is_local(user))) {
puts("Sorry, I can only change local passwords. Use yppasswd instead.");
exit(1);
}
/* if somebody got into changing utmp... */
if(gotuid && gotuid != pe->pw_uid) {
puts("UID and username does not match, imposter!");
exit(1);
}
printf( "Changing password for %s\n", user );
if(gotuid && pe->pw_passwd && pe->pw_passwd[0]) {
pwdstr = getpass("Enter old password: ");
if(strncmp(pe->pw_passwd, crypt(pwdstr, pe->pw_passwd), 13)) {
puts("Illegal password, imposter.");
exit(1);
}
}
redo_it:
pwdstr = getpass("Enter new password: ");
strncpy(pwdstr1, pwdstr, 9);
pwdstr = getpass("Re-type new password: ");
if(strncmp(pwdstr, pwdstr1, 8)) {
puts("You misspelled it. Password not changed.");
exit(0);
}
if((strlen(pwdstr) < 6) && gotuid) {
puts("The password must have at least 6 characters, try again.");
goto redo_it;
}
other = ucase = lcase = 0;
for(p = pwdstr; *p; p++) {
ucase = ucase || isupper(*p);
lcase = lcase || islower(*p);
other = other || !isalpha(*p);
}
if((!ucase || !lcase) && !other && gotuid) {
puts("The password must have both upper- and lowercase");
puts("letters, or non-letters; try again.");
goto redo_it;
}
r = 0;
for(p = pwdstr, q = pe->pw_name; *q && *p; q++, p++) {
if(tolower(*p) != tolower(*q)) {
r = 1;
break;
}
}
for(p = pwdstr + strlen(pwdstr)-1, q = pe->pw_name;
*q && p >= pwdstr; q++, p--) {
if(tolower(*p) != tolower(*q)) {
r += 2;
break;
}
}
if(gotuid && r != 3) {
puts("Please don't use something like your username as password!");
goto redo_it;
}
/* do various other checks for stupid passwords here... */
time(&tm);
salt[0] = bin_to_ascii(tm & 0x3f);
salt[1] = bin_to_ascii((tm >> 5) & 0x3f);
cryptstr = crypt(pwdstr, salt);
if(access("/etc/ptmp", F_OK) == 0) {
puts("/etc/ptmp exists, can't change password");
exit(1);
}
if(!(fd_out = fopen("/etc/ptmp", "w"))) {
puts("Can't open /etc/ptmp, can't update password");
exit(1);
}
if(!(fd_in = fopen("/etc/passwd", "r"))) {
puts("Can't read /etc/passwd, can't update password");
exit(1);
}
while(fgets(line, sizeof(line), fd_in)) {
if(!strncmp(line,user,strlen(user))) {
pe->pw_passwd = cryptstr;
if(putpwent(pe, fd_out) < 0) {
error = 1;
}
} else {
if(fputs(line,fd_out) < 0) {
error = 1;
}
}
if(error) {
puts("Error while writing new password file, password not changed.");
fclose(fd_out);
endpwent();
unlink("/etc/ptmp");
exit(1);
}
}
fclose(fd_in);
fclose(fd_out);
unlink("/etc/passwd.OLD");
link("/etc/passwd", "/etc/passwd.OLD");
unlink("/etc/passwd");
link("/etc/ptmp", "/etc/passwd");
unlink("/etc/ptmp");
chmod("/etc/passwd", 0644);
chown("/etc/passwd", 0, 0);
puts("Password changed.");
exit(0);
}
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