lib/other/crypt.c

   1 /*      crypt() - one-way password encryption function  Author: Kees J. Bot
   2  *                                                              7 Feb 1994
   3  * This routine does not encrypt anything, it uses the pwdauth
   4  * program to do the hard work.
   5  */
   6 #define nil ((void*)0)
   7 #define pipe _pipe
   8 #define fork _fork
   9 #define close _close
  10 #define dup2 _dup2
  11 #define execl _execl
  12 #define read _read
  13 #define _exit __exit
  14 #define write _write
  15 #define waitpid _waitpid
  16 #include <sys/types.h>
  17 #include <unistd.h>
  18 #include <string.h>
  19 #include <stdio.h>
  20 #include <errno.h>
  21 #include <stdarg.h>
  22 #include <sys/wait.h>
  23
  24 /* Set-uid root program to read /etc/shadow or encrypt passwords. */
  25 static char PWDAUTH[] = "/usr/lib/pwdauth";
  26 #define LEN     1024
  27
  28 static void tell(const char *s0, ...)
  29 {
  30         va_list ap;
  31         const char *s;
  32
  33         va_start(ap, s0);
  34         s= s0;
  35         while (s != nil) {
  36                 (void) write(2, s, strlen(s));
  37                 s= va_arg(ap, const char *);
  38         }
  39         va_end(ap);
  40 }
  41
  42 char *crypt(const char *key, const char *salt)
  43 {
  44         pid_t pid;
  45         int status;
  46         int pfd[2];
  47         static char pwdata[LEN];
  48         char *p= pwdata;
  49         const char *k= key;
  50         const char *s= salt;
  51         int n;
  52
  53         /* Fill pwdata[] with the key and salt. */
  54         while ((*p++ = *k++) != 0) if (p == pwdata+LEN-1) goto fail;
  55         while ((*p++ = *s++) != 0) if (p == pwdata+LEN-0) goto fail;
  56
  57         if (pipe(pfd) < 0) goto fail;
  58
  59         /* Prefill the pipe. */
  60         (void) write(pfd[1], pwdata, p - pwdata);
  61
  62         switch ((pid= fork())) {
  63         case -1:
  64                 close(pfd[0]);
  65                 close(pfd[1]);
  66                 goto fail;
  67         case 0:
  68                 /* Connect both input and output to the pipe. */
  69                 if (pfd[0] != 0) {
  70                         dup2(pfd[0], 0);
  71                         close(pfd[0]);
  72                 }
  73                 if (pfd[1] != 1) {
  74                         dup2(pfd[1], 1);
  75                         close(pfd[1]);
  76                 }
  77
  78                 execl(PWDAUTH, PWDAUTH, (char *) nil);
  79
  80                 tell("crypt(): ", PWDAUTH, ": ", strerror(errno), "\r\n",
  81                                                                 (char *) nil);
  82                 /* No pwdauth?  Fail! */
  83                 (void) read(0, pwdata, LEN);
  84                 _exit(1);
  85         }
  86         close(pfd[1]);
  87
  88         status= -1;
  89         while (waitpid(pid, &status, 0) == -1 && errno == EINTR) {}
  90         if (status != 0) {
  91                 close(pfd[0]);
  92                 goto fail;
  93         }
  94
  95         /* Read and return the result.  Check if it contains exactly one
  96          * string.
  97          */
  98         n= read(pfd[0], pwdata, LEN);
  99         close(pfd[0]);
 100         if (n < 0) goto fail;
 101         p = pwdata + n;
 102         n = 0;
 103         while (p > pwdata) if (*--p == 0) n++;
 104         if (n != 1) goto fail;
 105         return pwdata;
 106
 107 fail:
 108         pwdata[0] = salt[0] ^ 1;                /* make result != salt */
 109         pwdata[1] = 0;
 110         return pwdata;
 111 }
 112
 113 /*
 114  * $PchId: crypt.c,v 1.5 1996/04/11 07:46:11 philip Exp $
 115  */