tauth_userpasswd.c - plan9port - [fork] Plan 9 from user space
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       tauth_userpasswd.c (1097B)
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            1 #include <u.h>
            2 #include <libc.h>
            3 #include <auth.h>
            4 #include <authsrv.h>
            5 #include "authlocal.h"
            6 
            7 /*
            8  * compute the proper response.  We encrypt the ascii of
            9  * challenge number, with trailing binary zero fill.
           10  * This process was derived empirically.
           11  * this was copied from inet's guard.
           12  */
           13 static void
           14 netresp(char *key, long chal, char *answer)
           15 {
           16         uchar buf[8];
           17 
           18         memset(buf, 0, 8);
           19         sprint((char *)buf, "%lud", chal);
           20         if(encrypt(key, buf, 8) < 0)
           21                 abort();
           22         chal = (buf[0]<<24)+(buf[1]<<16)+(buf[2]<<8)+buf[3];
           23         sprint(answer, "%.8lux", chal);
           24 }
           25 
           26 AuthInfo*
           27 auth_userpasswd(char *user, char *passwd)
           28 {
           29         char key[DESKEYLEN], resp[16];
           30         AuthInfo *ai;
           31         Chalstate *ch;
           32 
           33         /*
           34          * Probably we should have a factotum protocol
           35          * to check a raw password.  For now, we use
           36          * p9cr, which is simplest to speak.
           37          */
           38         if((ch = auth_challenge("user=%q proto=p9cr role=server", user)) == nil)
           39                 return nil;
           40 
           41         passtokey(key, passwd);
           42         netresp(key, atol(ch->chal), resp);
           43         memset(key, 0, sizeof key);
           44 
           45         ch->resp = resp;
           46         ch->nresp = strlen(resp);
           47         ai = auth_response(ch);
           48         auth_freechal(ch);
           49         return ai;
           50 }