ref: 2fe3b28f86ed4aa291fb8a620b948abe9c6a1f84
dir: /sys/src/libauth/auth_userpasswd.c/
#include <u.h>
#include <libc.h>
#include <auth.h>
#include <authsrv.h>
#include "authlocal.h"
/*
* compute the proper response. We encrypt the ascii of
* challenge number, with trailing binary zero fill.
* This process was derived empirically.
* this was copied from inet's guard.
*/
static void
netresp(char key[DESKEYLEN], long chal, char *answer)
{
uchar buf[8];
memset(buf, 0, sizeof buf);
snprint((char *)buf, sizeof buf, "%lud", chal);
if(encrypt(key, buf, 8) < 0)
abort();
sprint(answer, "%.8ux", buf[0]<<24 | buf[1]<<16 | buf[2]<<8 | buf[3]);
}
AuthInfo*
auth_userpasswd(char *user, char *passwd)
{
char resp[16], key[DESKEYLEN];
AuthInfo *ai;
Chalstate *ch;
/*
* Probably we should have a factotum protocol
* to check a raw password. For now, we use
* p9cr, which is simplest to speak.
*/
if((ch = auth_challenge("user=%q proto=p9cr role=server", user)) == nil)
return nil;
passtodeskey(key, passwd);
netresp(key, atol(ch->chal), resp);
memset(key, 0, sizeof(key));
ch->resp = resp;
ch->nresp = strlen(resp);
ai = auth_response(ch);
auth_freechal(ch);
return ai;
}