Add real factotum.

libauth/auth_userpasswd.c

@@ -0,0 +1,50 @@
+#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, long chal, char *answer)
+{
+	uchar buf[8];
+
+	memset(buf, 0, 8);
+	sprint((char *)buf, "%lud", chal);
+	if(encrypt(key, buf, 8) < 0)
+		abort();
+	chal = (buf[0]<<24)+(buf[1]<<16)+(buf[2]<<8)+buf[3];
+	sprint(answer, "%.8lux", chal);
+}
+
+AuthInfo*
+auth_userpasswd(char *user, char *passwd)
+{
+	char key[DESKEYLEN], resp[16];
+	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;
+
+	passtokey(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;
+}