[svn-upgrade] Integrating new upstream version, shadow (19990709)

libmisc/valid.c

@@ -0,0 +1,101 @@
+/*
+ * Copyright 1989 - 1993, Julianne Frances Haugh
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Julianne F. Haugh nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY JULIE HAUGH AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL JULIE HAUGH OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <config.h>
+
+#include "rcsid.h"
+RCSID("$Id: valid.c,v 1.4 1999/03/07 19:14:44 marekm Exp $")
+
+#include <sys/types.h>
+#include <stdio.h>
+#include "prototypes.h"
+#include "defines.h"
+#include <pwd.h>
+
+/*
+ * valid - compare encrypted passwords
+ *
+ *	Valid() compares the DES encrypted password from the password file
+ *	against the password which the user has entered after it has been
+ *	encrypted using the same salt as the original.  Entries which do
+ *	not have a password file entry have a NULL pw_name field and this
+ *	is used to indicate that a dummy salt must be used to encrypt the
+ *	password anyway.
+ */
+
+int
+valid(const char *password, const struct passwd *ent)
+{
+	const char *encrypted;
+	const char *salt;
+
+	/*
+	 * Start with blank or empty password entries.  Always encrypt
+	 * a password if no such user exists.  Only if the ID exists and
+	 * the password is really empty do you return quickly.  This
+	 * routine is meant to waste CPU time.
+	 */
+
+	if (ent->pw_name && ! ent->pw_passwd[0]) {
+		if (! password[0])
+			return (1);	/* user entered nothing */
+		else
+			return (0);	/* user entered something! */
+	}
+
+	/*
+	 * If there is no entry then we need a salt to use.
+	 */
+
+	if (ent->pw_name == (char *) 0 || ent->pw_passwd[0] == '\0') {
+		salt = "xx";
+	} else {
+		salt = ent->pw_passwd;
+	}
+
+	/*
+	 * Now, perform the encryption using the salt from before on
+	 * the users input.  Since we always encrypt the string, it
+	 * should be very difficult to determine if the user exists by
+	 * looking at execution time.
+	 */
+
+	encrypted = pw_encrypt(password, salt);
+
+	/*
+	 * One last time we must deal with there being no password file
+	 * entry for the user.  We use the pw_name == NULL idiom to
+	 * cause non-existent users to not be validated.
+	 */
+
+	if (ent->pw_name && strcmp(encrypted, ent->pw_passwd) == 0)
+		return (1);
+	else
+		return (0);
+}