1 files changed, 82 insertions, 0 deletions
diff --git a/libmisc/valid.c b/libmisc/valid.c
new file mode 100644
index 0000000..326635f
--- /dev/null
+++ b/libmisc/valid.c
@@ -0,0 +1,82 @@
+/*
+ * SPDX-FileCopyrightText: 1989 - 1993, Julianne Frances Haugh
+ * SPDX-FileCopyrightText: 1996 - 1999, Marek Michałkiewicz
+ * SPDX-FileCopyrightText: 2003 - 2005, Tomasz Kłoczko
+ * SPDX-FileCopyrightText: 2007 - 2008, Nicolas François
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <config.h>
+
+#ident "$Id$"
+
+#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.
+ */
+bool valid (const char *password, const struct passwd *ent)
+{
+	const char *encrypted;
+	/*@observer@*/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 ((NULL != ent->pw_name) && ('\0' == ent->pw_passwd[0])) {
+		if ('\0' == password[0]) {
+			return true;	/* user entered nothing */
+		} else {
+			return false;	/* user entered something! */
+		}
+	}
+
+	/*
+	 * If there is no entry then we need a salt to use.
+	 */
+
+	if ((NULL == ent->pw_name) || ('\0' == ent->pw_passwd[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 (   (NULL != ent->pw_name)
+	    && (NULL != encrypted)
+	    && (strcmp (encrypted, ent->pw_passwd) == 0)) {
+		return true;
+	} else {
+		return false;
+	}
+}
+