add new function crypt_newhash to simplify creating new hashes.

does most of the work pwd_gensalt did, but also creates the hash.
(unused yet)

src/lib/libc/crypt/crypt.3

@@ -1,4 +1,4 @@
-.\" $OpenBSD: crypt.3,v 1.38 2014/05/16 22:11:00 jmc Exp $
+.\" $OpenBSD: crypt.3,v 1.39 2014/11/17 16:47:28 tedu Exp $
 .\"
 .\" FreeSec: libcrypt
 .\"
@@ -31,7 +31,7 @@
 .\"
 .\" Manual page, using -mandoc macros
 .\"
-.Dd $Mdocdate: May 16 2014 $
+.Dd $Mdocdate: November 17 2014 $
 .Dt CRYPT 3
 .Os
 .Sh NAME
@@ -55,6 +55,8 @@
 .Ft int
 .Fn crypt_checkpass "const char *password" "const char *hash"
 .Ft int
+.Fn crypt_newhash "const char *password" "login_cap_t *lc" "char *hash" "size_t hashsize"
+.Ft int
 .Fn encrypt "char *block" "int flag"
 .Ft int
 .Fn des_setkey "const char *key"
@@ -102,6 +104,19 @@ If the hash is NULL, authentication will always fail, but a default
 amount of work is performed to simulate the hashing operation.
 A successful match will return 0.
 A failure will return \-1 and set errno.
+.Pp
+The
+.Fn crypt_newhash
+function is provided to simplify the creation of new password hashes.
+The provided
+.Fa password
+is randomly salted and hashed and stored in
+.Fa hash .
+The login class argument
+.Fa lc
+is used to identify the preferred hashing algorithm and parameters.
+Refer to
+.Xr login.conf 5 .
 .Ss Extended crypt
 The
 .Ar key

src/lib/libc/crypt/cryptutil.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: cryptutil.c,v 1.1 2014/05/12 19:13:14 tedu Exp $ */
+/* $OpenBSD: cryptutil.c,v 1.2 2014/11/17 16:47:28 tedu Exp $ */
 /*
  * Copyright (c) 2014 Ted Unangst <tedu@openbsd.org>
  *
@@ -18,6 +18,7 @@
 #include <unistd.h>
 #include <string.h>
 #include <pwd.h>
+#include <login_cap.h>
 #include <errno.h>
 
 int
@@ -52,3 +53,30 @@ fail:
 	errno = EACCES;
 	return -1;
 }
+
+int
+crypt_newhash(const char *pass, login_cap_t *lc, char *hash, size_t hashlen)
+{
+	int rv = -1;
+	char *pref;
+	char *defaultpref = "blowfish,8";
+	const char *errstr;
+	int rounds;
+
+	if (lc == NULL ||
+	    (pref = login_getcapstr(lc, "localcipher", NULL, NULL)) == NULL)
+		pref = defaultpref;
+	if (strncmp(pref, "blowfish,", 9) != 0) {
+		errno = EINVAL;
+		goto err;
+	}
+	rounds = strtonum(pref + 9, 4, 31, &errstr);
+	if (errstr)
+		goto err;
+	rv = bcrypt_newhash(pass, rounds, hash, hashlen);
+
+err:
+	if (pref != defaultpref)
+		free(pref);
+	return rv;
+}