upstream commit

fix signed/unsigned errors reported by clang-3.7; add
 sshbuf_dup_string() to replace a common idiom of strdup(sshbuf_ptr()) with
 better safety checking; feedback and ok markus@

Upstream-ID: 71f926d9bb3f1efed51319a6daf37e93d57c8820
diff --git a/kexc25519.c b/kexc25519.c
index 8d8cd4a..0897b8c 100644
--- a/kexc25519.c
+++ b/kexc25519.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexc25519.c,v 1.9 2015/03/26 07:00:04 djm Exp $ */
+/* $OpenBSD: kexc25519.c,v 1.10 2016/05/02 08:49:03 djm Exp $ */
 /*
  * Copyright (c) 2001, 2013 Markus Friedl.  All rights reserved.
  * Copyright (c) 2010 Damien Miller.  All rights reserved.
@@ -86,8 +86,8 @@
     int hash_alg,
     const char *client_version_string,
     const char *server_version_string,
-    const char *ckexinit, size_t ckexinitlen,
-    const char *skexinit, size_t skexinitlen,
+    const u_char *ckexinit, size_t ckexinitlen,
+    const u_char *skexinit, size_t skexinitlen,
     const u_char *serverhostkeyblob, size_t sbloblen,
     const u_char client_dh_pub[CURVE25519_SIZE],
     const u_char server_dh_pub[CURVE25519_SIZE],