1 files changed, 37 insertions, 1 deletions

diff --git a/sshbuf-getput-basic.c b/sshbuf-getput-basic.c
index 06d6cc492..8ff8a0a28 100644
--- a/sshbuf-getput-basic.c
+++ b/sshbuf-getput-basic.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: sshbuf-getput-basic.c,v 1.3 2015/01/12 15:18:07 djm Exp $     */
+/*      $OpenBSD: sshbuf-getput-basic.c,v 1.4 2015/01/14 15:02:39 djm Exp $     */
 /*
  * Copyright (c) 2011 Damien Miller
  *
@@ -424,3 +424,39 @@ sshbuf_put_bignum2_bytes(struct sshbuf *buf, const void *v, size_t len)
                 memcpy(d + 4 + prepend, s, len);
         return 0;
 }
+
+int
+sshbuf_get_bignum2_bytes_direct(struct sshbuf *buf,
+    const u_char **valp, size_t *lenp)
+{
+        const u_char *d;
+        size_t len, olen;
+        int r;
+
+        if ((r = sshbuf_peek_string_direct(buf, &d, &olen)) < 0)
+                return r;
+        len = olen;
+        /* Refuse negative (MSB set) bignums */
+        if ((len != 0 && (*d & 0x80) != 0))
+                return SSH_ERR_BIGNUM_IS_NEGATIVE;
+        /* Refuse overlong bignums, allow prepended \0 to avoid MSB set */
+        if (len > SSHBUF_MAX_BIGNUM + 1 ||
+            (len == SSHBUF_MAX_BIGNUM + 1 && *d != 0))
+                return SSH_ERR_BIGNUM_TOO_LARGE;
+        /* Trim leading zeros */
+        while (len > 0 && *d == 0x00) {
+                d++;
+                len--;
+        }
+        if (valp != 0)
+                *valp = d;
+        if (lenp != NULL)
+                *lenp = len;
+        if (sshbuf_consume(buf, olen + 4) != 0) {
+                /* Shouldn't happen */
+                SSHBUF_DBG(("SSH_ERR_INTERNAL_ERROR"));
+                SSHBUF_ABORT();
+                return SSH_ERR_INTERNAL_ERROR;
+        }
+        return 0;
+}