Add CBB_discard_child(), which allows for a child CBB to be discarded.

Based on BoringSSL.

diff --git a/lib/libssl/bs_cbb.c b/lib/libssl/bs_cbb.c
index 9de75fb..bf7de3f 100644 (file)
--- a/lib/libssl/bs_cbb.c
+++ b/lib/libssl/bs_cbb.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: bs_cbb.c,v 1.17 2017/08/12 02:50:05 jsing Exp $       */
+/*     $OpenBSD: bs_cbb.c,v 1.18 2017/11/28 16:34:20 jsing Exp $       */
 /*
  * Copyright (c) 2014, Google Inc.
  *
@@ -271,6 +271,20 @@ CBB_flush(CBB *cbb)
        return 1;
 }
 
+void
+CBB_discard_child(CBB *cbb)
+{
+       if (cbb->child == NULL)
+               return;
+
+       cbb->base->len = cbb->offset;
+       
+       cbb->child->base = NULL;
+       cbb->child = NULL;
+       cbb->pending_len_len = 0;
+       cbb->pending_is_asn1 = 0;
+       cbb->offset = 0;
+}
 
 static int
 cbb_add_length_prefixed(CBB *cbb, CBB *out_contents, size_t len_len)

diff --git a/lib/libssl/bytestring.h b/lib/libssl/bytestring.h
index d8c8e6a..2e89a57 100644 (file)
--- a/lib/libssl/bytestring.h
+++ b/lib/libssl/bytestring.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: bytestring.h,v 1.15 2016/11/04 18:28:58 guenther Exp $        */
+/*     $OpenBSD: bytestring.h,v 1.16 2017/11/28 16:34:20 jsing Exp $   */
 /*
  * Copyright (c) 2014, Google Inc.
  *
@@ -393,6 +393,12 @@ int CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len);
  */
 int CBB_flush(CBB *cbb);
 
+/*
+ * CBB_discard_child discards the current unflushed child of |cbb|. Neither the
+ * child's contents nor the length prefix will be included in the output.
+ */
+void CBB_discard_child(CBB *cbb);
+
 /*
  * CBB_add_u8_length_prefixed sets |*out_contents| to a new child of |cbb|. The
  * data written to |*out_contents| will be prefixed in |cbb| with an 8-bit