commit a8653208ec76d228e889082d5c5e6ce781cdcd8d
author David Benjamin <davidben@chromium.org> Sun Jun 28 01:26:10 2015 -0400
committer Adam Langley <agl@google.com> Wed Jul 01 19:45:43 2015 +0000
tree 042c5519983b5e7fd8141e0249423b243fcabcb1
parent d63307199a9bc39fe86ec46a131d60c694af41f3

Add CBB_zero to set a CBB to the zero state.

One tedious thing about using CBB is that you can't safely CBB_cleanup
until CBB_init is successful, which breaks the general 'goto err' style
of cleanup. This makes it possible:

  CBB_zero ~ EVP_MD_CTX_init
  CBB_init ~ EVP_DigestInit
  CBB_cleanup ~ EVP_MD_CTX_cleanup

Change-Id: I085ecc4405715368886dc4de02285a47e7fc4c52
Reviewed-on: https://boringssl-review.googlesource.com/5267
Reviewed-by: Adam Langley <agl@google.com>

ssl/ssl_lib.c

diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
index 61546ca..91c66a4 100644
--- a/ssl/ssl_lib.c
+++ b/ssl/ssl_lib.c
@@ -2582,11 +2582,9 @@
     return 0;
   }
 
-  if (!CBB_init(&cbb, 4 + 16 + 1 + premaster_len * 2 + 1)) {
-    return 0;
-  }
-
-  if (!CBB_add_bytes(&cbb, (const uint8_t *)"RSA ", 4) ||
+  CBB_zero(&cbb);
+  if (!CBB_init(&cbb, 4 + 16 + 1 + premaster_len * 2 + 1) ||
+      !CBB_add_bytes(&cbb, (const uint8_t *)"RSA ", 4) ||
       /* Only the first 8 bytes of the encrypted premaster secret are
        * logged. */
       !cbb_add_hex(&cbb, encrypted_premaster, 8) ||
@@ -2624,11 +2622,9 @@
     return 0;
   }
 
-  if (!CBB_init(&cbb, 14 + 64 + 1 + master_len * 2 + 1)) {
-    return 0;
-  }
-
-  if (!CBB_add_bytes(&cbb, (const uint8_t *)"CLIENT_RANDOM ", 14) ||
+  CBB_zero(&cbb);
+  if (!CBB_init(&cbb, 14 + 64 + 1 + master_len * 2 + 1) ||
+      !CBB_add_bytes(&cbb, (const uint8_t *)"CLIENT_RANDOM ", 14) ||
       !cbb_add_hex(&cbb, client_random, 32) ||
       !CBB_add_bytes(&cbb, (const uint8_t *)" ", 1) ||
       !cbb_add_hex(&cbb, master, master_len) ||