From 5b9508c9a5d757223c62749c51eaf7453ff26691 Mon Sep 17 00:00:00 2001
From: Nick Mathewson <nickm@torproject.org>
Date: Mon, 3 Aug 2020 10:11:03 -0400
Subject: Add a tor_str_wipe_and_free() function.

Frequently we want to do

    if (s) {
      memwipe(s, 0, sizeof(s));
      tor_free(s);
    }

and it's good to have a way to do this concisely.
---
 src/lib/crypt_ops/crypto_util.c | 14 ++++++++++++++
 src/lib/crypt_ops/crypto_util.h | 10 ++++++++++
 2 files changed, 24 insertions(+)

(limited to 'src')

diff --git a/src/lib/crypt_ops/crypto_util.c b/src/lib/crypt_ops/crypto_util.c
index 67a1a9eb92..2f821fa024 100644
--- a/src/lib/crypt_ops/crypto_util.c
+++ b/src/lib/crypt_ops/crypto_util.c
@@ -109,3 +109,17 @@ memwipe(void *mem, uint8_t byte, size_t sz)
    **/
   memset(mem, byte, sz);
 }
+
+/**
+ * Securely all memory in <b>str</b>, then free it.
+ *
+ * As tor_free(), tolerates null pointers.
+ **/
+void
+tor_str_wipe_and_free_(char *str)
+{
+  if (!str)
+    return;
+  memwipe(str, 0, strlen(str));
+  tor_free_(str);
+}
diff --git a/src/lib/crypt_ops/crypto_util.h b/src/lib/crypt_ops/crypto_util.h
index 613a1bd0dd..b5d7f62521 100644
--- a/src/lib/crypt_ops/crypto_util.h
+++ b/src/lib/crypt_ops/crypto_util.h
@@ -14,8 +14,18 @@
 #define TOR_CRYPTO_UTIL_H
 
 #include "lib/cc/torint.h"
+#include "lib/malloc/malloc.h"
 
 /** OpenSSL-based utility functions. */
 void memwipe(void *mem, uint8_t byte, size_t sz);
 
+void tor_str_wipe_and_free_(char *str);
+/**
+ * Securely all memory in <b>str</b>, then free it.
+ *
+ * As tor_free(), tolerates null pointers, and sets <b>str</b> to NULL.
+ **/
+#define tor_str_wipe_and_free(str)                      \
+  FREE_AND_NULL(char, tor_str_wipe_and_free_, (str))
+
 #endif /* !defined(TOR_CRYPTO_UTIL_H) */
-- 
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