From deea96de7cc218556c65f5a17ab5c10651a452f0 Mon Sep 17 00:00:00 2001
From: dmiller <dmiller@e0a8ed71-7df4-0310-8962-fdc924857419>
Date: Sat, 8 Sep 2018 17:07:02 +0000
Subject: [PATCH] Make rand_bytes crypto-safe, use rand_pseudo_bytes for
 no-fail random

---
 nse_openssl.cc        | 8 ++++----
 nselib/openssl.luadoc | 7 ++++++-
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/nse_openssl.cc b/nse_openssl.cc
index cd613415e..ec187ee12 100644
--- a/nse_openssl.cc
+++ b/nse_openssl.cc
@@ -244,7 +244,9 @@ static int l_rand_bytes( lua_State *L ) /** rand_bytes( number bytes ) */
   unsigned char * result = (unsigned char *) malloc( len );
   if (!result) return luaL_error( L, "Couldn't allocate memory.");
 
-  RAND_bytes( result, len );
+  if (RAND_bytes( result, len ) != 1) {
+    return luaL_error(L, "Failure in RAND_bytes.");
+  }
   lua_pushlstring( L, (char *) result, len );
   free( result );
   return 1;
@@ -256,9 +258,7 @@ static int l_rand_pseudo_bytes( lua_State *L ) /** rand_pseudo_bytes( number byt
   unsigned char * result = (unsigned char *) malloc( len );
   if (!result) return luaL_error( L, "Couldn't allocate memory.");
 
-  if (RAND_bytes( result, len ) != 1) {
-    return luaL_error(L, "Failure in RAND_bytes.");
-  }
+  RAND_pseudo_bytes( result, len );
   lua_pushlstring( L, (char *) result, len );
   free( result );
   return 1;
diff --git a/nselib/openssl.luadoc b/nselib/openssl.luadoc
index 986870433..d8ba53aed 100644
--- a/nselib/openssl.luadoc
+++ b/nselib/openssl.luadoc
@@ -128,12 +128,17 @@ function bignum_div(a, b)
 -- @return bignum
 function bignum_add(a, b)
 
---- Returns a string containing random data.
+--- Returns a string containing cryptographically-strong random data.
+--
+-- If the PRNG has not been seeded with enough randomness, this function throws an error.
 -- @param bytes Length of the returned string in bytes.
 -- @return Random string.
 function rand_bytes(bytes)
 
 --- Returns a string containing pseudorandom data.
+--
+-- No indication is given whether or not the contents of the string are
+-- cryptographically strong.
 -- @param bytes Length of the returned string in bytes.
 -- @return Pseudorandom string.
 function rand_pseudo_bytes(bytes)