fixed segfault in bignum.h,

additional security limits,
refactoring
-- version 0.3.7

git-svn-id: https://bitcoin.svn.sourceforge.net/svnroot/bitcoin/trunk@121 1a98c847-1fd6-4fd8-948a-caf3550aa51b

1 files changed, 12 insertions, 6 deletions

diff --git a/bignum.h b/bignum.h
index 44dfd97909..0701f7930f 100644
--- a/bignum.h
+++ b/bignum.h
@@ -401,8 +401,16 @@ public:
 

     CBigNum& operator>>=(unsigned int shift)

     {

-        // Note: BN_rshift segfaults on 64-bit ubuntu 9.10 if 2^shift is greater than the number,

-        //       tested OK on 64-bit ubuntu 10.4

+        // Note: BN_rshift segfaults on 64-bit if 2^shift is greater than the number

+        //   if built on ubuntu 9.04 or 9.10, probably depends on version of openssl

+        CBigNum a = 1;

+        a <<= shift;

+        if (BN_cmp(&a, this) > 0)

+        {

+            *this = 0;

+            return *this;

+        }

+

         if (!BN_rshift(this, this, shift))

             throw bignum_error("CBigNum:operator>>= : BN_rshift failed");

         return *this;

@@ -511,10 +519,8 @@ inline const CBigNum operator<<(const CBigNum& a, unsigned int shift)
 

 inline const CBigNum operator>>(const CBigNum& a, unsigned int shift)

 {

-    CBigNum r;

-    // Note: BN_rshift segfaults on 64-bit ubuntu 9.10 if 2^shift is greater than the number

-    if (!BN_rshift(&r, &a, shift))

-        throw bignum_error("CBigNum:operator>> : BN_rshift failed");

+    CBigNum r = a;

+    r >>= shift;

     return r;

 }