Hash P2P messages as they are received instead of at process-time

src/net.cpp

@@ -758,12 +758,21 @@ int CNetMessage::readData(const char *pch, unsigned int nBytes)
         vRecv.resize(std::min(hdr.nMessageSize, nDataPos + nCopy + 256 * 1024));
     }
 
+    hasher.Write((const unsigned char*)pch, nCopy);
     memcpy(&vRecv[nDataPos], pch, nCopy);
     nDataPos += nCopy;
 
     return nCopy;
 }
 
+const uint256& CNetMessage::GetMessageHash() const
+{
+    assert(complete());
+    if (data_hash.IsNull())
+        hasher.Finalize(data_hash.begin());
+    return data_hash;
+}
+