Potential stack overflow in NTLM type-2 header parsing

The NTLM response parser allocates an alloca() buffer based on strlen(header) and then base64-decodes the attacker-controlled server header into it. Because the buffer is only sized to the input string length, any decode path that expands to the same size as the input or omits space for a terminator can overrun the stack. The code then also reads from fixed offsets in the decoded buffer once size>=48.