m_align
#define M_ALIGN(m, len) m_align(m, len)
#define MH_ALIGN(m, len) m_align(m, len)
#define MEXT_ALIGN(m, len) m_align(m, len)
m_align(m, fragsize - ciphdrsize);
m_align(m, 2 * 3);
m_align(m, 2);
m_align(m, 2);