Function msgToKey

proxy/cache.go:537–552

msgToKey constructs the cache key from type, class and question's name of m.

(m *dns.Msg)

// msgToKey constructs the cache key from type, class and question's name of m.
func msgToKey(m *dns.Msg) (b []byte) {
	q := m.Question[0]
	name := q.Name
	b = make([]byte, 1+packedMsgLenSz+packedMsgLenSz+len(name))

	// Put the DO flag.
	opt := m.IsEdns0()
	b[0] = mathutil.BoolToNumber[byte](opt != nil && opt.Do())

	// Put QTYPE, QCLASS, and QNAME.
	binary.BigEndian.PutUint16(b[1:], q.Qtype)
	binary.BigEndian.PutUint16(b[1+packedMsgLenSz:], q.Qclass)
	copy(b[1+2*packedMsgLenSz:], strings.ToLower(name))

	return b
}

const (
	// keyMaskIndex is the index of the byte with mask ones value.