next

    pub fn next(dr: *DnsResponse) Error!?Answer {
        if (dr.answers_remaining == 0) return null;
        dr.answers_remaining -= 1;
        const r = dr.bytes;
        var i = dr.bytes_index;
        while (i < r.len and r[i] -% 1 < 127) i += 1;
        if (r.len - i < 12) return error.InvalidDnsPacket;
        i = i + 1 + @intFromBool(r[i] != 0);
        const len = std.mem.readInt(u16, r[i + 8 ..][0..2], .big);
        if (i + 10 + len > r.len) return error.InvalidDnsPacket;
        defer dr.bytes_index = i + 10 + len;
        return .{
            .rr = @fromBackingInt(@intCast(r[i + 1])),
            .packet = r,
            .data_off = i + 10,
            .data_len = len,
        };
    }