nginx 100mb

    location ~ /(\d+)(.*) {
        set $size $1;
        set $unit $2;
        access_by_lua_block {
            local sent = 0
            local bufsize = 8192
            local payload = string.rep("0", bufsize)
            local _u = ngx.var.unit
            if _u ~= nil and _u ~= "" then
                _u = string.lower(_u)
            else
                _u = "m"
            end
            local size_table = {
                b = 1,
                k = 1024,
                m = 1048576,
                g = 1073741824,
            }
            local dsize = ngx.var.size * size_table[_u]
            if dsize > 1099511627776 then
                ngx.exit(404)
            end
            local range = ngx.req.get_headers()["Range"]
            if range ~= nil then
                local content_range = string.gsub(range, "=", "  ") .. "/" .. dsize
                ngx.header["Content-Range"] = content_range
                ngx.status = 206
            end
            ngx.header["Content-Length"] = dsize
            ngx.header["Content-Type"] = "application/octet-stream"
            local _bufferd = 0
            while sent < dsize do
                ngx.say(payload)
                _bufferd = _bufferd + bufsize
                if _bufferd > 524288 then
                    local ok, err = ngx.flush(true)
                    if not ok then
                        break
                    end
                    _bufferd = 0
                end
                sent = sent + bufsize
            end
        }
    }