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-- Because we deal with pre-authed sessions and streams we can't be host-specific
module:set_global();
local filters = require "util.filters";
local throttle = require "util.throttle";
local timer = require "util.timer";
local ceil = math.ceil;
local limits_cfg = module:get_option("limits", {});
local limits_resolution = module:get_option_number("limits_resolution", 1);
local default_bytes_per_second = 3000;
local default_burst = 2;
local rate_units = { b = 1, k = 3, m = 6, g = 9, t = 12 } -- Plan for the future.
local function parse_rate(rate, sess_type)
local quantity, unit, exp;
if rate then
quantity, unit = rate:match("^(%d+) ?([^/]+)/s$");
exp = quantity and rate_units[unit:sub(1,1):lower()];
end
if not exp then
module:log("error", "Error parsing rate for %s: %q, using default rate (%d bytes/s)", sess_type, rate, default_bytes_per_second);
return default_bytes_per_second;
end
return quantity*(10^exp);
end
local function parse_burst(burst, sess_type)
if type(burst) == "string" then
burst = burst:match("^(%d+) ?s$");
end
local n_burst = tonumber(burst);
if burst and not n_burst then
module:log("error", "Unable to parse burst for %s: %q, using default burst interval (%ds)", sess_type, tostring(burst), default_burst);
end
return n_burst or default_burst;
end
-- Process config option into limits table:
-- limits = { c2s = { bytes_per_second = X, burst_seconds = Y } }
local limits = {};
for sess_type, sess_limits in pairs(limits_cfg) do
limits[sess_type] = {
bytes_per_second = parse_rate(sess_limits.rate, sess_type);
burst_seconds = parse_burst(sess_limits.burst, sess_type);
};
end
local default_filter_set = {};
function default_filter_set.bytes_in(bytes, session)
local sess_throttle = session.throttle;
if sess_throttle then
local ok, balance, outstanding = sess_throttle:poll(#bytes, true);
if not ok then
session.log("debug", "Session over rate limit (%d) with %d (by %d), pausing", sess_throttle.max, #bytes, outstanding);
outstanding = ceil(outstanding);
session.conn:pause(); -- Read no more data from the connection until there is no outstanding data
local outstanding_data = bytes:sub(-outstanding);
bytes = bytes:sub(1, #bytes-outstanding);
timer.add_task(limits_resolution, function ()
if not session.conn then return; end
if sess_throttle:peek(#outstanding_data) then
session.log("debug", "Resuming paused session");
session.conn:resume();
end
-- Handle what we can of the outstanding data
session.data(outstanding_data);
end);
end
end
return bytes;
end
local type_filters = {
c2s = default_filter_set;
s2sin = default_filter_set;
s2sout = default_filter_set;
};
local function filter_hook(session)
local session_type = session.type:match("^[^_]+");
local filter_set, opts = type_filters[session_type], limits[session_type];
if opts then
session.throttle = throttle.create(opts.bytes_per_second * opts.burst_seconds, opts.burst_seconds);
filters.add_filter(session, "bytes/in", filter_set.bytes_in, 1000);
end
end
function module.load()
filters.add_filter_hook(filter_hook);
end
function module.unload()
filters.remove_filter_hook(filter_hook);
end
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