A script for Garry's Mod that monitors and logs outgoing net library messages

sv_netwatcher.lua

--[[
Commands:

net_getinfo: Prints out stats about the X biggest and most common net messages, where X is the value of net_maxlines
net_getinfo <net message>: Prints out stats about a specific net message
net_reset: Resets the interval and counts used in net_getinfo

net_addfilter <net message>: Prevents a net message from being logged or shown in net_getinfo
net_removefilter <net message>: Removes a net message from the filter list
net_checkfilter: Prints out all net messages that are on the filter list
net_clearfilter: Clears out all net messages from the filter

Convars:

net_logoutgoing: Outputs stats about every outgoing net message to the server console (Except where filtered)
net_maxlines: How many lines net_getinfo should show
]]

local doLog = CreateConVar("net_logoutgoing", 0, FCVAR_NONE)
local maxLines = CreateConVar("net_maxlines", 5, FCVAR_ARCHIVE)

net.StartTime = net.StartTime or CurTime()
net.NetworkData = net.NetworkData or {}
net.NetworkFilter = net.NetworkFilter or {}
net.MessageCount = net.MessageCount or 0
net.BytesCount = net.BytesCount or 0

local function AccessCheck(ply)
	if game.SinglePlayer() or not IsValid(ply) then
		return true
	end

	return false
end

local function printf(str, ...)
	print(string.format(str, ...))
end

local function perc(val, max)
	return math.Round((val / max) * 100, 2)
end

function net.LogOutgoing(filter)
	local recipients
	local typeID = TypeID(filter or nil)

	local playerCount = 0
	local broadcast = false

	if typeID == TYPE_ENTITY then
		recipients = string.format("client: %s (%s)", filter:Nick(), filter:SteamID())
		playerCount = 1
	elseif typeID == TYPE_TABLE then
		recipients = string.format("%s clients", #filter)
		playerCount = #filter
	elseif typeID == TYPE_RECIPIENTFILTER then
		recipients = string.format("%s clients", filter:GetCount())
		playerCount = filter:GetCount()
	else
		recipients = "everyone"
		playerCount = player.GetCount()
		broadcast = true
	end

	local name = net.CurrentMessageName
	local bytes = (net.BytesWritten() * playerCount)

	net.MessageCount = net.MessageCount + 1
	net.BytesCount = net.BytesCount + bytes

	net.NetworkData[name] = net.NetworkData[name] or {
		Count = 0,
		Bytes = 0,
		PlayerCount = 0,
		Broadcast = 0
	}

	net.NetworkData[name].Count = net.NetworkData[name].Count + 1
	net.NetworkData[name].Bytes = net.NetworkData[name].Bytes + bytes

	net.NetworkData[name].PlayerCount = net.NetworkData[name].PlayerCount + playerCount

	if broadcast then
		net.NetworkData[name].Broadcast = net.NetworkData[name].Broadcast + 1
	end

	if doLog:GetBool() and not net.NetworkFilter[name] then
		printf("Outgoing %s message %s (%s) to %s", net.IsUnreliable and "unreliable" or "reliable", name, string.NiceSize(bytes), recipients)
	end
end

concommand.Add("net_addfilter", function(ply, cmd, args)
	if not AccessCheck(ply) or not args[1] then
		return
	end

	net.NetworkFilter[args[1]] = true
end)

concommand.Add("net_removefilter", function(ply, cmd, args)
	if not AccessCheck(ply) or not args[1] then
		return
	end

	net.NetworkFilter[args[1]] = nil
end)

concommand.Add("net_checkfilter", function(ply)
	if not AccessCheck(ply) then
		return
	end

	if table.Count(net.NetworkFilter) == 0 then
		print("-------")
		print("No network messages are being filtered")
		print("-------")

		return
	end

	print("-------")
	print("Filtered network messages:")
	print("-------")

	for k in SortedPairs(net.NetworkFilter) do
		print(k)
	end

	print("-------")
end)

concommand.Add("net_clearfilter", function(ply)
	if not AccessCheck(ply) then
		return
	end

	net.NetworkFilter = {}
end)

concommand.Add("net_getinfo", function(ply, cmd, args)
	if not AccessCheck(ply) then
		return
	end

	print("-------")

	local time = CurTime() - net.StartTime
	local messageName = args[1]

	if messageName then
		if net.NetworkData[messageName] then
			print("Network data for message: " .. messageName)
			print("Interval: " .. string.NiceTime(time))
			print("-------")

			local data = net.NetworkData[messageName]

			printf("Times sent: %s (%s messages/sec, %s%%)", data.Count, math.Round(data.Count / time, 2), perc(data.Count, net.MessageCount))
			printf("Sent to %s players on average per message", math.Round(data.PlayerCount / data.Count))
			printf("Broadcast to everyone %s%% of the time (%s/%s messages)", perc(data.Broadcast, data.Count), data.Broadcast, data.Count)
			printf("Data sent: %s (%s/sec, %s%%)", string.NiceSize(data.Bytes), string.NiceSize(math.Round(data.Bytes / time)), perc(data.Bytes, net.BytesCount))
		else
			print("No network data found for this message")
		end
	else
		print("Biggest contributors to net library usage:")
		printf("Interval: %s", string.NiceTime(time))
		printf("Messages sent: %s", net.MessageCount)
		printf("Data sent: %s", string.NiceSize(net.BytesCount))
		print("-------")

		local keys = {}

		for k in pairs(net.NetworkData) do
			if net.NetworkFilter[k] then
				continue
			end

			keys[#keys + 1] = k
		end

		local function output()
			local max = {
				name = 0,
				count = 0,
				data = 0
			}

			local lines = {}

			for i = 1, math.min(#keys, maxLines:GetInt()) do
				local name = keys[i]
				local data = net.NetworkData[name]

				lines[name] = {
					string.format("Count: %s (%s messages/sec, %s%%)", data.Count, math.Round(data.Count / time, 2), perc(data.Count, net.MessageCount)),
					string.format("Data: %s (%s/sec, %s%%)", string.NiceSize(data.Bytes), string.NiceSize(math.Round(data.Bytes / time)), perc(data.Bytes, net.BytesCount))
				}

				max.name = math.max(max.name, #name + 2)
				max.count = math.max(max.count, #lines[name][1] + 1)
				max.data = math.max(max.data, #lines[name][2])
			end

			for i = 1, math.min(#keys, maxLines:GetInt()) do
				local name = keys[i]
				local line = lines[name]

				printf("%-" .. max.name .. "s %-" .. max.count .. "s %-" .. max.data .. "s", name .. ": ", line[1], line[2])
			end
		end

		print("Sorted by message size")
		print("-------")

		table.sort(keys, function(a, b)
			return net.NetworkData[a].Bytes > net.NetworkData[b].Bytes
		end)

		output()

		print("-------")
		print("Sorted by message count")
		print("-------")

		table.sort(keys, function(a, b)
			return net.NetworkData[a].Count > net.NetworkData[b].Count
		end)

		output()
	end

	print("-------")
end)

concommand.Add("net_reset", function(ply)
	if not AccessCheck(ply) then
		return
	end

	net.StartTime = CurTime()
	net.NetworkData = {}
	net.MessageCount = 0
	net.BytesCount = 0
end)

net.OldStart = net.OldStart or net.Start
net.OldSend = net.OldSend or net.Send
net.OldSendOmit = net.OldSendOmit or net.SendOmit
net.OldSendPAS = net.OldSendPAS or net.SendPAS
net.OldSendPVS = net.OldSendPVS or net.SendPVS
net.OldBroadcast = net.OldBroadcast or net.Broadcast

function net.Start(messageName, unreliable)
	net.CurrentMessageName = messageName
	net.IsUnreliable = unreliable or false

	net.OldStart(messageName, unreliable)
end

function net.Send(ply)
	net.LogOutgoing(ply)
	net.OldSend(ply)
end

function net.SendOmit(ply)
	local filter = RecipientFilter()

	filter:AddAllPlayers()

	if istable(ply) then
		for _, v in pairs(ply) do
			if v:IsPlayer() then
				filter:RemovePlayer(v)
			end
		end
	else
		filter:RemovePlayer(ply)
	end

	net.LogOutgoing(filter)
	net.OldSendOmit(ply)
end

function net.SendPAS(vec)
	local filter = RecipientFilter()

	filter:AddPAS(vec)

	net.LogOutgoing(filter)
	net.OldSendPAS(vec)
end

function net.SendPVS(vec)
	local filter = RecipientFilter()

	filter:AddPVS(vec)

	net.LogOutgoing(filter)
	net.OldSendPVS(vec)
end

function net.Broadcast()
	net.LogOutgoing()
	net.OldBroadcast()
end

Hi thanks for writing this up. This is awesome, helps a lot with debugging.
I'm seeing an error for some messages:
lua:67: attempt to perform arithmetic on a nil value
Any pointers? Thanks.

My only guess is that it's to do with how you are using the net library in general as that shouldn't be able to happen unless someone calls one of the net.Send/Broadcast functions without having called net.Start first