Rednet Spam Monitor server_api

local expiry = 3
local freshness = 60
local threshold = 10
local expired = 120

local operatingChannel = 26743
local messageList = {}
local activeSpam = {}
local locationDatabase = {}
local profileQueue = {}
local checkTimer = os.startTimer(1)

local findSpammers = function()
    local potentialSpammers = {}
    local topTargets = {}
    for k, message in pairs(messageList) do
        if message.expiry > os.clock() then
            local origin = tostring(message.origin)
            if not potentialSpammers[origin] then
                potentialSpammers[origin] = {count = 0, fiveIDs = {}}
                topTargets[origin] = {}
            end
            if not topTargets[origin][tostring(message.target)] then
                topTargets[origin][tostring(message.target)] = 0
            end
            topTargets[origin][tostring(message.target)] = topTargets[origin][tostring(message.target)] + 1
            potentialSpammers[origin].count = potentialSpammers[origin].count + 1
            table.insert(potentialSpammers[origin].fiveIDs, message.id)
            if #potentialSpammers[origin].fiveIDs > 5 then
                table.remove(potentialSpammers[origin].fiveIDs, 1)
            end
        end
    end

    for origin, v in pairs(potentialSpammers) do
        if v.count > threshold then
            local highestHit = 0
            local topTarget = nil
            for target, hit in pairs(topTargets[origin]) do
                if hit > highestHit then
                    highestHit = hit
                    topTarget = target
                end
            end
            table.insert(profileQueue, {origin = origin, id = v.fiveIDs[1], target = topTarget, time = os.clock()})
        end
    end

    os.queueEvent("ddosmonitor-profile-constructor-bump")
end

local function trilaterate( A, B, C )
    local a2b = B.vPosition - A.vPosition
    local a2c = C.vPosition - A.vPosition

    if math.abs( a2b:normalize():dot( a2c:normalize() ) ) > 0.999 then
        return nil
    end

    local d = a2b:length()
    local ex = a2b:normalize( )
    local i = ex:dot( a2c )
    local ey = (a2c - (ex * i)):normalize()
    local j = ey:dot( a2c )
    local ez = ex:cross( ey )

    local r1 = A.nDistance
    local r2 = B.nDistance
    local r3 = C.nDistance

    local x = (r1*r1 - r2*r2 + d*d) / (2*d)
    local y = (r1*r1 - r3*r3 - x*x + (x-i)*(x-i) + j*j) / (2*j)

    local result = A.vPosition + (ex * x) + (ey * y)

    local zSquared = r1*r1 - x*x - y*y
    if zSquared > 0 then
        local z = math.sqrt( zSquared )
        local result1 = result + (ez * z)
        local result2 = result - (ez * z)

        local rounded1, rounded2 = result1:round( nRoundSize ), result2:round( nRoundSize )
        if rounded1.x ~= rounded2.x or rounded1.y ~= rounded2.y or rounded1.z ~= rounded2.z then
            return rounded1, rounded2
        else
            return rounded1
        end
    end
    return result:round( nRoundSize )

end

local function narrow( p1, p2, fix )
    local dist1 = math.abs( (p1 - fix.vPosition):length() - fix.nDistance )
    local dist2 = math.abs( (p2 - fix.vPosition):length() - fix.nDistance )

    if math.abs(dist1 - dist2) < 0.01 then
        return p1, p2
    elseif dist1 < dist2 then
        return p1:round( nRoundSize )
    else
        return p2:round( nRoundSize )
    end
end

local getLocation = function(locations)
    -- PLEASE DON'T KILL ME FOR USING THESE VARIABLE NAMES, IT WAS WRITTEN BY DAN200
    -- Code taken from /rom/apis/gps by dan200
    local fixes = {}
    for k, location in pairs(locations) do
        table.insert(fixes, {vPosition = vector.new( location.x, location.y, location.z ), nDistance = location.dist})
    end

    local pos1, pos2 = trilaterate(fixes[1], fixes[2], fixes[3])
    if #fixes > 3 then
        for i = 4, #fixes do
            pos1, pos2 = narrow(pos1, pos2, fixes[i])
        end
    end

    if pos1 and pos2 then
        return "Possible locations: x: ".. pos1.x.." y: ".. pos1.y.." z: "..pos1.z, "or x: "..pos2.x.." y: "..pos2.y.." z: "..pos2.z
    elseif pos1 then
        return "Position: x: ".. pos1.x.." y: ".. pos1.y.." z: "..pos1.z
    else
        return "Unknown"
    end
end

local isInMessageList = function(id)
    for k,v in pairs(messageList) do
        if v.id == id then
            return true
        end
    end
    return false
end

local ddosMonitor = function()
    server.modem.open(rednet.CHANNEL_REPEAT)

    while true do
        local event, side, channel, reply, message, dist = os.pullEventRaw()
        if event == "modem_message" and channel == rednet.CHANNEL_REPEAT and type(message) == "table" then
            if message.nMessageID and message.nRecipient and not isInMessageList(message.nMessageID) then
                table.insert(messageList, {origin = reply, target = message.nRecipient, id = message.nMessageID, expiry = os.clock() + expiry})
                if #messageList > 100 then
                    table.remove(messageList, 1)
                end
            end
        elseif event == "timer" and side == checkTimer then
            findSpammers()
            checkTimer = os.startTimer(1)
        end
    end
end

local profileConstructor = function()
    while true do
        os.pullEvent()
        while #profileQueue > 0 do
            local currentProfile = profileQueue[1]
            table.remove(profileQueue, 1)
            local target = ""
            if tonumber(currentProfile.target) == rednet.CHANNEL_BROADCAST then
                target = "Broadcast"
            else
                target = currentProfile.target
            end
            if locationDatabase[currentProfile.origin] and (locationDatabase[currentProfile.origin].expiry > os.clock()) then
                cachedLocation = locationDatabase[currentProfile.origin]
                activeSpam[currentProfile.origin] = {active = os.clock(), locationA = cachedLocation.locationA, locationB = cachedLocation.locationB, target = target}
            else
                local responses = {}

                server.modem.open(operatingChannel)
                server.modem.transmit(operatingChannel, {
                    ddosMonitor = "request",
                    messageID = currentProfile.id
                })

                local timeout = os.startTimer(2)
                while true do
                    local event, side, channel, reply, message = os.pullEventRaw()
                    if event == "modem_message" and type(message) == "table" and message.ddosMonitor and message.ddosMonitor == "response" then
                        if message.x and message.y and message.z and message.dist and message.id and message.id == currentProfile.id then
                            table.insert(responses, {x = message.x, y = message.y, z = message.z, dist = message.dist})
                        end
                    elseif event == "timer" and side == timeout then
                        if #responses > 2 then
                            locationA, locationB = getLocation(responses)
                            locationDatabase[currentProfile.origin] = {locationA = locationA, locationB = locationB, expiry = os.clock() + freshness}
                            activeSpam[currentProfile.origin] = {active = os.clock(), locationA = locationA, locationB = locationB, target = target}
                        else
                            activeSpam[currentProfile.origin] = {active = os.clock(), locationA = "Unknown", target = target}
                        end
                        break
                    end
                end
            end
        end
    end
end

local main = function()
    while true do
        parallel.waitForAny(ddosMonitor, profileConstructor)
    end
end

server.runCoroutine(main)

local getData = function()
    local returnTable = {}
    local spamCopy = {}
    for k,v in pairs(activeSpam) do
        spamCopy[k] = v
    end
    for i = 1, 3 do
        local mostRecent = math.huge
        local mostRecentID = nil
        for id, v in pairs(spamCopy) do
            if ((os.clock() - v.active) < expired) and (os.clock() - v.active) < mostRecent then
                mostRecent = (os.clock() - v.active)
                mostRecentID = id
            end
        end
        if mostRecentID then
            table.insert(returnTable, {id = mostRecentID, time = mostRecent,
            locationA = spamCopy[mostRecentID].locationA, locationB = spamCopy[mostRecentID].locationB})
            spamCopy[mostRecentID] = nil
        end
    end

    local a = textutils.serialize(returnTable)
    return a
end

server.handleRequest("get", getData)