#! /usr/bin/lua
--[[

	Part of AREDN -- Used for creating Amateur Radio Emergency Data Networks
	Copyright (C) 2021 Tim Wilkinson
	Original Perl Copyright (C) 2015 Conrad Lara
	See Contributors file for additional contributors

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation version 3 of the License.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program.  If not, see <http://www.gnu.org/licenses/>.

	Additional Terms:

	Additional use restrictions exist on the AREDN(TM) trademark and logo.
		See AREDNLicense.txt for more info.

	Attributions to the AREDN Project must be retained in the source code.
	If importing this code into a new or existing project attribution
	to the AREDN project must be added to the source code.

	You must not misrepresent the origin of the material contained within.

	Modified versions must be modified to attribute to the original source
	and be marked in reasonable ways as differentiate it from the original
	version

--]]

require("nixio")
require("aredn.utils")
require("aredn.hardware")
aredn.info = require('aredn.info')
require("uci")

-- Whether to validate hosts and services before publishing
local validate = false
local validation_timeout = 150 * 60 -- 2.5 hours (so must fail 3 times in a row)
local validation_state = "/tmp/service-validation-state"

-- check what config gile we are building for
local uci_conf_file
if #arg == 0 then
    uci_conf_file = "olsrd"
else
    uci_conf_file = arg[1]
    if #arg == 2 and arg[2] == "validate" then
        validate = true
    end
end

if uci_conf_file == "olsrd6" then
    -- we only generate entries for IPv4 at the moment
    os.exit(0)
end

local cursor = uci.cursor()
local cursorm = uci.cursor("/etc/config.mesh")

local names = {}
local hosts = {}
local services = {}
local tunnels = {}
local wgtunnels = {}

function ip_to_hostname(ip)
    if ip and ip ~= "" and ip ~= "none" then
        local a, b, c, d = ip:match("(.*)%.(.*)%.(.*)%.(.*)")
        local revip = d .. "." .. c .. "." .. b .. "." .. a
        local f = io.popen("nslookup " .. ip)
        if f then
            local pattern = "^" .. revip .. "%.in%-addr%.arpa%s+name%s+=%s+(%S+)%.local%.mesh"
            for line in f:lines()
            do
                local host = line:match(pattern)
                if host then
                    f:close()
                    return host
                end
            end
            f:close()
        end
    end
    return ""
end

-- canonical names for this node
-- (they should up in reverse order, make the official name last)
local name = aredn.info.get_nvram("tactical")
if name ~= "" then
    names[#names + 1] = name
end
name = aredn.info.get_nvram("node")
if name ~= "" then
    names[#names + 1] = name
end

local dmz_mode = cursor:get("aredn", "@dmz[0]", "mode")
if dmz_mode ~= "0" then
    if nixio.fs.stat("/etc/config.mesh/aliases.dmz") then
        for line in io.lines("/etc/config.mesh/aliases.dmz")
        do
            local ip, host = line:match("(.*) (.*)")
            if host then
                hosts[#hosts + 1] = { ip = ip, host = host }
            end
        end
    end
    if nixio.fs.stat("/etc/ethers") then
        local noprop_ip = {}
        if nixio.fs.stat("/etc/hosts") then
            for line in io.lines("/etc/hosts")
            do
                local ip = line:match("^(%S+)%s.*#NOPROP$")
                if ip then
                    noprop_ip[ip] = true
                end
            end
        end
        for line in io.lines("/etc/ethers")
        do
            local ip = line:match("[0-9a-fA-F:]+%s+([%d%.]+)")
            if ip and not noprop_ip[ip] then
                local host = ip_to_hostname(ip)
                if host then
                    hosts[#hosts + 1] = { ip = ip, host = host }
                end
            end
        end
    end
end

-- add a name for the dtdlink and xlink interfaces
if name then
    local dtdip = aredn.hardware.get_interface_ip4(aredn.hardware.get_iface_name("dtdlink"))
    if dtdip then
        hosts[#hosts + 1] = { ip = dtdip, host = "dtdlink." .. name .. ".local.mesh" }
        if nixio.fs.stat("/etc/config.mesh/xlink") then
            local count = 0
            uci.cursor("/etc/config.mesh"):foreach("xlink", "interface",
                function(section)
                    if section.ipaddr then
                        hosts[#hosts + 1] = { ip = section.ipaddr, host = "xlink" .. count .. "." .. name .. ".local.mesh" }
                        count = count + 1
                    end
                end
            )
        end
    end
end

-- load the services
if nixio.fs.stat("/etc/config/services") then
    for line in io.lines("/etc/config/services")
    do
        if line:match("^%w+://[%w%-%.]+:%d+.*|tcp|[^|]+$") or line:match("^%w+://[%w%-%.]+:%d+.*|udp|[^|]+$") then
            services[#services + 1] = line
        end
    end
end

-- validation
if validate then
    -- Load previous state
    local vstate = {}
    if nixio.fs.stat(validation_state) then
        for line in io.lines(validation_state)
        do
            local last, key = line:match("^(%d+) (.*)$")
            if last then
                vstate[key] = tonumber(last)
            end
        end
    end
    local now = os.time()
    local last = now + validation_timeout
    local laniface = aredn.hardware.get_iface_name("lan")
    -- Add in local names so services checks pass
    for _, name in ipairs(names)
    do
        vstate[name:lower()] = last
    end
    -- Check we can reach all the IP addresses
    for _, host in ipairs(hosts)
    do
        if os.execute("/bin/ping -q -c 1 -W 1 " .. host.ip .. " > /dev/null 2>&1") == 0 then
            vstate[host.host:lower()] = last
        elseif os.execute("/usr/sbin/arping -q -f -c 1 -w 1 -I " .. laniface .. " " .. host.ip .. " > /dev/null 2>&1") == 0 then
            vstate[host.host:lower()] = last
        end
    end
    -- Check all the services have a valid host
    for _, service in ipairs(services)
    do
        local proto, hostname, port, path = service:match("^(%w+)://([%w%-%.]+):(%d+)(.*)|...|[^|]+$")
        local vs = vstate[hostname:lower()]
        if not vs or vs > now or dmz_mode == "0" then
            if port == "0" then
                -- no port so not a link - we can only check the hostname so have to assume the service is good
                vstate[service] = last
            elseif proto == "http" then
                -- http so looks like a link. http check it
                if not hostname:match("%.local%.mesh$") then
                    hostname = hostname .. ".local.mesh"
                end
                local status, effective_url = io.popen("/usr/bin/curl --max-time 10 --retry 0 --connect-timeout 2 --speed-time 5 --speed-limit 1000 --silent --output /dev/null --location --write-out '%{http_code} %{url_effective}' " .. "http://" .. hostname .. ":" .. port .. path):read("*a"):match("^(%d+) (.*)")
                if status == "200" or status == "401" then
                    vstate[service] = last
                elseif status == "301" or status == "302" or status == "303" or status == "307" or status == "308" then
		            -- Ended at a redirect rather than an actual page.
                    if effective_url:match("^https:") then
                        -- We cannot validate https: links so we just assume they're okay
                        vstate[service] = last
                    end
                end
            else
                -- valid port, but we dont know the protocol (we cannot trust the one defined in the services file because the UI wont set
                -- anything but 'tcp'). Check both tcp and udp and assume valid it either is okay
                -- tcp
                local s = nixio.socket("inet", "stream")
                s:setopt("socket", "sndtimeo", 2)
                local r = s:connect(hostname, tonumber(port))
                s:close()
                if r == true then
                    -- tcp connection succeeded
                    vstate[service] = last
                else
                    -- udp
                    s = nixio.socket("inet", "dgram")
                    s:setopt("socket", "rcvtimeo", 2)
                    s:connect(hostname, tonumber(port))
                    s:send("")
                    r = s:recv(0)
                    s:close()
                    if r ~= nil then
                        -- A nil response is an explicity rejection of the udp request. Otherwise we have
                        -- to assume the service is valid
                        vstate[service] = last
                    end
                end
            end
        end
    end

    -- Generate new hosts and services as long as they're valid
    local old_hosts = hosts
    hosts = {}
    for _, host in ipairs(old_hosts)
    do
        local lname = host.host:lower()
        local vs = vstate[lname]
        if not vs then
            hosts[#hosts + 1] = host
            vstate[lname] = last
        elseif vs > now then
            hosts[#hosts + 1] = host
        end
    end
    local old_services = services
    services = {}
    for _, service in ipairs(old_services)
    do
        local vs = vstate[service]
        if not vs then
            -- New services will be valid for a while, even if they're not there yet
            services[#services + 1] = service
            vstate[service] = last
        elseif vs > now then
            services[#services + 1] = service
        end
    end

    -- Store state for next time
    local f = io.open(validation_state, "w")
    if f then
        for key, last in pairs(vstate)
        do
            f:write(last .. " " .. key .. "\n")
        end
        f:close()
    end
end
-- end validation

-- load the tunnels
if nixio.fs.stat("/etc/local/mesh-firewall/02-vtund") then
    local tunnum = 50
    cursor:foreach("vtun", "client",
        function(section)
            if section.enabled == "1" then
                tunnels[#tunnels + 1] = "tun" .. tunnum
                tunnum = tunnum + 1
            end
        end
    )
    local maxclients = cursor:get("aredn", "@tunnel[0]", "maxclients")
    if not maxclients then
        maxclients = 10
    end
    tunnum = 50 + maxclients
    local wgtunnum = 0
    if cursor:get("wireguard", "@client[0]", "name") then
        tunnels[#tunnels + 1] = "wgc"
    end
    cursorm:foreach("vtun", "server",
        function(section)
            if section.enabled == "1" then
                if section.netip:match("/") then
                    tunnels[#tunnels + 1] = "wgs" .. wgtunnum
                    wgtunnum = wgtunnum + 1
                else
                    tunnels[#tunnels + 1] = "tun" .. tunnum
                    tunnum = tunnum + 1
                end
            end
        end
    )
end

-- add the nameservice plugin
print()
print([[LoadPlugin "olsrd_nameservice.so.0.4"]])
print([[{]])
print([[    PlParam "sighup-pid-file" "/var/run/dnsmasq/dnsmasq.pid"]])
print([[    PlParam "interval" "30"]])
print([[    PlParam "timeout" "300"]])
print([[    PlParam "name-change-script" "/usr/local/bin/olsrd-namechange"]])
for _, name in ipairs(names)
do
    print([[    PlParam "name" "]] .. name .. [["]])
end
for _, host in ipairs(hosts)
do
    print([[    PlParam "]] .. host.ip .. [[" "]] .. host.host .. [["]])
end
for _, service in ipairs(services)
do
    print([[    PlParam "service" "]] .. service .. [["]])
end
print([[}]])

-- add the ACTIVE tunnel interfaces
if #tunnels > 0 then
    local tun_weight = cursor:get("aredn", "@tunnel[0]", "weight")
    tun_weight = tonumber(tun_weight)
    local tuns = ""
    for _, tunnel in ipairs(tunnels)
    do
        tuns = tuns .. " \"" .. tunnel .. "\""
    end
    print()
    print([[Interface]] .. tuns)
    print([[{]])
    print([[     Ip4Broadcast 255.255.255.255]])
    local is_supernode = cursor:get("aredn", "@supernode[0]", "enable") == "1"
    if not tun_weight or tun_weight < 1 or is_supernode then
        print([[     Mode "ether"]])
    elseif tun_weight > 1 then
        print([[     LinkQualityMult default ]] .. (1 / tun_weight))
    end
    print([[}]])
end

-- add the XLINK interfaces
if nixio.fs.stat("/etc/config.mesh/xlink") then
    uci.cursor("/etc/config.mesh"):foreach("xlink", "interface",
        function(section)
            print()
            print([[Interface "]] .. section.ifname .. [["]])
            print([[{]])
            if section.peer then
                print([[     Ip4Broadcast ]] .. section.peer)
            else
                print([[     Ip4Broadcast 255.255.255.255]])
            end
            local weight = tonumber(section.weight)
            if weight then
                if weight > 1 then
                    print([[     LinkQualityMult default ]] .. (1 / weight))
                elseif weight < 1 then
                    print([[     Mode "ether"]])
                end
            else
                print([[     Mode "ether"]])
            end
            print([[}]])
        end
    )
end