396 lines
12 KiB
Lua
396 lines
12 KiB
Lua
--[[
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@module dhcpsrv
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@summary DHCP服务器端
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@version 1.0.0
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@date 2025.04.15
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@author wendal
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@usage
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-- 参考dhcpsrv.create函数
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]]
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local dhcpsrv = {}
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local udpsrv = require("udpsrv")
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local TAG = "dhcpsrv"
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----
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-- 参考地址
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-- https://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol
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local function dhcp_decode(buff)
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-- buff:seek(0)
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local dst = {}
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-- 开始解析dhcp
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dst.op = buff[0]
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dst.htype = buff[1]
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dst.hlen = buff[2]
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dst.hops = buff[3]
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buff:seek(4)
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dst.xid = buff:read(4)
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_, dst.secs = buff:unpack(">H")
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_, dst.flags = buff:unpack(">H")
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dst.ciaddr = buff:read(4)
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dst.yiaddr = buff:read(4)
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dst.siaddr = buff:read(4)
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dst.giaddr = buff:read(4)
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dst.chaddr = buff:read(16)
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-- 跳过192字节
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buff:seek(192, zbuff.SEEK_CUR)
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-- 解析magic
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_, dst.magic = buff:unpack(">I")
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-- 解析option
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local opt = {}
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while buff:len() > buff:used() do
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local tag = buff:read(1):byte()
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if tag ~= 0 then
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local len = buff:read(1):byte()
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if tag == 0xFF or len == 0 then
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break
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end
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local data = buff:read(len)
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if tag == 53 then
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-- 53: DHCP Message Type
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dst.msgtype = data:byte()
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end
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table.insert(opt, {tag, data})
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-- log.info(TAG, "tag", tag, "data", data:toHex())
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end
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end
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if dst.msgtype == nil then
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return -- 没有解析到msgtype，直接返回
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end
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dst.opts = opt
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return dst
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end
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local function dhcp_buff2ip(buff)
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return string.format("%d.%d.%d.%d", buff:byte(1), buff:byte(2), buff:byte(3), buff:byte(4))
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end
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local function dhcp_print_pkg(pkg)
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log.info(TAG, "XID", pkg.xid:toHex())
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log.info(TAG, "secs", pkg.secs)
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log.info(TAG, "flags", pkg.flags)
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log.info(TAG, "chaddr", pkg.chaddr:sub(1, pkg.hlen):toHex())
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log.info(TAG, "yiaddr", dhcp_buff2ip(pkg.yiaddr))
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log.info(TAG, "siaddr", dhcp_buff2ip(pkg.siaddr))
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log.info(TAG, "giaddr", dhcp_buff2ip(pkg.giaddr))
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log.info(TAG, "ciaddr", dhcp_buff2ip(pkg.ciaddr))
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log.info(TAG, "magic", string.format("%08X", pkg.magic))
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for _, opt in pairs(pkg.opts) do
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if opt[1] == 53 then
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log.info(TAG, "msgtype", opt[2]:byte())
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elseif opt[1] == 60 then
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log.info(TAG, "auth", opt[2])
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elseif opt[1] == 57 then
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log.info(TAG, "Maximum DHCP message size", opt[2]:byte() * 256 + opt[2]:byte(2))
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elseif opt[1] == 61 then
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log.info(TAG, "Client-identifier", opt[2]:toHex())
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elseif opt[1] == 55 then
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log.info(TAG, "Parameter request list", opt[2]:toHex())
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elseif opt[1] == 12 then
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log.info(TAG, "Host name", opt[2])
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-- elseif opt[1] == 58 then
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-- log.info(TAG, "Renewal (T1) time value", opt[2]:unpack(">I"))
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end
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end
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end
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local function dhcp_encode(pkg, buff)
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-- 合成DHCP包
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buff:seek(0)
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buff[0] = pkg.op
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buff[1] = pkg.htype
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buff[2] = pkg.hlen
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buff[3] = pkg.hops
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buff:seek(4)
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-- 写入XID
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buff:write(pkg.xid)
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-- 几个重要的参数
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buff:pack(">H", pkg.secs)
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buff:pack(">H", pkg.flags)
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buff:write(pkg.ciaddr)
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buff:write(pkg.yiaddr)
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buff:write(pkg.siaddr)
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buff:write(pkg.giaddr)
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-- 写入MAC地址
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buff:write(pkg.chaddr)
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-- 跳过192字节
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buff:seek(192, zbuff.SEEK_CUR)
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-- 写入magic
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buff:pack(">I", pkg.magic)
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-- 写入option
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for _, opt in pairs(pkg.opts) do
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buff:write(opt[1])
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buff:write(#opt[2])
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buff:write(opt[2])
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end
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buff:write(0xFF, 0x00)
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end
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----
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local function dhcp_send_x(srv, pkg, client, msgtype)
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local buff = zbuff.create(300)
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pkg.op = 2
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pkg.ciaddr = "\0\0\0\0"
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pkg.yiaddr = string.char(srv.opts.gw[1], srv.opts.gw[2], srv.opts.gw[3], client.ip)
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pkg.siaddr = string.char(srv.opts.gw[1], srv.opts.gw[2], srv.opts.gw[3], srv.opts.gw[4])
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pkg.giaddr = "\0\0\0\0"
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pkg.secs = 0
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pkg.opts = {} -- 复位option
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table.insert(pkg.opts, {53, string.char(msgtype)})
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table.insert(pkg.opts, {1, string.char(srv.opts.mark[1], srv.opts.mark[2], srv.opts.mark[3], srv.opts.mark[4])})
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table.insert(pkg.opts, {3, string.char(srv.opts.gw[1], srv.opts.gw[2], srv.opts.gw[3], srv.opts.gw[4])})
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table.insert(pkg.opts, {51, "\x00\x00\x1E\x00"}) -- 7200秒, 大概
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table.insert(pkg.opts, {54, string.char(srv.opts.gw[1], srv.opts.gw[2], srv.opts.gw[3], srv.opts.gw[4])})
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table.insert(pkg.opts, {6, string.char(223, 5, 5, 5)})
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table.insert(pkg.opts, {6, string.char(119, 29, 29, 29)})
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table.insert(pkg.opts, {6, string.char(srv.opts.gw[1], srv.opts.gw[2], srv.opts.gw[3], srv.opts.gw[4])})
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dhcp_encode(pkg, buff)
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local dst = "255.255.255.255"
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if 4 == msgtype then
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dst = string.format("%d.%d.%d.%d", srv.opts.gw[1], srv.opts.gw[2], srv.opts.gw[3], client.ip)
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end
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-- log.info(TAG, "发送", msgtype, dst, buff:query():toHex())
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srv.udp:send(buff, dst, 68)
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end
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local function dhcp_send_offer(srv, pkg, client)
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dhcp_send_x(srv, pkg, client, 2)
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end
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local function dhcp_send_ack(srv, pkg, client)
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dhcp_send_x(srv, pkg, client, 5)
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end
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local function dhcp_send_nack(srv, pkg, client)
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dhcp_send_x(srv, pkg, client, 6)
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end
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local function dhcp_handle_discover(srv, pkg)
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local mac = pkg.chaddr:sub(1, pkg.hlen)
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-- 看看是不是已经分配了ip
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for _, client in pairs(srv.clients) do
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if client.mac == mac then
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log.info(TAG, "发现已经分配的mac地址, send offer")
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dhcp_send_offer(srv, pkg, client)
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return
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end
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end
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-- TODO 清理已经过期的IP分配记录
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-- 分配一个新的ip
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if #srv.clients >= (srv.opts.ip_end - srv.opts.ip_start) then
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log.info(TAG, "没有可分配的ip了")
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return
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end
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local ip = nil
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for i = srv.opts.ip_start, srv.opts.ip_end, 1 do
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if srv.clients[i] == nil then
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ip = i
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break
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end
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end
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if ip == nil then
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log.info(TAG, "没有可分配的ip了")
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return
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end
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log.info(TAG, "分配ip", mac:toHex(), string.format("%d.%d.%d.%d", srv.opts.gw[1], srv.opts.gw[2], srv.opts.gw[3], ip))
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local client = {
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mac = mac,
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ip = ip,
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tm = mcu.ticks() // mcu.hz(),
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stat = 1
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}
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srv.clients[ip] = client
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log.info(TAG, "send offer")
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dhcp_send_offer(srv, pkg, client)
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end
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local function dhcp_handle_request(srv, pkg)
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local mac = pkg.chaddr:sub(1, pkg.hlen)
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-- 看看是不是已经分配了ip
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for _, client in pairs(srv.clients) do
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if client.mac == mac then
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log.info(TAG, "request,发现已经分配的mac地址, send ack", mac:toHex())
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client.tm = mcu.ticks() // mcu.hz()
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stat = 3
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dhcp_send_ack(srv, pkg, client)
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if srv.opts.ack_cb then
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local cip = string.format("%d.%d.%d.%d", srv.opts.gw[1], srv.opts.gw[2], srv.opts.gw[3], client.ip)
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srv.opts.ack_cb(cip, mac:toHex())
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end
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return
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end
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end
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-- 没有找到, 那应该返回NACK
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log.info(TAG, "request,对应mac地址没有分配ip, send nack")
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dhcp_send_nack(srv, pkg, {ip=pkg.yiaddr:byte(1)})
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end
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local function dhcp_pkg_handle(srv, pkg)
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-- 进行基本的检查
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if pkg.magic ~= 0x63825363 then
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log.warn(TAG, "dhcp数据包的magic不对劲,忽略该数据包", pkg.magic)
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return
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end
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if pkg.op ~= 1 then
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log.info(TAG, "op不对,忽略该数据包", pkg.op)
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return
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end
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if pkg.htype ~= 1 or pkg.hlen ~= 6 then
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log.warn(TAG, "htype/hlen 不认识, 忽略该数据包")
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return
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end
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-- 看看是不是能处理的类型, 当前只处理discover/request
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if pkg.msgtype == 1 or pkg.msgtype == 3 then
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else
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log.warn(TAG, "msgtype不是discover/request, 忽略该数据包", pkg.msgtype)
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return
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end
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-- 检查一下mac地址是否合法
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local mac = pkg.chaddr:sub(1, pkg.hlen)
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if mac == "\0\0\0\0\0\0" or mac == "\xFF\xFF\xFF\xFF\xFF\xFF" then
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log.warn(TAG, "mac地址为空, 忽略该数据包")
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return
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end
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-- 处理discover包
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if pkg.msgtype == 1 then
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log.info(TAG, "是discover包", mac:toHex())
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dhcp_handle_discover(srv, pkg)
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elseif pkg.msgtype == 3 then
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log.info(TAG, "是request包", mac:toHex())
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dhcp_handle_request(srv, pkg)
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end
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-- TODO 处理结束, 打印一下客户的列表?
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end
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local function dhcp_task(srv)
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while 1 do
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-- log.info("ulwip", "等待DHCP数据")
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local result, data = sys.waitUntil(srv.udp_topic, 1000)
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if result then
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-- log.info("ulwip", "收到dhcp数据包", data:toHex())
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-- 解析DHCP数据包
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local pkg = dhcp_decode(zbuff.create(#data, data))
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if pkg then
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-- dhcp_print_pkg(pkg)
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dhcp_pkg_handle(srv, pkg)
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end
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end
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end
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end
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--[[
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创建一个dhcp服务器
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@api dhcpsrv.create(opts)
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@table 选项,参考库的说明, 及demo的用法
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@return table 服务器对象
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@usage
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-- 创建一个dhcp服务器, 最简介的版本
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dhcpsrv.create({adapter=socket.LWIP_AP})
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-- 详细的版本
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-- 创建一个dhcp服务器
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local dhcpsrv_opts = {
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adapter=socket.LWIP_AP, -- 监听哪个网卡, 必须填写
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mark = {255, 255, 255, 0}, -- 网络掩码, 默认 255.255.255.0
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gw = {192, 168, 4, 1}, -- 网关, 默认自动获取网卡IP，如果获取失败则使用 192.168.4.1
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ip_start = 100, -- ip起始地址, 默认100
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ip_end = 200, -- ip结束地址, 默认200
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ack_cb = function(ip, mac) end, -- ack回调, 有客户端连接上来时触发, ip和mac地址会传进来
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}
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local mydhcpsrv = dhcpsrv.create(dhcpsrv_opts)
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-- 以下是一个打印客户端列表的例子, 非必选, 仅供参考
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-- clients是一个table, 包含MAC和IP的对应关系, 注意, IP只记录了最后一段数字, 非完整IP
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-- 注意, clients是动态变化的过程, mydhcpsrv对象的其他属性切勿修改, 仅提供clients的只读功能
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sys.taskInit(function()
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while true do
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sys.wait(10000)
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-- 这里可以打印一下当前的客户端列表
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for ip, client in pairs(mydhcpsrv.clients) do
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log.info(TAG, "client", ip, client.mac:toHex(), client.tm, client.stat)
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end
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end
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end)
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-- 自动分配网段功能说明：
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-- 如果不指定gw参数，系统会自动获取网卡IP作为网关地址
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-- 这样可以确保DHCP分配的IP与网卡IP在同一网段
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]]
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function dhcpsrv.create(opts)
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local srv = {}
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if not opts then
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opts = {}
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end
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srv.udp_topic = "dhcpd_inc"
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-- 自动获取网卡IP地址的函数
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local function get_adapter_ip()
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if not opts.adapter then
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return nil
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end
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-- 获取网卡IP地址
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local ip = netdrv.ipv4(opts.adapter)
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if not ip or ip == "0.0.0.0" then
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return nil
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end
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-- 简单解析IP地址：192.168.4.1 -> {192, 168, 4, 1}
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local a, b, c, d = ip:match("(%d+)%.(%d+)%.(%d+)%.(%d+)")
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if a and b and c and d then
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return {tonumber(a), tonumber(b), tonumber(c), tonumber(d)}
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end
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return nil
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end
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-- 补充参数
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if not opts.mark then
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opts.mark = {255, 255, 255, 0}
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end
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-- 如果没有指定网关，则自动获取网卡IP作为网关
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if not opts.gw then
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local adapter_ip = get_adapter_ip()
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if adapter_ip then
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opts.gw = adapter_ip
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log.info(TAG, "自动获取网卡IP作为网关", string.format("%d.%d.%d.%d", adapter_ip[1], adapter_ip[2], adapter_ip[3], adapter_ip[4]))
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else
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opts.gw = {192, 168, 4, 1}
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log.warn(TAG, "无法获取网卡IP，使用默认网关", string.format("%d.%d.%d.%d", opts.gw[1], opts.gw[2], opts.gw[3], opts.gw[4]))
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end
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end
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if not opts.dns then
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opts.dns = opts.gw
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end
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-- 根据网关IP自动设置IP分配范围
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if not opts.ip_start then
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opts.ip_start = 100
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end
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if not opts.ip_end then
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opts.ip_end = 200
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end
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srv.clients = {}
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srv.opts = opts
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srv.udp = udpsrv.create(67, srv.udp_topic, opts.adapter)
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srv.task = sys.taskInit(dhcp_task, srv)
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return srv
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end
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return dhcpsrv
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