Wake On LAN (WOL) Gateway

1/*
2   Wake On Lan Gateway for any ESP8266 based board. 
3   Compiled  on Arduine IDE version 1.8.3 and a Wemos D1 & Mini board
4   Copyright: the GNU  General Public License version 3 (GPL-3.0) by Eric Kreuwels, 2019
5
6   Directly  forwarding WOL UDP packets to a particular device on your network is in general  not a good idea.  
7   It potentially causes floading of data on your local LAN  induced by external sources
8   It is also limited as it only allows wakeup  one device per forwarded port in your router; this because routers typically don't  allow to forward UPD packets as a broadcast!!!
9
10   The WOL gateway solves  both issues:
11   When the WOL gateway receives a WOL packet (forwarded by the  router), it evaluates:
12   - If it is a Secure WOL packet (Prefix should be FF:FF:FF:FF:FF:FF)
13   - If the SecureOn password matches the SecureOn of your choice.
14   Only matching  secure WOL packets are broadcasted on your local LAN. 
15   - This prevents floading  of your LAN due random external UDP packets comming from your router
16   - Only  a WOL wakeble device on your local LAN that has a matching MAC address will respond  (even if it doesn't supportthe SecureOn option)
17   Router configuration is simple:
18     Give this WOL Gateway device a fixed IP address (assign it via the reserved  DHCP list in your router)
19     Forward a port of your linking on your router  (advice is from 49152 to 65 535 ) and forward only the UDP packets to this device  (port 50000)
20     See: https://www.utilizewindows.com/list-of-common-network-port-numbers/
21
22*/
23
24#include  <ESP8266WiFi.h>                  // istall board manager sw via http://arduino.esp8266.com/stable/package_esp8266com_index.json
25#include  <ESP8266WebServer.h>
26#include <WiFiUdp.h>
27
28////////////////////////////////////////////////
29//  Class to Send/Receive UDP's:
30////////////////////////////////////////////////
31class  BroadCastDeamon: public WiFiUDP {
32  public:
33  void PostUDP( const char *Packet,  IPAddress ip, unsigned int destPort) {
34     PostUDP(Packet, strlen(Packet), ip,  destPort);
35  }
36  void PostUDP( const char *Packet, int len, IPAddress ip,  unsigned int destPort) {
37    WiFiUDP::beginPacket( ip, destPort);
38    WiFiUDP::write(Packet,  len);
39    WiFiUDP::endPacket();
40  }
41  void BroadcastUDP( const char *Packet,  unsigned int destPort) {
42     BroadcastUDP(Packet, strlen(Packet), destPort);
43  }
44  void BroadcastUDP( const char *Packet, int len, unsigned int destPort )  {
45    IPAddress broadcastIP = WiFi.localIP() | (~WiFi.subnetMask());
46    PostUDP(Packet,  len, broadcastIP, destPort);
47  }  
48  
49  bool CheckReceived() {
50    //  if there's data available, read a packet and return length
51    packetSize = parsePacket();
52    if (packetSize)
53    {
54      //Serial.print("Received UDP packet from  [");
55      //Serial.print(broadcastUdp.remoteIP());
56      //Serial.print("]  : ");
57      // read the packet into packetBufffer
58      int len = read(packetBuffer,  255);
59      packetBuffer[len] = 0;
60      //Serial.println(packetBuffer);
61      return true;
62    }
63    return false;
64  }
65  char *GetPacketData()  {
66    return packetBuffer;
67  }
68  int GetPacketSize() {
69     return packetSize;
70  }
71  private:
72   char packetBuffer[256]; //buffer to hold last packet retreived
73   int  packetSize;
74};
75
76BroadCastDeamon WOLDeamon;
77
78////////////////////////////////
79//  the configuration Part of the code:
80
81// SecureOn for WOL has to be 6 hex bytes;  Advice change the default.
82byte SecureOn[7] = "123456"; // In most WOL apps  that support SecureOn you have to enter the bytes in HEX format like this: "31:32:33:34:35:36"  for "123456"
83// Receiver Port for WOL packets forwarded by the router
84unsigned  int WOLPort=50000; // just some random choice in the free range. But make sure you  forward UDP packets to this port in your router
85
86// Enter your own WLAN credentials
87char  wlanSSID[]="YourWiFiSSID";
88char wlanPWD[]="YourWiFIPWD";
89
90
91void  setup() {
92  delay(1000);
93  Serial.begin(115200);
94  delay(1000);
95  Serial.println("Starting  the WOL Gateway "); 
96  while (!ConnectToNetwork(wlanSSID, wlanPWD)) {
97    delay(2000);
98  }
99  WOLDeamon.begin(WOLPort);
100}
101
102
103
104void loop() {
105    HandleWOLReceived(SecureOn);
106    delay(10);
107}
108
109
110
111bool ConnectToNetwork(char *ssid, char *pass  )  {
112  int timeout=0;
113  bool succes=false;
114  WiFi.mode(WIFI_STA);
115  Serial.print("Connecting  SSID: ");
116  Serial.println(ssid);
117  WiFi.begin(ssid, pass);
118  while (WiFi.status()  != WL_CONNECTED && timeout < 10)
119  {
120      delay(1000);
121      timeout++;
122  }
123  if (WiFi.status() == WL_CONNECTED) {
124     Serial.println();
125     Serial.print("Connected,  IP address: ");
126     Serial.println(WiFi.localIP());
127     succes=true;
128  }
129  else {
130    Serial.println("Connecting to SSID Failed ");
131  }
132  // printWifiMode();
133  return succes;
134}
135
136
137
138#define WOL_SECURE_PACKET_SIZE  108
139bool HandleWOLReceived (byte *pwd) {
140  if (WOLDeamon.CheckReceived() &&  WOLDeamon.GetPacketSize() == WOL_SECURE_PACKET_SIZE) {
141     byte *pPrefix = (byte  *)WOLDeamon.GetPacketData();
142     byte *pPWD = pPrefix + 102; // start position  of the SecureOn
143     // check if it is has both a valid WOL prefix (6 times FF)  and that it contains the defined SecureOn password
144     for (int i=0; i<6; i++)  {
145       if (pPrefix[i] != 255 || pPWD[i] != pwd[i]) {
146         Serial.println("INVALID  WOL packet received");
147         return false;
148       }
149     }
150     //  Broadcast WOL packet on local LAN
151     Serial.println("Valid WOL packet received");
152     WOLDeamon.BroadcastUDP(WOLDeamon.GetPacketData(), WOL_SECURE_PACKET_SIZE, 7);  // accidently used for WOL (official for echo)
153     WOLDeamon.BroadcastUDP(WOLDeamon.GetPacketData(),  WOL_SECURE_PACKET_SIZE, 9); // (un)official WOL port
154  }
155  return true;
156}
157
158