Initial version

Simple proof of concept WebSocket server for Arduino. Implements parts
of version 8+ of the protocol enough to send simple messages backwards
and forwards.

WebSocketsServerEthernet.pde

@@ -0,0 +1,208 @@
+#include <Ethernet.h>
+#include <SPI.h>
+
+#include <sha1.h>
+#include <Base64.h>
+
+byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
+byte ip[] = { 10,0,0,50 };
+String ipaddress = "10.0.0.50";
+
+const char hex[] ="0123456789abcdef";
+
+boolean websocket = false;
+boolean handshakeDone = false;
+String key;
+
+Server server(80);
+
+void setup()
+{
+  Ethernet.begin(mac, ip);
+  server.begin();
+  //Serial.begin(9600);
+}
+
+// Read a line at a time
+String readLine(Client client)
+{
+  String data;
+
+  while (client.available()) 
+  {
+    char c = client.read();
+
+    data.concat(c);
+    if (c == '\n') {
+      return data;
+    }  
+  }
+}
+
+// Return true is line is "blank"
+boolean blankLine(String line) {
+  return (line.length() == 2 && line[0] == '\r' && line[1] == '\n');
+}
+
+// Send a standard http response header
+void httpOK(Client client) {
+  client.println("HTTP/1.1 200 OK");
+  client.println("Content-Type: text/html");
+  client.println();
+}
+
+// Send a header to switch to the web sockets protocol
+void webSocketOK(Client client, String key) {
+  client.println("HTTP/1.1 101 Switching Protocols");
+  client.println("Upgrade: websocket");
+  client.println("Connection: Upgrade");
+  client.print("Sec-WebSocket-Accept: ");
+  client.println(key);
+  client.println();
+}
+
+// Convert a SHA1 hash to a string
+char* hashToString(uint8_t* hash) {
+  char hashStr[40];
+
+  for (int i=0; i < 20; i++) {
+    hashStr[2*i] = hex[hash[i] >> 4];
+    hashStr[2*i+1] = hex[hash[i] & 0xf];     
+  }
+  hashStr[40] = '\0';
+
+  return hashStr;
+}
+
+// read a HTTP header a line at a time and decode
+void readHeader(Client client) {
+  String line = readLine(client); 
+  int colon = line.indexOf(":");
+
+  if (colon) {
+    String name = line.substring(0, colon).trim();
+    String value = line.substring(colon + 1).trim();
+
+    if (name == "Upgrade" && value == "websocket") {
+      websocket = true;
+    }
+    if (name == "Sec-WebSocket-Key") {
+      key = value;
+    }
+  }
+
+  if (blankLine(line)) { 
+    if (websocket) { 
+      key = key + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
+      Sha1.init();
+      Sha1.print(key);
+      char* hash = (char*)Sha1.result();
+      char encode[29];
+      base64_encode(encode, hash, 20);
+      webSocketOK(client, encode);
+      handshakeDone = true;
+    }
+    else {
+      httpOK(client);
+    }
+  }
+}
+
+// read and decode a web socket message
+String readMessage(Client client)
+{
+  String data;
+  unsigned char opcode;
+  unsigned char length;
+  boolean useMask;
+  unsigned char mask[4];
+
+  opcode = client.read();
+  //TODO check opcode
+  length = client.read();
+  useMask = ((length & 0x80) == 0x80);
+  length = length & 0x7F;
+  if (useMask) {
+    mask[0] = client.read();
+    mask[1] = client.read();
+    mask[2] = client.read();
+    mask[3] = client.read();
+  }
+
+  int noRead = 0;  
+  while (noRead < length) 
+  {
+    unsigned char masked = client.read();
+
+    if (useMask) {
+      unsigned char unmasked = masked ^ mask[noRead % 4];
+      data.concat(unmasked);
+    }
+    else {
+      data.concat(masked);
+    }
+
+    noRead++;
+  }
+
+  return data;
+}
+
+// encode and send a web socket message
+void sendMessage(Client client, String message) {
+  unsigned char mask[4];
+  int length = message.length();
+
+  mask[0] = random(256);
+  mask[1] = random(256);
+  mask[2] = random(256);
+  mask[3] = random(256);
+
+  client.write(0x81); // text message
+  client.write(length | 0x80); // length and mask
+  client.write(mask[0]);
+  client.write(mask[1]);
+  client.write(mask[2]);
+  client.write(mask[3]);
+
+  int noWrite = 0;
+  while (noWrite < length) {
+    unsigned char masked = message.charAt(noWrite) ^ mask[noWrite % 4];
+    client.write(masked);
+    noWrite++;
+  }
+}
+
+// Run a command when a message is received
+void runCommand(Client client, String command) {
+  // Change to do what you want here
+  sendMessage(client, command); // simple echo
+}
+
+void loop()
+{
+  Client client = server.available();
+
+  if (client) {
+    while (client.connected())
+    { 
+      if (client.available())
+      {
+        if (!handshakeDone) {
+          readHeader(client);
+        }
+        else {
+          String message = readMessage(client);
+          runCommand(client, message);
+        }
+      }
+    }
+
+    handshakeDone = false;
+    client.flush();
+    client.stop();
+  }
+}
+
+
+