HTTP Server serving a simple webpage which enables to remotely turn LED1 on/off. Compile, download, run and type 'IP_address/secret/' (don't forget the last '/') into your web browser and hit ENTER.

Fork of WebSwitch_mbed-os by Zoltan Hudak

Turn LED1, or other digital output, on/off using a web browser.

In this example we create a HTTP server that will serve a simple Web page to remotely turn LED1, or other digital output, on/off by using a web browser.

/media/uploads/hudakz/webswitch03.png/media/uploads/hudakz/webswitch_mobile01.jpg

Notice that DHCP is turned on by default. The IP address assigned to the WebSwitch server along with an instruction how to use it is printed to the connected PC's serial terminal window during program start up.
To use static IP address uncomment and adjust line #221 in main.cpp.

The project was inspired by the Tuxgraphics Web Switch. Thank you Guido!

For a Web Switch using

Revision:
0:e455fdb56bc8
Child:
2:33e8bb5615a6
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Thu Apr 06 18:58:40 2017 +0000
@@ -0,0 +1,203 @@
+#include "mbed.h"
+#include "EthernetInterface.h"
+#include "TCPServer.h"
+#include "TCPSocket.h"
+#include <stdio.h>
+#include <string>
+
+using namespace     std;
+
+#define PORT        80
+
+EthernetInterface   ethernet;
+TCPServer           server;
+TCPSocket           clientSocket;
+SocketAddress       clientAddress;
+char                receiveBuf[1024] = { };
+
+const int           OFF = 0;
+const int           ON = 1;
+
+DigitalOut          sw(LED1);
+
+const string        PASSWORD     = "secret";    // change as you like
+const string        HTTP_OK      = "HTTP/1.0 200 OK";
+const string        MOVED_PERM   = "HTTP/1.0 301 Moved Permanently\r\nLocation: ";
+const string        UNAUTHORIZED = "HTTP/1.0 401 Unauthorized";
+string              httpHeader;     // HTTP header
+string              httpContent;    // HTTP content
+// analyse the url given
+// return values: -1 invalid password
+//                -2 no command given but password valid
+//                -3 just refresh page
+//                 0 switch off
+//                 1 switch on
+//
+//                The string passed to this function will look like this:
+//                GET /password HTTP/1.....
+//                GET /password/ HTTP/1.....
+//                GET /password/?sw=1 HTTP/1.....
+
+//                GET /password/?sw=0 HTTP/1.....
+int8_t analyseURL(string& str) {
+    if(str.substr(5, PASSWORD.size()) != PASSWORD)
+        return(-1);
+
+    uint8_t pos = 5 + PASSWORD.size();
+
+    if(str.substr(pos, 1) == " ")
+        return(-2);
+
+    if(str.substr(pos++, 1) != "/")
+        return(-1);
+
+    string  cmd(str.substr(pos, 5));
+
+    if(cmd == "?sw=0")
+        return(OFF);
+
+    if(cmd == "?sw=1")
+        return(ON);
+
+    return(-3);
+}
+
+/**
+ * @brief
+ * @note
+ * @param
+ * @retval
+ */
+string& movedPermanently(uint8_t flag) {
+    if(flag == 1)
+        httpContent = "/" + PASSWORD + "/";
+    else
+        httpContent = "";
+
+    httpContent += "<h1>301 Moved Permanently</h1>\r\n";
+
+    return(httpContent);
+}
+
+/**
+ * @brief
+ * @note
+ * @param
+ * @retval
+ */
+string& showWebPage(uint8_t status) {
+    httpContent = "<h2>WebSwitch - Smart Home</h2>\r\n";
+
+    httpContent += "<pre>Temperature:\t21.8&deg;C\r\n</pre>";
+
+    if(status == ON) {
+        httpContent += "<pre>\r\nHeating:\t<font color=#FF0000>ON </font>";
+        httpContent += " <a href=\"./?sw=0\">[Turn off]</a>\r\n";
+    }
+    else {
+        httpContent += "<pre>\r\nHeating:\t<font color=#BBBBBB>OFF</font>";
+        httpContent += " <a href=\"./?sw=1\">[Turn on]</a>\r\n";
+    }
+
+    //httpContent += "  \r\n";
+    //httpContent += "  <a href=\".\">Refresh status]</a>\r\n";
+    httpContent += "</pre>\r\n";
+    httpContent += "<hr>\r\n";
+    httpContent += "<pre>2017 ARMmbed Open Source</pre>";
+    return httpContent;
+}
+
+/**
+ * @brief
+ * @note
+ * @param
+ * @retval
+ */
+void sendHTTP(TCPSocket& client, string& header, string& content) {
+    char    content_length[5] = { };
+
+    header += "\r\nContent-Type: text/html\r\n";
+    header += "Content-Length: ";
+    sprintf(content_length, "%d", content.length());
+    header += string(content_length) + "\r\n";
+    header += "Pragma: no-cache\r\n";
+    header += "Connection: About to close\r\n";
+    header += "\r\n";
+
+    string  webpage = header + content;
+    client.send((char*)webpage.c_str(), webpage.length());
+    printf("HTTP sent.\n\r");
+}
+
+/**
+ * @brief
+ * @note
+ * @param
+ * @retval
+ */
+int main(void) {
+
+    ethernet.connect();
+    printf("Usage: Type %s/%s/ into your web browser and hit ENTER\r\n", ethernet.get_ip_address(), PASSWORD);
+
+    /* Open the server on ethernet stack */
+    server.open(&ethernet);
+   
+    /* Bind the HTTP port (TCP 80) to the server */
+    server.bind(ethernet.get_ip_address(), 80);
+    
+    /* Can handle 5 simultaneous connections */
+    server.listen(5);
+
+    //listening for http GET request
+    while(true) {
+        server.accept(&clientSocket, &clientAddress);
+        printf("\r\n=========================================\r\n");
+        printf("Connection succeeded!\n\rIP: %s\n\r", clientAddress.get_ip_address());
+        clientSocket.recv(receiveBuf, 1023);
+        printf("Recieved Data: %d\n\r\n\r%.*s\n\r", strlen(receiveBuf), strlen(receiveBuf), receiveBuf);
+
+        string  received(receiveBuf);
+        if(received.substr(0, 3) != "GET") {
+            httpHeader = HTTP_OK;
+            httpContent = "<h1>200 OK</h1>";
+            sendHTTP(clientSocket, httpHeader, httpContent);
+            continue;
+        }
+
+        if(received.substr(0, 6) == "GET / ") {
+            httpHeader = HTTP_OK;
+            httpContent = "<p>Usage: Type http://ip_address/password/ into your web browser and hit ENTER</p>\r\n";
+            sendHTTP(clientSocket, httpHeader, httpContent);
+            continue;
+        }
+
+        int cmd = analyseURL(received);
+
+        if(cmd == -2) {
+
+            // redirect to the right base url
+            httpHeader = MOVED_PERM;
+            sendHTTP(clientSocket, httpHeader, movedPermanently(1));
+            continue;
+        }
+
+        if(cmd == -1) {
+            httpHeader = UNAUTHORIZED;
+            httpContent = "<h1>401 Unauthorized</h1>";
+            sendHTTP(clientSocket, httpHeader, httpContent);
+            continue;
+        }
+
+        if(cmd == ON) {
+            sw = ON;    // turn the switch on
+        }
+
+        if(cmd == OFF) {
+            sw = OFF;   // turn the switch off
+        }
+
+        httpHeader = HTTP_OK;
+        sendHTTP(clientSocket, httpHeader, showWebPage(sw));
+    }
+}