Diff: main.cpp

Revision:

2:e3807a060fa5

Parent:

1:ff73b1545aaa

Child:

3:6d25972a1b21

--- a/main.cpp	Thu Sep 05 10:36:51 2013 +0000
+++ b/main.cpp	Thu Sep 05 14:29:02 2013 +0000
@@ -1,15 +1,27 @@
+/*
+    This examples shows how to use the HTTPS library 
+    in order to download a webpage from twitter.com
+    
+    Don't forget to download certificates and copy on 
+    your mbed before running this program. You can 
+    download them from this link:
+    http://mbed.org/media/uploads/feb11/certificates-twitter.zip
+*/
+
 #include "mbed.h"
 #include "EthernetInterface.h"
 #include "CertificateManager.h"
 #include "HTTPSClient.h"
 
 const char host[] = "twitter.com";
-const char request[] = "https://twitter.com/";
+const char request[] = "https://twitter.com";
 LocalFileSystem local("local");
 
 int main()
 {
     set_time(1378370406);
+    
+    /* Starting Ethernet */
     EthernetInterface eth;
     if(eth.init() || eth.connect())
     {
@@ -17,8 +29,7 @@
         return -1;
     }
 
-    printf("IP address is %s\n\r", eth.getIPAddress());
-
+    /* Loading certificates in precomputed mode */
     CertificateManager::add("/local/cert1.der");
     CertificateManager::add("/local/cert2.der");
     CertificateManager::add("/local/cert3.der");
@@ -28,6 +39,7 @@
         return -1;
     }
 
+    /* Now, let's connect to twitter.com */
     HTTPSClient client;
     if(!client.connect(host))    
     {
@@ -35,10 +47,15 @@
         return -1;
     }
     printf("Connected to %s !\n", host);
+    
+    /*  Don't forget to call this method, it's an 
+        easy way to free a few KB of memory */
     CertificateManager::clear();
     
+    
+    /* Let's send our GET request to get the webpage */
     char buffer[256];
-    int bufferLength = sizeof(buffer)-1;
+    int bufferLength = sizeof(buffer);
     HTTPHeader header;
     int read = client.get(request, &header, buffer, bufferLength);
     if(header.getStatus() != HTTP_OK || read < 0)
@@ -47,30 +64,36 @@
         return -1;
     }
     
+    /* index.htm is used to store the webpage */
     FILE *fp = fopen("/local/index.htm", "w");
     if(fp == NULL)
     {
         printf("Failed to open file index.htm\n");
         return -1;
     }
-    fwrite(buffer, 1, read, fp);
+    fwrite(buffer, 1, read, fp);   // writing the first part of the body
+    
     int totalRead = read;
     while(totalRead < header.getBodyLength())
     {
         if(bufferLength > header.getBodyLength() - totalRead)
             bufferLength = header.getBodyLength() - totalRead;
         
+        /* This function does not send a get request but instead
+            just receive data from the host.
+        */
         read = client.get("", NULL, buffer, bufferLength);
         if(read < 0)
         {
             printf("Error while getting data from %s\n", host);
             return -1;
         }
-         fwrite(buffer, 1, read, fp);
+        fwrite(buffer, 1, read, fp);
         totalRead += read;
     }
+
+    /* We're done, let's close everything */
     fclose(fp);
-    
     printf("Disconnecting from %s\n", host);
     client.disconnect();
     eth.disconnect();