Diff: main.cpp

Revision:

4:1acb5d26ec21

Parent:

3:1e5d19eb7c9a

Child:

5:21e76b5af13b

--- a/main.cpp	Wed May 27 06:57:24 2015 +0000
+++ b/main.cpp	Thu May 28 04:29:26 2015 +0000
@@ -4,8 +4,12 @@
 #include "hcsr04.h"
 #include "GPS.h"
 
+#include "SHA1.h"
+#include "HMAC.h"
+
 #define TRIG_PIN D6
 #define ECHO_PIN D5
+#define HTTP_ENDPOINT "http://trash.coreyford.name/sensor"
 #define SENSOR_NAME "Throop"
 
 #define CELLULAR_NETWORK 1
@@ -21,7 +25,11 @@
 #endif
 
 int main() 
-{   
+{
+    char macAddress[6];
+    mbed_mac_address(macAddress);
+    printf("MAC address is %02X%02X%02X%02X%02X%02X\r\n", macAddress[0], macAddress[1], macAddress[2], macAddress[3], macAddress[4], macAddress[5]);
+    
     GPSSerial gps;
 
 #ifdef CELLULAR_NETWORK
@@ -40,11 +48,9 @@
     int gpsRet;
     char gpsBuf[512];
     double lat = 0, lon = 0;
-    char latStr[10] = "", lonStr[10] = "";
     
     HCSR04 distS(TRIG_PIN, ECHO_PIN);
     double distV;
-    char distStr[10] = "";
     char str[512];
     
     while (true) {
@@ -52,8 +58,7 @@
         distS.start();
         wait_ms(500); 
         distV = distS.get_dist_cm();
-        snprintf(distStr, 10, "%0.2f", distV);
-        printf("sensor reading: %s\r\n", distStr);
+        printf("sensor reading: %0.2f\r\n", distV);
         
         // GPS
         printf("trying GPS\r\n");
@@ -71,21 +76,34 @@
              && ch == 'A')
             {
                 printf("GPS Location: %.5f %.5f\r\n", lat, lon);
-                snprintf(latStr, 10, "%0.5f", lat);
-                snprintf(lonStr, 10, "%0.5f", lon);
                 break;
             }
         }
         
+        // Combine readings in JSON
+        char json[255];
+        snprintf(json, 255, "{\"distance\":%0.1f,\"latitude\":%0.5f,\"longitude\":%0.5f}", distV, lat, lon);
+           
+        // Compute a MAC (message authentication code) of the value,
+        // using our MAC (media access control) address as a key.
+        // Yay acronyms.
+        SHA1 hasher;
+        HMAC hmacer(&hasher, (uint8_t *)macAddress, sizeof(macAddress));
+        hmacer.update((uint8_t *)json, strlen(json));
+        uint8_t hmac[20];
+        hmacer.finalize(hmac);
+        char hmacHex[41], *hmacHexPtr = hmacHex;
+        for (int i = 0; i < 20; i++)
+            hmacHexPtr += sprintf(hmacHexPtr, "%02X", hmac[i]);
+        
         //POST data
         HTTPMap map;
         HTTPText inText(str, 512);
         map.put("name", SENSOR_NAME);
-        map.put("value", distStr);
-        map.put("latitude", latStr);
-        map.put("longitude", lonStr);
+        map.put("value", json);
+        map.put("mac", hmacHex);
         printf("\r\nTrying to post data...\r\n");
-        int ret = http.post("http://trash.coreyford.name/sensor", map, &inText);
+        int ret = http.post(HTTP_ENDPOINT, map, &inText);
         if (!ret)
         {
           printf("Executed POST successfully - read %d characters\r\n", strlen(str));