Diff: ble/GapAdvertisingData.h

Revision:

765:4cd91998cd48

Parent:

763:36c3e2b1f1ae

Child:

769:2d236d9afa9e

--- a/ble/GapAdvertisingData.h	Fri Aug 07 15:53:50 2015 +0100
+++ b/ble/GapAdvertisingData.h	Fri Aug 07 15:53:50 2015 +0100
@@ -209,7 +209,7 @@
      * advertising buffer to overflow, else BLE_ERROR_NONE.
      */
     ble_error_t addData(DataType advDataType, const uint8_t *payload, uint8_t len)
-     {
+    {
         /* ToDo: Check if an AD type already exists and if the existing */
         /*       value is exclusive or not (flags, etc.) */
 
@@ -234,27 +234,41 @@
     }
 
     /**
-     * update one advertising data field with the same AD type (see DataType)
+     * Update a particular ADV field in the advertising payload (based on
+     * matching type and length). Note: the length of the new data must be the
+     * same as the old one.
      *
-     * @param  advDataType The Advertising 'DataType' to add
-     * @param  payload     Pointer to the payload contents
-     * @param  len         Size of the payload in bytes
+     * @param[in] advDataType  The Advertising 'DataType' to add.
+     * @param[in] payload      Pointer to the payload contents.
+     * @param[in] len          Size of the payload in bytes.
      *
      * @return BLE_ERROR_UNSPECIFIED if the specified field is not found, else
      * BLE_ERROR_NONE.
      */
-    ble_error_t updateData(DataType advDataType, const uint8_t *payload, uint8_t len)
-     {
+    ble_error_t updateData(DataType_t advDataType, const uint8_t *payload, uint8_t len)
+    {
+        if ((payload == NULL) || (len == 0)) {
+            return BLE_ERROR_INVALID_PARAM;
+        }
+
+        /* A local struct to describe an ADV field. This definition comes from the Bluetooth Core Spec. (v4.2) Part C, Section 11. */
+        struct ADVField_t {
+            uint8_t  len;      /* Describes the length (in bytes) of the following 'type' and 'bytes'. */
+            uint8_t  type;     /* Should have the same representation of DataType_t (above). */
+            uint8_t  bytes[0]; /* A placeholder for variable length data. */
+        };
+
+        /* Iterate over the adv fields looking for the first match. */
         uint8_t byteIndex = 0;
-        
         while (byteIndex < _payloadLen) {
-            if (_payload[byteIndex + 1] == advDataType) { /* Check adv type */
-                if (_payload[byteIndex] == (len + 1)) { /* Check adv field length */
-                    memcpy(&_payload[byteIndex + 2], payload, len);
-                }
+            ADVField_t *currentADV = (ADVField_t *)&_payload[byteIndex];
+            if ((currentADV->len  == (len + 1)) && /* incoming 'len' only describes the payload, whereas ADV->len describes 'type + payload' */
+                (currentADV->type == advDataType)) {
+                memcpy(currentADV->bytes, payload, len);
                 return BLE_ERROR_NONE;
             }
-            byteIndex += (_payload[byteIndex] + 1);
+
+            byteIndex += (currentADV->len + 1); /* advance by len+1; '+1' is needed to span the len field itself. */
         }
 
         return BLE_ERROR_UNSPECIFIED;