Limited EEPROM reading; added EC_FIRST_EEPROM_CATEGORY_HEADER define.

NEWS

@@ -46,6 +46,7 @@ Changes in version 1.3.0:
 * Master state machine scheduled with timeout if idle, otherwise is executed
   as fast as possible (with schedule()).
 * Added dummy module for simulation purpuses.
+* Limited infinite EEPROM reading, if 0xffff limiter word is missing.
 * Removed EtherCAT line comments from 8139too drivers.
 
 -------------------------------------------------------------------------------

TODO

@@ -8,7 +8,6 @@ $Id$
 
 * Issues for release 1.3.0:
   - Take broadcast MAC address to register the first ethernet device.
-  - Limit EEPROM reading.
   - Implement ecrt_get_slave() with integer argument as ring position.
   - Handle missing rc_status in init script.
 

master/fsm_slave.c

@@ -366,7 +366,7 @@ void ec_fsm_slave_scan_state_datalink(ec_fsm_slave_t *fsm /**< slave state machi
 
     // Start fetching EEPROM size
 
-    fsm->sii_offset = 0x0040; // first category header
+    fsm->sii_offset = EC_FIRST_EEPROM_CATEGORY_OFFSET; // first category header
     ec_fsm_sii_read(&fsm->fsm_sii, slave, fsm->sii_offset, EC_FSM_SII_NODE);
     fsm->state = ec_fsm_slave_scan_state_eeprom_size;
     fsm->state(fsm); // execute state immediately
@@ -398,6 +398,13 @@ void ec_fsm_slave_scan_state_eeprom_size(ec_fsm_slave_t *fsm /**< slave state ma
 
     if (cat_type != 0xFFFF) { // not the last category
         fsm->sii_offset += cat_size + 2;
+        if (fsm->sii_offset >= EC_MAX_EEPROM_SIZE) {
+            EC_WARN("EEPROM size of slave %i exceeds"
+                    " %i words (0xffff limiter missing?).\n",
+                    slave->ring_position, EC_MAX_EEPROM_SIZE);
+            slave->eeprom_size = EC_FIRST_EEPROM_CATEGORY_OFFSET * 2;
+            goto alloc_eeprom;
+        }
         ec_fsm_sii_read(&fsm->fsm_sii, slave, fsm->sii_offset,
                         EC_FSM_SII_NODE);
         ec_fsm_sii_exec(&fsm->fsm_sii); // execute state immediately
@@ -406,6 +413,7 @@ void ec_fsm_slave_scan_state_eeprom_size(ec_fsm_slave_t *fsm /**< slave state ma
 
     slave->eeprom_size = (fsm->sii_offset + 1) * 2;
 
+alloc_eeprom:
     if (slave->eeprom_data) {
         EC_INFO("Freeing old EEPROM data on slave %i...\n",
                 slave->ring_position);
@@ -494,7 +502,7 @@ void ec_fsm_slave_scan_state_eeprom_data(ec_fsm_slave_t *fsm /**< slave state ma
         EC_READ_U16(slave->eeprom_data + 2 * 0x001C);
 
     // evaluate category data
-    cat_word = (uint16_t *) slave->eeprom_data + 0x0040;
+    cat_word = (uint16_t *) slave->eeprom_data + EC_FIRST_EEPROM_CATEGORY_OFFSET;
     while (EC_READ_U16(cat_word) != 0xFFFF) {
         cat_type = EC_READ_U16(cat_word) & 0x7FFF;
         cat_size = EC_READ_U16(cat_word + 1);

master/globals.h

@@ -65,6 +65,9 @@
 /** minimum size of a buffer used with ec_state_string() */
 #define EC_STATE_STRING_SIZE 32
 
+/** maximum EEPROM size in words, to avoid infinite reading. */
+#define EC_MAX_EEPROM_SIZE 512
+
 /******************************************************************************
  *  EtherCAT protocol
  *****************************************************************************/
@@ -82,6 +85,9 @@
 #define EC_MAX_DATA_SIZE (ETH_DATA_LEN - EC_FRAME_HEADER_SIZE \
                           - EC_DATAGRAM_HEADER_SIZE - EC_DATAGRAM_FOOTER_SIZE)
 
+/** word offset of first EEPROM category. */
+#define EC_FIRST_EEPROM_CATEGORY_OFFSET 0x40
+
 /*****************************************************************************/
 
 /**

master/slave.c

@@ -925,7 +925,7 @@ ssize_t ec_slave_write_eeprom(ec_slave_t *slave, /**< EtherCAT slave */
         return -EINVAL;
     }
 
-    cat_header = request.words + 0x0040; // first category header
+    cat_header = request.words + EC_FIRST_EEPROM_CATEGORY_OFFSET;
     cat_type = EC_READ_U16(cat_header);
     while (cat_type != 0xFFFF) { // cycle through categories
         if (cat_header + 1 > request.words + request.size) {