Fill struct pcap_stat.ps_drop from DAG CSAPI Stream Drop attribute if available.

Avoid potentially under-counting packet drop.

diff --git a/pcap-dag.c b/pcap-dag.c
index 1e6b3da63d2be423cffdf02edf8db8c9874d4639..6610af46cb50f24690712ee9a14bc15dad83621e 100644 (file)
--- a/pcap-dag.c
+++ b/pcap-dag.c
@@ -187,6 +187,8 @@ struct pcap_dag {
                                 * Same as in linux above, introduce
                                 * generally? */
        dag_card_ref_t dag_ref; /* DAG Configuration/Status API card reference */
                                 * Same as in linux above, introduce
                                 * generally? */
        dag_card_ref_t dag_ref; /* DAG Configuration/Status API card reference */

+       dag_component_t dag_root;       /* DAG CSAPI Root component */
+       attr_uuid_t drop_attr;  /* DAG Stream Drop Attribute handle, if available */

        struct timeval required_select_timeout;
                                /* Timeout caller must use in event loops */
 };
        struct timeval required_select_timeout;
                                /* Timeout caller must use in event loops */
 };


@@ -439,12 +441,8 @@ dag_read(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
                        break;
 
                default:
                        break;
 
                default:

-                       if (header->lctr) {
-                               if (pd->stat.ps_drop > (UINT_MAX - ntohs(header->lctr))) {
-                                       pd->stat.ps_drop = UINT_MAX;
-                               } else {
-                                       pd->stat.ps_drop += ntohs(header->lctr);
-                               }
+                       if ( (pd->drop_attr == kNullAttributeUuid) && (header->lctr) ) {
+                               pd->stat.ps_drop += ntohs(header->lctr);

                        }
                }
 
                        }
                }
 


@@ -798,6 +796,14 @@ static int dag_activate(pcap_t* p)
                goto failclose;
        }
 
                goto failclose;
        }
 

+       /* Try to find Stream Drop attribute */
+       pd->drop_attr = kNullAttributeUuid;
+       pd->dag_root = dag_config_get_root_component(pd->dag_ref);
+       if ( dag_component_get_subcomponent(pd->dag_root, kComponentStreamFeatures, 0) )
+       {
+               pd->drop_attr = dag_config_get_indexed_attribute_uuid(pd->dag_ref, kUint32AttributeStreamDropCount, pd->dag_stream/2);
+       }
+

        /* Set up default poll parameters for stream
         * Can be overridden by pcap_set_nonblock()
         */
        /* Set up default poll parameters for stream
         * Can be overridden by pcap_set_nonblock()
         */


@@ -1059,11 +1065,19 @@ static int
 dag_stats(pcap_t *p, struct pcap_stat *ps) {
        struct pcap_dag *pd = p->priv;
 
 dag_stats(pcap_t *p, struct pcap_stat *ps) {
        struct pcap_dag *pd = p->priv;
 

-       /* This needs to be filled out correctly.  Hopefully a dagapi call will
-                provide all necessary information.
-       */
-       /*pd->stat.ps_recv = 0;*/
-       /*pd->stat.ps_drop = 0;*/
+       /*
+        * Packet records received (ps_recv) are counted in dag_read().
+        * Packet records dropped (ps_drop) are read from Stream Drop attribute if present,
+        * otherwise integrate the ERF Header lctr counts (if available) in dag_read().
+        * We are reporting that no records are dropped by the card/driver (ps_ifdrop).
+        */
+
+       if(pd->drop_attr != kNullAttributeUuid) {
+               /* Note this counter will wrap at UINT_MAX.
+                * The application is responsible for polling ps_drop frequently enough
+                * to detect each wrap and integrate drop with a wider counter */
+               pd->stat.ps_drop = dag_config_get_uint32_attribute(pd->dag_ref, pd->drop_attr);
+       }

 
        *ps = pd->stat;
 
 
        *ps = pd->stat;