- interface packet interception capability added

eth_interface.c

@@ -68,6 +68,8 @@ EthInterface *ethintf_new(EthIODef *io) {
 
     memset(&ethIntf->evtCbTable, 0, sizeof(EthIntfEventCbTable));
 
+    ethIntf->interceptCb = NULL;
+
     ethIntf->linkState = false;
 
     ethintf_register(ethIntf);
@@ -88,8 +90,16 @@ static ThreadReturnType task_ethintf(ThreadParamType param) {
         case ETH_IIE_RECV_NOTIFY: {
             intf->ioDef->llRxRead(intf->ioDef); // read packets, will invoke RxStore
             while (mq_avail(intf->rxQ) > 0) {
+                // get the raw packet
                 RawPckt rawPckt = mq_top(intf->rxQ);
                 mq_pop(intf->rxQ);
+
+                // packet interception, if defined
+                if (intf->interceptCb != NULL) { 
+                   intf->interceptCb(intf, &rawPckt);
+                }
+
+                // packet processing
                 packsieve_input(&intf->sieve, &rawPckt);
             }
 
@@ -123,7 +133,7 @@ void ethinf_receive(EthInterface *intf, const RawPckt *rawPckt) {
     bool pushOK = mq_push(intf->rxQ, rawPckt);
     if (!pushOK) {
         dynmem_free(rawPckt->payload);
-        ERROR("Input queue full, packet dropped!\n");
+        ERROR("Interface RECEIVE queue full, packet dropped!\n");
     }
 }
 
@@ -131,7 +141,7 @@ void ethinf_transmit(EthInterface *intf, const RawPckt *rawPckt) {
     if (mq_push(intf->txQ, rawPckt)) {                              // push packet onto the message queue
         ethinf_push_notification(intf, ETH_IIE_TRANSMIT_NOTIFY, 0); // notify processing thread of the peding transmit
     } else {
-        ERROR("Interface transmit queue full!\n");
+        ERROR("Interface TRANSMIT queue full, packet dropped!\n");
     }
 }
 
@@ -190,3 +200,7 @@ void ethinf_up(EthInterface *intf) {
 void ethinf_down(EthInterface *intf) {
     intf->up = false;
 }
+
+void ethinf_set_intercept_callback(EthInterface * intf, EthIntfInterceptCb cb) {
+    intf->interceptCb = cb;
+}

eth_interface.h

@@ -3,15 +3,15 @@
 
 #include <stdbool.h>
 
-#include "packet_sieve.h"
-#include "prefab/packet_parsers/packet_parsers.h"
-#include "prefab/packet_parsers/ipv4_types.h"
 #include "arp_cache.h"
 #include "connection_block.h"
-#include "msg_queue.h"
 #include "gen_queue.h"
+#include "msg_queue.h"
+#include "packet_sieve.h"
 #include "prefab/conn_blocks/ipv4/ip_assembler.h"
 #include "prefab/packet_parsers/dhcp.h"
+#include "prefab/packet_parsers/ipv4_types.h"
+#include "prefab/packet_parsers/packet_parsers.h"
 
 #include <etherlib_options.h>
 
@@ -47,6 +47,13 @@ struct EthInterface_;
 
 typedef void (*EthIntfEvtCb)(struct EthInterface_ *intf);
 
+/**
+ * Function prototype for intercepting packets on an interface.
+ * @param intf pointer to corresponding Ethernet interface
+ * @param rawPckt pointer to the IMMUTABLE raw packet
+ */
+typedef void (*EthIntfInterceptCb)(struct EthInterface_ *intf, const RawPckt *rawPckt);
+
 typedef enum {
     ETH_EVT_LINK_CHANGE = 0,
     ETH_EVT_IP_CHANGE = 1,
@@ -83,6 +90,8 @@ typedef struct EthInterface_ {
     EthIntfEventCbTable evtCbTable; ///< Event callback table
     bool linkState;                 ///< Interface link state
     bool up;                        ///< Is the interface up?
+    EthIntfInterceptCb interceptCb; ///< Intercept callback
+
 } EthInterface;
 
 /**
@@ -152,6 +161,7 @@ void ethinf_set_link_state(EthInterface * intf, bool ls);
 /**
  * Get link state.
  * @param intf pointer to Ethernet interface
+ * @return link state
  */
 bool ethinf_get_link_state(EthInterface *intf);
 
@@ -167,4 +177,11 @@ void ethinf_up(EthInterface *intf);
  */
 void ethinf_down(EthInterface *intf);
 
+/**
+ * Set callback for packet interception.
+ * @param intf pointer to Ethernet interface
+ * @param cb intercept callback pointer
+ */
+void ethinf_set_intercept_callback(EthInterface *intf, EthIntfInterceptCb cb);
+
 #endif // ETHERLIB_ETH_INTERFACE_H