Add fault injection and sender-side metrics for reliability testing

main_dsender.c

@@ -1,7 +1,21 @@
-#include<stdio.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include "src/include/comm.h"
 #include "src/include/datalink.h"
 
-int main(){
+
+
+int main(int argc, char *argv[]) {
+
+    srand(time(NULL));
+
+    if (argc >= 2) {
+        int rate = atoi(argv[1]);
+        set_loss_rate(rate);
+        printf("Fault Injection Enabled: drop 1 in %d frames\n", rate);
+    }
+
     dsender();
     return 0;
-}
+}

src/include/comm.h

@@ -3,4 +3,5 @@
 #include "packet.h"
 
 void send_frame(int fd, frame_t *f);
-int receive_frame(int fd, frame_t *f);
+int receive_frame(int fd, frame_t *f);
+void set_loss_rate(int rate);

src/src/comm.c

@@ -2,8 +2,17 @@
 #include<unistd.h>
 #include "../include/packet.h"
 #include "../include/comm.h"
+#include <stdlib.h>
+#include <time.h>
+
+static int loss_rate = 0;  // 0 = no loss, N = drop 1 in N frames
+
 
 void send_frame(int fd, frame_t *f){
+     if (loss_rate > 0 && rand() % loss_rate == 0) {
+        printf("FAULT INJECTION: Frame dropped intentionally\n");
+        return;
+    }
     ssize_t bytes_written = write(fd, f, sizeof(*f));
     if(bytes_written > 0){
         printf("Sender: Data sent successfully!\n");
@@ -27,5 +36,8 @@ int receive_frame(int fd, frame_t *f){
     printf("Receiver: Error Reading file\n");
     return 0;
 }
+void set_loss_rate(int rate) {
+    loss_rate = rate;
+}