ARQ Protocol Implementation

Author: ayushmantripathy9

.gitignore

@@ -0,0 +1,2 @@
+.vscode
+run_code

ARQ Protocol/.gitignore

@@ -0,0 +1 @@
+6_19114018.zip

ARQ Protocol/Code/ARQ.c

@@ -0,0 +1,177 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdbool.h>
+
+#include "events.h"
+#include "interface_functions.h"
+
+// for simulating different testcases include different testcase file headers. (testcase_1.h, testcase_2.h , etc)
+// for running custom testcases, you can change the values in the testcase_1.h file
+#include "testcase_3.h"
+
+// Utility function to increment the frame number
+#define increment_frame_no(k) k = (1 - k);
+
+void receiver();
+void sender();
+
+/* 
+  For simulation purpose
+    turn = true  : receiver's turn
+    turn = false : sender's turn
+*/
+bool turn;
+bool DISCONNECT = false;
+
+int main()
+{
+    srand(seed);
+    while (DISCONNECT == false)
+    {
+        sender();
+        usleep(800000);
+        receiver();
+    }
+    return 0;
+}
+
+void sender()
+{
+    static int next_frame_to_send = 0;
+    static frame s;
+    static int flag = 0;
+
+    packet buffer;
+    event_type event;
+
+    if (!flag)
+    {
+        from_network_layer(&buffer);
+        s.packet_data = buffer;
+        s.seq_no = next_frame_to_send;
+        
+        printf("Sender   : Info = %d    Seq No = %d\n", s.packet_data.data, s.seq_no);
+        turn = true;
+        to_physical_layer(&s);
+        flag = true;
+    }
+
+    wait_for_event_sender(&event);
+
+    if (!turn)
+    {
+        switch (event)
+        {
+        case frame_arrival:
+            from_physical_layer(&s);
+            if (s.ack_no == next_frame_to_send)
+            {
+                printf("Sender   : Ack No = %d   Acknowledgement received Successfully\n", s.ack_no);
+                if (data > TOT_PACKETS)
+                {
+                    DISCONNECT = true;
+                    printf("\nProgram executed successfully!!\n"); // when all cases are completed.
+                    return;
+                }
+                from_network_layer(&buffer);
+                increment_frame_no(next_frame_to_send);
+
+                s.seq_no = next_frame_to_send;
+                s.packet_data = buffer;
+                printf("-------------------------------------------------------------\n");
+                printf("Sender   : Info = %d    Seq No = %d\n", s.packet_data.data, s.seq_no);
+
+                turn = true;
+            }
+            to_physical_layer(&s);
+
+            break;
+
+        case time_out:
+            printf("Sender   : Resending Frame\n");
+
+            turn = true;
+            to_physical_layer(&s);
+
+            break;
+
+        default:
+            break;
+        }
+    }
+}
+
+void receiver()
+{
+    static int frame_expected = 0;
+    frame r, s;
+    event_type event;
+
+    wait_for_event_receiver(&event);
+    if (turn == true)
+    {
+        switch (event)
+        {
+        case frame_arrival:
+            from_physical_layer(&r);
+            if (r.seq_no == frame_expected)
+            {
+                to_network_layer(&r.packet_data);
+                increment_frame_no(frame_expected);
+            }
+            else
+                printf("Receiver : Acknowledgement Resent\n");
+
+            s.ack_no = 1 - frame_expected;
+            turn = 0;
+
+            to_physical_layer(&s);
+
+            break;
+
+        case err:
+            turn = false; //  if frame was damaged during transmission, sender should send it again
+            printf("Receiver : Damaged Frame Received\n");
+            break;
+
+        default:
+            break;
+        }
+    }
+}
+
+void wait_for_event_sender(event_type *e)
+{
+    static int timer = 0;
+
+    if (turn == false)
+    {
+        timer++;
+        if (timer == TIMEOUT)
+        {
+            printf("Sender   : Ack not received => TIMEOUT event occurred\n");
+            timer = 0;
+            *e = time_out;
+            return;
+        }
+        if (DATA.err == 0)
+            *e = err;
+        else
+        {
+            *e = frame_arrival;
+            timer = 0;
+        }
+    }
+}
+
+void wait_for_event_receiver(event_type *e)
+{
+    if (turn == true)
+    {
+        if (DATA.err == 0)
+            *e = err;
+        else
+            *e = frame_arrival;
+    }
+}

ARQ Protocol/Code/data_struct.h

@@ -0,0 +1,13 @@
+typedef struct
+{
+    int data;
+} packet;
+
+typedef struct
+{
+    int kind;
+    int seq_no;
+    int ack_no;
+    packet packet_data;
+    int err;
+} frame;

ARQ Protocol/Code/events.h

@@ -0,0 +1,10 @@
+typedef enum
+{
+    frame_arrival,
+    err,time_out,
+    no_event
+} event_type;
+
+
+void wait_for_event_sender(event_type *);
+void wait_for_event_receiver(event_type *);

ARQ Protocol/Code/interface_functions.h

@@ -0,0 +1,31 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "data_struct.h"
+
+
+frame DATA;
+int data = 1;
+
+void from_network_layer(packet *buffer)
+{
+   (*buffer).data = data;
+   data++;
+}
+
+
+void to_physical_layer(frame *s)
+{
+   s->err = rand() % 4; // 0 is for error, otherwise no error occurred in transmission
+   DATA = *s;
+}
+
+void to_network_layer(packet *buffer)
+{
+   printf("Receiver : Packet %d received , Ack Sent\n", (*buffer).data);
+}
+
+void from_physical_layer(frame *buffer)
+{
+   *buffer = DATA;
+}

ARQ Protocol/Code/testcase_1.h

@@ -0,0 +1,7 @@
+// parameters of simulation
+const int seed = 9;
+#define TOT_PACKETS 10
+#define TIMEOUT 3
+
+
+

ARQ Protocol/Code/testcase_2.h

@@ -0,0 +1,4 @@
+// parameters of simulation
+const int seed = 2;
+#define TOT_PACKETS 12
+#define TIMEOUT 2

ARQ Protocol/Code/testcase_3.h

@@ -0,0 +1,4 @@
+// parameters of simulation
+const int seed = 400;
+#define TOT_PACKETS 8
+#define TIMEOUT 4

ARQ Protocol/Simulations/TestCase_1.png

@@ -1,2 +1,2 @@
 # Computer-Networks-Lab
-Lab Project for Computer Networks Laboratory (CSN-361) Course
+Lab Project(s) for Computer Networks Laboratory (CSN-361) Course