Congestion control using Leaky Bucket algorithm.

Source Code:

File Name: leakybucket.c

#include<stdio.h>
#include <stdlib.h>
#include <unistd.h>

#define NUM_PACKETS 10

// Custom random function to ensure non-zero result
int get_random(int max_value) {
    int result = (random() % 10) % max_value;
    return result == 0 ? 1 : result;
}

int main() {
    int packet_size[NUM_PACKETS];
    int i, clock_tick, bucket_size, output_rate;
    int remaining_data = 0, data_to_send, transmission_time, transmitted;

    // Generate random packet sizes
    for (i = 0; i < NUM_PACKETS; ++i)
        packet_size[i] = get_random(6) * 10;

    // Display the generated packet sizes
    for (i = 0; i < NUM_PACKETS; ++i)
        printf("\nPacket[%d]: %d bytes", i + 1, packet_size[i]);

    // Get output rate and bucket size from the user
    printf("\n\nEnter the Output Rate (bytes/unit time): ");
    scanf("%d", &output_rate);

    printf("Enter the Bucket Size (in bytes): ");
    scanf("%d", &bucket_size);

    // Process each incoming packet
    for (i = 0; i < NUM_PACKETS; ++i) {
        // Check if incoming packet + remaining data exceeds bucket size
        if ((packet_size[i] + remaining_data) > bucket_size) {
            if (packet_size[i] > bucket_size) {
                printf("\n\nIncoming Packet[%d] size (%d bytes) exceeds bucket capacity (%d bytes) - PACKET REJECTED!", i + 1, packet_size[i], bucket_size);
            } else {
                printf("\n\nBucket capacity exceeded for Packet[%d] - PACKET REJECTED!", i + 1);
            }
        } else {
            // Accept and add packet to bucket
            remaining_data += packet_size[i];
            printf("\n\nIncoming Packet[%d] size: %d bytes", i + 1, packet_size[i]);
            printf("\nTotal bytes to transmit (in bucket): %d", remaining_data);

            // Simulated transmission time (random)
            transmission_time = get_random(4) * 10;
            printf("\nEstimated transmission time: %d units", transmission_time);

            // Transmit data in units of time
            for (clock_tick = 10; clock_tick <= transmission_time; clock_tick += 10) {
                sleep(1);  // Simulate delay (1 second per 10 units)

                if (remaining_data > 0) {
                    if (remaining_data <= output_rate) {
                        transmitted = remaining_data;
                        remaining_data = 0;
                    } else {
                        transmitted = output_rate;
                        remaining_data -= output_rate;
                    }

                    printf("\nTransmitted %d bytes ---- Remaining in bucket: %d bytes", transmitted, remaining_data);
                } else {
                    printf("\nNo data to transmit at time unit %d!", clock_tick);
                }
            }
        }
    }

    return 0;
}

Output:

$ gcc leakybucket.c
$ ./a.out

Packet[1]: 30 bytes
Packet[2]: 10 bytes
Packet[3]: 10 bytes
Packet[4]: 50 bytes
Packet[5]: 30 bytes
Packet[6]: 50 bytes
Packet[7]: 10 bytes
Packet[8]: 20 bytes
Packet[9]: 30 bytes
Packet[10]: 10 bytes

Enter the Output Rate (bytes/unit time): 10
Enter the Bucket Size (in bytes): 15


Incoming Packet[1] size (30 bytes) exceeds bucket capacity (15 bytes) - PACKET REJECTED!

Incoming Packet[2] size: 10 bytes
Total bytes to transmit (in bucket): 10
Estimated transmission time: 20 units
Transmitted 10 bytes ---- Remaining in bucket: 0 bytes
No data to transmit at time unit 20!

Incoming Packet[3] size: 10 bytes
Total bytes to transmit (in bucket): 10
Estimated transmission time: 30 units
Transmitted 10 bytes ---- Remaining in bucket: 0 bytes
No data to transmit at time unit 20!
No data to transmit at time unit 30!

Incoming Packet[4] size (50 bytes) exceeds bucket capacity (15 bytes) - PACKET REJECTED!

Incoming Packet[5] size (30 bytes) exceeds bucket capacity (15 bytes) - PACKET REJECTED!

Incoming Packet[6] size (50 bytes) exceeds bucket capacity (15 bytes) - PACKET REJECTED!

Incoming Packet[7] size: 10 bytes
Total bytes to transmit (in bucket): 10
Estimated transmission time: 10 units
Transmitted 10 bytes ---- Remaining in bucket: 0 bytes

Incoming Packet[8] size (20 bytes) exceeds bucket capacity (15 bytes) - PACKET REJECTED!

Incoming Packet[9] size (30 bytes) exceeds bucket capacity (15 bytes) - PACKET REJECTED!

Incoming Packet[10] size: 10 bytes
Total bytes to transmit (in bucket): 10
Estimated transmission time: 10 units
Transmitted 10 bytes ---- Remaining in bucket: 0 bytes