1.c

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

#define SIZE 0x100

char motd[SIZE] = "> > > D-d-d-DROP the ROP! < < <";

void clean_stdin()
{
    while (1)
    {
        char c = getchar();
        if (c == '\n') break;
        if (c == EOF) exit(1);
    }
}

int getnum()
{
    int choice = ~0;
    scanf("%d", &choice);
    clean_stdin();
    return choice;
}

void read_motd(char* motd) {
    printf("Type in the new message of the day please:\n> ");
    char buf[SIZE] = {0};
    gets(buf);
    memcpy(motd, buf, SIZE);
}

int done = 0;
void main()
{
    setvbuf(stdout, NULL, _IONBF, 0);
    /* setvbuf(stdin, NULL, _IONBF, 0); */ // Breaks direct ret2libc
    printf("motd daemon v0.1 (c) 2019 BetterSoft\n");
    fflush(stdout);
    system("date"); // [bill] This is easier than manipulating time and makes our code cleaner.

    while (!done)
    {
        printf("\n");
        printf("=> How may I help you today?\n");
        printf("    1 - View message of the day\n");
        printf("    2 - Change message of the day\n");
        printf("    3 - Exit\n");

        printf("> ");
        int choice = getnum();
        printf("\n");

        switch (choice)
        {
            case 1:
                puts(motd);
                break;
            case 2:
            {
                read_motd(motd);
                break;
            }
            case 3:
                done = 1;
                break;
            default:
                printf("I don't recognize that option.\n");
                break;
        }
    }
    printf("Bye!\n");
}