B24EE1007_B24CS1023_B24CM1031_B24CM1050_B24CH1047_auth.c

#include "B24EE1007_B24CS1023_B24CM1031_B24CM1050_B24CH1047_auth.h"
#include <stdio.h>
#include <string.h>
#include <windows.h>
#include <wincrypt.h>

int validateCredentials(const char *username, const char *password) {
    if (strlen(username) == 0 || strlen(username) > MAX_USERNAME_LEN - 1) {
        return 0;
    }
    if (strlen(password) == 0 || strlen(password) > MAX_PASSWORD_LEN - 1) {
        return 0;
    }
    for (int i = 0; i < strlen(username); i++) {
        if (username[i] == ':' || username[i] == '\n') {
            return 0;
        }
    }
    return 1;
}

int userExists(const char *username) {
    FILE *file = fopen(USERS_FILE, "rb");
    if (!file) {
        return 0;
    }
    UserCredentials user;
    while (fread(&user, sizeof(UserCredentials), 1, file)) {
        if (strcmp(user.username, username) == 0) {
            fclose(file);
            return 1;
        }
    }
    fclose(file);
    return 0;
}

int authenticateUser(const char *username, const char *password) {
    if (!validateCredentials(username, password)) {
        return 0;
    }
    FILE *file = fopen(USERS_FILE, "rb");
    if (!file) {
        return 0;
    }    
    UserCredentials user;
    while (fread(&user, sizeof(UserCredentials), 1, file)) {
        if (strcmp(user.username, username) == 0) {
            fclose(file);
            return (strcmp(user.password, password) == 0);
        }
    }
    fclose(file);
    return 0;
}

int registerUser(const char *username, const char *password) {
    if (!validateCredentials(username, password)) {
        return 0;
    }
    if (userExists(username)) {
        return 0;
    }    
    FILE *file = fopen(USERS_FILE, "ab");
    if (!file) {
        return 0;
    }    
    UserCredentials newUser;
    strncpy(newUser.username, username, MAX_USERNAME_LEN);
    strncpy(newUser.password, password, MAX_PASSWORD_LEN);
    int result = fwrite(&newUser, sizeof(UserCredentials), 1, file);
    fclose(file);
    
    return result == 1;
}