This code implements a utility program in C that provides...

September 4, 2025 at 12:16 AM

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <regex.h>
#include <sys/wait.h>

// Funzione per validare l'input
int validaInput(const char *input) {
  regex_t regex;
  int controllo = regcomp(&regex, "^[a-zA-Z0-9.]+$", REG_EXTENDED);
  if (controllo) {
    fprintf(stderr, "Errore compilazione regex\n");
    return 0;
  } else {
    controllo = regexec(&regex, input, 0, NULL, 0);
    regfree(&regex);

    if (!controllo) {
      return 1;
    } else {
      return 0;
    }
  }
}

// Funzione per eseguire i comandi
void eseguiComando(char *argv[]) {
  // Avvio un processo figlio per eseguire execvp
  pid_t pid = fork();
  if (pid == 0) {
    execvp(argv[0], argv);
    perror("execvp");
    exit(1);
  } else if (pid > 0) {
    // Processo padre atende la fine del processo figlio
    wait(NULL);
  } else {
    perror("fork");
  }
}

// Funzione per controllare se il destinatario e online
void ping() {
  char dest[128];
  printf("Inserisci IP o Nome Destinazione: ");
  fgets(dest, sizeof(dest), stdin);
  dest[strcspn(dest, "\n")] = 0;
  
  // Controllo se il input e valido
  if (!validaInput(dest)) {
    printf("Input non valido!\n");
    return;
  }
  // Creo il comando da eseguire e lo passo alla funzione eseguiCOmando
  char *argv[] = {"ping", "-c", "1", dest, NULL};
  eseguiComando(argv);
}

// Funzione per tracciare il percorso fra utente e dest
void traceroute() {
  char dest[128];
  printf("Inserisci IP o Nome Destinazione: ");
  fgets(dest, sizeof(dest), stdin);
  dest[strcspn(dest, "\n")] = 0;

  // Controllo se il input e valido
  if (!validaInput(dest)) {
    printf("Input non valido!\n");
    return;
  }
  
  // Creo il comando da eseguire e lo passo alla funzione eseguiCOmando
  char *argv[] = {"traceroute", "-I", dest, NULL};
  eseguiComando(argv);
}
// Funzione per controllare la possibilita di inviare pacchetti fra utente e dest
void controllaPorta() {
  char dest[128];
  printf("Inserisci IP o Nome Destinazione: ");
  fgets(dest, sizeof(dest), stdin);
  dest[strcspn(dest, "\n")] = 0;

  // Controllo se il input e valido
  if (!validaInput(dest)) {
    printf("Input non valido!\n");
    return;
  }

  // Creo il comando da eseguire e lo passo alla funzione eseguiCOmando
  char *argv[] = {"nc", "-zv", dest, "80", NULL};
  eseguiComando(argv);
}

int main() {
  int scelta;
  while (1) {
    printf("\nMenu\n");
    printf("1. Ping\n");
    printf("2. Traccia Percorso\n");
    printf("3. Controlla Porta 80\n");
    printf("4. Esci\n");
    printf("Scelta: ");
    scanf("%d", &scelta);
    getchar();

    switch (scelta) {
      case 1: 
        ping(); 
        break;
      case 2: 
        traceroute(); 
        break;
      case 3: 
        controllaPorta(); 
        break;
      case 4: 
        exit(0);
      default: 
      printf("Scelta non valida.\n");
    }
  }
}

This code implements a utility program in C that provides network-related functionalities such as ping, traceroute, and checking if a port (specifically port 80) is open on a target destination. Here's what the code does in detail:

Components of the Code:

Input Validation (validaInput):
- The function validaInput checks if the user's input (destination address or domain) matches a specific pattern using regular expressions.
- It validates that the input only contains alphanumeric characters (letters and digits), dots (.), making it a valid hostname or IP address.
- If the pattern is valid, it returns 1 (true), otherwise, it returns 0 (false).
Child Processes for Command Execution (eseguiComando):
- The function eseguiComando takes an array of arguments (a command and its parameters) and executes it using the execvp system call.
- It forks a child process using fork(). The child process runs the desired command, and the parent process waits for it to complete.
- If there's an error in command execution, an error message is printed using perror.
ping Function:
- The user is prompted to input an IP address or hostname.
- If the input is valid, the program builds a command to ping the destination (ping -c 1 <dest>), which sends one ICMP Echo Request to the destination.
- The command is executed using eseguiComando.
traceroute Function:
- Similar to ping, the user is asked to input a destination address.
- If valid, the program builds a command to perform a trace route (traceroute -I <dest>) using the traceroute utility.
- The command is executed using eseguiComando.
controllaPorta Function:
- This function checks if port 80 is accessible/open on the given destination.
- It uses the nc (Netcat) command in verbose mode (-zv) to scan port 80 of the destination (nc -zv <dest> 80).
- The command is executed using eseguiComando.
main Function and Menu:
- The main function implements a looped menu system, allowing the user to repeatedly select one of the following options:
  1. Ping: Calls the ping function.
  2. Traccia Percorso (Trace Route): Calls the traceroute function.
  3. Controlla Porta 80: Calls the controllaPorta function to check port 80.
  4. Esci (Exit): Exits the program.
- The user's choice is read as input, and based on the selection, the appropriate function is executed.

Key Notes:

Safety: The program validates user inputs to ensure only valid hostnames or IP addresses are processed.
Compatibility: The code assumes the presence of standard network utilities like ping, traceroute, and nc on the system.
Privileges: Some commands like traceroute might require superuser privileges, depending on the system configuration.
Error Handling: Basic error handling is implemented (e.g., handling invalid inputs, failed process creation, or command execution errors).

Summary:

This program is a utility for performing basic network diagnostics. It allows the user to:

Ping a destination to check its availability.
Trace the route to a destination to analyze the network path.
Check whether port 80 on a specific destination is open.

By using a menu-based interface, users can execute these functionalities interactively in a loop until they choose to exit the program.

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