Function authenticate_cookie 

pub async fn authenticate_cookie(
    socket: &mut ControlSocket,
    path: &Path,
) -> Result<(), Error>

Authenticates using a cookie file.

Reads the authentication cookie from the specified path and sends its contents (hex-encoded) to Tor. The cookie file is typically 32 bytes and is created by Tor when CookieAuthentication is enabled.

Preconditions

• The socket must be connected
• Tor must be configured with CookieAuthentication 1
• The cookie file must exist and be readable
• The cookie file must be exactly 32 bytes

Postconditions

• On success: The socket is authenticated
• On failure: Tor may disconnect the socket

Arguments

• socket - A connected control socket
• path - Path to the authentication cookie file

Errors

Returns Error::Authentication with:

• AuthError::CookieUnreadable: Cannot read the cookie file (permissions, not found)
• AuthError::IncorrectCookieSize: Cookie file is not 32 bytes
• AuthError::IncorrectCookie: Cookie value was rejected by Tor

Security Considerations

• The cookie file should have restrictive permissions (e.g., 0600)
• Only the user running Tor should be able to read the cookie
• The cookie is transmitted in cleartext (hex-encoded) over the socket
• Consider using authenticate_safecookie for better security

Example

use stem_rs::auth::authenticate_cookie;
use stem_rs::ControlSocket;
use std::path::Path;

let mut socket = ControlSocket::connect_port("127.0.0.1:9051".parse()?).await?;
let cookie_path = Path::new("/var/run/tor/control.authcookie");
authenticate_cookie(&mut socket, cookie_path).await?;

Why 32 Bytes?

The cookie size is validated to prevent a malicious Tor instance from tricking the client into reading arbitrary files. Without this check, an attacker could claim that ~/.ssh/id_rsa is the cookie file.