Function is_valid_fingerprint 

pub fn is_valid_fingerprint(s: &str) -> bool

Validates a relay fingerprint string.

A valid fingerprint consists of exactly 40 hexadecimal characters (case-insensitive), representing a 160-bit SHA-1 hash of the relay’s identity key.

Arguments

• s - The string to validate

Returns

true if the string is a valid fingerprint, false otherwise.

Format

• Length: exactly 40 characters
• Characters: hexadecimal digits (0-9, a-f, A-F)

Example

use stem_rs::util::is_valid_fingerprint;

// Valid fingerprints (case-insensitive)
assert!(is_valid_fingerprint("9695DFC35FFEB861329B9F1AB04C46397020CE31"));
assert!(is_valid_fingerprint("9695dfc35ffeb861329b9f1ab04c46397020ce31"));

// Invalid fingerprints
assert!(!is_valid_fingerprint("9695DFC35FFEB861329B9F1AB04C4639702")); // Too short
assert!(!is_valid_fingerprint("ZZZZDFC35FFEB861329B9F1AB04C46397020CE31")); // Invalid chars

This Compiles But Is Wrong

use stem_rs::util::is_valid_fingerprint;

// Don't include the "$" prefix - that's for fingerprint references
let with_prefix = "$9695DFC35FFEB861329B9F1AB04C46397020CE31";
assert!(!is_valid_fingerprint(with_prefix)); // Returns false!

// Use is_valid_fingerprint_with_prefix for prefixed fingerprints
use stem_rs::util::is_valid_fingerprint_with_prefix;
assert!(is_valid_fingerprint_with_prefix(with_prefix));