fix: [torrust#976] do not allow invalid tracker keys

Author: josecelano

src/core/auth.rs

@@ -131,13 +131,37 @@ impl ExpiringKey {
     }
 }
 
-/// A randomly generated token used for authentication.
+/// A token used for authentication.
 ///
-/// It contains lower and uppercase letters and numbers.
-/// It's a 32-char string.
+/// - It contains only ascii alphanumeric chars: lower and uppercase letters and
+///   numbers.
+/// - It's a 32-char string.
 #[derive(Serialize, Deserialize, Debug, Eq, PartialEq, Clone, Display, Hash)]
 pub struct Key(String);
 
+impl Key {
+    /// # Errors
+    ///
+    /// Will return an error is the string represents an invalid key.
+    /// Valid keys can only contain 32 chars including 0-9, a-z and A-Z.
+    pub fn new(value: &str) -> Result<Self, ParseKeyError> {
+        if value.len() != AUTH_KEY_LENGTH {
+            return Err(ParseKeyError);
+        }
+
+        if !value.chars().all(|c| c.is_ascii_alphanumeric()) {
+            return Err(ParseKeyError);
+        }
+
+        Ok(Self(value.to_owned()))
+    }
+
+    #[must_use]
+    pub fn value(&self) -> &str {
+        &self.0
+    }
+}
+
 /// Error returned when a key cannot be parsed from a string.
 ///
 /// ```rust,no_run
@@ -159,10 +183,7 @@ impl FromStr for Key {
     type Err = ParseKeyError;
 
     fn from_str(s: &str) -> Result<Self, Self::Err> {
-        if s.len() != AUTH_KEY_LENGTH {
-            return Err(ParseKeyError);
-        }
-
+        Key::new(s)?;
         Ok(Self(s.to_string()))
     }
 }
@@ -209,6 +230,22 @@ mod tests {
             assert!(key.is_ok());
             assert_eq!(key.unwrap().to_string(), key_string);
         }
+
+        #[test]
+        fn length_should_be_32() {
+            let key = Key::new("");
+            assert!(key.is_err());
+
+            let string_longer_than_32 = "012345678901234567890123456789012"; // DevSkim: ignore  DS173237
+            let key = Key::new(string_longer_than_32);
+            assert!(key.is_err());
+        }
+
+        #[test]
+        fn should_only_include_alphanumeric_chars() {
+            let key = Key::new("%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%");
+            assert!(key.is_err());
+        }
     }
 
     mod expiring_auth_key {

tests/servers/api/v1/contract/context/auth_key.rs

@@ -136,10 +136,10 @@ async fn should_fail_generating_a_new_auth_key_when_the_provided_key_is_invalid(
     let invalid_keys = [
         // "", it returns 404
         // " ", it returns 404
-        "-1",      // Not a string
-        "invalid", // Invalid string
-        "GQEs2ZNcCm9cwEV9dBpcPB5OwNFWFiR", // Not a 32-char string
-                   // "%QEs2ZNcCm9cwEV9dBpcPB5OwNFWFiRd", // Invalid char. todo: this doesn't fail
+        "-1",                               // Not a string
+        "invalid",                          // Invalid string
+        "GQEs2ZNcCm9cwEV9dBpcPB5OwNFWFiR",  // Not a 32-char string
+        "%QEs2ZNcCm9cwEV9dBpcPB5OwNFWFiRd", // Invalid char.
     ];
 
     for invalid_key in invalid_keys {