Line data    Source code

       1              : // SPDX-License-Identifier: EUPL-1.2
       2              : //! A value that must never reach a log line, an error message or a response:
       3              : //! the `/q` admin token and the database URL with its password.
       4              : //! `Debug` and `Display` print nothing of it, and it is not `Serialize`, so a
       5              : //! `{:?}`, a `tracing` field or a state dump cannot carry it. The one way
       6              : //! out is [`Secret::expose`], and `dev/security.cypher` (`secret-exposed`)
       7              : //! lists every call with where the value goes.
       8              : 
       9              : /// A secret string; see the module documentation.
      10              : #[derive(Clone, PartialEq, Eq)]
      11              : pub struct Secret(String);
      12              : 
      13              : impl Secret {
      14              :     /// Wraps a value read from the environment or a mounted file.
      15           59 :     pub fn new(value: impl Into<String>) -> Self {
      16           59 :         Self(value.into())
      17           59 :     }
      18              : 
      19              :     /// The value itself, for the one call that needs it (a connect, a
      20              :     /// comparison). Never for a log line or an error.
      21          155 :     pub fn expose(&self) -> &str {
      22          155 :         &self.0
      23          155 :     }
      24              : }
      25              : 
      26              : impl std::fmt::Debug for Secret {
      27            8 :     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
      28            8 :         f.write_str("Secret(..)")
      29            8 :     }
      30              : }
      31              : 
      32              : impl std::fmt::Display for Secret {
      33            4 :     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
      34            4 :         f.write_str("[redacted]")
      35            4 :     }
      36              : }
      37              : 
      38              : #[cfg(test)]
      39              : mod tests {
      40              :     use super::Secret;
      41              : 
      42              :     #[test]
      43            4 :     fn neither_debug_nor_display_prints_the_value() {
      44            4 :         let s = Secret::new("postgresql://antares:hunter2@db/antares");
      45           12 :         for shown in [format!("{s:?}"), format!("{s}"), format!("{:#?}", Some(&s))] {
      46           12 :             assert!(!shown.contains("hunter2"), "{shown}");
      47              :         }
      48            4 :         assert_eq!(s.expose(), "postgresql://antares:hunter2@db/antares");
      49            4 :     }
      50              : }