TLA  Line data    Source code

       1                 : //! Definition and parser for channel binding flag (a part of the `GS2` header).
       2                 : 
       3                 : /// Channel binding flag (possibly with params).
       4 CBC           3 : #[derive(Debug, PartialEq, Eq)]
       5                 : pub enum ChannelBinding<T> {
       6                 :     /// Client doesn't support channel binding.
       7                 :     NotSupportedClient,
       8                 :     /// Client thinks server doesn't support channel binding.
       9                 :     NotSupportedServer,
      10                 :     /// Client wants to use this type of channel binding.
      11                 :     Required(T),
      12                 : }
      13                 : 
      14                 : impl<T> ChannelBinding<T> {
      15              32 :     pub fn and_then<R, E>(self, f: impl FnOnce(T) -> Result<R, E>) -> Result<ChannelBinding<R>, E> {
      16              32 :         use ChannelBinding::*;
      17              32 :         Ok(match self {
      18               1 :             NotSupportedClient => NotSupportedClient,
      19              31 :             NotSupportedServer => NotSupportedServer,
      20 UBC           0 :             Required(x) => Required(f(x)?),
      21                 :         })
      22 CBC          32 :     }
      23                 : }
      24                 : 
      25                 : impl<'a> ChannelBinding<&'a str> {
      26                 :     // NB: FromStr doesn't work with lifetimes
      27              35 :     pub fn parse(input: &'a str) -> Option<Self> {
      28              35 :         use ChannelBinding::*;
      29              35 :         Some(match input {
      30              35 :             "n" => NotSupportedClient,
      31              33 :             "y" => NotSupportedServer,
      32               1 :             other => Required(other.strip_prefix("p=")?),
      33                 :         })
      34              35 :     }
      35                 : }
      36                 : 
      37                 : impl<T: std::fmt::Display> ChannelBinding<T> {
      38                 :     /// Encode channel binding data as base64 for subsequent checks.
      39              35 :     pub fn encode<E>(
      40              35 :         &self,
      41              35 :         get_cbind_data: impl FnOnce(&T) -> Result<String, E>,
      42              35 :     ) -> Result<std::borrow::Cow<'static, str>, E> {
      43              35 :         use ChannelBinding::*;
      44              35 :         Ok(match self {
      45                 :             NotSupportedClient => {
      46                 :                 // base64::encode("n,,")
      47               2 :                 "biws".into()
      48                 :             }
      49                 :             NotSupportedServer => {
      50                 :                 // base64::encode("y,,")
      51              32 :                 "eSws".into()
      52                 :             }
      53               1 :             Required(mode) => {
      54               1 :                 let msg = format!(
      55               1 :                     "p={mode},,{data}",
      56               1 :                     mode = mode,
      57               1 :                     data = get_cbind_data(mode)?
      58                 :                 );
      59               1 :                 base64::encode(msg).into()
      60                 :             }
      61                 :         })
      62              35 :     }
      63                 : }
      64                 : 
      65                 : #[cfg(test)]
      66                 : mod tests {
      67                 :     use super::*;
      68                 : 
      69               1 :     #[test]
      70               1 :     fn channel_binding_encode() -> anyhow::Result<()> {
      71               1 :         use ChannelBinding::*;
      72               1 : 
      73               1 :         let cases = [
      74               1 :             (NotSupportedClient, base64::encode("n,,")),
      75               1 :             (NotSupportedServer, base64::encode("y,,")),
      76               1 :             (Required("foo"), base64::encode("p=foo,,bar")),
      77               1 :         ];
      78                 : 
      79               4 :         for (cb, input) in cases {
      80               3 :             assert_eq!(cb.encode(|_| anyhow::Ok("bar".to_owned()))?, input);
      81                 :         }
      82                 : 
      83               1 :         Ok(())
      84               1 :     }
      85                 : }