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              : #[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           24 :     pub fn and_then<R, E>(self, f: impl FnOnce(T) -> Result<R, E>) -> Result<ChannelBinding<R>, E> {
      16           24 :         Ok(match self {
      17           12 :             Self::NotSupportedClient => ChannelBinding::NotSupportedClient,
      18            0 :             Self::NotSupportedServer => ChannelBinding::NotSupportedServer,
      19           12 :             Self::Required(x) => ChannelBinding::Required(f(x)?),
      20              :         })
      21           24 :     }
      22              : }
      23              : 
      24              : impl<'a> ChannelBinding<&'a str> {
      25              :     // NB: FromStr doesn't work with lifetimes
      26           42 :     pub fn parse(input: &'a str) -> Option<Self> {
      27           42 :         Some(match input {
      28           42 :             "n" => Self::NotSupportedClient,
      29           18 :             "y" => Self::NotSupportedServer,
      30           14 :             other => Self::Required(other.strip_prefix("p=")?),
      31              :         })
      32           42 :     }
      33              : }
      34              : 
      35              : impl<T: std::fmt::Display> ChannelBinding<T> {
      36              :     /// Encode channel binding data as base64 for subsequent checks.
      37           30 :     pub fn encode<'a, E>(
      38           30 :         &self,
      39           30 :         get_cbind_data: impl FnOnce(&T) -> Result<&'a [u8], E>,
      40           30 :     ) -> Result<std::borrow::Cow<'static, str>, E> {
      41           30 :         Ok(match self {
      42           14 :             Self::NotSupportedClient => {
      43           14 :                 // base64::encode("n,,")
      44           14 :                 "biws".into()
      45              :             }
      46            2 :             Self::NotSupportedServer => {
      47            2 :                 // base64::encode("y,,")
      48            2 :                 "eSws".into()
      49              :             }
      50           14 :             Self::Required(mode) => {
      51           14 :                 use std::io::Write;
      52           14 :                 let mut cbind_input = vec![];
      53           14 :                 write!(&mut cbind_input, "p={mode},,",).unwrap();
      54           14 :                 cbind_input.extend_from_slice(get_cbind_data(mode)?);
      55           14 :                 base64::encode(&cbind_input).into()
      56              :             }
      57              :         })
      58           30 :     }
      59              : }
      60              : 
      61              : #[cfg(test)]
      62              : mod tests {
      63              :     use super::*;
      64              : 
      65              :     #[test]
      66            2 :     fn channel_binding_encode() -> anyhow::Result<()> {
      67            2 :         use ChannelBinding::*;
      68            2 : 
      69            2 :         let cases = [
      70            2 :             (NotSupportedClient, base64::encode("n,,")),
      71            2 :             (NotSupportedServer, base64::encode("y,,")),
      72            2 :             (Required("foo"), base64::encode("p=foo,,bar")),
      73            2 :         ];
      74              : 
      75            8 :         for (cb, input) in cases {
      76            6 :             assert_eq!(cb.encode(|_| anyhow::Ok(b"bar"))?, input);
      77              :         }
      78              : 
      79            2 :         Ok(())
      80            2 :     }
      81              : }