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 :         use ChannelBinding::*;
      17           24 :         Ok(match self {
      18           12 :             NotSupportedClient => NotSupportedClient,
      19            0 :             NotSupportedServer => NotSupportedServer,
      20           12 :             Required(x) => Required(f(x)?),
      21              :         })
      22           24 :     }
      23              : }
      24              : 
      25              : impl<'a> ChannelBinding<&'a str> {
      26              :     // NB: FromStr doesn't work with lifetimes
      27           42 :     pub fn parse(input: &'a str) -> Option<Self> {
      28           42 :         use ChannelBinding::*;
      29           42 :         Some(match input {
      30           42 :             "n" => NotSupportedClient,
      31           18 :             "y" => NotSupportedServer,
      32           14 :             other => Required(other.strip_prefix("p=")?),
      33              :         })
      34           42 :     }
      35              : }
      36              : 
      37              : impl<T: std::fmt::Display> ChannelBinding<T> {
      38              :     /// Encode channel binding data as base64 for subsequent checks.
      39           30 :     pub fn encode<'a, E>(
      40           30 :         &self,
      41           30 :         get_cbind_data: impl FnOnce(&T) -> Result<&'a [u8], E>,
      42           30 :     ) -> Result<std::borrow::Cow<'static, str>, E> {
      43           30 :         use ChannelBinding::*;
      44           30 :         Ok(match self {
      45              :             NotSupportedClient => {
      46              :                 // base64::encode("n,,")
      47           14 :                 "biws".into()
      48              :             }
      49              :             NotSupportedServer => {
      50              :                 // base64::encode("y,,")
      51            2 :                 "eSws".into()
      52              :             }
      53           14 :             Required(mode) => {
      54           14 :                 use std::io::Write;
      55           14 :                 let mut cbind_input = vec![];
      56           14 :                 write!(&mut cbind_input, "p={mode},,",).unwrap();
      57           14 :                 cbind_input.extend_from_slice(get_cbind_data(mode)?);
      58           14 :                 base64::encode(&cbind_input).into()
      59              :             }
      60              :         })
      61           30 :     }
      62              : }
      63              : 
      64              : #[cfg(test)]
      65              : mod tests {
      66              :     use super::*;
      67              : 
      68              :     #[test]
      69            2 :     fn channel_binding_encode() -> anyhow::Result<()> {
      70            2 :         use ChannelBinding::*;
      71            2 : 
      72            2 :         let cases = [
      73            2 :             (NotSupportedClient, base64::encode("n,,")),
      74            2 :             (NotSupportedServer, base64::encode("y,,")),
      75            2 :             (Required("foo"), base64::encode("p=foo,,bar")),
      76            2 :         ];
      77              : 
      78            8 :         for (cb, input) in cases {
      79            6 :             assert_eq!(cb.encode(|_| anyhow::Ok(b"bar"))?, input);
      80              :         }
      81              : 
      82            2 :         Ok(())
      83            2 :     }
      84              : }