cache expiry and singleretrival of cache vals

src/cache/hashcache.rs

@@ -23,34 +23,32 @@ use actix::prelude::*;
 use super::messages::*;
 use super::Save;
 use crate::errors::*;
-use crate::pow::PoWConfig;
 
 #[derive(Clone, Default)]
 /// cache datastructure implementing [Save]
 pub struct HashCache(HashMap<String, u32>);
 
 impl HashCache {
-    fn save(&mut self, config: PoWConfig) -> CaptchaResult<()> {
+    // save [PoWConfig] to cache
+    fn save(&mut self, config: Cache) -> CaptchaResult<()> {
         self.0.insert(config.string, config.difficulty_factor);
         Ok(())
     }
 
+    // retrive [PoWConfig] from cache. Deletes config post retrival
     fn retrive(&mut self, string: String) -> CaptchaResult<Option<u32>> {
-        if let Some(difficulty_factor) = self.0.get(&string) {
+        if let Some(difficulty_factor) = self.remove(&string) {
             Ok(Some(difficulty_factor.to_owned()))
         } else {
             Ok(None)
         }
     }
-}
 
-/* TODO cache of pow configs need to have lifetimes to prevent replay attacks
- * where lifetime = site's cool down period so that people can't generate pow
- * configs when the site is cool and  use them later with rainbow tables
- * when it's under attack.
- *
- * This comment stays until this feature is implemented.
- */
+    // delete [PoWConfig] from cache
+    fn remove(&mut self, string: &str) -> Option<u32> {
+        self.0.remove(string)
+    }
+}
 
 impl Save for HashCache {}
 
@@ -61,8 +59,31 @@ impl Actor for HashCache {
 /// cache a PoWConfig
 impl Handler<Cache> for HashCache {
     type Result = MessageResult<Cache>;
-    fn handle(&mut self, msg: Cache, _ctx: &mut Self::Context) -> Self::Result {
-        MessageResult(self.save(msg.0))
+    fn handle(&mut self, msg: Cache, ctx: &mut Self::Context) -> Self::Result {
+        use actix::clock::delay_for;
+        use std::time::Duration;
+
+        let addr = ctx.address();
+        let del_msg = DeleteString(msg.string.clone());
+
+        let duration: Duration = Duration::new(msg.duration.clone(), 0);
+        let wait_for = async move {
+            delay_for(duration).await;
+            addr.send(del_msg).await.unwrap().unwrap();
+        }
+        .into_actor(self);
+        ctx.spawn(wait_for);
+
+        MessageResult(self.save(msg))
+    }
+}
+
+/// Delte a PoWConfig
+impl Handler<DeleteString> for HashCache {
+    type Result = MessageResult<DeleteString>;
+    fn handle(&mut self, msg: DeleteString, _ctx: &mut Self::Context) -> Self::Result {
+        self.remove(&msg.0);
+        MessageResult(Ok(()))
     }
 }
 
@@ -77,14 +98,38 @@ impl Handler<Retrive> for HashCache {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::mcaptcha::VisitorResult;
+    use crate::pow::PoWConfig;
+
+    async fn sleep(time: u64) {
+        use actix::clock::delay_for;
+        use std::time::Duration;
+
+        let duration: Duration = Duration::new(time, 0);
+        delay_for(duration).await;
+    }
 
     #[actix_rt::test]
     async fn hashcache_works() {
+        const DIFFICULTY_FACTOR: u32 = 54;
+        const DURATION: u64 = 5;
         let addr = HashCache::default().start();
-        let cache: PoWConfig = PoWConfig::new(54);
-        let string = cache.string.clone();
-        addr.send(Cache(cache)).await.unwrap().unwrap();
-        let difficulty_factor = addr.send(Retrive(string)).await.unwrap().unwrap();
-        assert_eq!(difficulty_factor.unwrap(), 54);
+        let pow: PoWConfig = PoWConfig::new(DIFFICULTY_FACTOR);
+        let visitor_result = VisitorResult {
+            difficulty_factor: DIFFICULTY_FACTOR,
+            duration: DURATION,
+        };
+        let string = pow.string.clone();
+        let msg = Cache::new(&pow, &visitor_result);
+
+        addr.send(msg).await.unwrap().unwrap();
+
+        let cache_difficulty_factor = addr.send(Retrive(string.clone())).await.unwrap().unwrap();
+        assert_eq!(DIFFICULTY_FACTOR, cache_difficulty_factor.unwrap());
+
+        sleep(DURATION + DURATION).await;
+
+        let expired_string = addr.send(Retrive(string)).await.unwrap().unwrap();
+        assert_eq!(None, expired_string);
     }
 }

src/cache/mod.rs

@@ -23,22 +23,48 @@ use messages::*;
 pub mod hashcache;
 
 /// Describes actor handler trait impls that are required by a cache implementation
-pub trait Save: actix::Actor + actix::Handler<Retrive> + actix::Handler<Cache> {}
-
+pub trait Save:
+    actix::Actor + actix::Handler<Retrive> + actix::Handler<Cache> + actix::Handler<DeleteString>
+{
+}
 pub mod messages {
     //! Messages that can be sent to cache data structures implementing [Save][super::Save]
-    use crate::pow::PoWConfig;
     use actix::dev::*;
+    use derive_builder::Builder;
 
     use crate::errors::*;
+    use crate::mcaptcha::VisitorResult;
+    use crate::pow::PoWConfig;
 
-    /// Message to decrement the visitor count
-    #[derive(Message)]
+    /// Message to cache PoW difficulty factor and string
+    #[derive(Message, Builder)]
     #[rtype(result = "CaptchaResult<()>")]
-    pub struct Cache(pub PoWConfig);
+    pub struct Cache {
+        pub string: String,
+        pub difficulty_factor: u32,
+        pub duration: u64,
+    }
 
-    /// Message to decrement the visitor count
+    impl Cache {
+        pub fn new(p: &PoWConfig, v: &VisitorResult) -> Self {
+            CacheBuilder::default()
+                .string(p.string.clone())
+                .difficulty_factor(v.difficulty_factor)
+                .duration(v.duration)
+                .build()
+                .unwrap()
+        }
+    }
+
+    /// Message to retrive the the difficulty factor for the specified
+    /// string from the cache
     #[derive(Message)]
     #[rtype(result = "CaptchaResult<Option<u32>>")]
     pub struct Retrive(pub String);
+
+    /// Message to delete cached PoW difficulty factor and string
+    /// when they expire
+    #[derive(Message)]
+    #[rtype(result = "CaptchaResult<()>")]
+    pub struct DeleteString(pub String);
 }

src/data.rs

@@ -49,13 +49,11 @@ where
         if site_addr.is_none() {
             return None;
         }
-        let difficulty_factor = site_addr.unwrap().send(Visitor).await.unwrap();
-        let pow_config = PoWConfig::new(difficulty_factor);
-        self.cache
-            .send(Cache(pow_config.clone()))
-            .await
-            .unwrap()
-            .unwrap();
+        let mcaptcha = site_addr.unwrap().send(Visitor).await.unwrap();
+        let pow_config = PoWConfig::new(mcaptcha.difficulty_factor);
+
+        let cache_msg = Cache::new(&pow_config, &mcaptcha);
+        self.cache.send(cache_msg).await.unwrap().unwrap();
         Some(pow_config)
     }
 
@@ -138,14 +136,6 @@ mod tests {
         let work = config
             .prove_work(&work_req.string, work_req.difficulty_factor)
             .unwrap();
-
-        let insufficient_work = config.prove_work(&work_req.string, 1).unwrap();
-        let insufficient_work_payload = Work {
-            string: work_req.string.clone(),
-            result: insufficient_work.result,
-            nonce: insufficient_work.nonce,
-        };
-
         let mut payload = Work {
             string: work_req.string,
             result: work.result,
@@ -159,8 +149,14 @@ mod tests {
         let res = actors.verify_pow(payload.clone()).await;
         assert_eq!(res, Err(CaptchaError::StringNotFound));
 
+        let insufficient_work_req = actors.get_pow(MCAPTCHA_NAME.into()).await.unwrap();
+        let insufficient_work = config.prove_work(&insufficient_work_req.string, 1).unwrap();
+        let insufficient_work_payload = Work {
+            string: insufficient_work_req.string,
+            result: insufficient_work.result,
+            nonce: insufficient_work.nonce,
+        };
         let res = actors.verify_pow(insufficient_work_payload.clone()).await;
-
         assert_eq!(res, Err(CaptchaError::InsuffiencientDifficulty));
     }
 }

src/mcaptcha.rs

@@ -111,6 +111,11 @@ impl MCaptcha {
     pub fn get_difficulty(&self) -> u32 {
         self.defense.get_difficulty()
     }
+
+    /// get [MCaptcha]'s lifetime
+    pub fn get_duration(&self) -> u64 {
+        self.duration
+    }
 }
 impl Actor for MCaptcha {
     type Context = Context<Self>;
@@ -129,12 +134,30 @@ impl Handler<DeleteVisitor> for MCaptcha {
 }
 
 /// Message to increment the visitor count
+/// returns difficulty factor and lifetime
 #[derive(Message)]
-#[rtype(result = "u32")]
+#[rtype(result = "VisitorResult")]
 pub struct Visitor;
 
+/// Struct representing the return datatime of
+/// [Visitor] message. Contains MCaptcha lifetime
+/// and difficulty factor
+pub struct VisitorResult {
+    pub duration: u64,
+    pub difficulty_factor: u32,
+}
+
+impl VisitorResult {
+    fn new(m: &MCaptcha) -> Self {
+        VisitorResult {
+            duration: m.get_duration(),
+            difficulty_factor: m.get_difficulty(),
+        }
+    }
+}
+
 impl Handler<Visitor> for MCaptcha {
-    type Result = u32;
+    type Result = MessageResult<Visitor>;
 
     fn handle(&mut self, _: Visitor, ctx: &mut Self::Context) -> Self::Result {
         use actix::clock::delay_for;
@@ -150,7 +173,7 @@ impl Handler<Visitor> for MCaptcha {
         ctx.spawn(wait_for);
 
         self.add_visitor();
-        self.get_difficulty()
+        MessageResult(VisitorResult::new(&self))
     }
 }
 
@@ -209,12 +232,12 @@ pub mod tests {
     async fn counter_defense_tightenup_works() {
         let addr: MyActor = get_counter().start();
 
-        let mut difficulty_factor = addr.send(Visitor).await.unwrap();
-        assert_eq!(difficulty_factor, LEVEL_1.0);
+        let mut mcaptcha = addr.send(Visitor).await.unwrap();
+        assert_eq!(mcaptcha.difficulty_factor, LEVEL_1.0);
 
         race(addr.clone(), LEVEL_2).await;
-        difficulty_factor = addr.send(Visitor).await.unwrap();
-        assert_eq!(difficulty_factor, LEVEL_2.1);
+        mcaptcha = addr.send(Visitor).await.unwrap();
+        assert_eq!(mcaptcha.difficulty_factor, LEVEL_2.1);
     }
 
     #[actix_rt::test]
@@ -224,13 +247,13 @@ pub mod tests {
 
         race(addr.clone(), LEVEL_2).await;
         race(addr.clone(), LEVEL_2).await;
-        let mut difficulty_factor = addr.send(Visitor).await.unwrap();
-        assert_eq!(difficulty_factor, LEVEL_2.1);
+        let mut mcaptcha = addr.send(Visitor).await.unwrap();
+        assert_eq!(mcaptcha.difficulty_factor, LEVEL_2.1);
 
         let duration = Duration::new(DURATION, 0);
         delay_for(duration).await;
 
-        difficulty_factor = addr.send(Visitor).await.unwrap();
-        assert_eq!(difficulty_factor, LEVEL_1.1);
+        mcaptcha = addr.send(Visitor).await.unwrap();
+        assert_eq!(mcaptcha.difficulty_factor, LEVEL_1.1);
     }
 }