implementing auto-reconnection

lib/grammers-mtproto/src/mtp/encrypted.rs

@@ -1159,19 +1159,27 @@ impl Mtp for Encrypted {
         // Check to see if the next salt can be used already. If it can, drop the current one and,
         // if the next salt is the last one, fetch more.
         if let Some((start_secs, start_instant)) = self.start_salt_time {
-            if let Some(salt) = self.salts.get(self.salts.len() - 2) {
-                let now = start_secs + start_instant.elapsed().as_secs() as i32;
-                if now >= salt.valid_since + SALT_USE_DELAY {
-                    self.salts.pop();
-                    if self.salts.len() == 1 {
-                        info!("only one future salt remaining; asking for more salts");
-                        let body = tl::functions::GetFutureSalts {
-                            num: NUM_FUTURE_SALTS,
+            let should_fetch_salts = self.salts.len() < 2
+                || 'value: {
+                    if let Some(salt) = self.salts.get(self.salts.len() - 2) {
+                        let now = start_secs + start_instant.elapsed().as_secs() as i32;
+                        if now >= salt.valid_since + SALT_USE_DELAY {
+                            self.salts.pop();
+                            if self.salts.len() == 1 {
+                                info!("only one future salt remaining; asking for more salts");
+                                break 'value true;
+                            }
                         }
-                        .to_bytes();
-                        self.serialize_msg(&body, true);
                     }
+                    false
+                };
+
+            if should_fetch_salts {
+                let body = tl::functions::GetFutureSalts {
+                    num: NUM_FUTURE_SALTS,
                 }
+                .to_bytes();
+                self.serialize_msg(&body, true);
             }
         }
 
@@ -1246,6 +1254,18 @@ impl Mtp for Encrypted {
             updates: mem::take(&mut self.updates),
         })
     }
+
+    fn reset(&mut self) {
+        self.client_id = {
+            let mut buffer = [0u8; 8];
+            getrandom(&mut buffer).expect("failed to generate a secure client_id");
+            i64::from_le_bytes(buffer)
+        };
+        self.sequence = 0;
+        self.last_msg_id = 0;
+        self.pending_ack.clear();
+        self.msg_count = 0;
+    }
 }
 
 #[cfg(test)]

lib/grammers-mtproto/src/mtp/mod.rs

@@ -320,6 +320,9 @@ pub trait Mtp {
 
     /// Deserializes a single incoming message payload into zero or more responses.
     fn deserialize(&mut self, payload: &[u8]) -> Result<Deserialization, DeserializeError>;
+
+    /// Reset the state, as if a new instance was just created.
+    fn reset(&mut self);
 }
 
 #[cfg(test)]

lib/grammers-mtproto/src/mtp/plain.rs

@@ -113,6 +113,10 @@ impl Mtp for Plain {
             updates: Vec::new(),
         })
     }
+
+    fn reset(&mut self) {
+        self.buffer.clear();
+    }
 }
 
 #[cfg(test)]

lib/grammers-mtproto/src/transport/abridged.rs

@@ -97,6 +97,10 @@ impl Transport for Abridged {
         output.put(&input[header_len..header_len + len]);
         Ok(header_len + len)
     }
+
+    fn reset(&mut self) {
+        self.init = false;
+    }
 }
 
 #[cfg(test)]

lib/grammers-mtproto/src/transport/full.rs

@@ -115,6 +115,11 @@ impl Transport for Full {
         output.extend_from_slice(&input[8..len - 4]);
         Ok(len)
     }
+
+    fn reset(&mut self) {
+        self.recv_seq = 0;
+        self.send_seq = 0;
+    }
 }
 
 #[cfg(test)]

lib/grammers-mtproto/src/transport/intermediate.rs

@@ -66,6 +66,10 @@ impl Transport for Intermediate {
 
         Ok(len + 4)
     }
+
+    fn reset(&mut self) {
+        self.init = false;
+    }
 }
 
 #[cfg(test)]

lib/grammers-mtproto/src/transport/mod.rs

@@ -75,4 +75,7 @@ pub trait Transport {
     ///
     /// If successful, returns how many bytes of `input` were used.
     fn unpack(&mut self, input: &[u8], output: &mut BytesMut) -> Result<usize, Error>;
+
+    /// Reset the state, as if a new instance was just created.
+    fn reset(&mut self);
 }