Support extracting timestamps from blocks

substrate/client/src/serai/mod.rs

@@ -1,6 +1,6 @@
 use thiserror::Error;
 
-use scale::{Encode, Decode};
+use scale::{Encode, Decode, Compact};
 mod scale_value;
 pub(crate) use scale_value::{Value, Composite, scale_value, scale_composite};
 
@@ -59,6 +59,14 @@ impl SubxtConfig for SeraiConfig {
 #[derive(Debug)]
 pub struct Block(ChainBlock<SeraiConfig>);
 impl Block {
+  fn new(block: ChainBlock<SeraiConfig>) -> Result<Block, SeraiError> {
+    for extrinsic in &block.extrinsics {
+      if extrinsic.0.len() < 3 {
+        Err(SeraiError::InvalidNode)?;
+      }
+    }
+    Ok(Block(block))
+  }
   pub fn hash(&self) -> [u8; 32] {
     self.0.header.hash().into()
   }
@@ -66,6 +74,32 @@ impl Block {
     self.0.header.number
   }
 
+  /// Returns the time of this block, set by its producer, as a unix timestamp.
+  pub fn time(&self) -> Result<u64, SeraiError> {
+    for extrinsic in &self.0.extrinsics {
+      // Inherent/unsigned
+      let inherent = (extrinsic.0[0] >> 7) == 0;
+
+      // To timestamp pallet
+      use serai_runtime::Timestamp;
+      let timestamp =
+        extrinsic.0[1] == u8::try_from(PalletInfo::index::<Timestamp>().unwrap()).unwrap();
+
+      // set call
+      let set = extrinsic.0[2] == 0;
+
+      if inherent && timestamp && set {
+        if extrinsic.0.len() < 4 {
+          Err(SeraiError::InvalidNode)?;
+        }
+        return Ok(
+          Compact::<u64>::decode(&mut &extrinsic.0[3 ..]).map_err(|_| SeraiError::InvalidNode)?.0,
+        );
+      }
+    }
+    Err(SeraiError::InvalidNode)
+  }
+
   pub fn header(&self) -> &Header {
     &self.0.header
   }
@@ -146,7 +180,7 @@ impl Serai {
   }
 
   pub async fn get_latest_block(&self) -> Result<Block, SeraiError> {
-    Ok(Block(
+    Block::new(
       self
         .0
         .rpc()
@@ -155,7 +189,7 @@ impl Serai {
         .map_err(SeraiError::RpcError)?
         .ok_or(SeraiError::InvalidNode)?
         .block,
-    ))
+    )
   }
 
   // There is no provided method for this
@@ -207,7 +241,7 @@ impl Serai {
       return Ok(None);
     }
 
-    Ok(Some(Block(res.block)))
+    Ok(Some(Block::new(res.block)?))
   }
 
   // Ideally, this would be get_block_hash, not get_block_by_number

substrate/client/tests/time.rs

@@ -0,0 +1,31 @@
+use std::time::{Duration, SystemTime};
+
+use tokio::time::sleep;
+
+use serai_client::Serai;
+
+mod common;
+use common::serai;
+
+serai_test!(
+  async fn time() {
+    let serai = serai().await;
+
+    let mut number = serai.get_latest_block().await.unwrap().number();
+    let mut done = 0;
+    while done < 3 {
+      // Wait for the next block
+      let block = serai.get_latest_block().await.unwrap();
+      if block.number() == number {
+        sleep(Duration::from_secs(1)).await;
+        continue;
+      }
+      number = block.number();
+
+      // Make sure the time we extract from the block is within 5 seconds of now
+      let now = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap().as_secs();
+      assert!(now.saturating_sub(block.time().unwrap()) < 5);
+      done += 1;
+    }
+  }
+);