add exception handlers to transaction exchange code

nimbus/sync/handlers.nim

@@ -67,24 +67,38 @@ proc addToKnownByPeer(ctx: EthWireRef, txHashes: openArray[Hash256], peer: Peer,
 proc sendNewTxHashes(ctx: EthWireRef,
                      txHashes: seq[Hash256],
                      peers: seq[Peer]): Future[void] {.async.} =
-  for peer in peers:
-    # Add to known tx hashes and get hashes still to send to peer
-    var hashesToSend: seq[Hash256]
-    ctx.addToKnownByPeer(txHashes, peer, hashesToSend)
+  try:
 
-    # Broadcast to peer if at least 1 new tx hash to announce
-    if hashesToSend.len > 0:
-      await peer.newPooledTransactionHashes(hashesToSend)
+    for peer in peers:
+      # Add to known tx hashes and get hashes still to send to peer
+      var hashesToSend: seq[Hash256]
+      ctx.addToKnownByPeer(txHashes, peer, hashesToSend)
+
+      # Broadcast to peer if at least 1 new tx hash to announce
+      if hashesToSend.len > 0:
+        await peer.newPooledTransactionHashes(hashesToSend)
+
+  except TransportError:
+    debug "Transport got closed during sendNewTxHashes"
+  except CatchableError as e:
+    debug "Exception in sendNewTxHashes", exc = e.name, err = e.msg
 
 proc sendTransactions(ctx: EthWireRef,
                       txHashes: seq[Hash256],
                       txs: seq[Transaction],
                       peers: seq[Peer]): Future[void] {.async.} =
-  for peer in peers:
-    # This is used to avoid re-sending along pooledTxHashes
-    # announcements/re-broadcasts
-    ctx.addToKnownByPeer(txHashes, peer)
-    await peer.transactions(txs)
+  try:
+
+    for peer in peers:
+      # This is used to avoid re-sending along pooledTxHashes
+      # announcements/re-broadcasts
+      ctx.addToKnownByPeer(txHashes, peer)
+      await peer.transactions(txs)
+
+  except TransportError:
+    debug "Transport got closed during sendTransactions"
+  except CatchableError as e:
+    debug "Exception in sendTransactions", exc = e.name, err = e.msg
 
 proc inPool(ctx: EthWireRef, txHash: Hash256): bool =
   let res = ctx.txPool.getItem(txHash)
@@ -292,21 +306,30 @@ proc fetchTransactions(ctx: EthWireRef, reqHashes: seq[Hash256], peer: Peer): Fu
   debug "fetchTx: requesting txs",
     number = reqHashes.len
 
-  let res = await peer.getPooledTransactions(reqHashes)
-  if res.isNone:
-    error "not able to get pooled transactions"
+  try:
+
+    let res = await peer.getPooledTransactions(reqHashes)
+    if res.isNone:
+      error "not able to get pooled transactions"
+      return
+
+    let txs = res.get()
+    debug "fetchTx: received requested txs",
+      number = txs.transactions.len
+
+    # Remove from pending list regardless if tx is in result
+    for tx in txs.transactions:
+      let txHash = rlpHash(tx)
+      ctx.pending.excl txHash
+
+    ctx.txPool.jobAddTxs(txs.transactions)
+
+  except TransportError:
+    debug "Transport got closed during fetchTransactions"
+    return
+  except CatchableError as e:
+    debug "Exception in fetchTransactions", exc = e.name, err = e.msg
     return
-
-  let txs = res.get()
-  debug "fetchTx: received requested txs",
-    number = txs.transactions.len
-
-  # Remove from pending list regardless if tx is in result
-  for tx in txs.transactions:
-    let txHash = rlpHash(tx)
-    ctx.pending.excl txHash
-
-  ctx.txPool.jobAddTxs(txs.transactions)
 
   var newTxHashes = newSeqOfCap[Hash256](reqHashes.len)
   for txHash in reqHashes:
@@ -314,7 +337,7 @@ proc fetchTransactions(ctx: EthWireRef, reqHashes: seq[Hash256], peer: Peer): Fu
       newTxHashes.add txHash
 
   let peers = ctx.getPeers(peer)
-  if peers.len == 0:
+  if peers.len == 0 or newTxHashes.len == 0:
     return
 
   await ctx.sendNewTxHashes(newTxHashes, peers)