Refactor dialer and upgrade

libp2p/dialer.nim

@@ -47,52 +47,87 @@ type
     transports: seq[Transport]
     nameResolver: NameResolver
 
-proc dialAndUpgrade(
+proc tryDial(
+  peerId: Opt[PeerId],
+  hostname: string,
+  address: MultiAddress,
+  transport: Transport):
+  Future[Connection] {.async.} =
+  trace "Dialing address", address, peerId, hostname
+  result =
+    try:
+      libp2p_total_dial_attempts.inc()
+      await transport.dial(hostname, address)
+    except CancelledError as exc:
+      debug "Dialing canceled", msg = exc.msg, peerId
+      raise exc
+    except CatchableError as exc:
+      debug "Dialing failed", msg = exc.msg, peerId
+      libp2p_failed_dials.inc()
+      raise exc
+
+proc tryUpgrade(
+  peerId: Opt[PeerId],
+  hostname: string,
+  transport: Transport,
+  conn: Connection):
+  Future[Connection] {.async.} =
+  result =
+    try:
+      await transport.upgradeOutgoing(conn, peerId)
+    except CatchableError as exc:
+      # If we failed to upgrade the connection through one transport,
+      # we won't succeeded through another - no use in trying again
+      await conn.close()
+      debug "Upgrade failed", msg = exc.msg, peerId
+      if exc isnot CancelledError:
+        libp2p_failed_upgrades_outgoing.inc()
+      raise exc
+
+proc tryDialAndUpgrade(
+  peerId: Opt[PeerId],
+  hostname: string,
+  address: MultiAddress,
+  transport: Transport):
+  Future[Connection] {.async.} =
+
+  if transport.handles(address):   # check if it can dial it
+    let conn = await tryDial(peerId, hostname, address, transport)
+    # also keep track of the connection's bottom unsafe transport direction
+    # required by gossipsub scoring
+    conn.transportDir = Direction.Out
+    libp2p_successful_dials.inc()
+    let upgradedConn = await tryUpgrade(peerId, hostname, transport, conn)
+    doAssert not isNil(upgradedConn), "connection died after upgradeOutgoing"
+    debug "Dial successful", upgradedConn, peerId = upgradedConn.peerId
+    return upgradedConn
+  raise newException(DialFailedError, "Transport does not handle the address")
+
+proc tryDialAndUpgrade(
+  peerId: Opt[PeerId],
+  hostname: string,
+  address: MultiAddress,
+  transports: seq[Transport]):
+  Future[Connection] {.async.} =
+  for transport in transports:
+    try:
+      return await tryDialAndUpgrade(peerId, hostname, address, transport)
+    except CatchableError:
+      continue
+  raise newException(DialFailedError, "No transport succeeded")
+
+proc tryDialAndUpgrade(
   self: Dialer,
   peerId: Opt[PeerId],
   hostname: string,
-  address: MultiAddress):
+  addresses: seq[MultiAddress]):
   Future[Connection] {.async.} =
-
-  for transport in self.transports: # for each transport
-    if transport.handles(address):   # check if it can dial it
-      trace "Dialing address", address, peerId, hostname
-      let dialed =
-        try:
-          libp2p_total_dial_attempts.inc()
-          await transport.dial(hostname, address)
-        except CancelledError as exc:
-          debug "Dialing canceled", msg = exc.msg, peerId
-          raise exc
-        except CatchableError as exc:
-          debug "Dialing failed", msg = exc.msg, peerId
-          libp2p_failed_dials.inc()
-          return nil # Try the next address
-
-      # also keep track of the connection's bottom unsafe transport direction
-      # required by gossipsub scoring
-      dialed.transportDir = Direction.Out
-
-      libp2p_successful_dials.inc()
-
-      let conn =
-        try:
-          await transport.upgradeOutgoing(dialed, peerId)
-        except CatchableError as exc:
-          # If we failed to establish the connection through one transport,
-          # we won't succeeded through another - no use in trying again
-          await dialed.close()
-          debug "Upgrade failed", msg = exc.msg, peerId
-          if exc isnot CancelledError:
-            libp2p_failed_upgrades_outgoing.inc()
-
-          # Try other address
-          return nil
-
-      doAssert not isNil(conn), "connection died after upgradeOutgoing"
-      debug "Dial successful", conn, peerId = conn.peerId
-      return conn
-  return nil
+  for address in addresses:
+    try:
+      return await tryDialAndUpgrade(peerId, hostname, address, self.transports)
+    except CatchableError:
+      continue
+  raise newException(DialFailedError, "No address succeeded")
 
 proc expandDnsAddr(
   self: Dialer,
@@ -141,11 +176,10 @@ proc dialAndUpgrade(
         resolvedAddresses =
           if isNil(self.nameResolver): @[expandedAddress]
           else: await self.nameResolver.resolveMAddress(expandedAddress)
-
-      for resolvedAddress in resolvedAddresses:
-        result = await self.dialAndUpgrade(addrPeerId, hostname, resolvedAddress)
-        if not isNil(result):
-          return result
+      try:
+        return await self.tryDialAndUpgrade(addrPeerId, hostname, resolvedAddresses)
+      except CatchableError:
+        continue
 
 proc internalConnect(
   self: Dialer,