relays: generalize gatekeeper resolution

src/syndicate/relays.nim

@@ -27,11 +27,10 @@ type
   Turn = syndicate.Turn
   Handle = actors.Handle
 
-type
-  PacketHandler = proc (buf: seq[byte]) {.gcsafe.}
-  RelaySetup = proc (turn: var Turn; relay: Relay) {.gcsafe.}
+  PacketWriter = proc (turn: var Turn; buf: seq[byte]) {.closure, gcsafe.}
+  RelaySetup = proc (turn: var Turn; relay: Relay) {.closure, gcsafe.}
 
-  Relay* = ref object of RootObj
+  Relay* = ref object
     facet: Facet
     inboundAssertions: Table[Handle,
       tuple[localHandle: Handle, imported: seq[WireSymbol]]]
@@ -40,9 +39,9 @@ type
     imported: Membrane
     nextLocalOid: Oid
     pendingTurn: protocol.Turn
-    packetSender: PacketHandler
     wireBuf: BufferedDecoder
-    untrusted: bool
+    packetWriter: PacketWriter
+    peer: Cap
 
   SyncPeerEntity = ref object of Entity
     relay: Relay
@@ -108,19 +107,18 @@ proc deregister(relay: Relay; h: Handle) =
   if relay.outboundAssertions.pop(h, outbound):
     for e in outbound: releaseCapOut(relay, e)
 
-proc send(r: Relay; turn: var Turn; rOid: protocol.Oid; m: Event) =
-  if r.pendingTurn.len == 0:
+proc send(relay: Relay; turn: var Turn; rOid: protocol.Oid; m: Event) =
+  if relay.pendingTurn.len == 0:
     # If the pending queue is empty then schedule a packet
     # to be sent after pending I/O is processed.
     callSoon do ():
-      r.facet.run do (turn: var Turn):
+      relay.facet.run do (turn: var Turn):
         var pkt = Packet(
           orKind: PacketKind.Turn,
-          turn: move r.pendingTurn)
+          turn: move relay.pendingTurn)
         trace "C: ", pkt
-        assert(not r.packetSender.isNil, "missing packetSender proc")
-        r.packetSender(encode pkt)
-  r.pendingTurn.add TurnEvent(oid: rOid, event: m)
+        relay.packetWriter(turn, encode pkt)
+  relay.pendingTurn.add TurnEvent(oid: rOid, event: m)
 
 proc send(re: RelayEntity; turn: var Turn; ev: Event) =
   send(re.relay, turn, protocol.Oid re.oid, ev)
@@ -252,35 +250,28 @@ proc dispatch(relay: Relay; v: Value) {.gcsafe.} =
       when defined(posix):
         stderr.writeLine("discarding undecoded packet ", v)
 
-proc dispatch(relay: Relay; buf: seq[byte]) =
+proc recv(relay: Relay; buf: seq[byte]) =
   feed(relay.wireBuf, buf)
   var pr = decode(relay.wireBuf)
-  if pr.isSome: dispatch(relay, get pr)
+  if pr.isSome: dispatch(relay, pr.get)
 
 type
   RelayOptions* = object of RootObj
-    untrusted*: bool
+    packetWriter*: PacketWriter
+
   RelayActorOptions* = object of RelayOptions
     initialOid*: Option[Oid]
     initialCap*: Cap
     nextLocalOid*: Option[Oid]
 
-proc newRelay(turn: var Turn; opts: RelayOptions; setup: RelaySetup): Relay =
-  result = Relay(
-    facet: turn.facet,
-    wireBuf: newBufferedDecoder(0),
-    untrusted: opts.untrusted)
-  discard result.facet.preventInertCheck()
-  setup(turn, result)
-
-proc transportConnectionResolve(addrAss: Assertion; ds: Cap): gatekeeper.TransportConnection =
-  result.`addr` = addrAss
-  result.resolved = Resolved(orKind: ResolvedKind.accepted)
-  result.resolved.accepted.responderSession = ds
-
-proc spawnRelay*(name: string; turn: var Turn; ds: Cap; addrAss: Assertion; opts: RelayActorOptions; setup: RelaySetup) =
-  discard spawn(name, turn) do (turn: var Turn):
-    let relay = newRelay(turn, opts, setup)
+proc spawnRelay(name: string; turn: var Turn; opts: RelayActorOptions; setup: RelaySetup) =
+  spawn(name, turn) do (turn: var Turn):
+    let relay = Relay(
+        facet: turn.facet,
+        packetWriter: opts.packetWriter,
+        wireBuf: newBufferedDecoder(0),
+      )
+    discard relay.facet.preventInertCheck()
     if not opts.initialCap.isNil:
       var exported: seq[WireSymbol]
       discard rewriteCapOut(relay, opts.initialCap, exported)
@@ -288,132 +279,241 @@ proc spawnRelay*(name: string; turn: var Turn; ds: Cap; addrAss: Assertion; opts
       relay.nextLocalOid =
         if oid == 0.Oid: 1.Oid
         else: oid
+    assert opts.initialOid.isSome
     if opts.initialOid.isSome:
       var
         imported: seq[WireSymbol]
         wr = WireRef(
           orKind: WireRefKind.mine,
           mine: WireRefMine(oid: opts.initialOid.get))
-        res = rewriteCapIn(relay, turn.facet, wr, imported)
-      discard publish(turn, ds, transportConnectionResolve(addrAss, res))
-    else:
-      discard publish(turn, ds, transportConnectionResolve(addrAss, ds))
+      relay.peer = rewriteCapIn(relay, turn.facet, wr, imported)
+      assert not relay.peer.isNil
+    setup(turn, relay)
+
+proc rejected(detail: Value): Resolved =
+  result = Resolved(orKind: ResolvedKind.Rejected)
+  result.rejected.detail = detail
+
+proc accepted(cap: Cap): Resolved =
+  result = Resolved(orKind: ResolvedKind.accepted)
+  result.accepted.responderSession = cap
 
 when defined(posix):
-  import std/asyncnet
-  from std/nativesockets import AF_INET, AF_UNIX, IPPROTO_TCP, SOCK_STREAM, Protocol
 
-type ShutdownEntity* = ref object of Entity
-
-method retract(e: ShutdownEntity; turn: var Turn; h: Handle) =
-  stopActor(turn)
-
-type ConnectProc* = proc (turn: var Turn; ds: Cap) {.gcsafe.}
-
-export Tcp
-
-when defined(posix):
   import std/asyncfile
   export Unix
 
-  proc newStdioTunnel(facet: Facet; receiver: PacketHandler): PacketHandler =
-    let asyncStdin = openAsync("/dev/stdin") # this is universal now?
-    close(stdin)
-    const readSize = 0x2000
-    proc readCb(fut: Future[string]) {.gcsafe.} =
-      if fut.failed: terminate(facet, fut.error)
-      else:
-        receiver(cast[seq[byte]](fut.read))
-        asyncStdin.read(readSize).addCallback(readCb)
-    asyncStdin.read(readSize).addCallback(readCb)
-    proc sender(buf: seq[byte]) =
-      try:
-        if writeBytes(stdout, buf, 0, buf.len) != buf.len:
-          raise newException(IOError, "failed to write Preserves to stdout")
-        flushFile(stdout)
-      except CatchableError as err:
-        terminate(facet, err)
-    sender
+  type StdioControlEntity = ref object of Entity
+    stdin: AsyncFile
+
+  method message(entity: StdioControlEntity; turn: var Turn; ass: AssertionRef) =
+    if ass.value.preservesTo(ForceDisconnect).isSome:
+      close(entity.stdin)
+      close(stdout)
+
+  proc connectTransport(turn: var Turn; ds: Cap; ta: transportAddress.Stdio) =
+    ## Connect to an external dataspace over stdio.
+    proc stdoutWriter(turn: var Turn; buf: seq[byte]) =
+      ## Blocking write to stdout.
+      let n = writeBytes(stdout, buf, 0, buf.len)
+      flushFile(stdout)
+      if n != buf.len:
+        stopActor(turn)
+    var opts = RelayActorOptions(
+        packetWriter: stdoutWriter,
+        initialCap: ds,
+        initialOid: 0.Oid.some,
+      )
+    spawnRelay("stdio", turn, opts) do (turn: var Turn; relay: Relay):
+      let
+        facet = turn.facet
+        asyncStdin = openAsync("/dev/stdin") # this is universal now?
+      publish(turn, ds, TransportConnection(
+          `addr`: ta.toPreserves,
+          control: StdioControlEntity(stdin: asyncStdin).newCap(turn),
+          resolved: relay.peer.accepted,
+        ))
+      const stdinReadSize = 0x2000
+      proc readCb(pktFut: Future[string]) {.gcsafe.} =
+        if not pktFut.failed:
+          var buf = pktFut.read
+          if buf.len == 0:
+            run(facet) do (turn: var Turn): stopActor(turn)
+          else:
+            relay.recv(cast[seq[byte]](buf))
+            asyncStdin.read(stdinReadSize).addCallback(readCb)
+      asyncStdin.read(stdinReadSize).addCallback(readCb)
 
   proc connectStdio*(turn: var Turn; ds: Cap) =
     ## Connect to an external dataspace over stdin and stdout.
-    var opts = RelayActorOptions(
-      initialCap: ds,
-      initialOid: 0.Oid.some)
-    spawnRelay("stdio", turn, ds, Stdio().toPreserves, opts) do (turn: var Turn; relay: Relay):
-      proc receiver(buf: seq[byte]) = dispatch(relay, buf)
-      relay.packetSender = newStdioTunnel(turn.facet, receiver)
+    connectTransport(turn, ds, transportAddress.Stdio())
 
-  proc newTunnel(facet: Facet; receiver: PacketHandler; socket: AsyncSocket): PacketHandler =
-    const recvSize = 0x2000
-    proc recvCb(fut: Future[string]) {.gcsafe.} =
-      if fut.failed: terminate(facet, fut.error)
-      else:
-        receiver(cast[seq[byte]](fut.read))
-        if not socket.isClosed:
-          socket.recv(recvSize).addCallback(recvCb)
-    socket.recv(recvSize).addCallback(recvCb)
-    proc sender(buf: seq[byte]) =
-      asyncCheck(facet, socket.send(cast[string](buf)))
-    sender
+  import std/asyncnet
+  from std/nativesockets import AF_INET, AF_UNIX, IPPROTO_TCP, SOCK_STREAM, Protocol
 
-  proc connect*(turn: var Turn; ds: Cap; route: Route; addrAss: Assertion; socket: AsyncSocket; steps: seq[Value]) =
-    ## Relay a dataspace over an open `AsyncSocket`.
-    var shutdownCap: Cap
-    let
-      reenable = turn.facet.preventInertCheck()
-      connectionClosedCap = newCap(turn, ShutdownEntity())
-    discard bootActor("socket") do (turn: var Turn):
-      var ops = RelayActorOptions(
-        initialOid: 0.Oid.some)
-      spawnRelay("socket", turn, ds, addrAss, ops) do (turn: var Turn; relay: Relay):
-        let facet = turn.facet
-        proc receiver(buf: seq[byte]) = dispatch(relay, buf)
-        relay.packetSender = newTunnel(turn.facet, receiver, socket)
-        turn.facet.actor.atExit do (turn: var Turn): close(socket)
-        discard publish(turn, connectionClosedCap, true)
-        shutdownCap = newCap(turn, ShutdownEntity())
-      onPublish(turn, ds, TransportConnection ?: {0: ?addrAss, 2: ?:Rejected}) do (detail: Value):
-        raise newException(IOError, $detail)
-      onPublish(turn, ds, TransportConnection ?: {0: ?addrAss, 2: ?:ResolvedAccepted}) do (gatekeeper: Cap):
-        run(gatekeeper.relay) do (turn: var Turn):
-          reenable()
-          discard publish(turn, shutdownCap, true)
-          proc duringCallback(turn: var Turn; ass: Assertion; h: Handle): TurnAction =
-            let facet = inFacet(turn) do (turn: var Turn):
-              let o = ass.preservesTo Resolved; if o.isSome:
-                discard publish(turn, ds, ResolvePath(
-                  route: route, `addr`: addrAss, resolved: o.get))
-            proc action(turn: var Turn) =
-              stop(turn, facet)
-            result = action
-          var resolve = Resolve(
-              step: steps[0],
-              observer: newCap(turn, during(duringCallback)),
+  type SocketControlEntity = ref object of Entity
+    socket: AsyncSocket
+
+  method message(entity: SocketControlEntity; turn: var Turn; ass: AssertionRef) =
+    if ass.value.preservesTo(ForceDisconnect).isSome:
+      close(entity.socket)
+
+  type ShutdownEntity* = ref object of Entity
+  method retract(e: ShutdownEntity; turn: var Turn; h: Handle) =
+    stopActor(turn)
+
+  proc connect(turn: var Turn; ds: Cap; transAddr: Value; socket: AsyncSocket) =
+    proc socketWriter(turn: var Turn; buf: seq[byte]) =
+      asyncCheck(turn, socket.send(cast[string](buf)))
+    var ops = RelayActorOptions(
+        packetWriter: socketWriter,
+        initialOid: 0.Oid.some,
+      )
+    spawnRelay("socket", turn, ops) do (turn: var Turn; relay: Relay):
+      let facet = turn.facet
+      facet.actor.atExit do (turn: var Turn): close(socket)
+      publish(turn, ds, TransportConnection(
+          `addr`: transAddr,
+          control: SocketControlEntity(socket: socket).newCap(turn),
+          resolved: relay.peer.accepted,
+        ))
+      const recvSize = 0x4000
+      proc recvCb(pktFut: Future[string]) {.gcsafe.} =
+        if pktFut.failed or pktFut.read.len == 0:
+          run(facet) do (turn: var Turn): stopActor(turn)
+        else:
+          relay.recv(cast[seq[byte]](pktFut.read))
+          if not socket.isClosed:
+            socket.recv(recvSize).addCallback(recvCb)
+      socket.recv(recvSize).addCallback(recvCb)
+
+  proc connect(turn: var Turn; ds: Cap; ta: Value; socket: AsyncSocket; fut: Future[void]) =
+    let facet = turn.facet
+    fut.addCallback do ():
+      run(facet) do (turn: var Turn):
+        if fut.failed:
+          var ass = TransportConnection(
+              `addr`: ta,
+              resolved: Resolved(orKind: ResolvedKind.Rejected),
             )
-          discard publish(turn, gatekeeper, resolve)
+          ass.resolved.rejected.detail = embed fut.error
+          publish(turn, ds, ass)
+        else:
+          connect(turn, ds, ta, socket)
 
-  proc connect*(turn: var Turn; ds: Cap; route: Route; transport: Tcp; steps: seq[Value]) =
-    ## Relay a dataspace over TCP.
-    let socket = newAsyncSocket(
-      domain = AF_INET,
-      sockType = SOCK_STREAM,
-      protocol = IPPROTO_TCP,
-      buffered = false)
-    let fut = connect(socket, transport.host, Port transport.port)
-    addCallback(fut, turn) do (turn: var Turn):
-      connect(turn, ds, route, transport.toPreserves, socket, steps)
+  proc connectTransport(turn: var Turn; ds: Cap; ta: transportAddress.Tcp) =
+    let
+      facet = turn.facet
+      socket = newAsyncSocket(
+          domain = AF_INET,
+          sockType = SOCK_STREAM,
+          protocol = IPPROTO_TCP,
+          buffered = false,
+        )
+    connect(turn, ds, ta.toPreserves, socket, connect(socket, ta.host, Port ta.port))
 
-  proc connect*(turn: var Turn; ds: Cap; route: Route; transport: Unix; steps: seq[Value]) =
+  proc connectTransport(turn: var Turn; ds: Cap; ta: transportAddress.Unix) =
     ## Relay a dataspace over a UNIX socket.
     let socket = newAsyncSocket(
       domain = AF_UNIX,
       sockType = SOCK_STREAM,
       protocol = cast[Protocol](0),
       buffered = false)
-    let fut = connectUnix(socket, transport.path)
-    addCallback(fut, turn) do (turn: var Turn):
-      connect(turn, ds, route, transport.toPreserves, socket, steps)
+    connect(turn, ds, ta.toPreserves, socket, connectUnix(socket, ta.path))
+
+proc walk(turn: var Turn; ds, origin: Cap; route: Route; transOff, stepOff: int) {.gcsafe.} =
+  if stepOff < route.pathSteps.len:
+    let
+      step = route.pathSteps[stepOff]
+      rejectPat = ResolvedPathStep?:{
+          0: ?(origin.embed), 1: ?step, 2: ?:Rejected}
+      acceptPat = ResolvedPathStep?:{
+          0: ?(origin.embed), 1: ?step, 2: ?:ResolvedAccepted}
+    onPublish(turn, ds, rejectPat) do (detail: Value):
+      publish(turn, ds, ResolvePath(
+          route: route,
+          `addr`: route.transports[transOff],
+          resolved: detail.rejected,
+        ))
+    during(turn, ds, acceptPat) do (next: Cap):
+      walk(turn, ds, next, route, transOff, stepOff.succ)
+  else:
+    publish(turn, ds, ResolvePath(
+        route: route,
+        `addr`: route.transports[transOff],
+        resolved: origin.accepted,
+      ))
+
+proc connectRoute(turn: var Turn; ds: Cap; route: Route; transOff: int) =
+  let rejectPat = TransportConnection ?: {
+      0: ?route.transports[transOff],
+      2: ?:Rejected,
+    }
+  during(turn, ds, rejectPat) do (detail: Value):
+    publish(turn, ds, ResolvePath(
+        route: route,
+        `addr`: route.transports[transOff],
+        resolved: detail.rejected,
+      ))
+  let acceptPat = TransportConnection?:{
+      0: ?route.transports[transOff],
+      2: ?:ResolvedAccepted,
+    }
+  onPublish(turn, ds, acceptPat) do (origin: Cap):
+    walk(turn, ds, origin, route, transOff, 0)
+
+type StepCallback = proc (turn: var Turn; step: Value; origin, next: Cap) {.gcsafe.}
+
+proc spawnStepResolver(turn: var Turn; ds: Cap; stepType: Value; cb: StepCallback) =
+  spawn($stepType & "-step", turn) do (turn: var Turn):
+    let stepPat = grabRecord(stepType, grab())
+    let pat = ?Observe(pattern: ResolvedPathStep?:{1: stepPat}) ?? {0: grabLit(), 1: grab()}
+    during(turn, ds, pat) do (origin: Cap; stepDetail: Literal[Value]):
+      let step = toRecord(stepType, stepDetail.value)
+      proc duringCallback(turn: var Turn; ass: Value; h: Handle): TurnAction =
+        var res = ass.preservesTo Resolved
+        if res.isSome:
+          if res.get.orKind == ResolvedKind.accepted and
+              res.get.accepted.responderSession of Cap:
+            cb(turn, step, origin, res.get.accepted.responderSession.Cap)
+        else:
+          publish(turn, ds, ResolvedPathStep(
+              origin: origin, pathStep: step, resolved: res.get))
+        proc action(turn: var Turn) =
+          stop(turn)
+        result = action
+      publish(turn, origin, Resolve(
+          step: step, observer: newCap(turn, during(duringCallback))))
+
+proc spawnRelays*(turn: var Turn; ds: Cap) =
+  ## Spawn actors that manage routes and appeasing gatekeepers.
+  spawn("transport-connector", turn) do (turn: var Turn):
+    let pat = ?Observe(pattern: !TransportConnection) ?? { 0: grab() }
+      # Use a generic pattern and type matching
+      # in the during handler because it is easy.
+
+    let stdioPat = ?Observe(pattern: TransportConnection?:{0: ?:Stdio})
+    during(turn, ds, stdioPat) do:
+      connectTransport(turn, ds, Stdio())
+
+    # TODO: tcp pattern
+    during(turn, ds, pat) do (ta: Literal[transportAddress.Tcp]):
+      connectTransport(turn, ds, ta.value)
+
+    # TODO: unix pattern
+    during(turn, ds, pat) do (ta: Literal[transportAddress.Unix]):
+      connectTransport(turn, ds, ta.value)
+
+  spawn("path-resolver", turn) do (turn: var Turn):
+    let pat = ?Observe(pattern: !ResolvePath) ?? {0: grab()}
+    during(turn, ds, pat) do (route: Literal[Route]):
+      for i, transAddr in route.value.transports:
+        connectRoute(turn, ds, route.value, i)
+
+  spawnStepResolver(turn, ds, "ref".toSymbol) do (
+      turn: var Turn, step: Value, origin: Cap, next: Cap):
+    publish(turn, ds, ResolvedPathStep(
+        origin: origin, pathStep: step, resolved: next.accepted))
 
 type BootProc* = proc (turn: var Turn; ds: Cap) {.gcsafe.}
 
@@ -429,21 +529,7 @@ proc envRoute*: Route =
       raise newException(ValueError, "failed to parse $SYNDICATE_ROUTE " & $pr)
 
 proc resolve*(turn: var Turn; ds: Cap; route: Route; bootProc: BootProc) =
-  var
-    unix: Unix
-    tcp: Tcp
-    stdio: Stdio
-  doAssert(route.transports.len == 1, "only a single transport supported for routes")
-  if unix.fromPreserves route.transports[0]:
-    connect(turn, ds, route, unix, route.pathSteps)
-  elif tcp.fromPreserves route.transports[0]:
-    connect(turn, ds, route, tcp, route.pathSteps)
-  elif stdio.fromPreserves route.transports[0]:
-    doAssert(route.pathSteps.len == 0, "route steps not available over stdio")
-    connectStdio(turn, ds)
-    bootProc(turn, ds)
-  else:
-    raise newException(ValueError, "unsupported route")
+  during(turn, ds, ResolvePath ?: {0: ?route, 3: ?:ResolvedAccepted}) do (dst: Cap):
+    bootProc(turn, dst)
 
-  during(turn, ds, ResolvePath ?: { 0: ?route, 3: ?:ResolvedAccepted}) do (dest: Cap):
-    bootProc(turn, dest)
+# TODO: define a runActor that comes preloaded with relaying

syndicate.nimble

@@ -1,6 +1,6 @@
 # Package
 
-version = "20240119"
+version = "20240120"
 author        = "Emery Hemingway"
 description   = "Syndicated actors for conversational concurrency"
 license       = "Unlicense"

tests/test_chat.nim

@@ -1,7 +1,7 @@
 # SPDX-FileCopyrightText: ☭ Emery Hemingway
 # SPDX-License-Identifier: Unlicense
 
-import std/[asyncdispatch, asyncfile, os, parseopt]
+import std/[asyncdispatch, asyncfile, parseopt]
 import preserves, syndicate, syndicate/relays
 
 type
@@ -49,6 +49,7 @@ proc main =
       stderr.writeLine "--user: unspecified"
   else:
     runActor("chat") do (turn: var Turn; root: Cap):
+      spawnRelays(turn, root)
       resolve(turn, root, route) do (turn: var Turn; ds: Cap):
         chat(turn, ds, username)