From 66973aed3ff5cc28cb85523755d2d37f69064157 Mon Sep 17 00:00:00 2001
From: cheatfate <ka@hardcore.kiev.ua>
Date: Thu, 22 Nov 2018 16:12:46 +0200
Subject: [PATCH] Simple chat.

---
 examples/chat.nim               | 81 +++++++++++++++++++++++++++++++++
 libp2p/protobuf/minprotobuf.nim |  7 +--
 2 files changed, 85 insertions(+), 3 deletions(-)
 create mode 100644 examples/chat.nim

diff --git a/examples/chat.nim b/examples/chat.nim
new file mode 100644
index 000000000..b79a21f5b
--- /dev/null
+++ b/examples/chat.nim
@@ -0,0 +1,81 @@
+import asyncdispatch2, nimcrypto, strutils
+import ../libp2p/daemon/daemonapi
+
+const
+  ConsoleAddress = "/tmp/console-chat.sock"
+  ServerAddress = "/tmp/remote-chat.sock"
+  ServerProtocols = @["/test-chat-stream"]
+
+type
+  CustomData = ref object
+    api: DaemonAPI
+    remotes: seq[StreamTransport]
+
+proc threadMain(a: int) {.thread.} =
+  ## This procedure performs reading from `stdin` and sends data over
+  ## unix domain socket to main thread.
+  var transp = waitFor connect(initTAddress(ConsoleAddress))
+
+  while true:
+    var line = stdin.readLine()
+    let res = waitFor transp.write(line & "\r\n")
+
+proc serveThread(server: StreamServer,
+                 transp: StreamTransport) {.async.} =
+  ## This procedure perform readin on local unix domain socket and
+  ## sends data to remote clients.
+  var udata = getUserData[CustomData](server)
+  while true:
+    try:
+      var line = await transp.readLine()
+      if line.startsWith("/connect"):
+        var parts = line.split(" ")
+        if len(parts) == 2:
+          var address = fromHex(parts[1])
+          echo "= Searching for peer ", toHex(address)
+          var id = await udata.api.dhtFindPeer(address)
+          echo "= Connecting to peer ", toHex(address)
+          await udata.api.connect(id.peer, id.addresses)
+          echo "= Opening stream to peer chat ", toHex(address)
+          var stream = await udata.api.openStream(id.peer, ServerProtocols)
+          udata.remotes.add(transp)
+          echo "= Connected to peer chat ", toHex(address)
+      else:
+        var msg = line & "\r\n"
+        echo "<< ", msg
+        var pending = newSeq[Future[int]]()
+        for item in udata.remotes:
+          pending.add(item.write(msg))
+        if len(pending) > 0:
+          var results = await all(pending)
+    except:
+      break
+
+proc main() {.async.} =
+  var data = new CustomData
+  data.remotes = newSeq[StreamTransport]()
+
+  var lserver = createStreamServer(initTAddress(ConsoleAddress),
+                                   serveThread, udata = data)
+  lserver.start()
+  var thread: Thread[int]
+  thread.createThread(threadMain, 0)
+
+  echo "= Starting P2P node"
+  data.api = await newDaemonApi({DHTFull})
+  await sleepAsync(1000)
+  var id = await data.api.identity()
+
+  proc streamHandler(api: DaemonAPI, stream: P2PStream) {.async.} =
+    echo "= Peer ", toHex(stream.peer), " joined chat"
+    while true:
+      var line = await stream.transp.readLine()
+      echo ">> ", line
+
+  await data.api.addHandler(ServerProtocols, streamHandler)
+  echo "= Your PeerID is ", toHex(id.peer)
+  
+when isMainModule:
+  waitFor(main())
+  while true:
+    poll()
diff --git a/libp2p/protobuf/minprotobuf.nim b/libp2p/protobuf/minprotobuf.nim
index feaf1a75a..14d008df4 100644
--- a/libp2p/protobuf/minprotobuf.nim
+++ b/libp2p/protobuf/minprotobuf.nim
@@ -167,9 +167,10 @@ proc write*(pb: var ProtoBuffer, field: ProtoField) =
     assert(res == VarintStatus.Success)
     pb.offset += length
     assert(pb.isEnough(len(field.vbuffer)))
-    copyMem(addr pb.buffer[pb.offset], unsafeAddr field.vbuffer[0],
-            len(field.vbuffer))
-    pb.offset += len(field.vbuffer)
+    if len(field.vbuffer) > 0:
+      copyMem(addr pb.buffer[pb.offset], unsafeAddr field.vbuffer[0],
+              len(field.vbuffer))
+      pb.offset += len(field.vbuffer)
   else:
     discard