Async httpclient should now work. Changed recv behaviour.

asyncdispatch.recv no longer guarantees that it will read ALL the data
requested. The underlying WinAPI function doesn't guarantee this and it
already wasn't guaranteed anyway since the socket could disconnect
mid-transmission.

lib/pure/asyncdispatch.nim

@@ -328,11 +328,18 @@ when defined(windows) or defined(nimdoc):
 
   proc recv*(socket: TAsyncFD, size: int,
              flags: int = 0): PFuture[string] =
-    ## Reads ``size`` bytes from ``socket``. Returned future will complete once
-    ## all of the requested data is read. If socket is disconnected during the
-    ## recv operation then the future may complete with only a part of the
-    ## requested data read. If socket is disconnected and no data is available
-    ## to be read then the future will complete with a value of ``""``.
+    ## Reads **up to** ``size`` bytes from ``socket``. Returned future will
+    ## complete once all the data requested is read, a part of the data has been
+    ## read, or the socket has disconnected in which case the future will
+    ## complete with a value of ``""`.
+
+
+    # Things to note:
+    #   * When WSARecv completes immediately then ``bytesReceived`` is very
+    #     unreliable.
+    #   * Still need to implement message-oriented socket disconnection,
+    #     '\0' in the message currently signifies a socket disconnect. Who
+    #     knows what will happen when someone sends that to our socket.
     verifyPresence(socket)
     var retFuture = newFuture[string]()
     
@@ -350,8 +357,8 @@ when defined(windows) or defined(nimdoc):
             if bytesCount == 0 and dataBuf.buf[0] == '\0':
               retFuture.complete("")
             else:
-              var data = newString(size)
-              copyMem(addr data[0], addr dataBuf.buf[0], size)
+              var data = newString(bytesCount)
+              copyMem(addr data[0], addr dataBuf.buf[0], bytesCount)
               retFuture.complete($data)
           else:
             retFuture.fail(newException(EOS, osErrorMsg(errcode)))
@@ -378,8 +385,15 @@ when defined(windows) or defined(nimdoc):
       # ~ http://msdn.microsoft.com/en-us/library/ms741688%28v=vs.85%29.aspx
     else:
       # Request to read completed immediately.
-      var data = newString(size)
-      copyMem(addr data[0], addr dataBuf.buf[0], size)
+      # From my tests bytesReceived isn't reliable.
+      let realSize =
+        if bytesReceived == 0:
+          size
+        else:
+          bytesReceived
+      assert dataBuf.buf[0] != '\0'
+      var data = newString(realSize)
+      copyMem(addr data[0], addr dataBuf.buf[0], realSize)
       retFuture.complete($data)
       # We don't deallocate ``ol`` here because even though this completed
       # immediately poll will still be notified about its completion and it will
@@ -646,8 +660,7 @@ else:
     
     proc cb(sock: TAsyncFD): bool =
       result = true
-      let netSize = size - sizeRead
-      let res = recv(sock.TSocketHandle, addr readBuffer[sizeRead], netSize,
+      let res = recv(sock.TSocketHandle, addr readBuffer[0], size,
                      flags.cint)
       #echo("recv cb res: ", res)
       if res < 0:
@@ -659,17 +672,9 @@ else:
       elif res == 0:
         #echo("Disconnected recv: ", sizeRead)
         # Disconnected
-        if sizeRead == 0:
-          retFuture.complete("")
-        else:
-          readBuffer.setLen(sizeRead)
-          retFuture.complete(readBuffer)
+        retFuture.complete("")
       else:
-        sizeRead.inc(res)
-        if res != netSize:
-          result = false # We want to read all the data requested.
-        else:
-          retFuture.complete(readBuffer)
+        retFuture.complete(readBuffer)
       #echo("Recv cb result: ", result)
   
     addRead(socket, cb)