asyncnet: don't try to close the socket again [backport]

lib/pure/asyncnet.nim

@@ -713,8 +713,12 @@ elif defined(nimdoc):
 
 proc close*(socket: AsyncSocket) =
   ## Closes the socket.
+  if socket.closed: return
+
   defer:
     socket.fd.AsyncFD.closeSocket()
+    socket.closed = true # TODO: Add extra debugging checks for this.
+
   when defineSsl:
     if socket.isSsl:
       let res =
@@ -731,7 +735,6 @@ proc close*(socket: AsyncSocket) =
         discard
       elif res != 1:
         raiseSSLError()
-  socket.closed = true # TODO: Add extra debugging checks for this.
 
 when defineSsl:
   proc wrapSocket*(ctx: SslContext, socket: AsyncSocket) =
@@ -819,9 +822,9 @@ proc sendTo*(socket: AsyncSocket, address: string, port: Port, data: string,
   ## address or a hostname. If a hostname is specified this function will try
   ## each IP of that hostname. The returned future will complete once all data
   ## has been sent.
-  ## 
+  ##
   ## If an error occurs an OSError exception will be raised.
-  ## 
+  ##
   ## This proc is normally used with connectionless sockets (UDP sockets).
   assert(socket.protocol != IPPROTO_TCP,
          "Cannot `sendTo` on a TCP socket. Use `send` instead")
@@ -834,22 +837,22 @@ proc sendTo*(socket: AsyncSocket, address: string, port: Port, data: string,
     it = aiList
     success = false
     lastException: ref Exception
-  
+
   while it != nil:
     let fut = sendTo(socket.fd.AsyncFD, cstring(data), len(data), it.ai_addr,
                      it.ai_addrlen.SockLen, flags)
-    
+
     yield fut
 
     if not fut.failed:
       success = true
 
       break
-    
+
     lastException = fut.readError()
 
     it = it.ai_next
-  
+
   freeaddrinfo(aiList)
 
   if not success:
@@ -869,24 +872,24 @@ proc recvFrom*(socket: AsyncSocket, data: FutureVar[string], size: int,
   ## packet received.
   ##
   ## If an error occurs an OSError exception will be raised.
-  ## 
+  ##
   ## This proc is normally used with connectionless sockets (UDP sockets).
-  ## 
+  ##
   ## **Notes**
   ## * ``data`` must be initialized to the length of ``size``.
   ## * ``address`` must be initialized to 46 in length.
   template adaptRecvFromToDomain(domain: Domain) =
     var lAddr = sizeof(sAddr).SockLen
-    
+
     result = await recvFromInto(AsyncFD(getFd(socket)), cstring(data.mget()), size,
                                 cast[ptr SockAddr](addr sAddr), addr lAddr,
                                 flags)
-    
+
     data.mget().setLen(result)
     data.complete()
 
     getAddrString(cast[ptr SockAddr](addr sAddr), address.mget())
-    
+
     address.complete()
 
     when domain == AF_INET6:
@@ -901,7 +904,7 @@ proc recvFrom*(socket: AsyncSocket, data: FutureVar[string], size: int,
          "`date` was not initialized correctly. `size` != `len(data.mget())`")
   assert(46 == len(address.mget()),
          "`address` was not initialized correctly. 46 != `len(address.mget())`")
-  
+
   case socket.domain
   of AF_INET6:
     var sAddr: Sockaddr_in6
@@ -920,18 +923,18 @@ proc recvFrom*(socket: AsyncSocket, size: int,
   ## ``size``. Returned future will complete once one datagram has been received
   ## and will return tuple with: data of packet received; and address and port
   ## of datagram's sender.
-  ## 
+  ##
   ## If an error occurs an OSError exception will be raised.
-  ## 
+  ##
   ## This proc is normally used with connectionless sockets (UDP sockets).
   var
     data = newFutureVar[string]()
     address = newFutureVar[string]()
     port = newFutureVar[Port]()
-  
+
   data.mget().setLen(size)
   address.mget().setLen(46)
-  
+
   let read = await recvFrom(socket, data, size, address, port, flags)
 
   result = (data.mget(), address.mget(), port.mget())