[lwip-users] netconn_accept

[Sirjee Rooplall]

Hi,

 

I am using LWIP version 1.3.2, ATMEL UC3A port with freeRTOS.

 

I have to develop an application that acts as a server listening for a connection from a client.

 

Each of the clients is setup to connect to the server using the exact port number.

 

Example:

Client1 -> Connects to 192.168.0.1 port=1234

Client2 -> Connects to 192.168.0.1 port=1234

Client3 -> Connects to 192.168.0.1 port=1234

 

Under freeRTOS I have created 3 Tasks, each of the Tasks, bind and listen for a connection on port 1234.

 

Here is my problem.

 

When Task 1 is created it binds and listens to accept a connection from port 1234 using netconn_accept, this works fine.

But when Task 2 and 3 are created to listen to the same port, netconn_accept returns an error:

 

LWIP_ERROR("netconn_accept: invalid acceptmbox", (conn->acceptmbox != SYS_MBOX_NULL), return NULL;);

 

How do I resolve this problem.

 

Kind regards 

Sirjee. Rooplall

(Software Engineer)

 

 

 

 

 

 

 

 

[gold...@gmx.de]

Sirjee Rooplall wrote:

Under freeRTOS I have created 3 Tasks, each of the Tasks, bind and listen for a connection on port 1234.

That's not a problem in netconn_accept(): netconn_bind() will have returned an error before, as only one netconn (or pcb or socket, that doesn't depend on the API used or even the IP stack used) can bind to a port at a time. That's because TCP connections have to be uniquely identified by local address+port, remote address+port; a listening pcb does not have remote address+port and can thus cannot be uniquely identified if there's a second listening connection on the same port.

You'd have to create one central accepting thread that passes incoming connections to other threads to solve this.

Simon