After asking some questions on this forum, I felt it was time to contribute a little.

I am running lwIP on FreeRTOS and was building an application that should block on a combination of FreeRTOS queues and lwIP sockets. After realizing that the lwIP socket-api is based on FreeRTOS queues, I came up with the following.

xQueueHandle lwip_GetAcceptQ(int s)
// Add these functions to the end of lwIP's sockets.c
{
// Get FreeRTOS handle of accept queue
    xQueueHandle xQueue = NULL;
struct lwip_sock *sock;
    
sock = tryget_socket(s);
if((sock != NULL) && (sock->conn != NULL))
    {
xQueue = sock->conn->acceptmbox;
}
    
    return(xQueue);
}

xQueueHandle lwip_GetRecvQ(int s)
{
// Get FreeRTOS handle of receive queue
    xQueueHandle xQueue = NULL;
struct lwip_sock *sock;
    
sock = tryget_socket(s);
if((sock != NULL) && (sock->conn != NULL))
    {
xQueue = sock->conn->recvmbox;
}
    
    return(xQueue);
}

int lwip_DataInRecvQ(int s)
{
// Return 1 (TRUE)  if there is data in the socket receive pbuf(s),
    //        0 (FALSE) otherwise
    int iReturn = 0;
struct lwip_sock *sock;
    
sock = tryget_socket(s);
if((sock != NULL) && (sock->conn != NULL))
{
iReturn = (sock->lastdata != NULL);
}
    
    return(iReturn);
}

These functions return the queue handles that are (exclusively) used by lwIP for the given socket. Having the queue-id, one can simply add it to a queue set.

One note: use the lwip_DataInRecvQ(s) function to check is there is data available in the local socket buffers. This data must be read before attempting to block on the socket receive queue.

(tidied up a little. Is there no preview on the forum? Or an edit button?)

// Add these functions to the end of lwIP's sockets.c

xQueueHandle lwip_GetAcceptQ(int s)
{
    // Get FreeRTOS handle of accept queue
    xQueueHandle xQueue = NULL;
    struct lwip_sock *sock;
    
    sock = tryget_socket(s);
    if((sock != NULL) && (sock->conn != NULL))
    {
        xQueue = sock->conn->acceptmbox;
    }
    
    return(xQueue);
}

xQueueHandle lwip_GetRecvQ(int s)
{
    // Get FreeRTOS handle of receive queue
    xQueueHandle xQueue = NULL;
    struct lwip_sock *sock;
    
    sock = tryget_socket(s);
    if((sock != NULL) && (sock->conn != NULL))
    {
        xQueue = sock->conn->recvmbox;
    }
    
    return(xQueue);
}

int lwip_DataInRecvQ(int s)
{
    // Return 1 (TRUE)  if there is data in the socket receive pbuf(s),
    //        0 (FALSE) otherwise
    int iReturn = 0;
    struct lwip_sock *sock;
    
    sock = tryget_socket(s);
    if((sock != NULL) && (sock->conn != NULL))
    {
        iReturn = (sock->lastdata != NULL);
    }
    
    return(iReturn);
}

Thanks for the input.

Unfortunately there is no edit button!

Regards.

“Thanks for the input.”

Well, it was a long time ago since I wrote the pic18/wizC port. Now I'm all into PIC32.