LwIP netconn API is thread safety, I think. I have many waiting UDP / TCP
connections in separated thread and without problem.
Do you have this sample "echo server" from
http://cvs.savannah.gnu.org/viewvc/contrib/apps/udpecho/udpecho.c?revision=1.7&root=lwip&view=markup
This example required a quite big stack size ( cca > 4200 Bytes for each task )
by my mind.
Do you have sufficient stack size ?
Martin Persich
----- Original Message -----
From: Robert Braatz
To: [email protected]
Sent: Tuesday, April 13, 2010 9:53 PM
Subject: [lwip-users] multithread netconn / udp echo on two differentthreads
and ports
I have a general question about the thread safety for the actual lwip version
(download from cvs 9.4.2010).
Is the netconn API thread safe or have the same problems as socket api?
I create two tasks – each runs an udp echo server on an own netconn struct
with different ports listening.
If I send udp packets to only one port I get the correct feedback – if I send
packets to both ports I get the correct feedback from the higher prior thread
but the lower prior thread does
sometimes not answer.
Code for echo:
static struct netconn *conn;
static struct netbuf *buf;
static ip_addr_t *addr;
static ip_addr_t destip;
static unsigned short port;
static char buffer[4096];
static err_t ret;
netconn init:
conn = netconn_new(NETCONN_UDP);
netconn_bind(conn, NULL, 7001); // 7002 for thread 2
endless thread loop:
netconn_recv(conn,&buf);
addr = netbuf_fromaddr(buf);
destip = *addr;
port = netbuf_fromport(buf);
netbuf_copy(buf, buffer, buf->p->tot_len);
buffer[buf->p->tot_len] = '\0'; // Do something
with – e.g. print the test string
ret=netconn_sendto(conn,buf,&destip,port);
netbuf_delete(buf);
Second problem: If I use addr instead of copying the ip to destip and call
netconn_sendto(conn,buf,addr,port); I only catch an gratuitous arp packet
with my on ip on wireshark
Same problems if I connect and use netconn_send instead the above code:
netconn_recv(conn,&buf);
addr = netbuf_fromaddr(buf);
port = netbuf_fromport(buf);
ret=netconn_connect(conn, addr, port);
netbuf_copy(buf, buffer, buf->p->tot_len);
buffer[buf->p->tot_len] = '\0';
netconn_send(conn, buf);
netbuf_delete(buf);
here helps:
netconn_recv(conn,&buf);
addr = netbuf_fromaddr(buf);
destip = *addr;
port = netbuf_fromport(buf);
ret=netconn_connect(conn, &destip, port);
netbuf_copy(buf, buffer, buf->p->tot_len);
buffer[buf->p->tot_len] = '\0';
buf->addr=&destip;
buf->port=port;
netconn_send(conn, buf);
netbuf_delete(buf);
Many thanks for help
Robert
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