[ECOS] tftp server:re-use of loop iterator in nested loop when CYGSEM_NET_TFTPD_MULTITHREADED=1

[ECOS] tftp server:re-use of loop iterator in nested loop when CYGSEM_NET_TFTPD_MULTITHREADED=1

[Jürgen Lambrecht]

Hello,

We were looking at the code 
ecos/packages/net/common/current/src/tftp_server.c.
(ecos 3.x)
In the function 'tftpd_server(cyg_addrword_t p)', lines 647-668, the 
iterator 'i' is used in 2 nested for loops:

     for (i=0; i < CYGNUM_NET_MAX_INET_PROTOS; i++) {
       if (server->s[i] && FD_ISSET(server->s[i],&readfds)) {
         recv_len = sizeof(data);
         from_len = sizeof(from_addr);
         data_len = recvfrom(server->s[i], hdr, recv_len, 0,
&from_addr, &from_len);
         if ( data_len < 0) {
           diag_printf("TFTPD [%x]: can't read request\n", p);
         } else {
#ifdef CYGSEM_NET_TFTPD_MULTITHREADED
           // Close the socket and post on the semaphore some
           // another thread can start listening for requests. This
           // is not quite right. select could of returned with more than
           // one socket with data to read. Here we only deal with one 
of them
           for (i=0; i < CYGNUM_NET_MAX_INET_PROTOS; i++) {
             if (server->s[i]) {
               close (server->s[i]);
               server->s[i] = 0;
             }
           }
           sem_post(server->port);
#endif

At first sight, I would say this is a bug, or am I wrong?

Kind regards,
Jürgen

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Jürgen Lambrecht
R&D Associate
Tel: +32 (0)51 303045    Fax: +32 (0)51 310670
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Re: [ECOS] tftp server:re-use of loop iterator in nested loop when CYGSEM_NET_TFTPD_MULTITHREADED=1

[Andrew Lunn]

On Tue, Mar 22, 2011 at 02:05:19PM +0100, J?rgen Lambrecht wrote:
> Hello,
> 
> We were looking at the code
> ecos/packages/net/common/current/src/tftp_server.c.
> (ecos 3.x)
> In the function 'tftpd_server(cyg_addrword_t p)', lines 647-668, the
> iterator 'i' is used in 2 nested for loops:
> 
>     for (i=0; i < CYGNUM_NET_MAX_INET_PROTOS; i++) {
>       if (server->s[i] && FD_ISSET(server->s[i],&readfds)) {
>         recv_len = sizeof(data);
>         from_len = sizeof(from_addr);
>         data_len = recvfrom(server->s[i], hdr, recv_len, 0,
> &from_addr, &from_len);
>         if ( data_len < 0) {
>           diag_printf("TFTPD [%x]: can't read request\n", p);
>         } else {
> #ifdef CYGSEM_NET_TFTPD_MULTITHREADED
>           // Close the socket and post on the semaphore some
>           // another thread can start listening for requests. This
>           // is not quite right. select could of returned with more than
>           // one socket with data to read. Here we only deal with
> one of them
>           for (i=0; i < CYGNUM_NET_MAX_INET_PROTOS; i++) {
>             if (server->s[i]) {
>               close (server->s[i]);
>               server->s[i] = 0;
>             }
>           }
>           sem_post(server->port);
> #endif
> 
> At first sight, I would say this is a bug, or am I wrong?

Hi Joergen

Yes, it looks like a bug, and it is probably i bug i introduced when i
added IPv6 support. I think just changing the inner loop to j should
fix any problems.

    Andrew

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