Re: [ECOS] Re: Does FreeBSD stack support multiple IP addresses?

["Lambrecht Jürgen" <J.Lambrecht@TELEVIC.com>]

On 02/23/2016 04:59 PM, Grant Edwards wrote:
> On 2016-02-23, Lambrecht Jürgen <J.Lambrecht@TELEVIC.com> wrote:
>> On 02/22/2016 04:05 PM, Grant Edwards wrote:
>>> When I tried it, the SIOCAIFADDR ioctl() let me set both address and
>>> netmask in a single call.  The "case SIOCAIFADDR" code falls through
>>> into SIOCSIFNETMASK code.  That didn't work for you?
>> Indeed, I remember now that I saw that in the code, but then you have
>> the netmask according to the class A/B/C rules, and that is not what we
>> want.
>>
>>>> - It is only possible to assign a class A/B/C netmask. CIDR netmasks are
>>>>     not possible.
>>> I think that's always been the case for this version of the stack,
>>> hasn't it?
>> Indeed.
> I just re-ran my tests and verified again that I'm able to set the IP
> and netmask in a single call to ioctl(SIOCAIFADDR).  In my tests, I
> tried:
>
>   Address         Netmask
> -----------      --------------
>   11.0.0.104      255.0.0.0
>   11.0.0.104      255.255.0.0
>   11.0.0.104      255.255.255.0
>   11.0.0.104      255.240.0.0
I don't understand how you can do those 3 above. The netmask is 
calculated, and 11.0.0.104 is class A, so the netmask is 255.0.0.0 
(IN_CLASSA_NET).
It is only possible to change the netmask by using the subnetmask, but 
that is ANDed with the netmask, so you can only put bits to 0, not to 1!
See net/bsd_tcpip/current/src/sys/netinet/in.c, in_ifinit(ifp, ia, sin, 
scrub):
     if (IN_CLASSA(i))
         ia->ia_netmask = IN_CLASSA_NET;
     else if (IN_CLASSB(i))
         ia->ia_netmask = IN_CLASSB_NET;
     else
         ia->ia_netmask = IN_CLASSC_NET;
     /*
      * The subnet mask usually includes at least the standard network part,
      * but may may be smaller in the case of supernetting.
      * If it is set, we believe it.
      */
     if (ia->ia_subnetmask == 0) {
         ia->ia_subnetmask = ia->ia_netmask;
         ia->ia_sockmask.sin_addr.s_addr = htonl(ia->ia_subnetmask);
     } else
         ia->ia_netmask &= ia->ia_subnetmask;


OK, now I see it: you use
   SIOCAIFADDR
we use
   SIOCSIFADDR
(from http://sourceware.org/ml/ecos-discuss/2005-08/msg00015.html)

Where did you learn to use SIOCAIFADDR?
Could you send me your application code? (then I can also try it)
Our code is below.

Because, when I read SIOCAIFADDR it still calls in_ifinit (but with ifra 
instead of ifr (sin) and 0 instead of 1 (scrub, but in_ifscrub() is 
called separately) arguments...
So I still don't understand it.
You _do_ use net/bsd_tcpip right?
Or you don't use *'AF_INET'*? (then it does not call in_ifinit())
Maybe in our application, we use SIOCSIFADDR wrong?

>   11.0.0.104      240.0.0.0
>   192.168.222.104 240.0.0.0
>   192.168.222.104 255.0.0.0
>   192.168.222.104 255.240.0.0
>   192.168.222.104 255.255.0.0
>   192.168.222.104 255.255.240.0
>   192.168.222.104 255.255.255.0
>   192.168.222.104 255.255.255.240
>
> In all cases, subsequent calls to show_network_tables() showed the IP
> address and netmask I requested in the ioctl() call and the correct
> corresponding broadcast address.
>
> I'm using an eCos snapshot from 2014.
I update regurarely, I also applied the patch of Bernd for raw sockets 
and other fixes.
But that file bsd_tcpip/current/src/sys/netinet/in.c last change in CVS 
is from 2009.
>
>>>>     I fixed current/src/sys/netinet/in.c for it, but I also adapted
>>>>     the ioctl to combine setting IP address and netmask in 1 call
>>>>     (so I cannot commit it back). Let me know if you want my fix.
> The current SIOCAIFADDR code works fine for me.
>
>> I changed a bit the use of the members of the "inet"-something
>> struct (in the ioctl call) to also use the netmask struct member
>> that is already in it. Because normally, when you call ioctl
>> SIOCSIFNETMASK separately, you specify the netmask in the same
>> struct member where you put the IP address for the SIOCAIFADDR call.
> But the SIOCAIFADDR call as a _separate_ place where you put the
> desired netmask, and AFIACT, that works.
Where? in.c::in_ifinit() as I say above (from the second 
switch-case(SIOCAIFADDR)?
>
>> (I did a fast search in the linux code, but I am not used to that,
>> so I did not find the "Linux way")
>>
>>> I'm confused: based on my experiments and examination of the source
>>> code, it already works that way.
>>>
>> Well, it is both.  Indeed, as you say above, "code falls through
>> into SIOCSIFNETMASK code",
>> but then it sets "the netmask according to the class A/B/C rules",
>> so the netmask is _calculated_, not strictly _set_.  I am completely
>> sure about this, I read that whole code part.  (And my collegues did
>> the experimentation to set a 255.248.0.0 netmask resulting in a
>> 255.255.0.0 mask for 172.24.0.0 which is class B)
> I don't know what to tell you other than "it works fine for
> me". Unless the output from show_network_tables() is wrong...
>
No, I don't think so.
When I changed our SIOCSIFADDR code, I also saw the output of 
show_network_tables() changing.


Here some code how we did the ioctl's (before I changed it).

   set_ip_address(ETH_INTERFACE, IP_ADDRESS);
   set_netmask_address(ETH_INTERFACE, NETMASK_ADDRESS);
   set_broadcast_address(ETH_INTERFACE, BROADCAST_ADDRESS);


TLV_BOOL set_ip_address(const char *interface, const char *ip_address)
{
   int test_sock;
   struct sockaddr_in* addr=NULL;
   struct ifreq ifr;

   test_sock = socket( AF_INET, SOCK_DGRAM, 0 );
   //This can also be another type of socket, see 
http://ecos.sourceware.org/ml/ecos-discuss/2007-10/msg00012.html
   if( test_sock == -1 )
   {
     debug_printf("Cannot obtain IP sock\n");
     return TLV_FALSE;
   }

   memset(&ifr,0,sizeof( struct ifreq ) );
   strncpy(ifr.ifr_name,interface,IFNAMSIZ);
   //Delete old IP address, else there will be 2 IP addresses!
   if( ioctl( test_sock, SIOCGIFADDR, &ifr ) == -1 )
   {
     debug_printf("Cannot obtain IP address of %s: 
%s\n",interface,strerror(errno));
   }
   else
   {
     if( ioctl( test_sock, SIOCDIFADDR, &ifr ) != 0 )
     {
       debug_printf("Cannot suppress old IP for %s: 
%s\n",interface,strerror(errno));
     }
   }

   memset( &ifr, 0, sizeof( struct ifreq ) );
   addr= (struct sockaddr_in *)&(ifr.ifr_addr);
   memset(addr, 0, sizeof( struct sockaddr_in) );
   addr->sin_len=sizeof(struct sockaddr_in);
   addr->sin_family=AF_INET;
   addr->sin_addr.s_addr=inet_addr(ip_address);
   strncpy(ifr.ifr_name,interface,IFNAMSIZ);

   if( ioctl( test_sock, SIOCSIFADDR, &ifr ) != 0 )
   {
     debug_printf("Cannot set IP address of %s to %s: 
%s\n",interface,ip_address,strerror(errno));
     close(test_sock);
     return TLV_FALSE;;
   }
   else
   {
     close(test_sock);
     return TLV_TRUE;
   }
}

TLV_BOOL set_netmask_address(const char* interface,const char * address)
{
  int test_sock=0;
  struct sockaddr_in* addr=NULL;
  struct sockaddr * addrp=NULL;
  struct ifreq ifr;

  memset( &ifr, 0, sizeof( struct ifreq ) );
  addrp = (struct sockaddr *)&(ifr.ifr_addr);
  addr= (struct sockaddr_in *)addrp;
  memset(addr, 0, sizeof( struct sockaddr) );
  addr->sin_len=sizeof(struct sockaddr_in);
  addr->sin_family=AF_INET;
  addr->sin_addr.s_addr=inet_addr(address);

  test_sock = socket( AF_INET, SOCK_DGRAM, 0 );
  if( test_sock == -1 )
  {
   diag_printf("Cannot obtain ip socket:%s",strerror(errno));
   return TLV_FALSE;
  }

  strncpy( ifr.ifr_name,interface,IFNAMSIZ);
  if( ioctl( test_sock, SIOCSIFNETMASK, &ifr ) == -1 )
  {
   diag_printf("Impossible to set netmask of interface '%s' to '%s': 
'%s'",interface,address,strerror(errno));
   close(test_sock);
   return TLV_FALSE;
  }
close(test_sock);
  return TLV_TRUE;
}

TLV_BOOL set_broadcast_address(const char* interface,const char * address)
{
  int test_sock=0;
  struct sockaddr_in* addr=NULL;
  struct sockaddr * addrp=NULL;
  struct ifreq ifr;

  memset( &ifr, 0, sizeof( struct ifreq ) );
  addrp = (struct sockaddr *)&(ifr.ifr_addr);
  addr= (struct sockaddr_in *)addrp;
  memset(addr, 0, sizeof( struct sockaddr) );
  addr->sin_len=sizeof(struct sockaddr_in);
  addr->sin_family=AF_INET;
  addr->sin_addr.s_addr=inet_addr(address);

  test_sock = socket( AF_INET, SOCK_DGRAM, 0 );
  if( test_sock == -1 )
  {
   diag_printf("Cannot obtain ip socket:%s",strerror(errno));
   return TLV_FALSE;
  }

  strncpy( ifr.ifr_name,interface,IFNAMSIZ);
  if( ioctl( test_sock, SIOCSIFBRDADDR, &ifr ) == -1 )
  {
   diag_printf("Impossible to set broadcast of interface '%s' to '%s': 
'%s'",interface,address,strerror(errno));
   close(test_sock);
   return TLV_FALSE;
  }
close(test_sock);
  return TLV_TRUE;
}


Kind regards,
Jürgen

-- 
Jürgen Lambrecht
R&D Associate
Mobile: +32 499 644 531
Twitter: JGRLambrecht
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