On 02/23/2016 04:59 PM, Grant Edwards wrote:
> On 2016-02-23, Lambrecht Jürgen <j.lambre...@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
Tel: +32 (0)51 303045 Fax: +32 (0)51 310670
http://www.televic-rail.com
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