peril vs perl

[14:21] do you have your peril sensitive sunglasses?
[14:21] (and your towel?)
[14:26] damn. I only brought my perl sensitive sunglasses.

amazingly difficult to find 'getting a MAC address from a interface?' answer.

I was trying to convert a piece of network software to FreeBSD. Unfortunately, even though the author quotes
"should compile on any POSIX like OS," it doesn't (POSIX != LINUX). It should be obvious, when they drop things like:

  if (ioctl (sock, SIOCGIFADDR, &ifr) < 0)

throughout the code.

So the above is from a section of code trying to obtain the MAC address on a interface. Doing this task
on FreeBSD can be done through ioctl(), but is discouraged by the developers. They encourage you to use getifaddrs().

This strange and wonderful function grabs all sorts of information from the interface list, however, a couple of things
are not obvious about it's use. If you really want to play arround with IF_LINK type addresses on the interfaces returned
you need to be using sockaddr_dl not just sockaddr. Overloading sockaddr with magic casting is the new pink these days and
thats what's required. It confused me at first since the manpage has:

         struct ifaddrs   *ifa_next;         /* Pointer to next struct */
         char             *ifa_name;         /* Interface name */
         u_int             ifa_flags;        /* Interface flags */
         struct sockaddr  *ifa_addr;         /* Interface address */
         struct sockaddr  *ifa_netmask;      /* Interface netmask */
         struct sockaddr  *ifa_broadaddr;    /* Interface broadcast address */
         struct sockaddr  *ifa_dstaddr;      /* P2P interface destination */
         void             *ifa_data;         /* Address specific data */

for the structure.. same with /usr/include/ifaddrs.h. It turns out copying sa_data of sa_len from your friendly
struct sockaddr does not give your the ethernet address from ifa_addr. :( :( :( :(.

Too make a long story short:

/* getmac.c -- retrieve the mac address from a interface name */
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <net/if_dl.h>
#include <ifaddrs.h>

int main(int argc, char ** argv)
{
    struct ifaddrs   *ifaphead;
    unsigned char *   if_mac;
    int               found = 0;
    struct ifaddrs   *ifap;
    struct sockaddr_dl *sdl = NULL;

    if (argc < 2)
    {
        fprintf(stderr,"usage:\n");
        fprintf(stderr,"\t %s <interface name>\n",argv[0]);
        exit(1);
    }

    if (getifaddrs(&ifaphead) != 0)
    {
        perror("get_if_name: getifaddrs() failed");
        exit(1);
    }

    for (ifap = ifaphead; ifap && !found; ifap = ifap->ifa_next)
    {
        if ((ifap->ifa_addr->sa_family == AF_LINK))
        {
            if (strlen(ifap->ifa_name) == strlen(argv[1]))
                if (strcmp(ifap->ifa_name,argv[1]) == 0)
                {
                    found = 1;
                    sdl = (struct sockaddr_dl *)ifap->ifa_addr;
                    if (sdl)
                    {
                        /* I was returning this from a function before converting
                         * this snippet, which is why I make a copy here on the heap */
                        if_mac = malloc(sdl->sdl_alen);
                        memcpy(if_mac, LLADDR(sdl), sdl->sdl_alen);
                    }
                }
        }
    }
    if (!found)
    {
        fprintf (stderr,"Can't find interface %s.\n",argv[1]);
        if(ifaphead)
            freeifaddrs(ifaphead);
        exit(1);
    }

    fprintf (stdout, "%02X%02X%02X%02X%02X%02X\n",
        if_mac[0] , if_mac[1] , if_mac[2] ,
        if_mac[3] , if_mac[4] , if_mac[5] );

    if(ifaphead)
        freeifaddrs(ifaphead);
        
    exit(0);
}

command line new tabs in konqueror

The following is a simple shell script using the KDE dcop client to open new tabs in konqueror (or a new instance of konqueror if it's not running). I use this from pine's url-viewers setting to launch new tabs with a url contained in a email.

#!/bin/sh

KONQ_WIN=`dcop konq* | head -1`

if [ "$KONQ_WIN" = "" ]; then
    /usr/local/bin/konqueror $1 &
else
    NEW_TAB=`dcop $KONQ_WIN konqueror-mainwindow#1 action newtab`
    dcop $NEW_TAB activate
    dcop $KONQ_WIN konqueror-mainwindow#1 openURL $1
fi
return 0

fun with MSI, ACPI, and freebsd.

Last two weeks I had been working on and off on a problem related to ACPI and some 1u servers using MSI-9618 motherboards. After booting freebsd, I couldn't get the second NIC to work at all, it turns out after looking at 'vmstat -i' that em0 and em1 where sharing an interrupt:

# vmstat -i
interrupt                          total       rate
irq3: sio1                      52807402         55
irq4: sio0                          1604          0
irq14: ata0                           36          0
irq16: em0 em1+                  2527378          2
irq19: uhci1+                      86991          0
cpu0: timer                   1886077214       2000
cpu1: timer                   1886076861       2000
Total                         3827577486       4058

From past experience I knew this was from poor resource assignment from the BIOS when ACPI isn't enabled. So I built and installed the acpi.ko modules and installed it. These are webware 1185s from pogolinux. The chassis manual that comes with it labels them as P1-103 series and a part number as MS-9218 1U rackmounts.

Then when I booted, right after it should be switching to multi-user, it appeared to hang. I enabled ALT_BREAK_TO_DEBUGER in the kernel and tried again, except the keycode for break to debugger did nothing. I posted about the hang on the freebsd-acpi list with no response. Then out of hand I tried sshing to the box... it worked! So it wasn't really hung, just the serial console was unresponsive.

Now looking closer at the dmesg I realized the resources for sio0 and sio1 were wrong! sio0 was getting 0x2F8 and sio1 was getting 0x3F8 when it should be the other way around. I rechecked the BIOS settings, everything was ok. I downloaded a new BIOS from the MSI taiwan site that stated the fix was for 'redhat 4' installs. That didn't work.

I posted to freebsd-acpi again with what I knew. This time I got a reply and after some back and forth, I generated a new .asl file that would probe sio0 and sio1 in the correct order! Now all my interrupts are assigned correctly:

[root@pogo-1 ~]# vmstat -i
interrupt                          total       rate
irq1: atkbd0                           6          0
irq3: sio1                      13587145         55
irq4: sio0                          1243          0
irq14: ata0                           36          0
irq16: em0 uhci3                    3237          0
irq17: em1                            21          0
irq19: uhci1+                      66550          0
cpu0: timer                    485520843       2000
cpu1: timer                    485520575       2000
Total                          984699656       4056

And everything seems to be working great, although my post's problem according to the resulting discussion on freebsd-acpi seems to be more common than imagined!

http compression

One of the things I also use regularly at work is wget. In order to work on compression I needed a tool that would recursively spider a web site and had the appropriate features, but would also support compression. At the time, nothing out there supported this, so a year ago or so I finished a patch to wget to add compression.

You can check out the latest version of wget using the subversion repository outlined here. Apply this patch from the top directory and as long as your OS has zlib support, then you should be able to use the '-z' switch this patch adds to request compressed files from a webserver.

wget-zlib-04202006.patch

Here's an example how a 39K download turns into a 10K download with compression, and downloads in half the time.

$ ./wget http://172.16.17.1/index.html
--13:22:32--  http://172.16.17.1/index.html
Connecting to 172.16.17.1:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 39599 (39K) [text/html]
Saving to: `index.html'

100%[=======================================>] 39,599      --.-K/s   in 0.005s

13:22:32 (8.39 MB/s) - `index.html' saved [39599/39599]

$ ./wget -z http://172.16.17.1/index.html
--13:22:39--  http://172.16.17.1/index.html
Connecting to 172.16.17.1:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 10546 (10K) [text/html]
Saving to: `index.html.1'

100%[=======================================>] 10,546      --.-K/s   in 0.002s

13:22:39 (5.62 MB/s) - `index.html.1' saved [10546/10546]

$ diff index.html index.html.1
$ echo $?
0

lighttpd

In my job, I deal with a lot of tcp traffic, esp http, and ipv6.

For awhile I've been using both bozohttpd and Apache.
I used bozohttpd because it's simple, light weight, command line driven and easy to hack on. The big win for bozohttpd was the fact you could drop it into inetd and let inetd take care of the ipv6 compliance side. However, bozohttpd is lacking in several useful features and in many cases is missing some standards compliancy -- so in those cases I used Apache. Everyone here tests with Apache, but I absolutely despise Apache's convoluted "do everything" configuration and setup. It can take me hours to remember, research and setup even simple changes (esp if it requires a missing module!). Compiling Apache can be a royal PITA... Basically, it's too flexible.

Recently I've taken a liking to lighttpd. It's very fast, easily configurable, and restricted enough in it's feature set to allow easy module configuration. It only has one problem. You could use it for ipv6 and not ipv4 or vice versa. Common mistake really, people never take the time and effort to use sock storage structure and properly do a dual stack server, they try to 'hack' their ipv4 server into v6 with #ifdefs, etc. Bad bad bad. I digress.

Adjusting lighttpd to work on v4 and v6 in the same process was easy. Easy that is if you're using freebsd.

sysctl net.inet6.ip6.v6only=0

Then set up lighttpd to serve v6 addressing, and you're set. This basically enables v4 compat ipv6 addressing like ::ffff:172.16.17.1, so all their #ifdef'd ipv6 only code still chomps on the numbers just fine and listening on :: still gets you v4 traffic.

scripting up some tabs in kde's konsole app

[root@moby bin]$ cat bipcons.sh
#!/bin/sh

SESSIONS="
d44
co-04
c62-29
co-02
co-05
d84-1
d84-2
"

KONSOLE=`dcopclient $KONSOLE_DCOP`
CURSESSION=$KONSOLE_DCOP_SESSION
for A in $SESSIONS; do
NEWSESSION=`dcop $KONSOLE konsole newSession $A`
dcop $KONSOLE $NEWSESSION renameSession $A
# your command here on the next line!
dcop $KONSOLE $NEWSESSION sendSession "console $A"
done
dcop $CURSESSION closeSession

The above shell script I have saved to a icon on my kde desktop. The icon properties run this in the command section:

/usr/local/bin/konsole --script -e ~/bin/bipcons.sh

Basically it opens a new tab for each entry in $SESSIONS, assigns the tab name to that entry ($A) and then runs a command on that entry as well. In this example, the remote console app (http://www.conserver.com). Of course that app could be anything, like ssh.

Very useful stuff. Took me a long time to dig up this information on the web, so I'm posting it here for posterity.