Centroid.EU Blog

(this blog is mostly encrypted - adults only)

Hackepedia back online

October 27th, 2009

Hackepedia is back online after about a month of downtime.

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Someone asked if round-robin'ing was possible in wildcarddnsd. The feature was there once so there was still stub-code but it didn't work. I cleaned that up today and it seems to work. It makes wildcarddnsd a bit slower because the zones have to be written after every lookup, but otherwise NS, A and AAAA records do a wildcard round-robin now.

It's not in the repo HEAD yet but if you check out the ROUNDROBIN branch the code is added on to BETA_2.

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Thanks OpenBSD

October 25th, 2009

Theo de Raadt added my name to the list of people who do donations on their donations page. The list is quite large by now, and I always wondered why I wasn't added before. It turns out that if your donations accumulate to a certain amount (100 dollars CA or so) they put your name on the list. This is nice, it's a nice self-endorsement and it shows my passion for OpenBSD.

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OpenBSD 4.6 released

October 19th, 2009

OpenBSD 4.6 was released yesterday. I'm gonna have fun with this.

I just made a 15 euro bank donation to OpenBSD (which is 23 canadian dollars). I'm doing this in lieu of buying the CD's, but I'm looking forward to perhaps getting 4.8 on CD next year.

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2 letter .de domains

October 17th, 2009

On October 23rd starting at 9AM CEST, DENIC will open registrations for two letter .de domains. Other than saving bandwidth and being rare there is nothing special about 2 letter .de domains. There is 676 of them if you exclude numbers. Here is the story (in german) about this at heise.de.

Joker.com has pre-registrations on the 19th of October.

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No Hackepedia this week (again)

October 16th, 2009

The header says it all.

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Sphere.C

October 6th, 2009

Yesterday I came across some formulas which I haven't used in more than a decade and I made a program out of them, here is what the input and output looks like:

setebos$ ./sphere 1737 # moon         
Sphere with radius of 1737.000000
AREA   = 37914863.86
VOLUME = 21952706175.03
setebos$ ./sphere 3396 # mars         
Sphere with radius of 3396.000000
AREA   = 144925640.08
VOLUME = 164055824574.20
setebos$ ./sphere 71492 # jupiter     
Sphere with radius of 71492.000000
AREA   = 64228053049.52
VOLUME = 1530597322872156.00

And here is the source code including the formula for area and volume of a sphere:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int
main(int argc, char *argv[])
{
        double volume, radius;
        double area;

        if (argc != 2) {
                fprintf(stderr, "usage: ./sphere [radius]\n");
                exit(1);
        }

        radius = atof(argv[1]);

        volume = (4 * M_PI * (pow(radius, 3))) / 3;
        area = 4 * M_PI * (pow(radius, 2));

        printf("Sphere with radius of %f\n", radius);
        printf("AREA   = %.2f\n", area);
        printf("VOLUME = %.2f\n", volume);

        exit(0);
}

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Compiling and debugging a program

October 6th, 2009

Occasionally I'll post a small C program on this blog. This is how you can compile it on a UNIX-based computer. Also I add the (-g) compile option which includes the symbols in the file to make debugging easier. I'm using this on the program sphere.c which is below, here goes:


setebos$ ls sphere.c
sphere.c
setebos$ cc -g -o sphere sphere.c
/tmp//ccnSRGuU.o(.text+0x66): In function `main':
/usr/home/pjp/src/math/sphere.c:18: undefined reference to `pow'
/tmp//ccnSRGuU.o(.text+0x93):/usr/home/pjp/src/math/sphere.c:19: undefined reference to `pow'
collect2: ld returned 1 exit status
setebos$ cc -g -o sphere sphere.c -lm
setebos$ gdb -silent ./sphere
(gdb) list
2       #include <stdlib.h>
3       #include <math.h>
4
5       int
6       main(int argc, char *argv[])
7       {
8               double volume, radius;
9               double area;
10
11              if (argc != 2) {
(gdb) just press enter here
12                      fprintf(stderr, "usage: ./sphere [radius]\n");
13                      exit(1);
14              }
15
16              radius = atof(argv[1]);
17
18              volume = (4 * M_PI * (pow(radius, 3))) / 3;
19              area = 4 * M_PI * (pow(radius, 2));
20
21              printf("Sphere with radius of %f\n", radius);
(gdb) break 17
Breakpoint 1 at 0x1c0007df: file sphere.c, line 17.
(gdb) run 10
Starting program: /usr/home/pjp/src/math/sphere 10

Breakpoint 1, main (argc=2, argv=0xcfbfb9bc) at sphere.c:18
18              volume = (4 * M_PI * (pow(radius, 3))) / 3;
(gdb) print radius
$1 = 10
(gdb) n
19              area = 4 * M_PI * (pow(radius, 2));
(gdb) print volume
$2 = 4188.7902047863909
(gdb) n
21              printf("Sphere with radius of %f\n", radius);
(gdb) print area
$3 = 1256.6370614359173
(gdb) continue
Continuing.
Sphere with radius of 10.000000
AREA   = 1256.64
VOLUME = 4188.79

Program exited normally.
(gdb) quit
setebos$

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Alphabetical Countup

September 28th, 2009

Someone on IRC needed a program that counts the alphabetical characters in words and adds their value. So the value of A would be 1, the value of B would be 2 and "AB" would be 3 (1 + 2). I wrote this program for him:

#include <stdio.h>
#include <ctype.h>

int
main(int argc, char *argv[])
{
        int i;
        char *p;

        if (argc != 2) {
                fprintf(stderr, "usage: name [name]\n");
                exit(1);
        }
        p = argv[1];
        i = 0;
        while (*p) {
                i += (tolower(*p) - 'a') + 1;
                p++;
        }
        printf("the number of name %s is %d\n", argv[1], i);
        exit(0);
}

With counting up names and words one can see which ones are similar in value. Here are some examples:

Peter J. Philipp - Bermuda T. Triangle
Peter - daemonic, Titan, Zion, Yahoo, angelical
pbug - Pete, hacker, airhead, Bobby
centroid - demihuman, demonlike
solarscale - equinox, bridgekeeper, clockroom

I made a file called num2words.txt on the public download that has 234,000 words or so sorted to their respective alphabetic countup. The processing time it took on my home computer was roughly 2 hours. Because I didn't make the program efficient it took this long.

Here is a super quick awk statement that makes creating the wordlist super fast:

awk 'BEGIN { for (i = 65; i < 91; ++i) { c = sprintf("%c", i);  h[c] = \
h[tolower(c)] =  i - 64 } } { tot = 0; for (i = 1; i <= length(); ++i) \
tot += h[substr($0, i, 1)]; print tot, $0 }' /usr/share/dict/words | \
sort -n

Thanks goes to Figz for making this.

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