blog.darkstar.work - a simple url encoder/decoder

 a simple url encoder/decoder
 http://blog.darkstar.work

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2022-11-29

flex - fast lexical analyzer generator sample

Who remember flex: fast lexical analyzer generator?

Here is a short sample, I have written it under gnu linux and ported it to win32 using gnuwin32 flex and getoptwin:

%option noyywrap

%{
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "getopt.h"
#include <string.h> 
#define MAXLEN 1024

int i, j, idx, len, mode = 0;
char tmps[MAXLEN], reverse[MAXLEN];

%}
SEGA  [2][5][0-5]
SEGB  [2][0-4][0-9]
SEGC  [1][0-9]{2}
SEGD  [1-9][0-9]{0,1}
SEG   {SEGA}|{SEGB}|{SEGC}|{SEGD}
IP    {SEG}["."]{SEG}["."]{SEG}["."]{SEG}

HOSTDOMAINSEGMENT [0-9a-zA-Z_"\-"]+["."]
TOPLEVELDOMAIN [a-zA-Z]{2,7}
HOSTNAME {HOSTDOMAINSEGMENT}+{TOPLEVELDOMAIN}
USER [0-9A-Za-z_"\-""."]+

EMAIL1 {USER}"@"{HOSTNAME}
EMAIL2 {USER}"@"{IP}

URIPROTOCOL [a-zA-Z]{2,10}"://"
URISUFFIX [^ \t\n\r"@"","">""<""("")""{""}"]
URL1   {URIPROTOCOL}{HOSTNAME}{URISUFFIX}*
URL2   {URIPROTOCOL}{IP}{URISUFFIX}*

%%
<<EOF>> {
        exit(1);
    }

{EMAIL1} |
{EMAIL2} {
        if (strchr(yytext, '@') != (char *)NULL) 
        {
    switch((mode % 16)) 
    {
case 0: strcpy(tmps, yytext); break;
case 1: strcpy(tmps, strchr(yytext, (int)'@')); break;
case 2: strcpy(tmps, &strchr(yytext, (int)'@')[1]); break;
     case 4: 
strcpy(tmps, &strchr(yytext, (int)'@')[1]);
len = strlen(tmps); 
for (j = 0, idx = 0; ((j < len) && (j < MAXLEN-1)); j++) 
{
                            if (tmps[j] == '.'
                            {
                                for (i = idx; i <= j; 
                                    reverse[(len-j) + (i-idx)] = tmps[i++]);
                                idx = j + 1;
                            }
}
for (i = idx; i <= j; 
                            reverse[(len-j) + (i-idx)] = (i < len) ? tmps[i] : '.', i++);
reverse[len + 1] = '\0';
strcpy(tmps, reverse);
break;
case 8: strcpy(tmps, &strrchr(yytext, (int)'.')[1]); break;
default: strcpy(tmps, yytext); break;
    }
    (void) printf("%s\n", tmps);
        }
    }

{URL1} |
{URL2} {
if (mode < 16) 
{
            switch((mode % 16)) 
            {
                case 0: strcpy(tmps, yytext); break;
         case 1: strcpy(tmps, strchr(yytext, (int)'/')); break;
         case 2: strcpy(tmps, &strrchr(yytext, (int)'/')[1]); break
         case 4: 
                        strcpy(tmps, &strrchr(yytext, (int)'/')[1]);
                        len = strlen(tmps);
                        for (j = 0, idx = 0; ((j < len) && (j < MAXLEN-1)) ; j++)
     {
                            if (tmps[j] == '.'
                            {
                                for (i = idx; i <= j; 
                                    reverse[(len-j) + (i-idx)] = tmps[i++]);
                                idx = j + 1;
                            }
                        }
                        for (i = idx; i <= j; 
                            reverse[(len-j) + (i-idx)] = (i < len) ? tmps[i] : '.', i++);
                        reverse[len + 1] = '\0';
                        strcpy(tmps, reverse);
                        break;
                case 8: strcpy(tmps, &strrchr(yytext, (int)'.')[1]); break;
                default: strcpy(tmps, yytext); break;
            }
            (void) printf("%s\n", tmps);
        }     
    } 

^[\n;] { ; }

[\r\n]+ { ; }

. { ; }

%%
void yyerror() { exit(1); }

void usage(const char *cmd) 
{
    (void) printf("Usage: %s [-f file] [-a ] [ -r ] [ -u ]\n", cmd);
    (void) printf("\t simple email address and uri lexer reads from stdin \n");
    (void) printf("\t -a, --noat    \t print only hostname of email address (all chars left of \'@\') \n");
    (void) printf("\t -u, --nouser  \t print email without username \n");
    (void) printf("\t -t, --top     \t prints domain toplevel only, when using option -a | -u \n");
    (void) printf("\t -n, --nouris \t print only email address and not uris\n");
    (void) printf("\t -r, --reverse \t reverse the hostdomain / ip address segments\n");
    
    exit(0);
}

int _tmain(int argc, TCHAR** argv)
{
    static int verbose_flag;
    int c;

    while(1)
    {
        static struct option long_options[] =
        {
            {_T("help"), ARG_NONE, 0, _T('h')},
            {_T("noat"), ARG_NONE, 0, _T('a')},
            {_T("nouser"), ARG_NONE, 0, _T('u')},
            {_T("top"), ARG_NONE, 0, _T('t')},
            {_T("nouris"), ARG_NONE, 0, _T('n')},
            {_T("reverse"),     ARG_NONE, 0, _T('r')},
            { ARG_NULL,         ARG_NULL, ARG_NULL, ARG_NULL}
        }; 

        int option_index = 0;
        c = getopt_long(argc, argv, _T("hautnr:"), long_options, &option_index);
        if (c == -1) 
            break;
        switch (c) // Handle options
        {
            case 0: // If this option set a flag, do nothing else now.
                    if (long_options[option_index].flag != 0)
                        break;
                    _tprintf (_T("option %s"), long_options[option_index].name);
                    if (optarg)
                        _tprintf (_T(" with arg %s"), optarg);
                    _tprintf (_T("\n"));
                    break;
            case _T('u'): mode = 1; break
            case _T('a'): mode = 2; break
            case _T('r'): mode = 4; break;
            case _T('h'): usage(argv[0]); break;
            case _T('t'): mode = 8; break;
            case _T('n'): mode += 16; break;  
            case '?': break// getopt_long already printed an error message. 
            default: abort();
        }
    }
    (void) fflush(stdout);
    yyin = stdin;
    yylex();
    exit(0);
}

Original posted 2011 here: http://www.area23.at/he/security/flex

2022-11-15

Could too much function pointers (delegates) inside many huge loops have an effect of unoptimizable code?

We have this simple c modified code from stack overflow called funcptrtest.c:

include <stdio.h>
/*   C code for program funcptrtest.c 
  => https://pastebin.com/rUtXfgSG 
*/
const int b = 23;

// A normal function with an int parameter and void return type
void fun(int a)
{
  if (a < b)
    printf("Value of a (%d) is lesser then value of b (%d)\n", a, b);
  else if (a == b)
    printf("Value of a (%d) is equal value of b (%d)\n", a, b);
  else if (a > b)
    printf("Value of a (%d) is greater than value of b (%d)\n", a, b);
}

// main => NO KNR style int main(argc, argv) int argc; char **argv 
int main(int argc, char **argv)
{
    int i = 0;
    /* fun_ptr is a pointer to function fun()
           void (*fun_ptr)(int) = &fun;
         is equivalent of following two
           void (*fun_ptr)(int);
           fun_ptr = &fun;
    */
    void (*fun_ptr)(int) = &fun;

    // call once with static int
    (*fun_ptr)(b);

    // iterate through for loop
    for (i = 1; i < 101; i+=11)  {
        // Invoking fun() using fun_ptr
        (*fun_ptr)(i);
    }

    return 0;
}

We compile it now with gnu c compiler with gcc option -S and generate an assembler file:

gcc -S funcptrtest.c -o funcptrtest.asm

Result will be something like this:

.file   "funcptrtest.c"
        .text
        .globl  b
        .section        .rodata
        .align 4
        .type   b, @object
        .size   b, 4
b:
        .long   23
        .align 8
.LC0:
        .string "Value of a (%d) is lesser then value of b (%d)\n"
        .align 8
.LC1:
        .string "Value of a (%d) is equal value of b (%d)\n"
        .align 8
.LC2:
        .string "Value of a (%d) is greater than value of b (%d)\n"
        .text
        .globl  fun
        .type   fun, @function
fun:
.LFB0:
        .cfi_startproc
        endbr64
        pushq   %rbp
        .cfi_def_cfa_offset 16
        .cfi_offset 6, -16
        movq    %rsp, %rbp
        .cfi_def_cfa_register 6
        subq    $16, %rsp
        movl    %edi, -4(%rbp)
        movl    $23, %eax
        cmpl    %eax, -4(%rbp)
        jge     .L2.L2:
        movl    $23, %eax
        cmpl    %eax, -4(%rbp)
        jne     .L4
        movl    $23, %edx
        movl    -4(%rbp), %eax
        movl    %eax, %esi
        leaq    .LC1(%rip), %rax
        movq    %rax, %rdi
        movl    $0, %eax
        call    printf@PLT
        jmp     .L5
        .L2:
        movl    $23, %eax
        cmpl    %eax, -4(%rbp)
        jne     .L4
        movl    $23, %edx
        movl    -4(%rbp), %eax
        movl    %eax, %esi
        leaq    .LC1(%rip), %rax
        movq    %rax, %rdi
        movl    $0, %eax
        call    printf@PLT
.L2:
        movl    $23, %eax
        cmpl    %eax, -4(%rbp)
        jne     .L4
        movl    $23, %edx
        movl    -4(%rbp), %eax
        movl    %eax, %esi
        leaq    .LC1(%rip), %rax
        movq    %rax, %rdi
        movl    $0, %eax
        call    printf@PLT
        jmp     .L5
.L4:
        movl    $23, %eax
        cmpl    %eax, -4(%rbp)
        jle     .L5
        movl    $23, %edx
        movl    -4(%rbp), %eax
        movl    %eax, %esi
        leaq    .LC2(%rip), %rax
        movq    %rax, %rdi
        movl    $0, %eax
        call    printf@PLT
.L5:
        nop
        leave
        .cfi_def_cfa 7, 8
        ret
        .cfi_endproc     
.LFE0:
        .size   fun, .-fun
        .globl  main
        .type   main, @function
main:
.LFB1:
        .cfi_startproc
        endbr64
        pushq   %rbp
        .cfi_def_cfa_offset 16
        .cfi_offset 6, -16
        movq    %rsp, %rbp
        .cfi_def_cfa_register 6
        subq    $32, %rsp
        movl    %edi, -20(%rbp)
        movq    %rsi, -32(%rbp)
        movl    $0, -12(%rbp)
        leaq    fun(%rip), %rax
        movq    %rax, -8(%rbp)
        movl    $23, %edx
        movq    -8(%rbp), %rax
        movl    %edx, %edi
        call    *%rax
        movl    $1, -12(%rbp)
        jmp     .L7
.L8:
        movl    -12(%rbp), %eax
        movq    -8(%rbp), %rdx
        movl    %eax, %edi
        call    *%rdx
        addl    $11, -12(%rbp)
.L7:
        cmpl    $100, -12(%rbp)
        jle     .L8
        movl    $0, %eax
        leave
        .cfi_def_cfa 7, 8
        ret
        .cfi_endproc
.LFE1:
        .size   main, .-main
        .ident  "GCC: (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0"
        .section        .note.GNU-stack,"",@progbits
        .section        .note.gnu.property,"a"
        .align 8
        .long   1f - 0f
        .long   4f - 1f
        .long   5
0:
        .string "GNU"
1:
        .align 8
        .long   0xc0000002
        .long   3f - 2f
2:
        .long   0x3
3:
        .align 8
4:

Lets look, if a simple loop is faster than a function pointer delegate call:

/* program looptest.c */
include <stdio.h>

const int b = 23;

// main
int main(int argc, char **argv)
{
    int i = 0;
    int a = 23;

    /*
    if (a < b)
        printf("Value of a (%d) is lesser then value of b (%d)\n", a, b);
    else if (a == b)
       printf("Value of a (%d) is equal value of b (%d)\n", a, b);
    else if (a > b)
       printf("Value of a (%d) is greater than value of b (%d)\n", a, b);
    */

    // iterate through for loop
    for (i = 1; i < 4194304; i+=11)  {
        a = i;
        if (a < b)
           printf("Value of a (%d) is lesser then value of b (%d)\n", a, b);
        else if (a == b)
           printf("Value of a (%d) is equal value of b (%d)\n", a, b);
        else if (a > b)
           printf("Value of a (%d) is greater than value of b (%d)\n", a, b);
    }

    return 0;
}

/* program funcptrtest.c */
include <stdio.h>

const int b = 23;

// A normal function with an int parameter and void return type
void fun(int a)
{
  if (a < b)
    printf("Value of a (%d) is lesser then value of b (%d)\n", a, b);
  else if (a == b)
    printf("Value of a (%d) is equal value of b (%d)\n", a, b);
  else if (a > b)
    printf("Value of a (%d) is greater than value of b (%d)\n", a, b);
}

// main
int main(int argc, char **argv)
{
    int i = 0;
    /* fun_ptr is a pointer to function fun()

       void (*fun_ptr)(int) = &fun;
       is equivalent of following two
       void (*fun_ptr)(int);
       fun_ptr = &fun;
    */
    void (*fun_ptr)(int) = &fun;

    // call once with static int
    // (*fun_ptr)(b);

    // iterate through for loop
    for (i = 1; i < 4194304; i+=11)  {
        // Invoking fun() using fun_ptr
        (*fun_ptr)(i);
    }

    return 0;
}

Well, that's not so deterministic, of course our simple looptest.asm has a shorter assembler.

compile options

But execution time is not so huge difference, we have to simulate, that in many scenarios.

[To be continued ...]

2022-10-15

About identity & privacy

Most complete Identity of a person is defined / determined by different public, restricted or private accessible spheres.



[ to be continued ... ]


2022-10-11

It's about creating distributed service oriented communications

Attention:
This article isn't about daily standard electronic communications via network protocols (e.g. email services or shared network folders),  neither about user authentication / authorization nor groupware. 

It's about: 
Implementing or consuming customizable reliable distributed services;
by choosing & implementing a programmable extensible scalable, easily portable, standardized inter-compatible fail-safe resilient communication middleware, that's financially essential for most critical business processes.

For what kind of companies is that useful, important or relevant?
It's relevant for all companies, that consume many crtical data from external partners / service providers; 
then process received & own data inside different departments (maybe in different locations) with different areas of responsibility (e.g. fraud detection, critical real-time scaling of dynamic hardware (memory, harddisks and available CPUs, permanent risk adjustment and last but not least anonymized [General Data Protection Regulation] precise reporting for legal reasons);
finally  and ultimately share processed data to maybe different  external organisations with very deviating requirements, like government fraud reporting agency on one side and partners inside a foundation or joint umbrella organization however.

Overview most common distributed service oriented communication technologies in history

What technologies do you use in your company / organisation or as private person for distributed service oriented communication?

    1. antique: [ 1980s ]
    2. old: [ around the millennium ]
    3. Previous generation: [ since 2010 ]


    What local software suites / solutions / products and enterprise cloud services are included in your distributed service oriented communication(s workflows)?

    1. Microsoft BizTalk Server
    2. RabbitMQ [ github.com/rabbitmq ]
    3. Amazon Web Services [ aws ]
    4. Azure RestAPI Reference 

    [ to be continued ... ]






    -


    2022-10-02

    Curch music I like

     I'm left liberal atheist, but I want to show thou, that I like some church music very much.

    My favorirtes (church music)

    Gregorian Chant (gregorianischer Choral)


    Franz Schubert (deutsche Messe) (1)

    Zum Eingang („Wohin soll ich mich wenden“)
    Zum Evangelium und Credo („Noch lag die Schöpfung formlos da“)
    Zum Offertorium („Du gabst, o Herr, mir Sein und Leben“)
    Zum Sanctus („Heilig, heilig, heilig! Heilig ist der Herr!“)
    Nach der Elevation, oder: Nach der Wandlung („Betrachtend Deine Huld und Güte“) (2)
    Zum Agnus Dei („Mein Heiland, Herr und Meister“)
    Schlussgesang („Herr, Du hast mein Fleh’n vernommen“)
    Anhang. Das Gebet des Herrn („Anbetend Deine Macht und Größe“)

    Johann Sebastian Bach (H-Moll-Messe) (3)


    2022-09-25

    Bridge Mini-VM for reading XFS, JFS, ext[234], minix, btrfs, reiserfs ot any other non MS filesystem

    Howto access  XFS, JFS, ext[234], minix, btrfs, reiserfs ot any other non MS filesystem from Windows 7 - 11 without installing a maybe bogus kernel filesystem driver?

    1. Make a Mini-Vm with a totally slack and stripped linux kernel, that is bridged on a VM network adapter. Include all filesystem drivers and needed network adapter & drivers in that kernel and strip / kick out everything other, what's not needed. 
      Make the kernel similiar to a cisco router or PIX firewall kernel.
    2. Give the VM direct access to your harddisk, usb-devices, firewire & bluetooth devices.
    3. Enable the Mini linux VM to reEXport mounted filesystem over smb or nfs.
    4. Calculate the memory size, which is needed, that all filesystem mounts and all fs operatons work fast enough with paging and caching. 
    5. Choose the best scheduler for that mini-VM.
    6. Optimize all ioctl, (f)lush, (f)read, (f)write, (f)seek, (f)open, (f)close and all other filesystem operations.
    7. If you are hungry => oprimize the /proc /sys /dev filesystem.