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proxmark3/doc/cliparser.md
Philippe Teuwen 7a5786b9e4 fix a number of strx usages
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Note on Cliparser

Table of Contents

The old style with mixed custom commandline parsing of user parameters or options was messy and confusing. You can find all kinds in the Proxmark3 client. Samples

data xxxx h
script run x.lua -h
hf 14a raw -h
hf 14b raw -ss
lf search 1
lf config h H

even the external tools which we collected into this repo, under folder /tools/ folder uses their own argument parsing.

In order to counter this and unify it, there was discussion over at the official repository a few years ago link to issue and there it became clear a change is needed. Among the different solutions suggested @merlokk's idea of using the lib cliparser was agreed upon. The lib was adapted and implemented for commands like

[usb] pm3 --> emv
[usb] pm3 --> hf fido

And then it fell into silence since it wasn't well documented how to use the cliparser. Looking at source code wasn't very efficient. However the need of a better cli parsing was still there.

Fast forward today, where more commands has used the cliparser but it still wasn't the natural way when adding a new client command to the Proxmark3 client. After more discussions among @doegox, @iceman1001 and @mrwalker the concept became more clear on how to use the cliparser lib in the preferred way.

The aftermath was a design and layout specified which lead to a simpler implementation of the cliparser in the client source code while still unifying all helptexts with the new colours support and a defined layout. As seen below, the simplicity and clearness.

sample of new style helptext

Furthermore @mrwalker offered to take notes and thus this document was created.

This is the new and preferred way to implement helptext and cli parsing for Proxmark3 client commands and it's external tools.

cliparser setup and use

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The parser will format and color and layout as needed. It will also add the -h --help option automatic.

design comments

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  • where possible all options should be lowercase.
  • extended options preceded with -- should be short
  • options provided directly (without an option identifier) should be avoided.
  • -vv for extra verbose should be avoided; use of debug level is preferred.
  • with --options the equal is not needed (will work with and without) so don't use '=' e.g. cmd --cn 12345

common options

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-h --help       : help
--cn            : card number
--fn            : facility number
--q5            : target is LF T5555/Q5 card
--em            : target is LF EM4305/4469 card
--raw           : raw data
-d --data       : hex data supplied
-f --file       : filename supplied
-k --key        : key supplied
-n --keyno      : key number to use
-p --pwd        : password supplied
-v --verbose    : flag when output should provide more information, not considered debug.
-1 --buffer     : use the sample buffer

How to implement in source code

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setup the parser data structure

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Header file to include

#include "cliparser.h"

In the command function, setup the context

CLIParserContext *ctx;

define the context

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CLIParserInit (\<context\>, \<description\>, \<notes\n examples ... \>);

use -> to separate example and example comment and \n to separate examples. e.g. lf indala clone -r a0000000a0002021 -> this uses .....

CLIParserInit(&ctx, "lf indala clone",
              "clone INDALA UID to T55x7 or Q5/T5555 tag",
              "lf indala clone --heden 888\n"
              "lf indala clone --fc 123 --cn 1337\n"
              "lf indala clone -r a0000000a0002021\n"
              "lf indala clone -l -r 80000001b23523a6c2e31eba3cbee4afb3c6ad1fcf649393928c14e5");

define the options

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void *argtable[] = {
    arg_param_begin,
    arg_lit0("l", "long", "optional - long UID 224 bits"),
    arg_int0("c", "heden", "<decimal>", "Cardnumber for Heden 2L format"),
    arg_str0("r", "raw", "<hex>", "raw bytes"),
    arg_lit0("q", "Q5", "optional - specify writing to Q5/T5555 tag"),
    arg_int0(NULL, "fc", "<decimal>", "Facility Code (26 bit format)"),
    arg_int0(NULL, "cn", "<decimal>", "Cardnumber (26 bit format)"),
    arg_param_end
};

All options has a parameter index, since -h --help is added automatic, it will be assigned index 0. Hence all options you add will start at index 1 and upwards. It added in the define "arg_param_begin

Notes:

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bool option. true if supplied

bool : arg_lit0 ("<short option>", "<long option>", <"description">)

integer that is optional

optional integer : arg_int0 ("<short option>", "<long option>", "<format>", <"description">)

integer that is required

required integer : arg_int1 ("<short option>", "<long option>", "<format>", <"description">)

double that is optional

optional double : arg_dbl0 ("<short option>", "<long option>", "<format>", <"description">)

double that is required

required double : arg_dbl1 ("<short option>", "<long option>", "<format>", <"description">)

String option that is optional and only one instance can be provided

optional string : arg_str0 ("<short option>", "<long option>", "<format>", <"description">)

String option that is required and only one instance can be provided

required string : arg_str1 ("<short option>", "<long option>", "<format>", <"description">)

String option that is optional and can have up to 250 instances provided

optional string : arg_strx0 ("<short option>", "<long option>", "<format>", <"description">)

String option that is required/at least one instance and can have up to 250 instances

required string : arg_strx1 ("<short option>", "<long option>", "<format>", <"description">)

Unsigned values, like u32 and u64 can be accomplished with

unsigned integer optional

optional unsigned : arg_u64_0 ("<short option>", "<long option>", "<format>", <"description">)

unsigned integer required

required unsigned : arg_u64_1 ("<short option>", "<long option>", "<format>", <"description">)

if an option does not have a short or long option, use NULL in its place

show the menu

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CLIExecWithReturn(\<context\>, \<command line to parse\>, \<arg/opt table\>, \<return on error\>);

CLIExecWithReturn(ctx, Cmd, argtable, false);

clean up

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Once you have extracted the options, cleanup the context.

CLIParserFree(ctx);

retrieving options

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The parser will format and color and layout as needed. It will also add the -h --help option automatic.

bool option arg_get_lit(<context>, <opt index>);

is_long_uid = arg_get_lit(ctx, 1);

int option arg_get_int_def(<context>, <opt index>, <default value>);

cardnumber = arg_get_int_def(ctx, 2, -1);

uint32 arg_get_u32_def(<context>, <opt index>, <default value>);

cardnumber = arg_get_u32_def(ctx, 2, 0);

uint64 arg_get_u64_def(<context>, <opt index>, <default value>);

cardnumber = arg_get_u64_def(ctx, 2, 0);

hex option with return CLIGetHexWithReturn(<context>, <opt index>, <store variable>, <ptr to stored length>); ?? as an array of uint_8 ?? If failed to retrieve hexbuff, it will exit fct

uint8_t aid[2] = {0};
int aidlen;
CLIGetHexWithReturn(ctx, 2, aid, &aidlen);

hex option

uint8_t key[24] = {0};
int keylen = 0;
int res_klen = CLIParamHexToBuf(arg_get_str(ctx, 3), key, 24, &keylen);

quick test : seems res_keylen == 0 when ok so not key len ???

string option return CLIGetStrWithReturn(<context>,<opt index>, <uint8_t *>, <int *>); If failed to retrieve string, it will exit fct

uint8_t buffer[100];
int slen = sizeof(buffer); // <- slen MUST be the maximum number of characters that you want returned. e.g. Buffer Size
CLIGetStrWithReturn(ctx, 1, buffer, &slen);

string option
Getting a char array

int slen = 0;
char format[16] = {0};
int res = CLIParamStrToBuf(arg_get_str(ctx, 1), (uint8_t *)format, sizeof(format), &slen);

quick test : seem res == 0, then ok.  compare res == slen to see how many chars