CODEWITHSUNDEEP
cascii
mopodafordeya
mopodafordeya

Reputation: 635

Use c string to send multiple null characters. ASCII Armoring

How to use a C string to contain multiple null characters \x00.

Upvotes: 3

Views: 1186

Answers (3)

Philipp Claßen
Philipp Claßen

Reputation: 43999

A C string is only an array of chars terminated by a null character. However, if you treat it as an array, it can contain inner null characters:

char data[4] = { 'x', '\0', 'y', '\0' };

You have to be careful, however, as most of the standard library functions will not work, as they expect an C string ending with the first null character.

For example, strlen(data) will return 1 in the example above, as it stops after the first null character.

Upvotes: 3

poundifdef
poundifdef

Reputation: 19372

C's string functions (eg strlen(), printf(), etc) assume that the buffer will be null-terminated. If you have a buffer with multiple 0x00 characters, then you can't use any functions which treat 0x00 as a null character.

So instead of using, eg, strcpy() (or strncpy()) you would use memcpy() - to move the bytes of memory from one place to another, rather than relying on this null-terminated behavior.

Upvotes: 9

bobobobo
bobobobo

Reputation: 67266

All you have to do is something like

char* data = (char*)malloc( 8 ) ; // allocate space for 8 bytes
memset( data, 0, 8 ) ; // set all 8 bytes to 0's

Upvotes: 2

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