On 9/21/18 4:13 PM, [email protected] wrote:
>
> Hello there,
>
> we discovered a strange phenomenon in the project testssl.sh:
>
> After opening a TCP socket with a fd (here: 5), when writing to it,
> it seems that
>
> printf -- "$data" >&5 2>/dev/null
>
> does not do what it is intended. "$data" is a ClientHello like
>
> '\x16\x03\x01\x2\x00\x01\x00\x1\xfc\x03\x03\x54\x51\x1e\x7a\xde\xad\xbe\xef\x31\x33\x07\x00\x00\x00\x00\x00\xcf\xbd\x39\x04\xcc\x16\x0a\...'
>
> Each \x0a like the last one causes a new TCP fragment to begin which can be
> easily
> spotted when using wireshark while running e.g.
Newline? It's probably that stdout is line-buffered and the newline causes
a flush, which results in a write(2).
> If there's a workaround, please let me know. (tried to add "%b" with no
> effect). Otherwise I believe it's a bug.
How? Does the emitted output not correspond to what's passed to printf
in some way?
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU [email protected] http://tiswww.cwru.edu/~chet/
