Re: [dpdk-dev] [dpdk-stable] [PATCH v3] app/testpmd: fix support of hex string parser for flow API

["Zhao1, Wei" <wei.zhao1@intel.com>]

Hi, 

> -----Original Message-----
> From: Yigit, Ferruh
> Sent: Friday, March 22, 2019 10:56 PM
> To: Zhao1, Wei <wei.zhao1@intel.com>; dev@dpdk.org
> Cc: stable@dpdk.org; stephen@networkplumber.org; Ananyev, Konstantin
> <konstantin.ananyev@intel.com>
> Subject: Re: [dpdk-stable] [PATCH v3] app/testpmd: fix support of hex string
> parser for flow API
> 
> On 3/22/2019 3:15 AM, Wei Zhao wrote:
> > There is need for users to set configuration of HEX number for RSS
> > key. The key byte should be pass down as hex number not as char
> > string. This patch enable cmdline flow parse HEX number, in order to
> > not using string which pass ASIC number.
> >
> > Fixes: f4d623f96119 ("app/testpmd: fix missing RSS fields in flow
> > action")
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Wei Zhao <wei.zhao1@intel.com>
> > Tested-by: Peng Yuan <yuan.peng@intel.com>
> 
> <...>
> 
> > @@ -4475,6 +4486,138 @@ parse_string(struct context *ctx, const struct
> token *token,
> >  	return -1;
> >  }
> >
> > +static uint32_t
> > +get_hex_val(char c)
> > +{
> > +	switch (c) {
> > +	case '0': case '1': case '2': case '3': case '4': case '5':
> > +	case '6': case '7': case '8': case '9':
> > +		return c - '0';
> > +	case 'A': case 'B': case 'C': case 'D': case 'E': case 'F':
> > +		return c - 'A' + 10;
> > +	case 'a': case 'b': case 'c': case 'd': case 'e': case 'f':
> > +		return c - 'a' + 10;
> > +	default:
> > +		return 0;
> > +	}
> > +}
> > +
> > +static int
> > +parse_hex_string(const char *src, uint8_t *dst, uint32_t *size) {
> > +	const char *c;
> > +	uint32_t i;
> > +
> > +	/* Check input parameters */
> > +	if ((src == NULL) ||
> > +		(dst == NULL) ||
> > +		(size == NULL) ||
> > +		(*size == 0))
> > +		return -1;
> > +	if ((*size & 1) != 0)
> > +		return -1;
> > +
> > +	for (c = src, i = 0; i < *size; c++, i++) {
> > +		if (isxdigit(*c))
> > +			continue;
> > +		else
> > +			return -1;
> > +	}
> > +
> > +	*size = *size / 2;
> > +
> > +	/* Convert chars to bytes */
> > +	for (i = 0; i < *size; i++)
> > +		dst[i] = get_hex_val(src[2 * i]) * 16 +
> > +			get_hex_val(src[2 * i + 1]);
> > +
> > +	return 0;
> > +}
> 
> I can see this has been discussed already but what would you think updating
> the 'parse_hex_string' something like following, it is less code to maintain:
> 
> static int
> parse_hex_string(const char *src, uint8_t *dst, uint32_t *size) {
>   int len;
>   int i
>   for (i = 0, len = 0; i < *size; i += 2) {
>     char tmp[3];
>     snprintf(tmp, 3, src + i);
>     dst[len++] = strtoul(tmp, NULL, 16);
>   }
>   dst[len] = 0;
>   *size = len;
>   return 0;
> }
> 
> (indeed with better error checking on strtoul ;) )


Why delete these check from parse_hex_string()?
 
	/* Check input parameters */
	if ((src == NULL) ||
	(dst == NULL) ||
		(size == NULL) ||
		(*size == 0))
		return -1;
	if ((*size & 1) != 0)
		return -1;
	for (c = src, i = 0; i < *size; c++, i++) {
		if (isxdigit(*c))
			continue;
		else
			return -1;
	}



> 
> <...>
> 
> > +	/* Output buffer is not necessarily NUL-terminated. */
> > +	memcpy(buf, hex_tmp, hexlen);
> > +	memset((uint8_t *)buf + len, 0x00, size - hexlen);
> 
> Can't this overflow the 'buf'? since "len = 2 * hexlen"
> I guess intention is "buf + hexlen"