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，Ferruh

> -----Original Message-----
> From: Yigit, Ferruh
> Sent: Monday, March 25, 2019 5:36 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 3/25/2019 9:25 AM, Zhao1, Wei wrote:
> > Hi，Ferruh
> >
> >> -----Original Message-----
> >> From: Yigit, Ferruh
> >> Sent: Monday, March 25, 2019 4:46 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 3/25/2019 3:39 AM, Zhao1, Wei wrote:
> >>> 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()?
> >>
> >> The point is using 'strtoul' instead of your functions, so that you
> >> won't need 'get_hex_val()' at all, or won't need 'isxdigit()' because
> >> 'strtoul' will check it, won't need size should be multiply of two
> >> restriction '(*size & 1)' because of implementation change. Probably
> >> you will need NULL checks, but again point is why not using 'strtoul'
> instead of writing your version of it?
> >
> > Yes, we can use 'strtoul' , but my point is that  I think we need these check
> code even  if we use the code 'strtoul' .
> > isxdigit(*c)) is need because  *c may be sring "0xrgh" which is not hex.
> > If we use strtoul  will return 0 for that ,we can not distinguish between
> error or input is zero.
> > '(*size & 1) can be delete, I agree.
> >
> > 	/* Check input parameters */
> > 	if ((src == NULL) ||
> > 	(dst == NULL) ||
> > 		(size == NULL) ||
> > 		(*size == 0))
> > 		return -1;
> > 	for (c = src, i = 0; i < *size; c++, i++) {
> > 		if (isxdigit(*c))
> > 			continue;
> > 		else
> > 			return -1;
> > 	}
> >
> 
> Please feel free to keep/add whatever check is required, I wasn't suggesting
> the final implementation.
> 
> 'strtol' can detect invalid chars, by providing non-NULL to second argument,
> so 'isxdigit()' is not required but more checks needed.

Get ,  thank you.

> 
> Overall you previously mentioned 'strtol' can't be used, but it can be used
> and I believe it is better way to go, but I am asking what do you think about it?
> Checks and implementation details can be handled.

Ok, update in v4
> 
> >
> >>>
> >>> 	/* 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"
> >