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: Zhao1, Wei
> Sent: Tuesday, April 9, 2019 3:38 PM
> To: Yigit, Ferruh <ferruh.yigit@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
> 
> Hi,  Ferruh
> 
> > -----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 ;) )
> >
> > <...>
> 
> 
> 
> I have change code style as your guide as bellow, but strtoul() seems do not
> work, it return c with a none-null every time.
> you can have a try yourself.
> 
> 
> static int
> parse_hex_string(const char *src, uint8_t *dst, uint32_t *size)
> {
> 	char *c = NULL;
> 	uint32_t i, len;
> 	char tmp[3];
> 
> 	/* Check input parameters */
> 	if ((src == NULL) ||
> 		(dst == NULL) ||
> 		(size == NULL) ||
> 		(*size == 0))
> 		return -1;
> 
> 	/* Convert chars to bytes */
> 	for (i = 0, len = 0; i < *size; i += 2) {
> 		snprintf(tmp, 3, "%s" ,src + i);
> 		dst[len++] = strtoul(tmp, &c, 16);
> 		if(c)
> 			return -1;
>  	}
> 	dst[len] = 0;
> 	*size = len;
> 
> 	return 0;
> }
> 

As this code with strtoul do not work, I suggest we use v3 of get_hex_val(), do you think so?


> >
> > > +	/* 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"