Re: [libvirt] [PATCH 1/2] util: Functions to update host network device's multicast filter
On 10/08/2014 09:36 AM, Laine Stump wrote:
On 10/06/2014 05:37 PM, akrowiak(a)linux.vnet.ibm.com wrote:
> From: Tony Krowiak <akrowiak(a)linux.vnet.ibm.com>
>
> This patch provides the utility functions to needed to synchronize the
> changes made to a guest domain network device's multicast filter
> with the corresponding macvtap device's filter on the host:
>
> * Get/add/remove multicast MAC addresses
> * Get the macvtap device's RX filter list
>
> Signed-off-by: Tony Krowiak <akrowiak(a)linux.vnet.ibm.com>
> ---
> +/**
> + * virMacAddrParseHex:
> + * @str: string hexadecimal representation of MAC address, e.g.,
"F801EFCE3aCB"
> + * @addr: 6-byte MAC address
> + *
> + * Parse the hexadecimal representation of a MAC address
> + *
> + * Return 0 upon success, or -1 in case of error.
> + */
> +int
> +virMacAddrParseHex(const char* str, virMacAddrPtr addr)
Wrong spacing around '*'.
> +{
> + if (strlen(str) != VIR_MAC_HEXLEN)
> + return -1;
> +
> + size_t iaddr;
> + size_t istr;
> +
> +
> + for (istr = 0, iaddr = 0; iaddr < VIR_MAC_BUFLEN; istr += 2, iaddr++) {
> + unsigned int hex;
> +
> + if (sscanf(&str[istr], "%02x", &hex) != 1)
> + break;
I'm not keen on sscanf(), but since we're already using it elsewhere,
and the existing virMacAddrParse uses the normally-blacklisted strtoul()
(and using virStrToLong_ui() on pieces of the string would require a
terminating character after each piece), I don't have a ready answer for
an alternative.
Why not just open-code it? It's just two input bytes per iteration, and
we already have a helper function that makes it a very short function.
And strspn makes it easy to do input validation before starting the loop:
int
virMacAddrParseHex(const char *str, virMacAddrPtr addr)
{
size_t i;
if (strspn(str, "0123456789abcdefABCDEF") != VIR_MAC_HEXLEN ||
str[VIR_MAC_HEXLEN])
return -1;
for (i = 0; i < VIR_MAC_BUFLEN; i++)
addr->addr[i] = (virHexToBin(str[2 * i]) << 4 |
virHexToBin(str[2 * i + 1]));
return 0;
}
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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