On 12/22/2010 11:58 AM, Laine Stump wrote:
Later patches will add the possibility to define a network's netmask as a prefix (0-32, or 0-128 in the case of IPv6). To make it easier to deal with definition of both kinds (prefix or netmask), add two new functions:
virNetworkDefNetmask: return a copy of the netmask into a virSocketAddr. If no netmask was specified in the XML, create a default netmask based on the network class of the virNetworkDef's IP address.
virNetworkDefPrefix: return the netmask as numeric prefix (or the default prefix for the network class of the virNetworkDef's IP address, if no netmask was specified in the XML)
+int virNetworkDefPrefix(const virNetworkDefPtr def) +{ + if (VIR_SOCKET_HAS_ADDR(&def->netmask)) { + return virSocketGetNumNetmaskBits(&def->netmask); + } else if (VIR_SOCKET_IS_FAMILY(&def->ipAddress, AF_INET)) { + /* Return the natural prefix for the network's ip address. + * On Linux we could use the IN_CLASSx() macros, but those + * aren't guaranteed on all platforms, so we just deal with + * the bits ourselves. + */ + const unsigned char *octets + = (const unsigned char *)(&def->ipAddress.data.inet4.sin_addr.s_addr);
Is this type-punning guaranteed to work on both big- and little-endian systems? Or are you better off doing: unsigned char octet = ntohl(def->ipAddress.data.inet4.sin_addr.s_addr) >> 24; and use octet instead of octets[0]? -- Eric Blake eblake@redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org