[libvirt] [PATCH 1/3] Utility functions to produce an IPv4 broadcast address

[Stefan Berger]

On 12/31/2010 06:33 AM, Laine Stump wrote:
> These functions work only for IPv4, becasue IPv6 doesn't have the same
> concept of "broadcast address" as IPv4. They merely OR the inverse of
> the netmask with the given host address, thus turning on all the host
> bits.
> ---
>   src/libvirt_private.syms |    2 +
>   src/util/network.c       |   55 ++++++++++++++++++++++++++++++++++++++++++++++
>   src/util/network.h       |    6 +++++
>   3 files changed, 63 insertions(+), 0 deletions(-)
>
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index a959ad9..19e581c 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -558,6 +558,8 @@ virShrinkN;
>
>
>   # network.h
> +virSocketAddrBroadcast;
> +virSocketAddrBroadcastByPrefix;
>   virSocketAddrIsNetmask;
>   virSocketAddrMask;
>   virSocketAddrMaskByPrefix;
> diff --git a/src/util/network.c b/src/util/network.c
> index 61044fc..f58986e 100644
> --- a/src/util/network.c
> +++ b/src/util/network.c
> @@ -341,6 +341,61 @@ virSocketAddrMaskByPrefix(virSocketAddrPtr addr, unsigned int prefix)
>   }
>
>   /**
> + * virSocketAddrBroadcast:
> + * @addr: address that needs to be turned into broadcast address (IPv4 only)
> + * @netmask: the netmask address
> + * @broadcast: virSocketAddr to recieve the broadcast address
> + *
> + * Mask ON the host bits of @addr according to @netmask, turning it
> + * into a broadcast address.
> + *
> + * Returns 0 in case of success, or -1 on error.
> + */
> +int
> +virSocketAddrBroadcast(const virSocketAddrPtr addr,
> +                       const virSocketAddrPtr netmask,
> +                       virSocketAddrPtr       broadcast)
> +{
> +    if ((addr->data.stor.ss_family != AF_INET) ||
> +        (netmask->data.stor.ss_family != AF_INET)) {
> +        broadcast->data.stor.ss_family = AF_UNSPEC;
> +        return -1;
> +    }
> +
> +    broadcast->data.stor.ss_family = AF_INET;
> +    broadcast->len = addr->len;
> +    broadcast->data.inet4.sin_addr.s_addr
> +        = (addr->data.inet4.sin_addr.s_addr
> +           | ~netmask->data.inet4.sin_addr.s_addr);
> +    return 0;
> +}
> +
> +/**
> + * virSocketAddrBroadcastByPrefix:
> + * @addr: address that needs to be turned into broadcast address (IPv4 only)
> + * @prefix: prefix (# of 1 bits) of netmask to apply
> + * @broadcast: virSocketAddr to recieve the broadcast address
> + *
> + * Mask off the host bits of @addr according to @prefix, turning it
> + * into a network address.
> + *
> + * Returns 0 in case of success, or -1 on error.
> + */
> +int
> +virSocketAddrBroadcastByPrefix(const virSocketAddrPtr addr,
> +                               unsigned int           prefix,
> +                               virSocketAddrPtr       broadcast)
> +{
> +    virSocketAddr netmask;
> +
> +    if (virSocketAddrPrefixToNetmask(prefix,&netmask,
> +                                     addr->data.stor.ss_family)<  0)
> +        return -1;
> +
> +    return virSocketAddrBroadcast(addr,&netmask, broadcast);
> +}
> +
> +/**
>    * virSocketCheckNetmask:
>    * @addr1: a first network address
>    * @addr2: a second network address
> diff --git a/src/util/network.h b/src/util/network.h
> index 2fcee43..bcbc607 100644
> --- a/src/util/network.h
> +++ b/src/util/network.h
> @@ -77,6 +77,12 @@ int virSocketAddrMask     (virSocketAddrPtr addr,
>                              const virSocketAddrPtr netmask);
>   int virSocketAddrMaskByPrefix(virSocketAddrPtr addr,
>                                 unsigned int prefix);
> +int virSocketAddrBroadcast(const virSocketAddrPtr addr,
> +                           const virSocketAddrPtr netmask,
> +                           virSocketAddrPtr       broadcast);
> +int virSocketAddrBroadcastByPrefix(const virSocketAddrPtr addr,
> +                                   unsigned int           prefix,
> +                                   virSocketAddrPtr       broadcast);
>
>   int virSocketGetNumNetmaskBits(const virSocketAddrPtr netmask);
>   int virSocketAddrPrefixToNetmask(unsigned int prefix,
ACK.

    Stefan