[libvirt] [PATCHv2 2/4] network: provide internal API to return IP of a network

[Eric Blake]

On 07/20/2011 02:11 AM, Laine Stump wrote:
> The new listenNetwork atribute needs to learn an IP address based on a

s/atribute/attribute/

> named network. This patch provides a function networkGetNetworkAddress
> which provides that.
>
> Some networks have an IP address explicitly in their configuration
> (ie, those with a forward type of "none", "route", or "nat"). For
> those, we can just return the IP address from the config.
>
> The rest will have a physical device associated with them (either via
> <bridge name='...'/>,<forward ... dev='...'/>, or possibly via a pool
> of interfaces inside the network's<forward>  element) and we will need
> to ask the kernel for the current IP address of that device (via the

s/the current/a current/ - the kernel may know more than one, but we 
only care about finding at least one (and as you pointed out in the 
previous patch, you only get the first).

> newly added ifaceGetIPAddress

Missing )

>
> If networkGetNetworkAddress encounters an error while trying to learn
> the address for a network, it will return -1. In the case that libvirt
> has been compiled without the network driver, a static inline version
> of the function, which returns -2, will be used. This allows
> differentiating between a failure of the network driver, and its
> complete absence.
> ---
>   src/libvirt_network.syms    |    1 +
>   src/network/bridge_driver.c |  100 +++++++++++++++++++++++++++++++++++++++++++
>   src/network/bridge_driver.h |    7 +++
>   3 files changed, 108 insertions(+), 0 deletions(-)

> +
> +/*
> + * networkGetNetworkAddress:
> + * @netname: the name of a network
> + * @netaddr: string representation of IP address for that network.
> + *
> + * Attempt to return the IP (v4) address associated with the named

s/the IP/an IP/

> + * network. If a libvirt virtual network, that will be provided in the
> + * configuration. For host bridge and direct (macvtap) networks, we
> + * must do an ioctl to learn the address.
> + *
> + * Note: This function returns the 1st IPv4 address it finds. It might
> + * be useful if it was more flexible, but the current use (getting a
> + * listen address for qemu's vnc/spice graphics server) can only use a
> + * single address anyway.
> + *
> + * Returns 0 on success, and puts a string (which must be free'd by
> + * the caller) into *netaddr. Returns -1 on failure

Might also be worth mentioning -2 on complete lack of support.

> +    case VIR_NETWORK_FORWARD_ROUTE:
> +        /* if there's an ipv4def, get it's address */
> +        ipdef = virNetworkDefGetIpByIndex(netdef, AF_INET, 0);
> +        if (!ipdef) {
> +            networkReportError(VIR_ERR_INTERNAL_ERROR,
> +                               _("network '%s' doesn't have an IP address"),

It might have an IPv6 address though, so touch up the error message:

s/IP/IPv4/

> +    case VIR_NETWORK_FORWARD_BRIDGE:
> +        if ((devname = netdef->bridge))
> +            break;
> +        /*
> +         * If netdef->bridge wasn't set, this is a direct-mode
> +         * interface, so purposefully fall through to the next case
> +         */
> +    case VIR_NETWORK_FORWARD_PRIVATE:

Coverity will probably gripe at this one.  We may need to re-word this:

/* Fall through if netdef->bridge wasn't set, since this is a 
direct-mode interface */

> +++ b/src/network/bridge_driver.h
> @@ -40,6 +40,8 @@ int networkAllocateActualDevice(virDomainNetDefPtr iface);
>   int networkNotifyActualDevice(virDomainNetDefPtr iface);
>   int networkReleaseActualDevice(virDomainNetDefPtr iface);
>
> +int networkGetNetworkAddress(const char *netname, char **netaddr);

ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2)

> +
>   int networkBuildDhcpDaemonCommandLine(virNetworkObjPtr network,
>                                         virCommandPtr *cmdout, char *pidfile,
>                                         dnsmasqContext *dctx);
> @@ -57,6 +59,11 @@ networkReleaseActualDevice(virDomainNetDefPtr iface ATTRIBUTE_UNUSED)
>   { return 0; }
>
>   static inline int
> +networkGetNetworkAddress(const char *netname ATTRIBUTE_UNUSED,
> +                         char **netaddr ATTRIBUTE_UNUSED)
> +   { return -2; }

# define networkGetNetworkAddress(netname, netaddr) (-2)


ACK with those nits fixed.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org