[libvirt] [PATCH-v5.1] Support for static routes on a virtual bridge

Laine Stump laine at laine.org
Mon May 13 20:16:19 UTC 2013


On 05/07/2013 01:42 PM, Gene Czarcinski wrote:
> network: static route support for <network>
>
> This update includes Laine Stump's comments/suggestions.  Once
> again he has improved my over-engineered solutions.  My original
> patch and his patch have been squashed/merged with this being the
> result.  That plus a little simplified code added to
> bridge_driver.c to handle the zero address situations.
>
> This code does not restrict any combination of
> address/netmask/prefix for a static route specification.  The
> metric attribute has been added so that existing route specifications
> can be overridden.
>
> Documentation has been updated to reflect a v1.0.6 target.
>
> This patch adds the <route> subelement of <network> to define a static
> route.  the address and prefix (or netmask) attribute identify the
> destination network, and the gateway attribute specifies the next hop
> address (which must be directly reachable from the containing
> <network>) which is to receive the packets destined for
> "address/(prefix|netmask)".
>
> Tests are done to validate that the input definitions are
> correct.  For example, for a static route ip definition,
> the address must be a network address and not a host address.
> Additional checks are added to ensure that the specified gateway
> is directly reachable via a network defined on this bridge.
>
> The command used is of the following form:
>
> ip route add <address>/<prefix> via <gateway> dev <virbr-bridge> \
> proto static metric 1

This should say "metric <metric>".


>
> For family='ipv4' address='0.0.0.0' netmask='0.0.0.0' or prefix='0' is
> supported.
>
> For family='ipv6' address='::' prefix=0' is supported.
>
> Anytime an attempt is made to define a static route which duplicates
> an existing static route (for example, address=::, prefix=0, metric=1),
> the following error message will be sent to syslog:
>     RTNETLINK answers: File exists
>
> This can be overridden by increasing the value of metric.  Caution should
> be used when doing this ... especially for a default route.
>
> Note: The use of the command-line interface should be replaced by
> direct use of libnl so that error conditions can be handled better.  But,
> that is being left as an exersize for another day.


exercise

> .
> Signed-off-by: Gene Czarcinski <gene at czarc.net>
> ---
>  docs/formatnetwork.html.in                         |  77 +++++
>  docs/schemas/network.rng                           |  22 ++
>  src/conf/network_conf.c                            | 340 ++++++++++++++++++++-
>  src/conf/network_conf.h                            |  22 ++
>  src/libvirt_private.syms                           |   1 +
>  src/network/bridge_driver.c                        |  64 ++++
>  src/util/virnetdev.c                               |  46 +++
>  src/util/virnetdev.h                               |   7 +
>  .../networkxml2xmlin/dhcp6host-routed-network.xml  |   2 +
>  .../networkxml2xmlout/dhcp6host-routed-network.xml |   2 +
>  10 files changed, 582 insertions(+), 1 deletion(-)
>
> diff --git a/docs/formatnetwork.html.in b/docs/formatnetwork.html.in
> index d72bd0a..4c7e74f 100644
> --- a/docs/formatnetwork.html.in
> +++ b/docs/formatnetwork.html.in
> @@ -546,6 +546,56 @@
>        starting.
>      </p>
>  
> +    <h5><a name="elementsStaticroute">Static Routes</a></h5>
> +    <p>
> +      Static route definitions are used to provide routing
> +      information to the virtualization host for networks which are not
> +      defined as a network on one of the virtual bridges so that such

which are not directly reachable from the virtualization host, but *are*
reachable from a guest domain that is itself reachable from the host.

> +      networks can be reachable from the virtualization
> +      host <span class="since">Since 1.0.6</span>.
> +    </p>
> +
> +    <p>
> +      As shown in <a href="formatnetwork.html#examplesNoGateway">this example</a>,
> +      it is possible to define a virtual bridge interface with no

s/virtual bridge/virtual network/

> +      IPv4 or IPv6 networks.  Such interfaces are useful in supporting

s/networks/addresses/
s/interfaces/networks/


> +      networks which have no visibility or direct connectivity with the
> +      virtualization host, but can be used to support
> +      virtual networks which only have guest connectivity.

which are only reachable via a guest.


>   A guest
> +      with connectivity to the guest-only network and another network

"with connectivity *both* to .... and ...."

> +      that is directly reachable from the host can act as a gateway between the
> +      networks.  A static route added to the "visible" network definition


"host-visible"


> +      provides the routing information so that IP packets can be sent
> +      from the virtualization host to guests on the hidden network.
> +    </p>
> +
> +    <p>
> +      Here is a fragment of a definition which shows the static
> +      route specification as well as the  IPv4 and IPv6 definitions
> +      for network addresses which are referred to in the
> +      <code>gateway</code> gateway address specifications.  Note
> +      that the third static route specification includes the
> +      <code>metric</code> attribute specification with a value of 2.
> +      This indicates that this particular definition is overriding another
> +      route definition with the same address and prefix but with a lower
> +      value for the metric.


Actually it's the opposite - the lower the metric, the more preferred it
is. You can think of the metric as the "cost" of travelling in this
direction.

If someone wanted to have a route that automatically overrode an
existing route when the libvirt network was started, they would need to
setup their system config to give the "permanent" route a higher metric.


> +    </p>
> +
> +    <pre>
> +      ...
> +        <ip address="192.168.122.1" netmask="255.255.255.0">
> +          <dhcp>
> +            <range start="192.168.122.128" end="192.168.122.254" />
> +          </dhcp>
> +        </ip>
> +        <route address="192.168.222.0" prefix="24" gateway="192.168.122.2" />
> +        <ip family="ipv6" address="2001:db8:ca2:2::1" prefix="64" />
> +        <route family="ipv6" address="2001:db8:ca2:3::" prefix="64" gateway="2001:db8:ca2:2::2"/>
> +        <route family="ipv6" address="2001:db9:4:1::" prefix="64" gateway="2001:db8:ca2:2::3" metric='2'>
> +        </route>
> +      ...
> +    </pre>
> +
>      <h3><a name="elementsAddress">Addressing</a></h3>
>  
>      <p>
> @@ -577,6 +627,7 @@
>            </dhcp>
>          </ip>
>          <ip family="ipv6" address="2001:db8:ca2:2::1" prefix="64" />
> +        <route family="ipv6" address="2001:db9:ca1:1::" prefix="64" gateway="2001:db8:ca2:2::2" />
>        </network></pre>
>  
>      <dl>
> @@ -826,6 +877,32 @@
>          </ip>
>        </network></pre>
>  
> +    <p>
> +      Below is yet another IPv6 variation.  This variation has only IPv6
> +      defined with DHCPv6 on the primary IPv6 network.  A static link
> +      if defined for a second IPv6 network which will not be visable on


s/visable/visible/


> +      the bridge interface but will have a static route defined for this
> +      network via the specified gateway. Note that the gateway address
> +      must be directly reachable via (on the same subnet as) one of the
> +      <ip> addresses defined for this <network>.
> +      <span class="since">Since 1.0.5</span>


s/1.0.5/1.0.6/


> +    </p>
> +
> +    <pre>
> +      <network>
> +        <name>net7</name>
> +        <bridge name="virbr7" />
> +        <forward mode="route"/>
> +        <ip family="ipv6" address="2001:db8:ca2:7::1" prefix="64" >
> +          <dhcp>
> +            <range start="2001:db8:ca2:7::100" end="2001:db8:ca2::1ff" />
> +            <host id="0:4:7e:7d:f0:7d:a8:bc:c5:d2:13:32:11:ed:16:ea:84:63" name="lucas" ip="2001:db8:ca2:2:3::4" />
> +          </dhcp>
> +        </ip>
> +        <route family="ipv6" address="2001:db8:ca2:8::" prefix="64" gateway="2001:db8:ca2:7::4" >
> +        </route>
> +      </network></pre>
> +
>      <h3><a name="examplesPrivate">Isolated network config</a></h3>
>  
>      <p>
> diff --git a/docs/schemas/network.rng b/docs/schemas/network.rng
> index 493edae..ded8580 100644
> --- a/docs/schemas/network.rng
> +++ b/docs/schemas/network.rng
> @@ -316,6 +316,28 @@
>              </optional>
>            </element>
>          </zeroOrMore>
> +        <!-- <route> element -->
> +        <zeroOrMore>
> +          <!-- The (static) route element specifies a network address and gateway
> +               address to access that network. Both the network address and
> +               the gateway address must be specified. -->
> +          <element name="route">
> +            <optional>
> +              <attribute name="family"><ref name="addr-family"/></attribute>
> +            </optional>
> +            <attribute name="address"><ref name="ipAddr"/></attribute>
> +            <optional>
> +              <choice>
> +                <attribute name="netmask"><ref name="ipv4Addr"/></attribute>
> +                <attribute name="prefix"><ref name="ipPrefix"/></attribute>
> +              </choice>
> +            </optional>
> +            <attribute name="gateway"><ref name="ipAddr"/></attribute>
> +            <optional>
> +              <attribute name="metric"><ref name="unsignedInt"/></attribute>
> +            </optional>
> +          </element>
> +        </zeroOrMore>
>        </interleave>
>      </element>
>    </define>
> diff --git a/src/conf/network_conf.c b/src/conf/network_conf.c
> index 8abfa53..12ac879 100644
> --- a/src/conf/network_conf.c
> +++ b/src/conf/network_conf.c
> @@ -143,6 +143,12 @@ virNetworkIpDefClear(virNetworkIpDefPtr def)
>  }
>  
>  static void
> +virNetworkRouteDefClear(virNetworkRouteDefPtr def)
> +{
> +    VIR_FREE(def->family);
> +}
> +
> +static void
>  virNetworkDNSTxtDefClear(virNetworkDNSTxtDefPtr def)
>  {
>      VIR_FREE(def->name);
> @@ -221,6 +227,11 @@ virNetworkDefFree(virNetworkDefPtr def)
>      }
>      VIR_FREE(def->ips);
>  
> +    for (ii = 0 ; ii < def->nroutes && def->routes ; ii++) {
> +        virNetworkRouteDefClear(&def->routes[ii]);
> +    }
> +    VIR_FREE(def->routes);
> +
>      for (ii = 0; ii < def->nPortGroups && def->portGroups; ii++) {
>          virPortGroupDefClear(&def->portGroups[ii]);
>      }
> @@ -1270,6 +1281,219 @@ cleanup:
>  }
>  
>  static int
> +virNetworkRouteDefParseXML(const char *networkName,
> +                           xmlNodePtr node,
> +                           xmlXPathContextPtr ctxt,
> +                           virNetworkRouteDefPtr def)
> +{
> +    /*
> +     * virNetworkRouteDef object is already allocated as part
> +     * of an array.  On failure clear: it out, but don't free it.
> +     */
> +
> +    xmlNodePtr save;
> +    char *address = NULL, *netmask = NULL;
> +    char *gateway = NULL;
> +    unsigned long prefix = 0, metric = 0;
> +    int result = -1;
> +    int prefixRc, metricRc;
> +    virSocketAddr testAddr;
> +
> +    save = ctxt->node;
> +    ctxt->node = node;
> +
> +    /* grab raw data from XML */
> +    def->family = virXPathString("string(./@family)", ctxt);
> +    address = virXPathString("string(./@address)", ctxt);
> +    netmask = virXPathString("string(./@netmask)", ctxt);
> +    gateway = virXPathString("string(./@gateway)", ctxt);
> +    prefixRc = virXPathULong("string(./@prefix)", ctxt, &prefix);
> +    if (prefixRc == -2) {
> +        virReportError(VIR_ERR_XML_ERROR,
> +                       _("Invalid prefix specified "
> +                         "in route definition of network '%s'"),
> +                       networkName);
> +        goto cleanup;
> +    }
> +    def->has_prefix = (prefixRc == 0);
> +    def->prefix = prefix;
> +    metricRc = virXPathULong("string(./@metric)", ctxt, &metric);
> +    if (metricRc == -2) {
> +        virReportError(VIR_ERR_XML_ERROR,
> +                       _("Invalid metric specified "
> +                         "in route definition of network '%s'"),
> +                       networkName);
> +        goto cleanup;
> +    }
> +    def->has_metric = (metricRc == 0);
> +    def->metric = metric;
> +
> +    /* Note: both network and gateway addresses must be specified */
> +
> +    if (!address) {
> +        virReportError(VIR_ERR_XML_ERROR,
> +                       _("Missing required address attribute "
> +                         "in route definition of network '%s'"),
> +                       networkName);
> +        goto cleanup;
> +    }
> +
> +    if (!gateway) {
> +        virReportError(VIR_ERR_XML_ERROR,
> +                       _("Missing required gateway attribute "
> +                         "in route definition of network '%s'"),
> +                       networkName);
> +        goto cleanup;
> +    }
> +
> +    if (virSocketAddrParse(&def->address, address, AF_UNSPEC) < 0) {
> +        virReportError(VIR_ERR_XML_ERROR,
> +                       _("Bad network address '%s' "
> +                         "in route definition of network '%s'"),
> +                       address, networkName);
> +        goto cleanup;
> +    }
> +
> +    if (virSocketAddrParse(&def->gateway, gateway, AF_UNSPEC) < 0) {
> +        virReportError(VIR_ERR_XML_ERROR,
> +                       _("Bad gateway address '%s' "
> +                         "in route definition of network '%s'"),
> +                       gateway, networkName);
> +        goto cleanup;
> +    }
> +
> +    /* validate network address, etc. for each family */
> +    if ((def->family == NULL) || (STREQ(def->family, "ipv4"))) {
> +        if (!(VIR_SOCKET_ADDR_IS_FAMILY(&def->address, AF_INET) ||
> +              VIR_SOCKET_ADDR_IS_FAMILY(&def->address, AF_UNSPEC))) {
> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,


This should be VIR_ERR_XML_ERROR. CONFIG_UNSUPPORTED is reserved for
cases where a configuration is theoretically okay, but this particular
driver doesn't support it. Same comment applies for all the other uses
of VIR_ERR_CONFIG_UNSUPPORTED in this patch.


> +                           _("%s family specified for non-IPv4 address '%s' "
> +                             "in route definition of network '%s'"),
> +                           def->family == NULL? "no" : "ipv4",
> +                           address, networkName);
> +            goto cleanup;
> +        }
> +        if (!VIR_SOCKET_ADDR_IS_FAMILY(&def->gateway, AF_INET)) {
> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                           _("%s family specified for non-IPv4 gateway '%s' "
> +                             "in route definition of network '%s'"),
> +                           def->family == NULL? "no" : "ipv4",
> +                           address, networkName);
> +            goto cleanup;
> +        }
> +        if (netmask) {
> +            if (virSocketAddrParse(&def->netmask, netmask, AF_UNSPEC) < 0) {
> +                virReportError(VIR_ERR_XML_ERROR,
> +                               _("Bad netmask address '%s' "
> +                                 "in route definition of network '%s'"),
> +                               netmask, networkName);
> +                goto cleanup;
> +            }
> +            if (!VIR_SOCKET_ADDR_IS_FAMILY(&def->netmask, AF_INET)) {
> +                virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                               _("network '%s' has invalid netmask '%s' "
> +                                 "for address '%s' (both must be IPv4)"),
> +                               networkName, netmask, address);
> +                goto cleanup;
> +            }
> +            if (def->has_prefix) {
> +                /* can't have both netmask and prefix at the same time */
> +                virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                               _("route definition '%s' cannot have both "
> +                                 "a prefix and a netmask"),
> +                               networkName);
> +                goto cleanup;
> +            }
> +        }
> +        if (def->prefix > 32) {
> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                           _("Invalid IPv4 prefix %u for '%s' specified "
> +                             "in route definition of network '%s'"),
> +                           def->prefix,
> +                           def->family == NULL? "no" : "ipv4", networkName);


This should really just say "Invalid prefix %u specified in route
definition of network '%s'".


> +            goto cleanup;
> +        }
> +    } else if (STREQ(def->family, "ipv6")) {
> +        if (!VIR_SOCKET_ADDR_IS_FAMILY(&def->address, AF_INET6)) {
> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                           _("ipv6 family specified for non-IPv6 address '%s' "
> +                             "in route definition of network '%s'"),
> +                           address, networkName);
> +            goto cleanup;
> +        }
> +        if (netmask) {
> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                           _("specifying netmask invalid for IPv6 address '%s' "
> +                             "in route definition of network '%s'"),
> +                           address, networkName);
> +            goto cleanup;
> +        }
> +        if (!VIR_SOCKET_ADDR_IS_FAMILY(&def->gateway, AF_INET6)) {
> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                           _("ipv6 specified for non-IPv6 gateway address '%s' "
> +                             "in route definition of network '%s'"),
> +                           gateway, networkName);
> +            goto cleanup;
> +        }
> +        if (def->prefix > 128) {
> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                           _("Invalid IPv6 prefix %u for '%s' specified "
> +                             "in route definition of network '%s'"),
> +                           def->prefix, def->family, networkName);


This one should also be simplified.


> +            goto cleanup;
> +        }
> +    } else {
> +        virReportError(VIR_ERR_XML_ERROR,
> +                       _("Unrecognized family '%s' "
> +                         "in route definition of network'%s'"),
> +                       def->family, networkName);
> +        goto cleanup;
> +    }
> +
> +    /* make sure the address is a network address */
> +    if (netmask) {
> +        if (virSocketAddrMask(&def->address, &def->netmask, &testAddr) < 0) {
> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,

This is an INTERNAL error - we've already validated address and netmask,
and assured that both of them are IPv4, so there shouldn't be any reason
for this to fail.

> +                           _("error converting address '%s' with netmask '%s' "
> +                             "to network-address "
> +                             "in route definition of network '%s'"),
> +                           address, netmask, networkName);
> +            goto cleanup;
> +        }
> +    } else {
> +        if (virSocketAddrMaskByPrefix(&def->address,
> +                                      def->prefix, &testAddr) < 0) {
> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,

This is also INTERNAL.

> +                           _("error converting address '%s' with prefix %u "
> +                             "to network-address "
> +                             "in route definition of network '%s'"),
> +                           address, def->prefix, networkName);
> +            goto cleanup;
> +        }
> +    }
> +    if (!virSocketAddrEqual(&def->address, &testAddr)) {
> +        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                       _("address '%s' in route definition of network '%s' "
> +                         "is not a network address"),
> +                       address, networkName);
> +        goto cleanup;
> +    }
> +
> +    result = 0;
> +
> +cleanup:
> +    if (result < 0) {
> +        virNetworkRouteDefClear(def);
> +    }
> +    VIR_FREE(address);
> +    VIR_FREE(netmask);
> +    VIR_FREE(gateway);
> +
> +    ctxt->node = save;
> +    return result;
> +}
> +
> +static int
>  virNetworkPortGroupParseXML(virPortGroupDefPtr def,
>                              xmlNodePtr node,
>                              xmlXPathContextPtr ctxt)
> @@ -1684,8 +1908,9 @@ virNetworkDefParseXML(xmlXPathContextPtr ctxt)
>      char *tmp;
>      char *stp = NULL;
>      xmlNodePtr *ipNodes = NULL;
> +    xmlNodePtr *routeNodes = NULL;
>      xmlNodePtr *portGroupNodes = NULL;
> -    int nIps, nPortGroups;
> +    int nIps, nPortGroups, nRoutes;
>      xmlNodePtr dnsNode = NULL;
>      xmlNodePtr virtPortNode = NULL;
>      xmlNodePtr forwardNode = NULL;
> @@ -1839,6 +2064,68 @@ virNetworkDefParseXML(xmlXPathContextPtr ctxt)
>      }
>      VIR_FREE(ipNodes);
>  
> +    nRoutes = virXPathNodeSet("./route", ctxt, &routeNodes);
> +    if (nRoutes < 0)
> +        goto error;
> +
> +    if (nRoutes > 0) {
> +        int ii;
> +
> +        /* allocate array to hold all the route definitions */
> +        if (VIR_ALLOC_N(def->routes, nRoutes) < 0) {
> +            virReportOOMError();
> +            goto error;
> +        }
> +        /* parse each definition */
> +        for (ii = 0; ii < nRoutes; ii++) {
> +            int ret = virNetworkRouteDefParseXML(def->name, routeNodes[ii],
> +                                              ctxt, &def->routes[ii]);
> +            if (ret < 0)
> +                goto error;
> +            def->nroutes++;
> +        }
> +
> +        /* now validate the correctness of any static route gateways specified
> +         *
> +         * note: the parameters within each definition are verified/assumed valid;
> +         * the question being asked and answered here is if the specified gateway
> +         * is directly reachable from this bridge.
> +         */
> +        nRoutes = def->nroutes;
> +        nIps = def->nips;
> +        for (ii = 0; ii < nRoutes; ii++) {
> +            int jj;
> +            virSocketAddr testAddr, testGw;
> +            bool addrMatch;
> +            virNetworkRouteDefPtr gwdef = &def->routes[ii];
> +            addrMatch = false;
> +            for (jj = 0; jj < nIps; jj++) {
> +                virNetworkIpDefPtr def2 = &def->ips[jj];
> +                if (VIR_SOCKET_ADDR_FAMILY(&gwdef->gateway)
> +                    != VIR_SOCKET_ADDR_FAMILY(&def2->address)) {
> +                    continue;
> +                }
> +                int prefix = virNetworkIpDefPrefix(def2);
> +                virSocketAddrMaskByPrefix(&def2->address, prefix, &testAddr);
> +                virSocketAddrMaskByPrefix(&gwdef->gateway, prefix, &testGw);
> +                if (VIR_SOCKET_ADDR_VALID(&testAddr) &&
> +                    VIR_SOCKET_ADDR_VALID(&testGw) &&
> +                    virSocketAddrEqual(&testAddr, &testGw)) {
> +                    addrMatch = true;
> +                    break;
> +                }
> +            }
> +            if (!addrMatch) {
> +                char *gw = virSocketAddrFormat(&gwdef->gateway);
> +                virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                               _("unreachable static route gateway '%s' specified for network '%s'"),
> +                               gw, def->name);
> +                VIR_FREE(gw);
> +                goto error;
> +            }
> +        }
> +    }
> +

Hmm. routeNodes is freed in the error case, but not in the normal case.
Following the pattern of the rest of this function, you would need a
VIR_FREE(routeNodes) right here.


>      forwardNode = virXPathNode("./forward", ctxt);
>      if (forwardNode &&
>          virNetworkForwardDefParseXML(def->name, forwardNode, ctxt, &def->forward) < 0) {
> @@ -1911,6 +2198,7 @@ virNetworkDefParseXML(xmlXPathContextPtr ctxt)
>      return def;
>  
>  error:
> +    VIR_FREE(routeNodes);
>      VIR_FREE(stp);
>      virNetworkDefFree(def);
>      VIR_FREE(ipNodes);
> @@ -2136,6 +2424,51 @@ error:
>  }
>  
>  static int
> +virNetworkRouteDefFormat(virBufferPtr buf,
> +                      const virNetworkRouteDefPtr def)
> +{
> +    int result = -1;
> +
> +    virBufferAddLit(buf, "<route");
> +
> +    if (def->family) {
> +        virBufferAsprintf(buf, " family='%s'", def->family);
> +    }
> +    if (VIR_SOCKET_ADDR_VALID(&def->address)) {
> +        char *addr = virSocketAddrFormat(&def->address);
> +        if (!addr)
> +            goto error;
> +        virBufferAsprintf(buf, " address='%s'", addr);
> +        VIR_FREE(addr);
> +    }
> +    if (VIR_SOCKET_ADDR_VALID(&def->netmask)) {
> +        char *addr = virSocketAddrFormat(&def->netmask);
> +        if (!addr)
> +            goto error;
> +        virBufferAsprintf(buf, " netmask='%s'", addr);
> +        VIR_FREE(addr);
> +    }
> +    if (def->has_prefix) {
> +        virBufferAsprintf(buf," prefix='%u'", def->prefix);
> +    }
> +    if (VIR_SOCKET_ADDR_VALID(&def->gateway)) {
> +        char *addr = virSocketAddrFormat(&def->gateway);
> +        if (!addr)
> +            goto error;
> +        virBufferAsprintf(buf, " gateway='%s'", addr);
> +        VIR_FREE(addr);
> +    }
> +    if (def->has_metric && def->metric > 0) {
> +        virBufferAsprintf(buf," metric='%u'", def->metric);
> +    }

Ah yes - since a metric of 0 isn't allowed (it's reserved for direct
routes), we need to check for that in the parser.

> +    virBufferAddLit(buf, "/>\n");
> +
> +    result = 0;
> +error:
> +    return result;
> +}
> +
> +static int
>  virPortGroupDefFormat(virBufferPtr buf,
>                        const virPortGroupDefPtr def)
>  {
> @@ -2347,6 +2680,11 @@ virNetworkDefFormatInternal(virBufferPtr buf,
>              goto error;
>      }
>  
> +    for (ii = 0; ii < def->nroutes; ii++) {
> +        if (virNetworkRouteDefFormat(buf, &def->routes[ii]) < 0)
> +            goto error;
> +    }
> +
>      if (virNetDevVPortProfileFormat(def->virtPortProfile, buf) < 0)
>          goto error;
>  
> diff --git a/src/conf/network_conf.h b/src/conf/network_conf.h
> index e187f05..43f80d4 100644
> --- a/src/conf/network_conf.h
> +++ b/src/conf/network_conf.h
> @@ -149,6 +149,25 @@ struct _virNetworkIpDef {
>      virSocketAddr bootserver;
>     };
>  
> +typedef struct _virNetworkRouteDef virNetworkRouteDef;
> +typedef virNetworkRouteDef *virNetworkRouteDefPtr;
> +struct _virNetworkRouteDef {
> +    char *family;               /* ipv4 or ipv6 - default is ipv4 */
> +    virSocketAddr address;      /* Routed Network IP address */
> +
> +    /* One or the other of the following two will be used for a given
> +     * Network address, but never both. The parser guarantees this.
> +     * The virSocketAddrGetIpPrefix() can be used to get a
> +     * valid prefix.
> +     */
> +    virSocketAddr netmask;      /* ipv4 - either netmask or prefix specified */
> +    unsigned int prefix;        /* ipv6 - only prefix allowed */
> +    bool has_prefix;            /* prefix= was specified */
> +    unsigned int metric;        /* value for metric (defaults to 1) */
> +    bool has_metric;            /* metric= was specified */


It's good that you duplicated the has_* idea for this.


> +    virSocketAddr gateway;      /* gateway IP address for ip-route */
> +   };
> +
>  typedef struct _virNetworkForwardIfDef virNetworkForwardIfDef;
>  typedef virNetworkForwardIfDef *virNetworkForwardIfDefPtr;
>  struct _virNetworkForwardIfDef {
> @@ -224,6 +243,9 @@ struct _virNetworkDef {
>      size_t nips;
>      virNetworkIpDefPtr ips; /* ptr to array of IP addresses on this network */
>  
> +    size_t nroutes;
> +    virNetworkRouteDefPtr routes; /* ptr to array of static routes on this interface */
> +
>      virNetworkDNSDef dns;   /* dns related configuration */
>      virNetDevVPortProfilePtr virtPortProfile;
>  
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index d4cb4a3..dfa4779 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -1463,6 +1463,7 @@ virMacAddrSetRaw;
>  
>  
>  # util/virnetdev.h
> +virNetDevAddRoute;
>  virNetDevClearIPv4Address;
>  virNetDevExists;
>  virNetDevGetIndex;
> diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c
> index 9c5a8ae..4392e20 100644
> --- a/src/network/bridge_driver.c
> +++ b/src/network/bridge_driver.c
> @@ -2391,6 +2391,7 @@ out:
>      return ret;
>  }
>  
> +/* add an IP address to a bridge */
>  static int
>  networkAddAddrToBridge(virNetworkObjPtr network,
>                         virNetworkIpDefPtr ipdef)
> @@ -2411,6 +2412,55 @@ networkAddAddrToBridge(virNetworkObjPtr network,
>      return 0;
>  }
>  
> +/* add an IP (static) route to a bridge */
> +static int
> +networkAddRouteToBridge(virNetworkObjPtr network,
> +                        virNetworkRouteDefPtr routedef)
> +{
> +    int prefix = 0;
> +    unsigned int metric;
> +    virSocketAddrPtr addr = &routedef->address;
> +    virSocketAddrPtr mask = &routedef->netmask;
> +    virSocketAddr zero;
> +
> +    /* this creates an all-0 address of the appropriate family */
> +    ignore_value(virSocketAddrParse(&zero,
> +                                    (VIR_SOCKET_ADDR_IS_FAMILY(addr,AF_INET)
> +                                     ? "0.0.0.0" : "::"),
> +                                    VIR_SOCKET_ADDR_FAMILY(addr)));
> +
> +    if (virSocketAddrEqual(addr, &zero)) {
> +        if (routedef->has_prefix && routedef->prefix == 0)
> +            prefix = 0;
> +        else if ((VIR_SOCKET_ADDR_IS_FAMILY(mask, AF_INET) &&
> +                virSocketAddrEqual(mask, &zero)))
> +            prefix = 0;
> +        else
> +            prefix = virSocketAddrGetIpPrefix(addr, mask, routedef->prefix);
> +    } else {
> +        prefix = virSocketAddrGetIpPrefix(addr, mask, routedef->prefix);
> +    }


Much simpler! :-)


> +
> +    if (prefix < 0) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR,
> +                       _("network '%s' has an invalid netmask "
> +                         "or IP address in route definition"),
> +                       network->def->name);
> +        return -1;
> +    }
> +
> +    if (routedef->has_metric && routedef->metric > 0)
> +        metric = routedef->metric;
> +    else
> +        metric = 1;
> +
> +    if (virNetDevAddRoute(network->def->bridge, &routedef->address,
> +                          prefix, &routedef->gateway, metric) < 0) {
> +        return -1;
> +    }
> +    return 0;
> +}
> +
>  static int
>  networkStartNetworkVirtual(struct network_driver *driver,
>                            virNetworkObjPtr network)
> @@ -2419,6 +2469,7 @@ networkStartNetworkVirtual(struct network_driver *driver,
>      bool v4present = false, v6present = false;
>      virErrorPtr save_err = NULL;
>      virNetworkIpDefPtr ipdef;
> +    virNetworkRouteDefPtr routedef;
>      char *macTapIfName = NULL;
>      int tapfd = -1;
>  
> @@ -2495,6 +2546,19 @@ networkStartNetworkVirtual(struct network_driver *driver,
>      if (virNetDevSetOnline(network->def->bridge, 1) < 0)
>          goto err2;
>  
> +    for (ii = 0; ii < network->def->nroutes; ii++) {
> +        routedef = &network->def->routes[ii];
> +        /* Add the IP route to the bridge */
> +        /* ignore errors, error msg will be generated */
> +        /* but libvirt will not know and net-destroy will work. */
> +        if (VIR_SOCKET_ADDR_VALID(&routedef->gateway)) {
> +            if (networkAddRouteToBridge(network, routedef) < 0) {
> +                /* an error occurred adding the static route */
> +                continue; /* for now, do nothing */
> +            }
> +        }
> +    }
> +
>      /* If forward.type != NONE, turn on global IP forwarding */
>      if (network->def->forward.type != VIR_NETWORK_FORWARD_NONE &&
>          networkEnableIpForwarding(v4present, v6present) < 0) {
> diff --git a/src/util/virnetdev.c b/src/util/virnetdev.c
> index d987b8e..01aaff1 100644
> --- a/src/util/virnetdev.c
> +++ b/src/util/virnetdev.c
> @@ -783,6 +783,52 @@ cleanup:
>  }
>  
>  /**
> + * virNetDevSetGateway:


Oops. Forgot to change the name.


> + * @ifname: the interface name
> + * @addr: the IP network address (IPv4 or IPv6)
> + * @prefix: number of 1 bits in the netmask
> + * @gateway: via address for route (same as @addr)
> + *
> + * Add a route for a network IP address to an interface. This function
> + * *does not* remove any previously added IP static routes.
> + *
> + * Returns 0 in case of success or -1 in case of error.
> + */
> +
> +int
> +virNetDevAddRoute(const char *ifname,
> +                  virSocketAddrPtr addr,
> +                  unsigned int prefix,
> +                  virSocketAddrPtr gateway,
> +                  unsigned int metric)
> +{
> +    virCommandPtr cmd = NULL;
> +    char *addrstr = NULL, *gatewaystr = NULL;
> +    int ret = -1;
> +
> +    if (!(addrstr = virSocketAddrFormat(addr)))
> +        goto cleanup;
> +    if (!(gatewaystr = virSocketAddrFormat(gateway)))
> +        goto cleanup;
> +    cmd = virCommandNew(IP_PATH);
> +    virCommandAddArgList(cmd, "route", "add", NULL);
> +    virCommandAddArgFormat(cmd, "%s/%u", addrstr, prefix);
> +    virCommandAddArgList(cmd, "via", gatewaystr, "dev", ifname,
> +                              "proto", "static", "metric", NULL);
> +    virCommandAddArgFormat(cmd, "%u", metric);
> +
> +    if (virCommandRun(cmd, NULL) < 0)
> +        goto cleanup;
> +
> +    ret = 0;
> +cleanup:
> +    VIR_FREE(addrstr);
> +    VIR_FREE(gatewaystr);
> +    virCommandFree(cmd);
> +    return ret;
> +}
> +
> +/**
>   * virNetDevClearIPv4Address:
>   * @ifname: the interface name
>   * @addr: the IP address (IPv4 or IPv6)
> diff --git a/src/util/virnetdev.h b/src/util/virnetdev.h
> index 551ea22..0b394ad 100644
> --- a/src/util/virnetdev.h
> +++ b/src/util/virnetdev.h
> @@ -42,6 +42,13 @@ int virNetDevSetIPv4Address(const char *ifname,
>                              virSocketAddr *addr,
>                              unsigned int prefix)
>      ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_RETURN_CHECK;
> +int virNetDevAddRoute(const char *ifname,
> +                      virSocketAddrPtr addr,
> +                      unsigned int prefix,
> +                      virSocketAddrPtr gateway,
> +                      unsigned int metric)
> +    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(4)
> +    ATTRIBUTE_NONNULL(5) ATTRIBUTE_RETURN_CHECK;
>  int virNetDevClearIPv4Address(const char *ifname,
>                                virSocketAddr *addr,
>                                unsigned int prefix)
> diff --git a/tests/networkxml2xmlin/dhcp6host-routed-network.xml b/tests/networkxml2xmlin/dhcp6host-routed-network.xml
> index 2693d87..40f6dfe 100644
> --- a/tests/networkxml2xmlin/dhcp6host-routed-network.xml
> +++ b/tests/networkxml2xmlin/dhcp6host-routed-network.xml
> @@ -19,4 +19,6 @@
>        <host id='0:1:0:1:18:aa:62:fe:0:16:3e:44:55:66' name='badbob' ip='2001:db8:ac10:fd01::1:24' />
>      </dhcp>
>    </ip>
> +  <route address="192.168.222.0" netmask="255.255.255.0" gateway="192.168.122.10"/>
> +  <route family="ipv6" address="2001:db8:ac10:fc00::" prefix="64" gateway="2001:db8:ac10:fd01::1:24"/>
>  </network>
> diff --git a/tests/networkxml2xmlout/dhcp6host-routed-network.xml b/tests/networkxml2xmlout/dhcp6host-routed-network.xml
> index 1d3035b..fc8666b 100644
> --- a/tests/networkxml2xmlout/dhcp6host-routed-network.xml
> +++ b/tests/networkxml2xmlout/dhcp6host-routed-network.xml
> @@ -21,4 +21,6 @@
>        <host id='0:1:0:1:18:aa:62:fe:0:16:3e:44:55:66' name='badbob' ip='2001:db8:ac10:fd01::1:24' />
>      </dhcp>
>    </ip>
> +  <route address='192.168.222.0' netmask='255.255.255.0' gateway='192.168.122.10'/>
> +  <route family='ipv6' address='2001:db8:ac10:fc00::' prefix='64' gateway='2001:db8:ac10:fd01::1:24'/>
>  </network>


ACK with the above nits fixed. I have fixed them all (see attached
interdiff) and pushed.

Thanks for the contribution!

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