ovn-northd: support IPAM with externally specified MAC

The current IPAM implementation allocates both a MAC address and
an IPv4 address when dynamic address allocation is requested. This
patch adds the ability to specify a fixed MAC address for use with
dynamic IPv4 address allocation.

Example:
   ovn-nbctl lsp-set-addresses p1 "00:01:02:03:04:05 dynamic"

Acked-by: Ben Pfaff <blp@ovn.org>
Acked-by: Russell Bryant <russell@ovn.org>
Signed-off-by: Lance Richardson <lrichard@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>

NEWS

@@ -3,6 +3,7 @@ Post-v2.6.0
    - OVN:
      * QoS is now implemented via egress shaping rather than ingress policing.
      * DSCP marking is now supported, via the new northbound QoS table.
+     * IPAM now supports fixed MAC addresses.
    - Fixed regression in table stats maintenance introduced in OVS
      2.3.0, wherein the number of OpenFlow table hits and misses was
      not accurate.

ovn/lib/ovn-util.c

@@ -62,6 +62,26 @@ add_ipv6_netaddr(struct lport_addresses *laddrs, struct in6_addr addr,
     inet_ntop(AF_INET6, &na->network, na->network_s, sizeof na->network_s);
 }
 
+/* Returns true if specified address specifies a dynamic address,
+ * supporting the following formats:
+ *
+ *    "dynamic":
+ *        Both MAC and IP are to be allocated dynamically.
+ *
+ *    "xx:xx:xx:xx:xx:xx dynamic":
+ *        Use specified MAC address, but allocate an IP address
+ *        dynamically.
+ */
+bool
+is_dynamic_lsp_address(const char *address)
+{
+    struct eth_addr ea;
+    int n;
+    return (!strcmp(address, "dynamic")
+            || (ovs_scan(address, ETH_ADDR_SCAN_FMT" dynamic%n",
+                         ETH_ADDR_SCAN_ARGS(ea), &n) && address[n] == '\0'));
+}
+
 /* Extracts the mac, IPv4 and IPv6 addresses from * 'address' which
  * should be of the format 'MAC [IP1 IP2 ..]" where IPn should be a
  * valid IPv4 or IPv6 address and stores them in the 'ipv4_addrs' and

ovn/lib/ovn-util.h

@@ -53,7 +53,7 @@ struct lport_addresses {
     struct ipv6_netaddr *ipv6_addrs;
 };
 
-
+bool is_dynamic_lsp_address(const char *address);
 bool extract_lsp_addresses(const char *address, struct lport_addresses *);
 bool extract_lrp_networks(const struct nbrec_logical_router_port *,
                           struct lport_addresses *);

ovn/northd/ovn-northd.c

@@ -815,7 +815,7 @@ ipam_insert_lsp_addresses(struct ovn_datapath *od, struct ovn_port *op,
                           char *address)
 {
     if (!od || !op || !address || !strcmp(address, "unknown")
-        || !strcmp(address, "dynamic")) {
+        || is_dynamic_lsp_address(address)) {
         return;
     }
 
@@ -940,7 +940,7 @@ ipam_get_unused_ip(struct ovn_datapath *od, uint32_t subnet, uint32_t mask)
 
 static bool
 ipam_allocate_addresses(struct ovn_datapath *od, struct ovn_port *op,
-                        ovs_be32 subnet, ovs_be32 mask)
+                        const char *addrspec, ovs_be32 subnet, ovs_be32 mask)
 {
     if (!od || !op || !op->nbsp) {
         return false;
@@ -952,16 +952,26 @@ ipam_allocate_addresses(struct ovn_datapath *od, struct ovn_port *op,
     }
 
     struct eth_addr mac;
+    bool check_mac;
+    int n = 0;
+
+    if (ovs_scan(addrspec, ETH_ADDR_SCAN_FMT" dynamic%n",
+                 ETH_ADDR_SCAN_ARGS(mac), &n)
+        && addrspec[n] == '\0') {
+        check_mac = true;
+    } else {
         uint64_t mac64 = ipam_get_unused_mac();
         if (!mac64) {
             return false;
         }
         eth_addr_from_uint64(mac64, &mac);
+        check_mac = false;
+    }
 
     /* Add MAC/IP to MACAM/IPAM hmaps if both addresses were allocated
      * successfully. */
     ipam_insert_ip(od, ip, false);
-    ipam_insert_mac(&mac, false);
+    ipam_insert_mac(&mac, check_mac);
 
     char *new_addr = xasprintf(ETH_ADDR_FMT" "IP_FMT,
                                ETH_ADDR_ARGS(mac), IP_ARGS(htonl(ip)));
@@ -1018,9 +1028,10 @@ build_ipam(struct hmap *datapaths, struct hmap *ports)
                 }
 
                 for (size_t j = 0; j < nbsp->n_addresses; j++) {
-                    if (!strcmp(nbsp->addresses[j], "dynamic")
+                    if (is_dynamic_lsp_address(nbsp->addresses[j])
                         && !nbsp->dynamic_addresses) {
-                        if (!ipam_allocate_addresses(od, op, subnet, mask)
+                        if (!ipam_allocate_addresses(od, op,
+                                             nbsp->addresses[j], subnet, mask)
                             || !extract_lsp_addresses(nbsp->dynamic_addresses,
                                             &op->lsp_addrs[op->n_lsp_addrs])) {
                             static struct vlog_rate_limit rl
@@ -1197,7 +1208,7 @@ join_logical_ports(struct northd_context *ctx,
                     if (!strcmp(nbsp->addresses[j], "unknown")) {
                         continue;
                     }
-                    if (!strcmp(nbsp->addresses[j], "dynamic")) {
+                    if (is_dynamic_lsp_address(nbsp->addresses[j])) {
                         if (nbsp->dynamic_addresses) {
                             if (!extract_lsp_addresses(nbsp->dynamic_addresses,
                                             &op->lsp_addrs[op->n_lsp_addrs])) {
@@ -3078,7 +3089,7 @@ build_lswitch_flows(struct hmap *datapaths, struct hmap *ports,
                     ovn_multicast_add(mcgroups, &mc_unknown, op);
                     op->od->has_unknown = true;
                 }
-            } else if (!strcmp(op->nbsp->addresses[i], "dynamic")) {
+            } else if (is_dynamic_lsp_address(op->nbsp->addresses[i])) {
                 if (!op->nbsp->dynamic_addresses
                     || !ovs_scan(op->nbsp->dynamic_addresses,
                             ETH_ADDR_SCAN_FMT, ETH_ADDR_SCAN_ARGS(mac))) {

ovn/ovn-nb.xml

@@ -479,6 +479,35 @@
             column="other_config" key="subnet"/> in the port's <ref
             table="Logical_Switch"/>.
           </dd>
+
+          <dt><code>Ethernet address followed by keyword "dynamic"</code></dt>
+          <dd>
+
+            <p>
+              The keyword <code>dynamic</code> after the MAC address indicates
+              that <code>ovn-northd</code> should choose an unused IPv4 address
+              from the logical port's subnet and store it with the specified
+              MAC in the port's <ref column="dynamic_addresses"/> column.
+              <code>ovn-northd</code> will use the subnet specified in <ref
+              table="Logical_Switch" column="other_config" key="subnet"/> in
+              the port's <ref table="Logical_Switch"/> table.
+            </p>
+
+            <p>
+              Examples:
+            </p>
+
+            <dl>
+              <dt><code>80:fa:5b:06:72:b7 dynamic</code></dt>
+              <dd>
+                This indicates that the logical port owns the specified
+                MAC address and <code>ovn-northd</code> should allocate an
+                unused IPv4 address for the logical port from the corresponding
+                logical switch subnet.
+              </dd>
+            </dl>
+          </dd>
+
         </dl>
       </column>
 
@@ -487,9 +516,9 @@
           Addresses assigned to the logical port by <code>ovn-northd</code>, if
           <code>dynamic</code> is specified in <ref column="addresses"/>.
           Addresses will be of the same format as those that populate the <ref
-          column="addresses"/> column.  Note that these addresses are
+          column="addresses"/> column.  Note that dynamically assigned
-          constructed and managed locally in ovn-northd, so they cannot be
+          addresses are constructed and managed locally in ovn-northd, so they
-          reconstructed in the event that the database is lost.
+          cannot be reconstructed in the event that the database is lost.
         </p>
       </column>
 

tests/ovn.at

@@ -4689,6 +4689,13 @@ AT_CHECK([ovn-nbctl get Logical-Switch-Port p30 dynamic_addresses], [0],
      ["0a:00:00:00:00:20 192.168.1.17"
 ])
 
+# Test static MAC address with dynamically allocated IP
+ovn-nbctl --wait=sb lsp-add sw0 p31 -- lsp-set-addresses p31 \
+"fe:dc:ba:98:76:54 dynamic"
+AT_CHECK([ovn-nbctl get Logical-Switch-Port p31 dynamic_addresses], [0],
+     ["fe:dc:ba:98:76:54 192.168.1.18"
+])
+
 as ovn-sb
 OVS_APP_EXIT_AND_WAIT([ovsdb-server])