tnl-arp-cache: Add a command to add or modify an ARP cache entry.

This allows the ARP cache to be prepopulated for testing purposes, so
that tests don't lose the first packet to each destination.  (I guess
this feature could have other uses too.)

Signed-off-by: Ben Pfaff <[email protected]>
Acked-by: Andy Zhou <[email protected]>

lib/tnl-arp-cache.c

@@ -30,6 +30,7 @@
 #include "packets.h"
 #include "poll-loop.h"
 #include "seq.h"
+#include "socket-util.h"
 #include "timeval.h"
 #include "tnl-arp-cache.h"
 #include "unaligned.h"
@@ -95,41 +96,46 @@ tnl_arp_delete(struct tnl_arp_entry *arp)
     ovsrcu_postpone(arp_entry_free, arp);
 }
 
-int
-tnl_arp_snoop(const struct flow *flow, struct flow_wildcards *wc,
-              const char name[IFNAMSIZ])
+static void
+tnl_arp_set(const char name[IFNAMSIZ], ovs_be32 dst, const struct eth_addr mac)
 {
-    struct tnl_arp_entry *arp;
-
-    if (flow->dl_type != htons(ETH_TYPE_ARP)) {
-        return EINVAL;
-    }
-
-    /* Exact Match on all ARP flows. */
-    memset(&wc->masks.nw_proto, 0xff, sizeof wc->masks.nw_proto);
-    memset(&wc->masks.nw_src, 0xff, sizeof wc->masks.nw_src);
-    memset(&wc->masks.arp_sha, 0xff, sizeof wc->masks.arp_sha);
-
     ovs_mutex_lock(&mutex);
-    arp = tnl_arp_lookup__(name, flow->nw_src);
+    struct tnl_arp_entry *arp = tnl_arp_lookup__(name, dst);
     if (arp) {
-        if (eth_addr_equals(arp->mac, flow->arp_sha)) {
+        if (eth_addr_equals(arp->mac, mac)) {
             arp->expires = time_now() + ARP_ENTRY_DEFAULT_IDLE_TIME;
             ovs_mutex_unlock(&mutex);
-            return 0;
+            return;
         }
         tnl_arp_delete(arp);
         seq_change(tnl_conf_seq);
     }
 
     arp = xmalloc(sizeof *arp);
 
-    arp->ip = flow->nw_src;
-    arp->mac = flow->arp_sha;
+    arp->ip = dst;
+    arp->mac = mac;
     arp->expires = time_now() + ARP_ENTRY_DEFAULT_IDLE_TIME;
     ovs_strlcpy(arp->br_name, name, sizeof arp->br_name);
     cmap_insert(&table, &arp->cmap_node, (OVS_FORCE uint32_t) arp->ip);
     ovs_mutex_unlock(&mutex);
+}
+
+int
+tnl_arp_snoop(const struct flow *flow, struct flow_wildcards *wc,
+              const char name[IFNAMSIZ])
+{
+    if (flow->dl_type != htons(ETH_TYPE_ARP)) {
+        return EINVAL;
+    }
+
+    /* Exact Match on all ARP flows. */
+    memset(&wc->masks.nw_proto, 0xff, sizeof wc->masks.nw_proto);
+    memset(&wc->masks.nw_src, 0xff, sizeof wc->masks.nw_src);
+    memset(&wc->masks.arp_sha, 0xff, sizeof wc->masks.arp_sha);
+
+    tnl_arp_set(name, flow->nw_src, flow->arp_sha);
+
     return 0;
 }
 
@@ -172,6 +178,28 @@ tnl_arp_cache_flush(struct unixctl_conn *conn, int argc OVS_UNUSED,
     unixctl_command_reply(conn, "OK");
 }
 
+static void
+tnl_arp_cache_add(struct unixctl_conn *conn, int argc OVS_UNUSED,
+                  const char *argv[], void *aux OVS_UNUSED)
+{
+    const char *br_name = argv[1];
+    struct eth_addr mac;
+    struct in_addr ip;
+
+    if (lookup_ip(argv[2], &ip)) {
+        unixctl_command_reply_error(conn, "bad IP address");
+        return;
+    }
+
+    if (!eth_addr_from_string(argv[3], &mac)) {
+        unixctl_command_reply_error(conn, "bad MAC address");
+        return;
+    }
+
+    tnl_arp_set(br_name, ip.s_addr, mac);
+    unixctl_command_reply(conn, "OK");
+}
+
 #define MAX_IP_ADDR_LEN 17
 
 static void
@@ -208,5 +236,6 @@ tnl_arp_cache_init(void)
     cmap_init(&table);
 
     unixctl_command_register("tnl/arp/show", "", 0, 0, tnl_arp_cache_show, NULL);
+    unixctl_command_register("tnl/arp/set", "BRIDGE IP MAC", 3, 3, tnl_arp_cache_add, NULL);
     unixctl_command_register("tnl/arp/flush", "", 0, 0, tnl_arp_cache_flush, NULL);
 }

ofproto/ofproto-tnl-unixctl.man

@@ -18,6 +18,10 @@ Delete ipv4_address/plen route from OVS routing table.
 OVS builds ARP cache by snooping are messages. This command shows
 ARP cache table.
 .
+.IP "\fBtnl/arp/set \fIbridge ip mac\fR"
+Adds or modifies an ARP cache entry in \fIbridge\fR, mapping \fIip\fR
+to \fImac\fR.
+.
 .IP "\fBtnl/arp/flush\fR"
 Flush ARP table.
 .