[ovs-dev] [PATCH V2] bfd: Allow users to set local/remote src/dst MAC address.

[Alex Wang]

This commit adds options for configuring the MAC addresses
in BFD state machine.  Therein, the "bfd_local_src_mac" and
"bfd_local_dst_mac" configure the MAC address of sent BFD
packets.  The "bfd_remote_dst_mac" configure the matching
of MAC address on recevied BFD packets.

Signed-off-by: Alex Wang <alexw at nicira.com>

---
PATCH -> V2:
- simplify the code.
---
 lib/bfd.c            |   47 +++++++++++++++++++++++++++++++++--------------
 vswitchd/vswitch.xml |   23 +++++++++++++++++++----
 2 files changed, 52 insertions(+), 18 deletions(-)

diff --git a/lib/bfd.c b/lib/bfd.c
index 9069582..5c86451 100644
--- a/lib/bfd.c
+++ b/lib/bfd.c
@@ -169,8 +169,10 @@ struct bfd {
 
     uint32_t rmt_disc;            /* bfd.RemoteDiscr. */
 
-    uint8_t eth_dst[ETH_ADDR_LEN];/* Ethernet destination address. */
-    bool eth_dst_set;             /* 'eth_dst' set through database. */
+    uint8_t local_eth_src[ETH_ADDR_LEN]; /* Local eth src address. */
+    uint8_t local_eth_dst[ETH_ADDR_LEN]; /* Local eth dst address. */
+
+    uint8_t rmt_eth_dst[ETH_ADDR_LEN];   /* Remote eth dst address. */
 
     ovs_be32 ip_src;              /* IPv4 source address. */
     ovs_be32 ip_dst;              /* IPv4 destination address. */
@@ -388,8 +390,6 @@ bfd_configure(struct bfd *bfd, const char *name, const struct smap *cfg,
 
         bfd_set_state(bfd, STATE_DOWN, DIAG_NONE);
 
-        memcpy(bfd->eth_dst, eth_addr_bfd, ETH_ADDR_LEN);
-
         bfd_status_changed(bfd);
     }
 
@@ -440,13 +440,25 @@ bfd_configure(struct bfd *bfd, const char *name, const struct smap *cfg,
         need_poll = true;
     }
 
-    hwaddr = smap_get(cfg, "bfd_dst_mac");
-    if (hwaddr && eth_addr_from_string(hwaddr, ea) && !eth_addr_is_zero(ea)) {
-        memcpy(bfd->eth_dst, ea, ETH_ADDR_LEN);
-        bfd->eth_dst_set = true;
-    } else if (bfd->eth_dst_set) {
-        memcpy(bfd->eth_dst, eth_addr_bfd, ETH_ADDR_LEN);
-        bfd->eth_dst_set = false;
+    hwaddr = smap_get(cfg, "bfd_local_src_mac");
+    if (hwaddr && eth_addr_from_string(hwaddr, ea)) {
+        memcpy(bfd->local_eth_src, ea, ETH_ADDR_LEN);
+    } else {
+        memset(bfd->local_eth_src, 0, ETH_ADDR_LEN);
+    }
+
+    hwaddr = smap_get(cfg, "bfd_local_dst_mac");
+    if (hwaddr && eth_addr_from_string(hwaddr, ea)) {
+        memcpy(bfd->local_eth_dst, ea, ETH_ADDR_LEN);
+    } else {
+        memset(bfd->local_eth_dst, 0, ETH_ADDR_LEN);
+    }
+
+    hwaddr = smap_get(cfg, "bfd_remote_dst_mac");
+    if (hwaddr && eth_addr_from_string(hwaddr, ea)) {
+        memcpy(bfd->rmt_eth_dst, ea, ETH_ADDR_LEN);
+    } else {
+        memset(bfd->rmt_eth_dst, 0, ETH_ADDR_LEN);
     }
 
     ip_src = smap_get(cfg, "bfd_src_ip");
@@ -600,8 +612,14 @@ bfd_put_packet(struct bfd *bfd, struct ofpbuf *p,
 
     ofpbuf_reserve(p, 2); /* Properly align after the ethernet header. */
     eth = ofpbuf_put_uninit(p, sizeof *eth);
-    memcpy(eth->eth_src, eth_src, ETH_ADDR_LEN);
-    memcpy(eth->eth_dst, bfd->eth_dst, ETH_ADDR_LEN);
+    memcpy(eth->eth_src,
+           eth_addr_is_zero(bfd->local_eth_src) ? eth_src
+                                                : bfd->local_eth_src,
+           ETH_ADDR_LEN);
+    memcpy(eth->eth_dst,
+           eth_addr_is_zero(bfd->local_eth_dst) ? eth_addr_bfd
+                                                : bfd->local_eth_dst,
+           ETH_ADDR_LEN);
     eth->eth_type = htons(ETH_TYPE_IP);
 
     ip = ofpbuf_put_zeros(p, sizeof *ip);
@@ -657,7 +675,8 @@ bfd_should_process_flow(const struct bfd *bfd_, const struct flow *flow,
     bool check_tnl_key;
 
     memset(&wc->masks.dl_dst, 0xff, sizeof wc->masks.dl_dst);
-    if (bfd->eth_dst_set && memcmp(bfd->eth_dst, flow->dl_dst, ETH_ADDR_LEN)) {
+    if (!eth_addr_is_zero(bfd->rmt_eth_dst)
+        && memcmp(bfd->rmt_eth_dst, flow->dl_dst, ETH_ADDR_LEN)) {
         return false;
     }
 
diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
index bff8fb6..ff9be17 100644
--- a/vswitchd/vswitch.xml
+++ b/vswitchd/vswitch.xml
@@ -2081,12 +2081,27 @@
           tunnel key.
 	</column>
 
-	<column name="bfd" key="bfd_dst_mac">
+	<column name="bfd" key="bfd_local_src_mac">
 	  Set to an Ethernet address in the form
 	  <var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>
-	  to set the MAC used as destination for transmitted BFD packets and
-	  expected as destination for received BFD packets.  The default is
-	  <code>00:23:20:00:00:01</code>.
+	  to set the MAC used as source for transmitted BFD packets.  The
+	  default is the mac address of the BFD enabled interface.
+	</column>
+
+	<column name="bfd" key="bfd_local_dst_mac">
+	  Set to an Ethernet address in the form
+	  <var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>
+	  to set the MAC used as destination for transmitted BFD packets.  The
+	  default is <code>00:23:20:00:00:01</code>.
+	</column>
+
+	<column name="bfd" key="bfd_remoe_dst_mac">
+	  Set to an Ethernet address in the form
+	  <var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>
+	  to set the MAC used for checking the destination of received BFD packets.
+	  Packets with different destination MAC will not be considered as BFD packets.
+	  If not specified the destination MAC address of received BFD packets
+	  are not checked.
 	</column>
 
 	<column name="bfd" key="bfd_src_ip">
-- 
1.7.9.5