map: BR rule lookup update

Update to the MAP rule lookup (in IPv6) based on the rule's source
prefix instead of DMR

Type: improvement

Per RFC, the DMR is allowed to serve multiple MAP Basic Mapping Rules, but this
capability was prevented by the above logic.

Updates to the code include populating a new hash table based on the MAP rule
ip6 prefix and length, changing several functions to reference this new table,
and slight alterations to a few functions regarding pre-lookup bitmasking.

All changes are commented with [dgeist] and are in need of peer review,
especially the bitmask alterations.

An attempt was made at generating an additonal MAP rule in the test_map_br test
harness, but the coding appears very much oriented towards testing just one
rule. I would appreciate suggestions on how to test multi-rule cases.

Issue: VPP-2111
Change-Id: Id1fea280eba625e23cd893575d9b63aac7f48405
Signed-off-by: Dan Geist <dan@polter.net>

1 files changed, 23 insertions, 5 deletions

diff --git a/src/plugins/map/lpm.c b/src/plugins/map/lpm.c
index c0e5bad1417..a2fc3337167 100644
--- a/src/plugins/map/lpm.c
+++ b/src/plugins/map/lpm.c
@@ -28,7 +28,13 @@ masked_address32 (uint32_t addr, uint8_t len)
 static uint64_t
 masked_address64 (uint64_t addr, uint8_t len)
 {
-  return len == 64 ? addr : addr & ~(~0ull >> len);
+  /* This was originally causing non-64-bit masks to not match due to LSB vs
+   * MSB masking (0s at the head of the value) Probably needs some corner case
+   * checking in case my masking logic was off [dgeist]
+   *
+   * return len == 64 ? addr : addr & ~(~0ull >> len);
+   */
+  return len == 64 ? addr : addr & ((1ull << (len)) - 1);
 }
 
 static void
@@ -126,13 +132,25 @@ lpm_128_add (lpm_t *lpm, void *addr_v, u8 pfxlen, u32 value)
   BVT(clib_bihash_kv) kv;
   ip6_address_t *addr = addr_v;
 
-  kv.key[0] = masked_address64(addr->as_u64[0], pfxlen > 64 ? 64 : pfxlen);
+  /* This is a quick hack. It works for pfxlen < 64 but needs validation for
+   * other [dgeist]
+   *
+   * kv.key[0] = masked_address64(addr->as_u64[0], pfxlen > 64 ? 64 : pfxlen);
+   */
+  kv.key[0] = masked_address64 (addr->as_u64[0], pfxlen > 64 ? 64 : 64);
   kv.key[1] = masked_address64(addr->as_u64[1], pfxlen > 64 ? pfxlen - 64 : 0);
   kv.key[2] = pfxlen;
   kv.value = value;
   BV(clib_bihash_add_del)(&lpm->bihash, &kv, 1);
   lpm->prefix_length_refcount[pfxlen]++;
-  lpm->prefix_lengths_bitmap = clib_bitmap_set (lpm->prefix_lengths_bitmap, 128 - pfxlen, 1);
+  /* Populating the lengths bitmap table with prefix of 48 instead of 80
+   * (128 - 48) [dgeist]
+   *
+   * lpm->prefix_lengths_bitmap = clib_bitmap_set (
+   *   lpm->prefix_lengths_bitmap, 128 - pfxlen, 1);
+   */
+  lpm->prefix_lengths_bitmap = clib_bitmap_set (
+    lpm->prefix_lengths_bitmap, pfxlen > 64 ? 128 - pfxlen : pfxlen, 1);
 }
 
 static void
@@ -148,8 +166,8 @@ lpm_128_delete (lpm_t *lpm, void *addr_v, u8 pfxlen)
   /* refcount accounting */
   ASSERT (lpm->prefix_length_refcount[pfxlen] > 0);
   if (--lpm->prefix_length_refcount[pfxlen] == 0) {
-    lpm->prefix_lengths_bitmap = clib_bitmap_set (lpm->prefix_lengths_bitmap, 
-						  128 - pfxlen, 0);
+      lpm->prefix_lengths_bitmap =
+	clib_bitmap_set (lpm->prefix_lengths_bitmap, 128 - pfxlen, 0);
   }
 }