From 9a74622ca1994669cdb3bac0bb2f6df2febd2744 Mon Sep 17 00:00:00 2001
From: Jan Moskyto Matejka <mq@ucw.cz>
Date: Wed, 10 Feb 2016 13:26:07 +0100
Subject: [PATCH] Updated RTA hashes to 32-bit values.

... and reworked the hashes a bit. Also added mem_hash function
which just computes a hash of given memory block.
---
 lib/hash.h     | 12 ++++++++++++
 nest/route.h   | 18 +++++++++---------
 nest/rt-attr.c | 29 ++++++++++-------------------
 3 files changed, 31 insertions(+), 28 deletions(-)

diff --git a/lib/hash.h b/lib/hash.h
index a73f647a..f4a953a3 100644
--- a/lib/hash.h
+++ b/lib/hash.h
@@ -178,3 +178,15 @@
 
 #define HASH_WALK_FILTER_END } while (0)
 
+static inline uint
+mem_hash(void *p, int s)
+{
+  const char *pp = p;
+  const u64 multiplier = 0xb38bc09a61202731ULL;
+  u64 value = 0x001047d54778bcafULL;
+  for (int i=0;i<s;i++)
+    value = value*multiplier + pp[i];
+
+  return ((value >> 32) ^ (value & 0xffffffff));
+}
+
diff --git a/nest/route.h b/nest/route.h
index b68f614f..22fca331 100644
--- a/nest/route.h
+++ b/nest/route.h
@@ -345,22 +345,22 @@ struct rte_src {
 
 typedef struct rta {
   struct rta *next, **pprev;		/* Hash chain */
+  u32 uc;				/* Use count */
+  u32 hash_key;				/* Hash over important fields */
+  struct mpnh *nexthops;		/* Next-hops for multipath routes */
+  struct ea_list *eattrs;		/* Extended Attribute chain */
   struct rte_src *src;			/* Route source that created the route */
-  unsigned uc;				/* Use count */
+  struct hostentry *hostentry;		/* Hostentry for recursive next-hops */
+  struct iface *iface;			/* Outgoing interface */
+  ip_addr gw;				/* Next hop */
+  ip_addr from;				/* Advertising router */
+  u32 igp_metric;			/* IGP metric to next hop (for iBGP routes) */
   byte source;				/* Route source (RTS_...) */
   byte scope;				/* Route scope (SCOPE_... -- see ip.h) */
   byte cast;				/* Casting type (RTC_...) */
   byte dest;				/* Route destination type (RTD_...) */
   byte flags;				/* Route flags (RTF_...), now unused */
   byte aflags;				/* Attribute cache flags (RTAF_...) */
-  u16 hash_key;				/* Hash over important fields */
-  u32 igp_metric;			/* IGP metric to next hop (for iBGP routes) */
-  ip_addr gw;				/* Next hop */
-  ip_addr from;				/* Advertising router */
-  struct hostentry *hostentry;		/* Hostentry for recursive next-hops */
-  struct iface *iface;			/* Outgoing interface */
-  struct mpnh *nexthops;		/* Next-hops for multipath routes */
-  struct ea_list *eattrs;		/* Extended Attribute chain */
 } rta;
 
 #define RTS_DUMMY 0			/* Dummy route to be removed soon */
diff --git a/nest/rt-attr.c b/nest/rt-attr.c
index 0637867b..9777a2d2 100644
--- a/nest/rt-attr.c
+++ b/nest/rt-attr.c
@@ -56,6 +56,8 @@
 #include "lib/resource.h"
 #include "lib/string.h"
 
+#include <stddef.h>
+
 pool *rta_pool;
 
 static slab *rta_slab;
@@ -875,7 +877,8 @@ ea_dump(ea_list *e)
 inline uint
 ea_hash(ea_list *e)
 {
-  u32 h = 0;
+  const u64 mul = 0x68576150f3d6847;
+  u64 h = 0xafcef24eda8b29;
   int i;
 
   if (e)			/* Assuming chain of length 1 */
@@ -883,29 +886,18 @@ ea_hash(ea_list *e)
       for(i=0; i<e->count; i++)
 	{
 	  struct eattr *a = &e->attrs[i];
-	  h ^= a->id;
+	  h ^= a->id; h *= mul;
 	  if (a->type & EAF_EMBEDDED)
 	    h ^= a->u.data;
 	  else
 	    {
 	      struct adata *d = a->u.ptr;
-	      int size = d->length;
-	      byte *z = d->data;
-	      while (size >= 4)
-		{
-		  h ^= *(u32 *)z;
-		  z += 4;
-		  size -= 4;
-		}
-	      while (size--)
-		h = (h >> 24) ^ (h << 8) ^ *z++;
+	      h ^= mem_hash(d->data, d->length);
 	    }
+	  h *= mul;
 	}
-      h ^= h >> 16;
-      h ^= h >> 6;
-      h &= 0xffff;
     }
-  return h;
+  return (h >> 32) ^ (h & 0xffffffff);
 }
 
 /**
@@ -954,9 +946,8 @@ rta_alloc_hash(void)
 static inline uint
 rta_hash(rta *a)
 {
-  /* XXXX fully convert to u32 hashing */
-  return (((uint) (uintptr_t) a->src) ^ (ipa_hash(a->gw) >> 16) ^
-	  (mpnh_hash(a->nexthops) >> 16) ^ ea_hash(a->eattrs)) & 0xffff;
+  return mem_hash(a + offsetof(rta, src), sizeof(rta) - offsetof(rta, src)) ^
+	 mpnh_hash(a->nexthops) ^ ea_hash(a->eattrs);
 }
 
 static inline int