From 2af0e3a74c40e5df946813324574ccc18feb4761 Mon Sep 17 00:00:00 2001
From: Mohsin Kazmi <sykazmi@cisco.com>
Date: Tue, 20 Nov 2018 11:11:12 +0100
Subject: [PATCH] flow-hash: Add symmetric flag for flow hashing

When 'Symmetric' flag is enabled, it will sort the addresses
and hence, same flow hash will be calculated on both directions.

Change-Id: I5d846f8d0b94ca1121e03d15b02bb56edb5887b1
Signed-off-by: Mohsin Kazmi <sykazmi@cisco.com>
---
 src/vnet/ip/ip.api   |  4 +++-
 src/vnet/ip/ip4.h    | 18 +++++++++++++++++-
 src/vnet/ip/ip6.h    | 18 +++++++++++++++++-
 src/vnet/ip/lookup.h |  4 +++-
 4 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/src/vnet/ip/ip.api b/src/vnet/ip/ip.api
index b08af5657fc..6ae0e023d5f 100644
--- a/src/vnet/ip/ip.api
+++ b/src/vnet/ip/ip.api
@@ -20,7 +20,7 @@
     called through a shared memory interface. 
 */
 
-option version = "1.3.0";
+option version = "1.4.0";
 import "vnet/ip/ip_types.api";
 import "vnet/fib/fib_types.api";
 import "vnet/ethernet/ethernet_types.api";
@@ -181,6 +181,7 @@ define ip_neighbor_add_del_reply
     @param dport - if non-zero include dport in flow hash
     @param proto -if non-zero include proto in flow hash
     @param reverse - if non-zero include reverse in flow hash
+    @param symmetric - if non-zero include symmetry in flow hash
 */
 autoreply define set_ip_flow_hash
 {
@@ -194,6 +195,7 @@ autoreply define set_ip_flow_hash
   u8 dport;
   u8 proto;
   u8 reverse;
+  u8 symmetric;
 };
 
 /** \brief IPv6 router advertisement config request
diff --git a/src/vnet/ip/ip4.h b/src/vnet/ip/ip4.h
index 9cb54bdfc41..31ca10feece 100644
--- a/src/vnet/ip/ip4.h
+++ b/src/vnet/ip/ip4.h
@@ -308,7 +308,6 @@ ip4_compute_flow_hash (const ip4_header_t * ip,
 
   a = (flow_hash_config & IP_FLOW_HASH_REVERSE_SRC_DST) ? t2 : t1;
   b = (flow_hash_config & IP_FLOW_HASH_REVERSE_SRC_DST) ? t1 : t2;
-  b ^= (flow_hash_config & IP_FLOW_HASH_PROTO) ? ip->protocol : 0;
 
   t1 = is_tcp_udp ? tcp->src : 0;
   t2 = is_tcp_udp ? tcp->dst : 0;
@@ -316,6 +315,23 @@ ip4_compute_flow_hash (const ip4_header_t * ip,
   t1 = (flow_hash_config & IP_FLOW_HASH_SRC_PORT) ? t1 : 0;
   t2 = (flow_hash_config & IP_FLOW_HASH_DST_PORT) ? t2 : 0;
 
+  if (flow_hash_config & IP_FLOW_HASH_SYMMETRIC)
+    {
+      if (b < a)
+	{
+	  c = a;
+	  a = b;
+	  b = c;
+	}
+      if (t2 < t1)
+	{
+	  t2 += t1;
+	  t1 = t2 - t1;
+	  t2 = t2 - t1;
+	}
+    }
+
+  b ^= (flow_hash_config & IP_FLOW_HASH_PROTO) ? ip->protocol : 0;
   c = (flow_hash_config & IP_FLOW_HASH_REVERSE_SRC_DST) ?
     (t1 << 16) | t2 : (t2 << 16) | t1;
 
diff --git a/src/vnet/ip/ip6.h b/src/vnet/ip/ip6.h
index aef24454413..6e0cfff5164 100644
--- a/src/vnet/ip/ip6.h
+++ b/src/vnet/ip/ip6.h
@@ -468,7 +468,6 @@ ip6_compute_flow_hash (const ip6_header_t * ip,
 
   a = (flow_hash_config & IP_FLOW_HASH_REVERSE_SRC_DST) ? t2 : t1;
   b = (flow_hash_config & IP_FLOW_HASH_REVERSE_SRC_DST) ? t1 : t2;
-  b ^= (flow_hash_config & IP_FLOW_HASH_PROTO) ? protocol : 0;
 
   t1 = is_tcp_udp ? tcp->src : 0;
   t2 = is_tcp_udp ? tcp->dst : 0;
@@ -476,6 +475,23 @@ ip6_compute_flow_hash (const ip6_header_t * ip,
   t1 = (flow_hash_config & IP_FLOW_HASH_SRC_PORT) ? t1 : 0;
   t2 = (flow_hash_config & IP_FLOW_HASH_DST_PORT) ? t2 : 0;
 
+  if (flow_hash_config & IP_FLOW_HASH_SYMMETRIC)
+    {
+      if (b < a)
+	{
+	  c = a;
+	  a = b;
+	  b = c;
+	}
+      if (t2 < t1)
+	{
+	  t2 += t1;
+	  t1 = t2 - t1;
+	  t2 = t2 - t1;
+	}
+    }
+
+  b ^= (flow_hash_config & IP_FLOW_HASH_PROTO) ? protocol : 0;
   c = (flow_hash_config & IP_FLOW_HASH_REVERSE_SRC_DST) ?
     ((t1 << 16) | t2) : ((t2 << 16) | t1);
 
diff --git a/src/vnet/ip/lookup.h b/src/vnet/ip/lookup.h
index 374023835f4..4c598e3a460 100644
--- a/src/vnet/ip/lookup.h
+++ b/src/vnet/ip/lookup.h
@@ -64,6 +64,7 @@
 #define IP_FLOW_HASH_SRC_PORT (1<<3)
 #define IP_FLOW_HASH_DST_PORT (1<<4)
 #define IP_FLOW_HASH_REVERSE_SRC_DST (1<<5)
+#define IP_FLOW_HASH_SYMMETRIC (1<<6)
 
 /** Default: 5-tuple without the "reverse" bit */
 #define IP_FLOW_HASH_DEFAULT (0x1F)
@@ -74,7 +75,8 @@ _(dst, IP_FLOW_HASH_DST_ADDR)                   \
 _(sport, IP_FLOW_HASH_SRC_PORT)                 \
 _(dport, IP_FLOW_HASH_DST_PORT)                 \
 _(proto, IP_FLOW_HASH_PROTO)	                \
-_(reverse, IP_FLOW_HASH_REVERSE_SRC_DST)
+_(reverse, IP_FLOW_HASH_REVERSE_SRC_DST)	\
+_(symmetric, IP_FLOW_HASH_SYMMETRIC)
 
 /**
  * A flow hash configuration is a mask of the flow hash options
-- 
2.16.6