tcp: IPv6 flow label support

Type:feature

For cases when proxy is in use IPv6 flow label received in origin pkt needs to be added
to ipv6 header of outgoing pkts from proxy to original destination and vice versa.

Signed-off-by: Tarun Gupta <tarungup@cisco.com>
Change-Id: I143f7e67237c0f865333078628a016b50ad5e630
Signed-off-by: Tarun Gupta <tarungup@cisco.com>

3 files changed, 36 insertions, 10 deletions

diff --git a/src/vnet/ip/ip6.h b/src/vnet/ip/ip6.h
index 94c5080a0aa..28b1af749f6 100644
--- a/src/vnet/ip/ip6.h
+++ b/src/vnet/ip/ip6.h
@@ -655,21 +655,23 @@ void ip6_hbh_set_next_override (uword next);
  * @param src - source IP
  * @param dst - destination IP
  * @param prot - payload proto
+ * @param flow_label - flow label
  *
  * @return - pointer to start of IP header
  */
 always_inline void *
-vlib_buffer_push_ip6 (vlib_main_t * vm, vlib_buffer_t * b,
-		      ip6_address_t * src, ip6_address_t * dst, int proto)
+vlib_buffer_push_ip6_custom (vlib_main_t * vm, vlib_buffer_t * b,
+			     ip6_address_t * src, ip6_address_t * dst,
+			     int proto, u32 flow_label)
 {
   ip6_header_t *ip6h;
   u16 payload_length;
 
   /* make some room */
   ip6h = vlib_buffer_push_uninit (b, sizeof (ip6_header_t));
-
+  ASSERT (flow_label < 1 << 20);
   ip6h->ip_version_traffic_class_and_flow_label =
-    clib_host_to_net_u32 (0x6 << 28);
+    clib_host_to_net_u32 ((0x6 << 28) | flow_label);
 
   /* calculate ip6 payload length */
   payload_length = vlib_buffer_length_in_chain (vm, b);
@@ -689,6 +691,25 @@ vlib_buffer_push_ip6 (vlib_main_t * vm, vlib_buffer_t * b,
   return ip6h;
 }
 
+/**
+ * Push IPv6 header to buffer
+ *
+ * @param vm - vlib_main
+ * @param b - buffer to write the header to
+ * @param src - source IP
+ * @param dst - destination IP
+ * @param prot - payload proto
+ *
+ * @return - pointer to start of IP header
+ */
+always_inline void *
+vlib_buffer_push_ip6 (vlib_main_t * vm, vlib_buffer_t * b,
+		      ip6_address_t * src, ip6_address_t * dst, int proto)
+{
+  return vlib_buffer_push_ip6_custom (vm, b, src, dst, proto,
+				      0 /* flow label */ );
+
+}
 #endif /* included_ip_ip6_h */
 
 /*
diff --git a/src/vnet/tcp/tcp.h b/src/vnet/tcp/tcp.h
index 7309e0ad109..4b0a0ddea53 100644
--- a/src/vnet/tcp/tcp.h
+++ b/src/vnet/tcp/tcp.h
@@ -435,6 +435,7 @@ typedef struct _tcp_connection
   u32 last_fib_check;	/**< Last time we checked fib route for peer */
   u16 mss;		/**< Our max seg size that includes options */
   u32 timestamp_delta;	/**< Offset for timestamp */
+  u32 ipv6_flow_label;	/**< flow label for ipv6 header */
 } tcp_connection_t;
 
 /* *INDENT-OFF* */
diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index 71e9d7bbdb0..c7e9792afaa 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -842,8 +842,10 @@ tcp_send_reset_w_pkt (tcp_connection_t * tc, vlib_buffer_t * pkt,
       int bogus = ~0;
       ASSERT ((pkt_ih6->ip_version_traffic_class_and_flow_label & 0xF0) ==
 	      0x60);
-      ih6 = vlib_buffer_push_ip6 (vm, b, &pkt_ih6->dst_address,
-				  &pkt_ih6->src_address, IP_PROTOCOL_TCP);
+      ih6 = vlib_buffer_push_ip6_custom (vm, b, &pkt_ih6->dst_address,
+					 &pkt_ih6->src_address,
+					 IP_PROTOCOL_TCP,
+					 tc->ipv6_flow_label);
       th->checksum = ip6_tcp_udp_icmp_compute_checksum (vm, b, ih6, &bogus);
       ASSERT (!bogus);
     }
@@ -909,8 +911,9 @@ tcp_push_ip_hdr (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
       ip6_header_t *ih;
       int bogus = ~0;
 
-      ih = vlib_buffer_push_ip6 (vm, b, &tc->c_lcl_ip6,
-				 &tc->c_rmt_ip6, IP_PROTOCOL_TCP);
+      ih = vlib_buffer_push_ip6_custom (vm, b, &tc->c_lcl_ip6,
+					&tc->c_rmt_ip6, IP_PROTOCOL_TCP,
+					tc->ipv6_flow_label);
       th->checksum = ip6_tcp_udp_icmp_compute_checksum (vm, b, ih, &bogus);
       ASSERT (!bogus);
     }
@@ -2278,8 +2281,9 @@ tcp_output_push_ip (vlib_main_t * vm, vlib_buffer_t * b0,
     ih0 = vlib_buffer_push_ip4 (vm, b0, &tc0->c_lcl_ip4, &tc0->c_rmt_ip4,
 				IP_PROTOCOL_TCP, tcp_csum_offload (tc0));
   else
-    ih0 = vlib_buffer_push_ip6 (vm, b0, &tc0->c_lcl_ip6, &tc0->c_rmt_ip6,
-				IP_PROTOCOL_TCP);
+    ih0 =
+      vlib_buffer_push_ip6_custom (vm, b0, &tc0->c_lcl_ip6, &tc0->c_rmt_ip6,
+				   IP_PROTOCOL_TCP, tc0->ipv6_flow_label);
 
 }