Merge pull request #1183 from dpino/ipv6-flow-label

Allow setting flow-label in ingress packets

src/apps/lwaftr/lwaftr.lua

@@ -217,12 +217,12 @@ local function prepend_ethernet_header(pkt, ether_type)
    return pkt
 end
 
-local function write_ipv6_header(ptr, src, dst, tc, next_header, payload_length)
+local function write_ipv6_header(ptr, src, dst, tc, flow_label, next_header, payload_length)
    local h = ffi.cast(ipv6_header_ptr_t, ptr)
    h.v_tc_fl = 0
    lib.bitfield(32, h, 'v_tc_fl', 0, 4, 6)   -- IPv6 Version
    lib.bitfield(32, h, 'v_tc_fl', 4, 8, tc)  -- Traffic class
-   lib.bitfield(32, h, 'v_tc_fl', 12, 20, 0) -- Flow label
+   lib.bitfield(32, h, 'v_tc_fl', 12, 20, flow_label) -- Flow label
    h.payload_length = htons(payload_length)
    h.next_header = next_header
    h.hop_limit = constants.default_ttl
@@ -740,14 +740,15 @@ function LwAftr:encapsulate_and_transmit(pkt, ipv6_dst, ipv6_src, pkt_src_link)
    local payload_length = get_ethernet_payload_length(pkt)
    local l3_header = get_ethernet_payload(pkt)
    local traffic_class = get_ipv4_dscp_and_ecn(l3_header)
+   local flow_label = self.conf.internal_interface.flow_label
    -- Note that this may invalidate any pointer into pkt.data.  Be warned!
    pkt = packet.shiftright(pkt, ipv6_header_size)
    write_ethernet_header(pkt, n_ethertype_ipv6)
    -- Fetch possibly-moved L3 header location.
    l3_header = get_ethernet_payload(pkt)
 
    write_ipv6_header(l3_header, ipv6_src, ipv6_dst, traffic_class,
-                     proto_ipv4, payload_length)
+                     flow_label, proto_ipv4, payload_length)
 
    if debug then
       print("encapsulated packet:")

src/lib/yang/snabb-softwire-v2.yang

@@ -723,6 +723,13 @@ module snabb-softwire-v2 {
          "Maximum packet size to recieve on the IPv6 interface.";
       }
 
+      leaf flow-label {
+        type uint32;
+        default 0;
+        description
+          "IPv6 flow label";
+      }
+
       uses traffic-filters;
       uses icmp-policy;
       uses vlan-tagging;