feat: Support Traffic Steering for Service Function Chaining

cmd/core/display_utils.go

@@ -267,6 +267,10 @@ func displayFar(sb *strings.Builder, far *ie.IE) {
 			if err == nil {
 				writeLineTabbed(sb, fmt.Sprintf("Header Enrichment: %s : %s ", headerEnrichment.HeaderFieldName, headerEnrichment.HeaderFieldValue), 3)
 			}
+			forwardingPolicyIdentifier, err := forwardingParameter.ForwardingPolicyIdentifier()
+			if err == nil {
+				writeLineTabbed(sb, fmt.Sprintf("Fordward Policy Identifier: %s ", forwardingPolicyIdentifier), 3)
+			}
 		}
 	}
 	if updateForwardingParameters, err := far.UpdateForwardingParameters(); err == nil {
@@ -289,6 +293,10 @@ func displayFar(sb *strings.Builder, far *ie.IE) {
 			if err == nil {
 				writeLineTabbed(sb, fmt.Sprintf("Header Enrichment: %s : %s ", headerEnrichment.HeaderFieldName, headerEnrichment.HeaderFieldValue), 3)
 			}
+			forwardingPolicyIdentifier, err := updateForwardingParameter.ForwardingPolicyIdentifier()
+			if err == nil {
+				writeLineTabbed(sb, fmt.Sprintf("Fordward Policy Identifier: %s ", forwardingPolicyIdentifier), 3)
+			}
 		}
 	}
 

cmd/core/pfcp_session_handlers.go

@@ -1,9 +1,11 @@
 package core
 
 import (
+	"encoding/base64"
 	"encoding/binary"
 	"fmt"
 	"net"
+	"strconv"
 
 	"github.com/edgecomllc/eupf/cmd/ebpf"
 
@@ -480,6 +482,21 @@ func composeFarInfo(far *ie.IE, localIp net.IP, farInfo ebpf.FarInfo) (ebpf.FarI
 				return ebpf.FarInfo{}, fmt.Errorf("IPv6 not supported yet")
 			}
 		}
+		forwardingPolicyIndex := findIEindex(forward, 41) // IE Type Forwarding Policy
+		if forwardingPolicyIndex == -1 {
+			log.Info().Msg("WARN: No ForwardingPolicy")
+		} else {
+			forwardingPolicyIdentifier, _ := forward[forwardingPolicyIndex].ForwardingPolicyIdentifier()
+
+			forwardingPolicyIdentifierDecode, err := base64.StdEncoding.DecodeString(forwardingPolicyIdentifier)
+			if err == nil {
+				uint32Value, err := strconv.ParseUint(string(forwardingPolicyIdentifierDecode), 10, 32)
+				if err == nil {
+					farInfo.ForwardingPolicyIdentifier = uint32(uint32Value)
+				}
+			}
+			// TODO support pre-defined policy if forwardingPolicyIdentifier is not base64 treat it as referring to a pre-defined policy
+		}
 	}
 	transportLevelMarking, err := GetTransportLevelMarking(far)
 	if err == nil {

cmd/ebpf/pdr.go

@@ -149,12 +149,13 @@ func (bpfObjects *BpfObjects) DeleteDownlinkPdrIp6(ipv6 net.IP) error {
 }
 
 type FarInfo struct {
-	Action                uint8
-	OuterHeaderCreation   uint8
-	Teid                  uint32
-	RemoteIP              uint32
-	LocalIP               uint32
-	TransportLevelMarking uint16
+	Action                     uint8
+	OuterHeaderCreation        uint8
+	Teid                       uint32
+	RemoteIP                   uint32
+	LocalIP                    uint32
+	TransportLevelMarking      uint16
+	ForwardingPolicyIdentifier uint32
 }
 
 func (f FarInfo) MarshalJSON() ([]byte, error) {
@@ -163,12 +164,13 @@ func (f FarInfo) MarshalJSON() ([]byte, error) {
 	binary.LittleEndian.PutUint32(remoteIP, f.RemoteIP)
 	binary.LittleEndian.PutUint32(localIP, f.LocalIP)
 	data := map[string]interface{}{
-		"action":                  f.Action,
-		"outer_header_creation":   f.OuterHeaderCreation,
-		"teid":                    f.Teid,
-		"remote_ip":               remoteIP.String(),
-		"local_ip":                localIP.String(),
-		"transport_level_marking": f.TransportLevelMarking,
+		"action":                       f.Action,
+		"outer_header_creation":        f.OuterHeaderCreation,
+		"teid":                         f.Teid,
+		"remote_ip":                    remoteIP.String(),
+		"local_ip":                     localIP.String(),
+		"transport_level_marking":      f.TransportLevelMarking,
+		"forwarding_policy_identifier": f.ForwardingPolicyIdentifier,
 	}
 	return json.Marshal(data)
 }

cmd/ebpf/xdp/n3n6_entrypoint.c

@@ -38,6 +38,7 @@
 #include "xdp/utils/parsers.h"
 #include "xdp/utils/csum.h"
 #include "xdp/utils/gtp_utils.h"
+#include "xdp/utils/nsh_utils.h"
 #include "xdp/utils/routing.h"
 #include "xdp/utils/icmp.h"
 
@@ -313,6 +314,23 @@ static __always_inline enum xdp_action handle_gtp_packet(struct packet_context *
         }
     }
 
+    // Check for forwarding policy identifier
+    if (far->forwarding_policy_identifier) {
+        /*
+         * TODO: support predefined traffic steering policy. Should check
+         * first if the forwarding policy identifier refers to a pre-defined
+         * policy, if not we treat this as a SFC ID as below.
+        */ 
+        // NOTE: The FIB tables need to have been populate prior. 
+        // Traffic with forwarding_policy_identifier should'nt be the first traffic to be received
+        if (ctx->ip4) {
+            if (-1 == add_nsh_over_ip4_headers(ctx, far->forwarding_policy_identifier)) {
+                upf_printk("upf: failed to NSH encapsulate packet");
+                return XDP_ABORTED;
+            }
+        }
+    }
+
     /*
      * Decrement IP TTL and reply TTL exeeded message (debug purspose only)
      */

cmd/ebpf/xdp/pdr.h

@@ -114,6 +114,7 @@ struct far_info {
     __u32 localip;
     /* first octet DSCP value in the Type-of-Service, second octet shall contain the ToS/Traffic Class mask field, which shall be set to "0xFC". */
     __u16 transport_level_marking;
+    __u32 forwarding_policy_identifier;
 };
 
 /* FAR ID -> FAR */

cmd/ebpf/xdp/utils/gtp_utils.h

@@ -242,7 +242,7 @@ static __always_inline __u32 add_gtp_over_ip4_headers(struct packet_context *ctx
     // udp->check = cs;
 
     /* Update packet pointers */
-    context_set_ip4(ctx, (char *)(long)ctx->xdp_ctx->data, (const char *)(long)ctx->xdp_ctx->data_end, eth, ip, udp, gtp);
+    context_set_ip4(ctx, (char *)(long)ctx->xdp_ctx->data, (const char *)(long)ctx->xdp_ctx->data_end, eth, ip, udp, gtp, 0);
     return 0;
 }