bpf/init.sh: move node config generation to Go

This refactors writes to node_config.h in init.sh to a Go implementation
and centralizes most writes to node_config.h in writeNodeConfigHeader().

Signed-off-by: Robin Gögge <r.goegge@isovalent.com>

bpf/init.sh

@@ -157,11 +157,6 @@ function setup_proxy_rules()
 	fi
 }
 
-function mac2array()
-{
-	echo "{0x${1//:/,0x}}"
-}
-
 function rnd_mac_addr()
 {
     local lower=$(od /dev/urandom -N5 -t x1 -An | sed 's/ /:/g')
@@ -186,37 +181,6 @@ function encap_fail()
 	exit 1
 }
 
-# node_config.h header generation
-case "${MODE}" in
-	*)
-		sed -i '/^#.*CILIUM_NET_MAC.*$/d' $RUNDIR/globals/node_config.h
-		CILIUM_NET_MAC=$(ip link show $HOST_DEV2 | grep ether | awk '{print $2}')
-		CILIUM_NET_MAC=$(mac2array $CILIUM_NET_MAC)
-
-		# Remove the entire '#ifndef ... #endif block
-		# Each line must contain the string '#.*CILIUM_NET_MAC.*'
-		sed -i '/^#.*CILIUM_NET_MAC.*$/d' $RUNDIR/globals/node_config.h
-		echo "#ifndef CILIUM_NET_MAC" >> $RUNDIR/globals/node_config.h
-		echo "#define CILIUM_NET_MAC { .addr = ${CILIUM_NET_MAC}}" >> $RUNDIR/globals/node_config.h
-		echo "#endif /* CILIUM_NET_MAC */" >> $RUNDIR/globals/node_config.h
-
-		sed -i '/^#.*HOST_IFINDEX.*$/d' $RUNDIR/globals/node_config.h
-		HOST_IDX=$(cat "${SYSCLASSNETDIR}/${HOST_DEV2}/ifindex")
-		echo "#define HOST_IFINDEX $HOST_IDX" >> $RUNDIR/globals/node_config.h
-
-		sed -i '/^#.*HOST_IFINDEX_MAC.*$/d' $RUNDIR/globals/node_config.h
-		HOST_MAC=$(ip link show $HOST_DEV1 | grep ether | awk '{print $2}')
-		HOST_MAC=$(mac2array $HOST_MAC)
-		echo "#define HOST_IFINDEX_MAC { .addr = ${HOST_MAC}}" >> $RUNDIR/globals/node_config.h
-
-		sed -i '/^#.*CILIUM_IFINDEX.*$/d' $RUNDIR/globals/node_config.h
-		CILIUM_IDX=$(cat "${SYSCLASSNETDIR}/${HOST_DEV1}/ifindex")
-		echo "#define CILIUM_IFINDEX $CILIUM_IDX" >> $RUNDIR/globals/node_config.h
-
-		CILIUM_EPHEMERAL_MIN=$(cat "${PROCSYSNETDIR}/ipv4/ip_local_port_range" | awk '{print $1}')
-		echo "#define EPHEMERAL_MIN $CILIUM_EPHEMERAL_MIN" >> $RUNDIR/globals/node_config.h
-esac
-
 	# If the host does not have an IPv6 address assigned, assign our generated host
 	# IP to make the host accessible to endpoints
 	if [ "$IP6_HOST" != "<nil>" ]; then
@@ -283,11 +247,6 @@ else
 	ip link del cilium_sit   2> /dev/null || true
 fi
 
-if [ "$MODE" = "tunnel" ]; then
-	sed -i '/^#.*TUNNEL_MODE.*$/d' $RUNDIR/globals/node_config.h
-	echo "#define TUNNEL_MODE 1" >> $RUNDIR/globals/node_config.h
-fi
-
 # Remove eventual existing encapsulation device from previous run
 case "${TUNNEL_PROTOCOL}" in
   "<nil>")

pkg/datapath/linux/config/config.go

@@ -13,6 +13,7 @@ import (
 	"io"
 	"net"
 	"sort"
+	"strconv"
 	"strings"
 	"text/template"
 
@@ -57,6 +58,7 @@ import (
 	"github.com/cilium/cilium/pkg/netns"
 	"github.com/cilium/cilium/pkg/node"
 	"github.com/cilium/cilium/pkg/option"
+	"github.com/cilium/cilium/pkg/sysctl"
 	wgtypes "github.com/cilium/cilium/pkg/wireguard/types"
 )
 
@@ -637,6 +639,30 @@ func (h *HeaderfileWriter) WriteNodeConfig(w io.Writer, cfg *datapath.LocalNodeC
 	cDefinesMap["CIDR_IDENTITY_RANGE_START"] = fmt.Sprintf("%d", identity.MinLocalIdentity)
 	cDefinesMap["CIDR_IDENTITY_RANGE_END"] = fmt.Sprintf("%d", identity.MaxLocalIdentity)
 
+	if option.Config.TunnelingEnabled() {
+		cDefinesMap["TUNNEL_MODE"] = "1"
+	}
+
+	ciliumNetLink, err := netlink.LinkByName(defaults.SecondHostDevice)
+	if err != nil {
+		return err
+	}
+	cDefinesMap["CILIUM_NET_MAC"] = fmt.Sprintf("{.addr=%s}", mac.CArrayString(ciliumNetLink.Attrs().HardwareAddr))
+	cDefinesMap["HOST_IFINDEX"] = fmt.Sprintf("%d", ciliumNetLink.Attrs().Index)
+
+	ciliumHostLink, err := netlink.LinkByName(defaults.HostDevice)
+	if err != nil {
+		return err
+	}
+	cDefinesMap["HOST_IFINDEX_MAC"] = fmt.Sprintf("{.addr=%s}", mac.CArrayString(ciliumHostLink.Attrs().HardwareAddr))
+	cDefinesMap["CILIUM_IFINDEX"] = fmt.Sprintf("%d", ciliumHostLink.Attrs().Index)
+
+	ephemeralMin, err := getEphemeralPortRangeMin()
+	if err != nil {
+		return err
+	}
+	cDefinesMap["EPHEMERAL_MIN"] = fmt.Sprintf("%d", ephemeralMin)
+
 	// Since golang maps are unordered, we sort the keys in the map
 	// to get a consistent written format to the writer. This maintains
 	// the consistency when we try to calculate hash for a datapath after
@@ -671,6 +697,24 @@ func (h *HeaderfileWriter) WriteNodeConfig(w io.Writer, cfg *datapath.LocalNodeC
 	return fw.Flush()
 }
 
+func getEphemeralPortRangeMin() (int, error) {
+	ephemeralPortRangeStr, err := sysctl.Read("net.ipv4.ip_local_port_range")
+	if err != nil {
+		return 0, fmt.Errorf("unable to read net.ipv4.ip_local_port_range: %w", err)
+	}
+	ephemeralPortRange := strings.Split(ephemeralPortRangeStr, "\t")
+	if len(ephemeralPortRange) != 2 {
+		return 0, fmt.Errorf("invalid ephemeral port range: %s", ephemeralPortRangeStr)
+	}
+	ephemeralPortMin, err := strconv.Atoi(ephemeralPortRange[0])
+	if err != nil {
+		return 0, fmt.Errorf("unable to parse min port value %s for ephemeral range: %w",
+			ephemeralPortRange[0], err)
+	}
+
+	return ephemeralPortMin, nil
+}
+
 // vlanFilterMacros generates VLAN_FILTER macros which
 // are written to node_config.h
 func vlanFilterMacros() (string, error) {