unix: add nexthop types and consts

Fixes golang/go#38249

Change-Id: Ie8149ac16d09e76d6c5aa4d47edd947a647c381f
Reviewed-on: https://go-review.googlesource.com/c/sys/+/227357
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Matt Layher <mdlayher@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

unix/linux/types.go

@@ -106,6 +106,7 @@ struct termios2 {
 #include <linux/netfilter/nfnetlink.h>
 #include <linux/netfilter.h>
 #include <linux/netlink.h>
+#include <linux/nexthop.h>
 #include <linux/openat2.h>
 #include <linux/perf_event.h>
 #include <linux/random.h>
@@ -2303,3 +2304,23 @@ const (
 type FsverityDigest C.struct_fsverity_digest
 
 type FsverityEnableArg C.struct_fsverity_enable_arg
+
+// nexthop
+
+type Nhmsg C.struct_nhmsg
+
+type NexthopGrp C.struct_nexthop_grp
+
+const (
+	NHA_UNSPEC     = C.NHA_UNSPEC
+	NHA_ID         = C.NHA_ID
+	NHA_GROUP      = C.NHA_GROUP
+	NHA_GROUP_TYPE = C.NHA_GROUP_TYPE
+	NHA_BLACKHOLE  = C.NHA_BLACKHOLE
+	NHA_OIF        = C.NHA_OIF
+	NHA_GATEWAY    = C.NHA_GATEWAY
+	NHA_ENCAP_TYPE = C.NHA_ENCAP_TYPE
+	NHA_ENCAP      = C.NHA_ENCAP
+	NHA_GROUPS     = C.NHA_GROUPS
+	NHA_MASTER     = C.NHA_MASTER
+)

unix/ztypes_linux.go

@@ -2325,3 +2325,32 @@ type FsverityEnableArg struct {
 	Sig_ptr        uint64
 	_              [11]uint64
 }
+
+type Nhmsg struct {
+	Family   uint8
+	Scope    uint8
+	Protocol uint8
+	Resvd    uint8
+	Flags    uint32
+}
+
+type NexthopGrp struct {
+	Id     uint32
+	Weight uint8
+	Resvd1 uint8
+	Resvd2 uint16
+}
+
+const (
+	NHA_UNSPEC     = 0x0
+	NHA_ID         = 0x1
+	NHA_GROUP      = 0x2
+	NHA_GROUP_TYPE = 0x3
+	NHA_BLACKHOLE  = 0x4
+	NHA_OIF        = 0x5
+	NHA_GATEWAY    = 0x6
+	NHA_ENCAP_TYPE = 0x7
+	NHA_ENCAP      = 0x8
+	NHA_GROUPS     = 0x9
+	NHA_MASTER     = 0xa
+)