unix/linux: Prefixmsg and PrefixCacheinfo structs

These structs and enumeration constants are used
to parse RTM_NEWPREFIX netlink messages.

Fixes golang/go#77662

Change-Id: I1e7a92e771701c0c790c15e58ad78cd8fe1e5cf5
Reviewed-on: https://go-review.googlesource.com/c/sys/+/746420
Reviewed-by: Mark Freeman <markfreeman@google.com>
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Junyang Shao <shaojunyang@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Florian Lehner <lehner.florian86@gmail.com>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

unix/linux/types.go

@@ -932,12 +932,17 @@ const (
 	RTN_THROW             = C.RTN_THROW
 	RTN_NAT               = C.RTN_NAT
 	RTN_XRESOLVE          = C.RTN_XRESOLVE
+	PREFIX_UNSPEC         = C.PREFIX_UNSPEC
+	PREFIX_ADDRESS        = C.PREFIX_ADDRESS
+	PREFIX_CACHEINFO      = C.PREFIX_CACHEINFO
 	SizeofNlMsghdr        = C.sizeof_struct_nlmsghdr
 	SizeofNlMsgerr        = C.sizeof_struct_nlmsgerr
 	SizeofRtGenmsg        = C.sizeof_struct_rtgenmsg
 	SizeofNlAttr          = C.sizeof_struct_nlattr
 	SizeofRtAttr          = C.sizeof_struct_rtattr
 	SizeofIfInfomsg       = C.sizeof_struct_ifinfomsg
+	SizeofPrefixmsg       = C.sizeof_struct_prefixmsg
+	SizeofPrefixCacheinfo = C.sizeof_struct_prefix_cacheinfo
 	SizeofIfAddrmsg       = C.sizeof_struct_ifaddrmsg
 	SizeofIfAddrlblmsg    = C.sizeof_struct_ifaddrlblmsg
 	SizeofIfaCacheinfo    = C.sizeof_struct_ifa_cacheinfo
@@ -959,6 +964,10 @@ type RtAttr C.struct_rtattr
 
 type IfInfomsg C.struct_ifinfomsg
 
+type Prefixmsg C.struct_prefixmsg
+
+type PrefixCacheinfo C.struct_prefix_cacheinfo
+
 type IfAddrmsg C.struct_ifaddrmsg
 
 type IfAddrlblmsg C.struct_ifaddrlblmsg

unix/ztypes_linux.go

@@ -684,12 +684,17 @@ const (
 	RTN_THROW             = 0x9
 	RTN_NAT               = 0xa
 	RTN_XRESOLVE          = 0xb
+	PREFIX_UNSPEC         = 0x0
+	PREFIX_ADDRESS        = 0x1
+	PREFIX_CACHEINFO      = 0x2
 	SizeofNlMsghdr        = 0x10
 	SizeofNlMsgerr        = 0x14
 	SizeofRtGenmsg        = 0x1
 	SizeofNlAttr          = 0x4
 	SizeofRtAttr          = 0x4
 	SizeofIfInfomsg       = 0x10
+	SizeofPrefixmsg       = 0xc
+	SizeofPrefixCacheinfo = 0x8
 	SizeofIfAddrmsg       = 0x8
 	SizeofIfAddrlblmsg    = 0xc
 	SizeofIfaCacheinfo    = 0x10
@@ -735,6 +740,22 @@ type IfInfomsg struct {
 	Change uint32
 }
 
+type Prefixmsg struct {
+	Family  uint8
+	Pad1    uint8
+	Pad2    uint16
+	Ifindex int32
+	Type    uint8
+	Len     uint8
+	Flags   uint8
+	Pad3    uint8
+}
+
+type PrefixCacheinfo struct {
+	Preferred_time uint32
+	Valid_time     uint32
+}
+
 type IfAddrmsg struct {
 	Family    uint8
 	Prefixlen uint8