1 files changed, 188 insertions, 0 deletions
diff --git a/src/syscall/netlink_linux.go b/src/syscall/netlink_linux.go
new file mode 100644
index 0000000..a503a07
--- /dev/null
+++ b/src/syscall/netlink_linux.go
@@ -0,0 +1,188 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Netlink sockets and messages
+
+package syscall
+
+import (
+	"sync"
+	"unsafe"
+)
+
+// Round the length of a netlink message up to align it properly.
+func nlmAlignOf(msglen int) int {
+	return (msglen + NLMSG_ALIGNTO - 1) & ^(NLMSG_ALIGNTO - 1)
+}
+
+// Round the length of a netlink route attribute up to align it
+// properly.
+func rtaAlignOf(attrlen int) int {
+	return (attrlen + RTA_ALIGNTO - 1) & ^(RTA_ALIGNTO - 1)
+}
+
+// NetlinkRouteRequest represents a request message to receive routing
+// and link states from the kernel.
+type NetlinkRouteRequest struct {
+	Header NlMsghdr
+	Data   RtGenmsg
+}
+
+func (rr *NetlinkRouteRequest) toWireFormat() []byte {
+	b := make([]byte, rr.Header.Len)
+	*(*uint32)(unsafe.Pointer(&b[0:4][0])) = rr.Header.Len
+	*(*uint16)(unsafe.Pointer(&b[4:6][0])) = rr.Header.Type
+	*(*uint16)(unsafe.Pointer(&b[6:8][0])) = rr.Header.Flags
+	*(*uint32)(unsafe.Pointer(&b[8:12][0])) = rr.Header.Seq
+	*(*uint32)(unsafe.Pointer(&b[12:16][0])) = rr.Header.Pid
+	b[16] = byte(rr.Data.Family)
+	return b
+}
+
+func newNetlinkRouteRequest(proto, seq, family int) []byte {
+	rr := &NetlinkRouteRequest{}
+	rr.Header.Len = uint32(NLMSG_HDRLEN + SizeofRtGenmsg)
+	rr.Header.Type = uint16(proto)
+	rr.Header.Flags = NLM_F_DUMP | NLM_F_REQUEST
+	rr.Header.Seq = uint32(seq)
+	rr.Data.Family = uint8(family)
+	return rr.toWireFormat()
+}
+
+var pageBufPool = &sync.Pool{New: func() any {
+	b := make([]byte, Getpagesize())
+	return &b
+}}
+
+// NetlinkRIB returns routing information base, as known as RIB, which
+// consists of network facility information, states and parameters.
+func NetlinkRIB(proto, family int) ([]byte, error) {
+	s, err := Socket(AF_NETLINK, SOCK_RAW|SOCK_CLOEXEC, NETLINK_ROUTE)
+	if err != nil {
+		return nil, err
+	}
+	defer Close(s)
+	sa := &SockaddrNetlink{Family: AF_NETLINK}
+	if err := Bind(s, sa); err != nil {
+		return nil, err
+	}
+	wb := newNetlinkRouteRequest(proto, 1, family)
+	if err := Sendto(s, wb, 0, sa); err != nil {
+		return nil, err
+	}
+	lsa, err := Getsockname(s)
+	if err != nil {
+		return nil, err
+	}
+	lsanl, ok := lsa.(*SockaddrNetlink)
+	if !ok {
+		return nil, EINVAL
+	}
+	var tab []byte
+
+	rbNew := pageBufPool.Get().(*[]byte)
+	defer pageBufPool.Put(rbNew)
+done:
+	for {
+		rb := *rbNew
+		nr, _, err := Recvfrom(s, rb, 0)
+		if err != nil {
+			return nil, err
+		}
+		if nr < NLMSG_HDRLEN {
+			return nil, EINVAL
+		}
+		rb = rb[:nr]
+		tab = append(tab, rb...)
+		msgs, err := ParseNetlinkMessage(rb)
+		if err != nil {
+			return nil, err
+		}
+		for _, m := range msgs {
+			if m.Header.Seq != 1 || m.Header.Pid != lsanl.Pid {
+				return nil, EINVAL
+			}
+			if m.Header.Type == NLMSG_DONE {
+				break done
+			}
+			if m.Header.Type == NLMSG_ERROR {
+				return nil, EINVAL
+			}
+		}
+	}
+	return tab, nil
+}
+
+// NetlinkMessage represents a netlink message.
+type NetlinkMessage struct {
+	Header NlMsghdr
+	Data   []byte
+}
+
+// ParseNetlinkMessage parses b as an array of netlink messages and
+// returns the slice containing the NetlinkMessage structures.
+func ParseNetlinkMessage(b []byte) ([]NetlinkMessage, error) {
+	var msgs []NetlinkMessage
+	for len(b) >= NLMSG_HDRLEN {
+		h, dbuf, dlen, err := netlinkMessageHeaderAndData(b)
+		if err != nil {
+			return nil, err
+		}
+		m := NetlinkMessage{Header: *h, Data: dbuf[:int(h.Len)-NLMSG_HDRLEN]}
+		msgs = append(msgs, m)
+		b = b[dlen:]
+	}
+	return msgs, nil
+}
+
+func netlinkMessageHeaderAndData(b []byte) (*NlMsghdr, []byte, int, error) {
+	h := (*NlMsghdr)(unsafe.Pointer(&b[0]))
+	l := nlmAlignOf(int(h.Len))
+	if int(h.Len) < NLMSG_HDRLEN || l > len(b) {
+		return nil, nil, 0, EINVAL
+	}
+	return h, b[NLMSG_HDRLEN:], l, nil
+}
+
+// NetlinkRouteAttr represents a netlink route attribute.
+type NetlinkRouteAttr struct {
+	Attr  RtAttr
+	Value []byte
+}
+
+// ParseNetlinkRouteAttr parses m's payload as an array of netlink
+// route attributes and returns the slice containing the
+// NetlinkRouteAttr structures.
+func ParseNetlinkRouteAttr(m *NetlinkMessage) ([]NetlinkRouteAttr, error) {
+	var b []byte
+	switch m.Header.Type {
+	case RTM_NEWLINK, RTM_DELLINK:
+		b = m.Data[SizeofIfInfomsg:]
+	case RTM_NEWADDR, RTM_DELADDR:
+		b = m.Data[SizeofIfAddrmsg:]
+	case RTM_NEWROUTE, RTM_DELROUTE:
+		b = m.Data[SizeofRtMsg:]
+	default:
+		return nil, EINVAL
+	}
+	var attrs []NetlinkRouteAttr
+	for len(b) >= SizeofRtAttr {
+		a, vbuf, alen, err := netlinkRouteAttrAndValue(b)
+		if err != nil {
+			return nil, err
+		}
+		ra := NetlinkRouteAttr{Attr: *a, Value: vbuf[:int(a.Len)-SizeofRtAttr]}
+		attrs = append(attrs, ra)
+		b = b[alen:]
+	}
+	return attrs, nil
+}
+
+func netlinkRouteAttrAndValue(b []byte) (*RtAttr, []byte, int, error) {
+	a := (*RtAttr)(unsafe.Pointer(&b[0]))
+	if int(a.Len) < SizeofRtAttr || int(a.Len) > len(b) {
+		return nil, nil, 0, EINVAL
+	}
+	return a, b[SizeofRtAttr:], rtaAlignOf(int(a.Len)), nil
+}