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|
package netlink
import (
"context"
"syscall"
"unsafe"
)
// RouteConn represents a NETLINK_ROUTE socket.
type RouteConn struct{ *conn }
// DialRoute returns the address of a newly connected [RouteConn].
func DialRoute() (*RouteConn, error) {
c, err := dial(syscall.NETLINK_ROUTE, 0)
if err != nil {
return nil, err
}
return &RouteConn{c}, nil
}
// rtnlConsume consumes a message from rtnetlink.
func rtnlConsume(resp []syscall.NetlinkMessage) error {
for i := range resp {
switch resp[i].Header.Type {
case syscall.NLMSG_DONE:
return Complete{}
case syscall.NLMSG_ERROR:
if e := As[syscall.NlMsgerr](resp[i].Data); e != nil {
if e.Error == 0 {
return Complete{}
}
return syscall.Errno(-e.Error)
}
return syscall.EBADE
}
}
return nil
}
// InAddr is equivalent to struct in_addr.
type InAddr [4]byte
// RtAttrMsg holds syscall.RtAttr alongside its payload.
type RtAttrMsg[D any] struct {
syscall.RtAttr
Data D
}
// populate populates the Len field of the embedded syscall.RtAttr.
func (attr *RtAttrMsg[M]) populate() {
attr.Len = syscall.SizeofRtAttr + uint16(unsafe.Sizeof(attr.Data))
}
// writeIfAddrmsg writes an ifaddrmsg structure to conn.
func (c *RouteConn) writeIfAddrmsg(
typ, flags uint16,
msg *syscall.IfAddrmsg,
attrs ...RtAttrMsg[InAddr],
) bool {
c.typ, c.flags = typ, syscall.NLM_F_REQUEST|syscall.NLM_F_ACK|flags
if !add(c.conn, msg) {
return false
}
for _, attr := range attrs {
attr.populate()
if !add(c.conn, &attr) {
return false
}
}
return true
}
// SendIfAddrmsg sends an ifaddrmsg structure to rtnetlink.
func (c *RouteConn) SendIfAddrmsg(
ctx context.Context,
typ, flags uint16,
msg *syscall.IfAddrmsg,
attrs ...RtAttrMsg[InAddr],
) error {
if !c.writeIfAddrmsg(typ, flags, msg, attrs...) {
return syscall.ENOMEM
}
return c.Roundtrip(ctx, rtnlConsume)
}
// writeNewaddrLo writes a RTM_NEWADDR message for the loopback address.
func (c *RouteConn) writeNewaddrLo(lo uint32) bool {
return c.writeIfAddrmsg(
syscall.RTM_NEWADDR,
syscall.NLM_F_CREATE|syscall.NLM_F_EXCL,
&syscall.IfAddrmsg{
Family: syscall.AF_INET,
Prefixlen: 8,
Flags: syscall.IFA_F_PERMANENT,
Scope: syscall.RT_SCOPE_HOST,
Index: lo,
},
RtAttrMsg[InAddr]{syscall.RtAttr{
Type: syscall.IFA_LOCAL,
}, InAddr{127, 0, 0, 1}},
RtAttrMsg[InAddr]{syscall.RtAttr{
Type: syscall.IFA_ADDRESS,
}, InAddr{127, 0, 0, 1}},
)
}
// SendNewaddrLo sends a RTM_NEWADDR message for the loopback address to the kernel.
func (c *RouteConn) SendNewaddrLo(ctx context.Context, lo uint32) error {
if !c.writeNewaddrLo(lo) {
return syscall.ENOMEM
}
return c.Roundtrip(ctx, rtnlConsume)
}
// writeIfInfomsg writes an ifinfomsg structure to conn.
func (c *RouteConn) writeIfInfomsg(
typ, flags uint16,
msg *syscall.IfInfomsg,
) bool {
c.typ, c.flags = typ, syscall.NLM_F_REQUEST|syscall.NLM_F_ACK|flags
return add(c.conn, msg)
}
// SendIfInfomsg sends an ifinfomsg structure to rtnetlink.
func (c *RouteConn) SendIfInfomsg(
ctx context.Context,
typ, flags uint16,
msg *syscall.IfInfomsg,
) error {
if !c.writeIfInfomsg(typ, flags, msg) {
return syscall.ENOMEM
}
return c.Roundtrip(ctx, rtnlConsume)
}
|
