Add ErrDumpInterrupted

Add a specific error to report that a netlink response had
NLM_F_DUMP_INTR set, indicating that the set of results may be
incomplete or inconsistent.

unix.EINTR was previously returned (with no results) when the
NLM_F_DUMP_INTR flag was set. Now, errors.Is(err, unix.EINTR) will
still work. But, this will be a breaking change for any code that's
checking for equality with unix.EINTR.

Return results with ErrDumpInterrupted. Results may be incomplete
or inconsistent, but give the caller the option of using them.

Look for NLM_F_DUMP_INTR in more places:
- linkSubscribeAt, neighSubscribeAt, routeSubscribeAt
  - can do an initial dump, which may report inconsistent results
  -> if there's an error callback, call it with ErrDumpInterrupted
- socketDiagXDPExecutor
  - makes an NLM_F_DUMP request, without using Execute()
  -> give it the same behaviour as functions that do use Execute()

Signed-off-by: Rob Murray <[email protected]>

addr_linux.go

@@ -1,6 +1,7 @@
 package netlink
 
 import (
+	"errors"
 	"fmt"
 	"net"
 	"strings"
@@ -169,21 +170,27 @@ func (h *Handle) addrHandle(link Link, addr *Addr, req *nl.NetlinkRequest) error
 // AddrList gets a list of IP addresses in the system.
 // Equivalent to: `ip addr show`.
 // The list can be filtered by link and ip family.
+//
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func AddrList(link Link, family int) ([]Addr, error) {
 	return pkgHandle.AddrList(link, family)
 }
 
 // AddrList gets a list of IP addresses in the system.
 // Equivalent to: `ip addr show`.
 // The list can be filtered by link and ip family.
+//
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func (h *Handle) AddrList(link Link, family int) ([]Addr, error) {
 	req := h.newNetlinkRequest(unix.RTM_GETADDR, unix.NLM_F_DUMP)
 	msg := nl.NewIfAddrmsg(family)
 	req.AddData(msg)
 
-	msgs, err := req.Execute(unix.NETLINK_ROUTE, unix.RTM_NEWADDR)
-	if err != nil {
-		return nil, err
+	msgs, executeErr := req.Execute(unix.NETLINK_ROUTE, unix.RTM_NEWADDR)
+	if executeErr != nil && !errors.Is(executeErr, ErrDumpInterrupted) {
+		return nil, executeErr
 	}
 
 	indexFilter := 0
@@ -212,7 +219,7 @@ func (h *Handle) AddrList(link Link, family int) ([]Addr, error) {
 		res = append(res, addr)
 	}
 
-	return res, nil
+	return res, executeErr
 }
 
 func parseAddr(m []byte) (addr Addr, family int, err error) {

bridge_linux.go

@@ -1,6 +1,7 @@
 package netlink
 
 import (
+	"errors"
 	"fmt"
 
 	"github.com/vishvananda/netlink/nl"
@@ -9,21 +10,27 @@ import (
 
 // BridgeVlanList gets a map of device id to bridge vlan infos.
 // Equivalent to: `bridge vlan show`
+//
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func BridgeVlanList() (map[int32][]*nl.BridgeVlanInfo, error) {
 	return pkgHandle.BridgeVlanList()
 }
 
 // BridgeVlanList gets a map of device id to bridge vlan infos.
 // Equivalent to: `bridge vlan show`
+//
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func (h *Handle) BridgeVlanList() (map[int32][]*nl.BridgeVlanInfo, error) {
 	req := h.newNetlinkRequest(unix.RTM_GETLINK, unix.NLM_F_DUMP)
 	msg := nl.NewIfInfomsg(unix.AF_BRIDGE)
 	req.AddData(msg)
 	req.AddData(nl.NewRtAttr(unix.IFLA_EXT_MASK, nl.Uint32Attr(uint32(nl.RTEXT_FILTER_BRVLAN))))
 
-	msgs, err := req.Execute(unix.NETLINK_ROUTE, unix.RTM_NEWLINK)
-	if err != nil {
-		return nil, err
+	msgs, executeErr := req.Execute(unix.NETLINK_ROUTE, unix.RTM_NEWLINK)
+	if executeErr != nil && !errors.Is(executeErr, ErrDumpInterrupted) {
+		return nil, executeErr
 	}
 	ret := make(map[int32][]*nl.BridgeVlanInfo)
 	for _, m := range msgs {
@@ -51,7 +58,7 @@ func (h *Handle) BridgeVlanList() (map[int32][]*nl.BridgeVlanInfo, error) {
 			}
 		}
 	}
-	return ret, nil
+	return ret, executeErr
 }
 
 // BridgeVlanAdd adds a new vlan filter entry

chain_linux.go

@@ -1,6 +1,8 @@
 package netlink
 
 import (
+	"errors"
+
 	"github.com/vishvananda/netlink/nl"
 	"golang.org/x/sys/unix"
 )
@@ -56,13 +58,19 @@ func (h *Handle) chainModify(cmd, flags int, link Link, chain Chain) error {
 // ChainList gets a list of chains in the system.
 // Equivalent to: `tc chain list`.
 // The list can be filtered by link.
+//
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func ChainList(link Link, parent uint32) ([]Chain, error) {
 	return pkgHandle.ChainList(link, parent)
 }
 
 // ChainList gets a list of chains in the system.
 // Equivalent to: `tc chain list`.
 // The list can be filtered by link.
+//
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func (h *Handle) ChainList(link Link, parent uint32) ([]Chain, error) {
 	req := h.newNetlinkRequest(unix.RTM_GETCHAIN, unix.NLM_F_DUMP)
 	index := int32(0)
@@ -78,9 +86,9 @@ func (h *Handle) ChainList(link Link, parent uint32) ([]Chain, error) {
 	}
 	req.AddData(msg)
 
-	msgs, err := req.Execute(unix.NETLINK_ROUTE, unix.RTM_NEWCHAIN)
-	if err != nil {
-		return nil, err
+	msgs, executeErr := req.Execute(unix.NETLINK_ROUTE, unix.RTM_NEWCHAIN)
+	if executeErr != nil && !errors.Is(executeErr, ErrDumpInterrupted) {
+		return nil, executeErr
 	}
 
 	var res []Chain
@@ -108,5 +116,5 @@ func (h *Handle) ChainList(link Link, parent uint32) ([]Chain, error) {
 		res = append(res, chain)
 	}
 
-	return res, nil
+	return res, executeErr
 }

class_linux.go

@@ -201,14 +201,20 @@ func classPayload(req *nl.NetlinkRequest, class Class) error {
 
 // ClassList gets a list of classes in the system.
 // Equivalent to: `tc class show`.
+//
 // Generally returns nothing if link and parent are not specified.
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func ClassList(link Link, parent uint32) ([]Class, error) {
 	return pkgHandle.ClassList(link, parent)
 }
 
 // ClassList gets a list of classes in the system.
 // Equivalent to: `tc class show`.
+//
 // Generally returns nothing if link and parent are not specified.
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func (h *Handle) ClassList(link Link, parent uint32) ([]Class, error) {
 	req := h.newNetlinkRequest(unix.RTM_GETTCLASS, unix.NLM_F_DUMP)
 	msg := &nl.TcMsg{
@@ -222,9 +228,9 @@ func (h *Handle) ClassList(link Link, parent uint32) ([]Class, error) {
 	}
 	req.AddData(msg)
 
-	msgs, err := req.Execute(unix.NETLINK_ROUTE, unix.RTM_NEWTCLASS)
-	if err != nil {
-		return nil, err
+	msgs, executeErr := req.Execute(unix.NETLINK_ROUTE, unix.RTM_NEWTCLASS)
+	if executeErr != nil && !errors.Is(executeErr, ErrDumpInterrupted) {
+		return nil, executeErr
 	}
 
 	var res []Class
@@ -295,7 +301,7 @@ func (h *Handle) ClassList(link Link, parent uint32) ([]Class, error) {
 		res = append(res, class)
 	}
 
-	return res, nil
+	return res, executeErr
 }
 
 func parseHtbClassData(class Class, data []syscall.NetlinkRouteAttr) (bool, error) {

conntrack_linux.go

@@ -45,6 +45,9 @@ type InetFamily uint8
 
 // ConntrackTableList returns the flow list of a table of a specific family
 // conntrack -L [table] [options]          List conntrack or expectation table
+//
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func ConntrackTableList(table ConntrackTableType, family InetFamily) ([]*ConntrackFlow, error) {
 	return pkgHandle.ConntrackTableList(table, family)
 }
@@ -84,10 +87,13 @@ func ConntrackDeleteFilters(table ConntrackTableType, family InetFamily, filters
 
 // ConntrackTableList returns the flow list of a table of a specific family using the netlink handle passed
 // conntrack -L [table] [options]          List conntrack or expectation table
+//
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func (h *Handle) ConntrackTableList(table ConntrackTableType, family InetFamily) ([]*ConntrackFlow, error) {
-	res, err := h.dumpConntrackTable(table, family)
-	if err != nil {
-		return nil, err
+	res, executeErr := h.dumpConntrackTable(table, family)
+	if executeErr != nil && !errors.Is(executeErr, ErrDumpInterrupted) {
+		return nil, executeErr
 	}
 
 	// Deserialize all the flows
@@ -96,7 +102,7 @@ func (h *Handle) ConntrackTableList(table ConntrackTableType, family InetFamily)
 		result = append(result, parseRawData(dataRaw))
 	}
 
-	return result, nil
+	return result, executeErr
 }
 
 // ConntrackTableFlush flushes all the flows of a specified table using the netlink handle passed

devlink_linux.go

@@ -1,6 +1,7 @@
 package netlink
 
 import (
+	"errors"
 	"fmt"
 	"net"
 	"strings"
@@ -466,6 +467,8 @@ func (h *Handle) getEswitchAttrs(family *GenlFamily, dev *DevlinkDevice) {
 
 // DevLinkGetDeviceList provides a pointer to devlink devices and nil error,
 // otherwise returns an error code.
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func (h *Handle) DevLinkGetDeviceList() ([]*DevlinkDevice, error) {
 	f, err := h.GenlFamilyGet(nl.GENL_DEVLINK_NAME)
 	if err != nil {
@@ -478,9 +481,9 @@ func (h *Handle) DevLinkGetDeviceList() ([]*DevlinkDevice, error) {
 	req := h.newNetlinkRequest(int(f.ID),
 		unix.NLM_F_REQUEST|unix.NLM_F_ACK|unix.NLM_F_DUMP)
 	req.AddData(msg)
-	msgs, err := req.Execute(unix.NETLINK_GENERIC, 0)
-	if err != nil {
-		return nil, err
+	msgs, executeErr := req.Execute(unix.NETLINK_GENERIC, 0)
+	if executeErr != nil && !errors.Is(executeErr, ErrDumpInterrupted) {
+		return nil, executeErr
 	}
 	devices, err := parseDevLinkDeviceList(msgs)
 	if err != nil {
@@ -489,11 +492,14 @@ func (h *Handle) DevLinkGetDeviceList() ([]*DevlinkDevice, error) {
 	for _, d := range devices {
 		h.getEswitchAttrs(f, d)
 	}
-	return devices, nil
+	return devices, executeErr
 }
 
 // DevLinkGetDeviceList provides a pointer to devlink devices and nil error,
 // otherwise returns an error code.
+//
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func DevLinkGetDeviceList() ([]*DevlinkDevice, error) {
 	return pkgHandle.DevLinkGetDeviceList()
 }
@@ -646,6 +652,8 @@ func parseDevLinkAllPortList(msgs [][]byte) ([]*DevlinkPort, error) {
 
 // DevLinkGetPortList provides a pointer to devlink ports and nil error,
 // otherwise returns an error code.
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func (h *Handle) DevLinkGetAllPortList() ([]*DevlinkPort, error) {
 	f, err := h.GenlFamilyGet(nl.GENL_DEVLINK_NAME)
 	if err != nil {
@@ -658,19 +666,21 @@ func (h *Handle) DevLinkGetAllPortList() ([]*DevlinkPort, error) {
 	req := h.newNetlinkRequest(int(f.ID),
 		unix.NLM_F_REQUEST|unix.NLM_F_ACK|unix.NLM_F_DUMP)
 	req.AddData(msg)
-	msgs, err := req.Execute(unix.NETLINK_GENERIC, 0)
-	if err != nil {
-		return nil, err
+	msgs, executeErr := req.Execute(unix.NETLINK_GENERIC, 0)
+	if executeErr != nil && !errors.Is(executeErr, ErrDumpInterrupted) {
+		return nil, executeErr
 	}
 	ports, err := parseDevLinkAllPortList(msgs)
 	if err != nil {
 		return nil, err
 	}
-	return ports, nil
+	return ports, executeErr
 }
 
 // DevLinkGetPortList provides a pointer to devlink ports and nil error,
 // otherwise returns an error code.
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func DevLinkGetAllPortList() ([]*DevlinkPort, error) {
 	return pkgHandle.DevLinkGetAllPortList()
 }
@@ -738,15 +748,18 @@ func (h *Handle) DevlinkGetDeviceResources(bus string, device string) (*DevlinkR
 
 // DevlinkGetDeviceParams returns parameters for devlink device
 // Equivalent to: `devlink dev param show <bus>/<device>`
+//
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func (h *Handle) DevlinkGetDeviceParams(bus string, device string) ([]*DevlinkParam, error) {
 	_, req, err := h.createCmdReq(nl.DEVLINK_CMD_PARAM_GET, bus, device)
 	if err != nil {
 		return nil, err
 	}
 	req.Flags |= unix.NLM_F_DUMP
-	respmsg, err := req.Execute(unix.NETLINK_GENERIC, 0)
-	if err != nil {
-		return nil, err
+	respmsg, executeErr := req.Execute(unix.NETLINK_GENERIC, 0)
+	if executeErr != nil && !errors.Is(executeErr, ErrDumpInterrupted) {
+		return nil, executeErr
 	}
 	var params []*DevlinkParam
 	for _, m := range respmsg {
@@ -761,11 +774,14 @@ func (h *Handle) DevlinkGetDeviceParams(bus string, device string) ([]*DevlinkPa
 		params = append(params, p)
 	}
 
-	return params, nil
+	return params, executeErr
 }
 
 // DevlinkGetDeviceParams returns parameters for devlink device
 // Equivalent to: `devlink dev param show <bus>/<device>`
+//
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func DevlinkGetDeviceParams(bus string, device string) ([]*DevlinkParam, error) {
 	return pkgHandle.DevlinkGetDeviceParams(bus, device)
 }

filter_linux.go

@@ -405,14 +405,20 @@ func (h *Handle) filterModify(filter Filter, proto, flags int) error {
 
 // FilterList gets a list of filters in the system.
 // Equivalent to: `tc filter show`.
+//
 // Generally returns nothing if link and parent are not specified.
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func FilterList(link Link, parent uint32) ([]Filter, error) {
 	return pkgHandle.FilterList(link, parent)
 }
 
 // FilterList gets a list of filters in the system.
 // Equivalent to: `tc filter show`.
+//
 // Generally returns nothing if link and parent are not specified.
+// If the returned error is [ErrDumpInterrupted], results may be inconsistent
+// or incomplete.
 func (h *Handle) FilterList(link Link, parent uint32) ([]Filter, error) {
 	req := h.newNetlinkRequest(unix.RTM_GETTFILTER, unix.NLM_F_DUMP)
 	msg := &nl.TcMsg{
@@ -426,9 +432,9 @@ func (h *Handle) FilterList(link Link, parent uint32) ([]Filter, error) {
 	}
 	req.AddData(msg)
 
-	msgs, err := req.Execute(unix.NETLINK_ROUTE, unix.RTM_NEWTFILTER)
-	if err != nil {
-		return nil, err
+	msgs, executeErr := req.Execute(unix.NETLINK_ROUTE, unix.RTM_NEWTFILTER)
+	if executeErr != nil && !errors.Is(executeErr, ErrDumpInterrupted) {
+		return nil, executeErr
 	}
 
 	var res []Filter
@@ -516,7 +522,7 @@ func (h *Handle) FilterList(link Link, parent uint32) ([]Filter, error) {
 		}
 	}
 
-	return res, nil
+	return res, executeErr
 }
 
 func toTcGen(attrs *ActionAttrs, tcgen *nl.TcGen) {