diff --git a/pkg/netlinksafe/netlink.go b/pkg/netlinksafe/netlink.go new file mode 100644 index 00000000..0f7f45b6 --- /dev/null +++ b/pkg/netlinksafe/netlink.go @@ -0,0 +1,321 @@ +// Package netlinksafe wraps vishvandanda/netlink functions that may return EINTR. +// +// A Handle instantiated using [NewHandle] or [NewHandleAt] can be used in place +// of a netlink.Handle, it's a wrapper that replaces methods that need to be +// wrapped. Functions that use the package handle need to be called as "netlinksafe.X" +// instead of "netlink.X". +// +// The wrapped functions currently return EINTR when NLM_F_DUMP_INTR flagged +// in a netlink response, meaning something changed during the dump so results +// may be incomplete or inconsistent. +// +// At present, the possibly incomplete/inconsistent results are not returned +// by netlink functions along with the EINTR. So, it's not possible to do +// anything but retry. After maxAttempts the EINTR will be returned to the +// caller. +package netlinksafe + +import ( + "log" + + "github.com/pkg/errors" + "github.com/vishvananda/netlink" + "github.com/vishvananda/netlink/nl" + "github.com/vishvananda/netns" +) + +// Arbitrary limit on max attempts at netlink calls if they are repeatedly interrupted. +const maxAttempts = 5 + +type Handle struct { + *netlink.Handle +} + +func NewHandle(nlFamilies ...int) (Handle, error) { + nlh, err := netlink.NewHandle(nlFamilies...) + if err != nil { + return Handle{}, err + } + return Handle{nlh}, nil +} + +func NewHandleAt(ns netns.NsHandle, nlFamilies ...int) (Handle, error) { + nlh, err := netlink.NewHandleAt(ns, nlFamilies...) + if err != nil { + return Handle{}, err + } + return Handle{nlh}, nil +} + +func (h Handle) Close() { + if h.Handle != nil { + h.Handle.Close() + } +} + +func retryOnIntr(f func() error) { + for attempt := 0; attempt < maxAttempts; attempt++ { + if err := f(); !errors.Is(err, netlink.ErrDumpInterrupted) { + return + } + } + log.Printf("netlink call interrupted after %d attempts", maxAttempts) +} + +func discardErrDumpInterrupted(err error) error { + if errors.Is(err, netlink.ErrDumpInterrupted) { + // The netlink function has returned possibly-inconsistent data along with the + // error. Discard the error and return the data. This restores the behaviour of + // the netlink package prior to v1.2.1, in which NLM_F_DUMP_INTR was ignored in + // the netlink response. + log.Printf("discarding ErrDumpInterrupted: %+v", errors.WithStack(err)) + return nil + } + return err +} + +// AddrList calls netlink.AddrList, retrying if necessary. +func AddrList(link netlink.Link, family int) ([]netlink.Addr, error) { + var addrs []netlink.Addr + var err error + retryOnIntr(func() error { + addrs, err = netlink.AddrList(link, family) //nolint:forbidigo + return err + }) + return addrs, discardErrDumpInterrupted(err) +} + +// LinkByName calls h.Handle.LinkByName, retrying if necessary. The netlink function +// doesn't normally ask the kernel for a dump of links. But, on an old kernel, it +// will do as a fallback and that dump may get inconsistent results. +func (h Handle) LinkByName(name string) (netlink.Link, error) { + var link netlink.Link + var err error + retryOnIntr(func() error { + link, err = h.Handle.LinkByName(name) //nolint:forbidigo + return err + }) + return link, discardErrDumpInterrupted(err) +} + +// LinkByName calls netlink.LinkByName, retrying if necessary. The netlink +// function doesn't normally ask the kernel for a dump of links. But, on an old +// kernel, it will do as a fallback and that dump may get inconsistent results. +func LinkByName(name string) (netlink.Link, error) { + var link netlink.Link + var err error + retryOnIntr(func() error { + link, err = netlink.LinkByName(name) //nolint:forbidigo + return err + }) + return link, discardErrDumpInterrupted(err) +} + +// LinkList calls h.Handle.LinkList, retrying if necessary. +func (h Handle) LinkList() ([]netlink.Link, error) { + var links []netlink.Link + var err error + retryOnIntr(func() error { + links, err = h.Handle.LinkList() //nolint:forbidigo + return err + }) + return links, discardErrDumpInterrupted(err) +} + +// LinkList calls netlink.Handle.LinkList, retrying if necessary. +func LinkList() ([]netlink.Link, error) { + var links []netlink.Link + var err error + retryOnIntr(func() error { + links, err = netlink.LinkList() //nolint:forbidigo + return err + }) + return links, discardErrDumpInterrupted(err) +} + +// RouteList calls h.Handle.RouteList, retrying if necessary. +func (h Handle) RouteList(link netlink.Link, family int) ([]netlink.Route, error) { + var routes []netlink.Route + var err error + retryOnIntr(func() error { + routes, err = h.Handle.RouteList(link, family) //nolint:forbidigo + return err + }) + return routes, err +} + +// RouteList calls netlink.RouteList, retrying if necessary. +func RouteList(link netlink.Link, family int) ([]netlink.Route, error) { + var route []netlink.Route + var err error + retryOnIntr(func() error { + route, err = netlink.RouteList(link, family) //nolint:forbidigo + return err + }) + return route, discardErrDumpInterrupted(err) +} + +// BridgeVlanList calls netlink.BridgeVlanList, retrying if necessary. +func BridgeVlanList() (map[int32][]*nl.BridgeVlanInfo, error) { + var err error + var info map[int32][]*nl.BridgeVlanInfo + retryOnIntr(func() error { + info, err = netlink.BridgeVlanList() //nolint:forbidigo + return err + }) + return info, discardErrDumpInterrupted(err) +} + +// RouteListFiltered calls h.Handle.RouteListFiltered, retrying if necessary. +func (h Handle) RouteListFiltered(family int, filter *netlink.Route, filterMask uint64) ([]netlink.Route, error) { + var routes []netlink.Route + var err error + retryOnIntr(func() error { + routes, err = h.Handle.RouteListFiltered(family, filter, filterMask) //nolint:forbidigo + return err + }) + return routes, err +} + +// RouteListFiltered calls netlink.RouteListFiltered, retrying if necessary. +func RouteListFiltered(family int, filter *netlink.Route, filterMask uint64) ([]netlink.Route, error) { + var route []netlink.Route + var err error + retryOnIntr(func() error { + route, err = netlink.RouteListFiltered(family, filter, filterMask) //nolint:forbidigo + return err + }) + return route, discardErrDumpInterrupted(err) +} + +// QdiscList calls netlink.QdiscList, retrying if necessary. +func QdiscList(link netlink.Link) ([]netlink.Qdisc, error) { + var qdisc []netlink.Qdisc + var err error + retryOnIntr(func() error { + qdisc, err = netlink.QdiscList(link) //nolint:forbidigo + return err + }) + return qdisc, discardErrDumpInterrupted(err) +} + +// QdiscList calls h.Handle.QdiscList, retrying if necessary. +func (h *Handle) QdiscList(link netlink.Link) ([]netlink.Qdisc, error) { + var qdisc []netlink.Qdisc + var err error + retryOnIntr(func() error { + qdisc, err = h.Handle.QdiscList(link) //nolint:forbidigo + return err + }) + return qdisc, err +} + +// LinkGetProtinfo calls netlink.LinkGetProtinfo, retrying if necessary. +func LinkGetProtinfo(link netlink.Link) (netlink.Protinfo, error) { + var protinfo netlink.Protinfo + var err error + retryOnIntr(func() error { + protinfo, err = netlink.LinkGetProtinfo(link) //nolint:forbidigo + return err + }) + return protinfo, discardErrDumpInterrupted(err) +} + +// LinkGetProtinfo calls h.Handle.LinkGetProtinfo, retrying if necessary. +func (h *Handle) LinkGetProtinfo(link netlink.Link) (netlink.Protinfo, error) { + var protinfo netlink.Protinfo + var err error + retryOnIntr(func() error { + protinfo, err = h.Handle.LinkGetProtinfo(link) //nolint:forbidigo + return err + }) + return protinfo, err +} + +// RuleListFiltered calls netlink.RuleListFiltered, retrying if necessary. +func RuleListFiltered(family int, filter *netlink.Rule, filterMask uint64) ([]netlink.Rule, error) { + var rules []netlink.Rule + var err error + retryOnIntr(func() error { + rules, err = netlink.RuleListFiltered(family, filter, filterMask) //nolint:forbidigo + return err + }) + return rules, discardErrDumpInterrupted(err) +} + +// RuleListFiltered calls h.Handle.RuleListFiltered, retrying if necessary. +func (h *Handle) RuleListFiltered(family int, filter *netlink.Rule, filterMask uint64) ([]netlink.Rule, error) { + var rules []netlink.Rule + var err error + retryOnIntr(func() error { + rules, err = h.Handle.RuleListFiltered(family, filter, filterMask) //nolint:forbidigo + return err + }) + return rules, err +} + +// FilterList calls netlink.FilterList, retrying if necessary. +func FilterList(link netlink.Link, parent uint32) ([]netlink.Filter, error) { + var filters []netlink.Filter + var err error + retryOnIntr(func() error { + filters, err = netlink.FilterList(link, parent) //nolint:forbidigo + return err + }) + return filters, discardErrDumpInterrupted(err) +} + +// FilterList calls h.Handle.FilterList, retrying if necessary. +func (h *Handle) FilterList(link netlink.Link, parent uint32) ([]netlink.Filter, error) { + var filters []netlink.Filter + var err error + retryOnIntr(func() error { + filters, err = h.Handle.FilterList(link, parent) //nolint:forbidigo + return err + }) + return filters, err +} + +// RuleList calls netlink.RuleList, retrying if necessary. +func RuleList(family int) ([]netlink.Rule, error) { + var rules []netlink.Rule + var err error + retryOnIntr(func() error { + rules, err = netlink.RuleList(family) //nolint:forbidigo + return err + }) + return rules, discardErrDumpInterrupted(err) +} + +// RuleList calls h.Handle.RuleList, retrying if necessary. +func (h *Handle) RuleList(family int) ([]netlink.Rule, error) { + var rules []netlink.Rule + var err error + retryOnIntr(func() error { + rules, err = h.Handle.RuleList(family) //nolint:forbidigo + return err + }) + return rules, err +} + +// ConntrackDeleteFilters calls netlink.ConntrackDeleteFilters, retrying if necessary. +func ConntrackDeleteFilters(table netlink.ConntrackTableType, family netlink.InetFamily, filters ...netlink.CustomConntrackFilter) (uint, error) { + var deleted uint + var err error + retryOnIntr(func() error { + deleted, err = netlink.ConntrackDeleteFilters(table, family, filters...) //nolint:forbidigo + return err + }) + return deleted, discardErrDumpInterrupted(err) +} + +// ConntrackDeleteFilters calls h.Handle.ConntrackDeleteFilters, retrying if necessary. +func (h *Handle) ConntrackDeleteFilters(table netlink.ConntrackTableType, family netlink.InetFamily, filters ...netlink.CustomConntrackFilter) (uint, error) { + var deleted uint + var err error + retryOnIntr(func() error { + deleted, err = h.Handle.ConntrackDeleteFilters(table, family, filters...) //nolint:forbidigo + return err + }) + return deleted, err +}