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https://github.com/coredns/coredns.git
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70fb03f711
Eagerly set name in newElem and make Name() read-only to avoid racy lazy writes under concurrent lookups. Add tests for empty-name comparisons and concurrent access to Less/Name(). In addition, regression tests to CloudDNS plugin. Signed-off-by: Ville Vesilehto <ville@vesilehto.fi>
104 lines
2.3 KiB
Go
104 lines
2.3 KiB
Go
package tree
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import "github.com/miekg/dns"
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// Elem is an element in the tree.
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type Elem struct {
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m map[uint16][]dns.RR
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name string // owner name
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}
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// newElem returns a new elem.
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func newElem(rr dns.RR) *Elem {
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e := Elem{m: make(map[uint16][]dns.RR)}
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e.m[rr.Header().Rrtype] = []dns.RR{rr}
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// Eagerly set the cached owner name to avoid racy lazy writes later.
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e.name = rr.Header().Name
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return &e
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}
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// Types returns the types of the records in e. The returned list is not sorted.
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func (e *Elem) Types() []uint16 {
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t := make([]uint16, len(e.m))
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i := 0
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for ty := range e.m {
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t[i] = ty
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i++
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}
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return t
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}
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// Type returns the RRs with type qtype from e.
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func (e *Elem) Type(qtype uint16) []dns.RR { return e.m[qtype] }
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// TypeForWildcard returns the RRs with type qtype from e. The ownername returned is set to qname.
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func (e *Elem) TypeForWildcard(qtype uint16, qname string) []dns.RR {
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rrs := e.m[qtype]
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if rrs == nil {
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return nil
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}
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copied := make([]dns.RR, len(rrs))
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for i := range rrs {
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copied[i] = dns.Copy(rrs[i])
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copied[i].Header().Name = qname
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}
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return copied
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}
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// All returns all RRs from e, regardless of type.
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func (e *Elem) All() []dns.RR {
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list := []dns.RR{}
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for _, rrs := range e.m {
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list = append(list, rrs...)
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}
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return list
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}
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// Name returns the name for this node.
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func (e *Elem) Name() string {
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// Read-only: name is eagerly set in newElem and should not be mutated here.
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if e.name != "" {
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return e.name
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}
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for _, rrs := range e.m {
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return rrs[0].Header().Name
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}
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return ""
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}
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// Empty returns true is e does not contain any RRs, i.e. is an empty-non-terminal.
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func (e *Elem) Empty() bool { return len(e.m) == 0 }
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// Insert inserts rr into e. If rr is equal to existing RRs, the RR will be added anyway.
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func (e *Elem) Insert(rr dns.RR) {
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t := rr.Header().Rrtype
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if e.m == nil {
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e.m = make(map[uint16][]dns.RR)
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e.m[t] = []dns.RR{rr}
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return
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}
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rrs, ok := e.m[t]
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if !ok {
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e.m[t] = []dns.RR{rr}
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return
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}
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rrs = append(rrs, rr)
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e.m[t] = rrs
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}
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// Delete removes all RRs of type rr.Header().Rrtype from e.
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func (e *Elem) Delete(rr dns.RR) {
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if e.m == nil {
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return
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}
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t := rr.Header().Rrtype
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delete(e.m, t)
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}
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// Less is a tree helper function that calls less.
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func Less(a *Elem, name string) int { return less(name, a.Name()) }
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