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plugin/etcd+kubernetes: Persist truncated state to client if CNAME lookup response is truncated (#4715)

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Persist the TC bit to client response for truncated CNAME lookups.
Signed-off-by: Chris O'Haver <cohaver@infoblox.com>
This commit is contained in:
Chris O'Haver
2022-02-22 09:38:57 -05:00
committed by GitHub
parent d3a118e1c1
commit 66dc74caeb
5 changed files with 206 additions and 110 deletions
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46
plugin/backend_lookup.go
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@@ -14,10 +14,10 @@ import (
)
// A returns A records from Backend or an error.
func A(ctx context.Context, b ServiceBackend, zone string, state request.Request, previousRecords []dns.RR, opt Options) (records []dns.RR, err error) {
func A(ctx context.Context, b ServiceBackend, zone string, state request.Request, previousRecords []dns.RR, opt Options) (records []dns.RR, truncated bool, err error) {
services, err := checkForApex(ctx, b, zone, state, opt)
if err != nil {
return nil, err
return nil, false, err
}
dup := make(map[string]struct{})
@@ -44,7 +44,7 @@ func A(ctx context.Context, b ServiceBackend, zone string, state request.Request
if dns.IsSubDomain(zone, dns.Fqdn(serv.Host)) {
state1 := state.NewWithQuestion(serv.Host, state.QType())
state1.Zone = zone
nextRecords, err := A(ctx, b, zone, state1, append(previousRecords, newRecord), opt)
nextRecords, tc, err := A(ctx, b, zone, state1, append(previousRecords, newRecord), opt)
if err == nil {
// Not only have we found something we should add the CNAME and the IP addresses.
@@ -53,6 +53,9 @@ func A(ctx context.Context, b ServiceBackend, zone string, state request.Request
records = append(records, nextRecords...)
}
}
if tc {
truncated = true
}
continue
}
// This means we can not complete the CNAME, try to look else where.
@@ -62,6 +65,9 @@ func A(ctx context.Context, b ServiceBackend, zone string, state request.Request
if e1 != nil {
continue
}
if m1.Truncated {
truncated = true
}
// Len(m1.Answer) > 0 here is well?
records = append(records, newRecord)
records = append(records, m1.Answer...)
@@ -77,14 +83,14 @@ func A(ctx context.Context, b ServiceBackend, zone string, state request.Request
// nada
}
}
return records, nil
return records, truncated, nil
}
// AAAA returns AAAA records from Backend or an error.
func AAAA(ctx context.Context, b ServiceBackend, zone string, state request.Request, previousRecords []dns.RR, opt Options) (records []dns.RR, err error) {
func AAAA(ctx context.Context, b ServiceBackend, zone string, state request.Request, previousRecords []dns.RR, opt Options) (records []dns.RR, truncated bool, err error) {
services, err := checkForApex(ctx, b, zone, state, opt)
if err != nil {
return nil, err
return nil, false, err
}
dup := make(map[string]struct{})
@@ -112,7 +118,7 @@ func AAAA(ctx context.Context, b ServiceBackend, zone string, state request.Requ
if dns.IsSubDomain(zone, dns.Fqdn(serv.Host)) {
state1 := state.NewWithQuestion(serv.Host, state.QType())
state1.Zone = zone
nextRecords, err := AAAA(ctx, b, zone, state1, append(previousRecords, newRecord), opt)
nextRecords, tc, err := AAAA(ctx, b, zone, state1, append(previousRecords, newRecord), opt)
if err == nil {
// Not only have we found something we should add the CNAME and the IP addresses.
@@ -121,6 +127,9 @@ func AAAA(ctx context.Context, b ServiceBackend, zone string, state request.Requ
records = append(records, nextRecords...)
}
}
if tc {
truncated = true
}
continue
}
// This means we can not complete the CNAME, try to look else where.
@@ -129,6 +138,9 @@ func AAAA(ctx context.Context, b ServiceBackend, zone string, state request.Requ
if e1 != nil {
continue
}
if m1.Truncated {
truncated = true
}
// Len(m1.Answer) > 0 here is well?
records = append(records, newRecord)
records = append(records, m1.Answer...)
@@ -145,7 +157,7 @@ func AAAA(ctx context.Context, b ServiceBackend, zone string, state request.Requ
}
}
}
return records, nil
return records, truncated, nil
}
// SRV returns SRV records from the Backend.
@@ -223,7 +235,7 @@ func SRV(ctx context.Context, b ServiceBackend, zone string, state request.Reque
// Internal name, we should have some info on them, either v4 or v6
// Clients expect a complete answer, because we are a recursor in their view.
state1 := state.NewWithQuestion(srv.Target, dns.TypeA)
addr, e1 := A(ctx, b, zone, state1, nil, opt)
addr, _, e1 := A(ctx, b, zone, state1, nil, opt)
if e1 == nil {
extra = append(extra, addr...)
}
@@ -289,7 +301,7 @@ func MX(ctx context.Context, b ServiceBackend, zone string, state request.Reques
}
// Internal name
state1 := state.NewWithQuestion(mx.Mx, dns.TypeA)
addr, e1 := A(ctx, b, zone, state1, nil, opt)
addr, _, e1 := A(ctx, b, zone, state1, nil, opt)
if e1 == nil {
extra = append(extra, addr...)
}
@@ -329,11 +341,11 @@ func CNAME(ctx context.Context, b ServiceBackend, zone string, state request.Req
}
// TXT returns TXT records from Backend or an error.
func TXT(ctx context.Context, b ServiceBackend, zone string, state request.Request, previousRecords []dns.RR, opt Options) (records []dns.RR, err error) {
func TXT(ctx context.Context, b ServiceBackend, zone string, state request.Request, previousRecords []dns.RR, opt Options) (records []dns.RR, truncated bool, err error) {
services, err := b.Services(ctx, state, true, opt)
if err != nil {
return nil, err
return nil, false, err
}
dup := make(map[string]struct{})
@@ -360,8 +372,10 @@ func TXT(ctx context.Context, b ServiceBackend, zone string, state request.Reque
if dns.IsSubDomain(zone, dns.Fqdn(serv.Host)) {
state1 := state.NewWithQuestion(serv.Host, state.QType())
state1.Zone = zone
nextRecords, err := TXT(ctx, b, zone, state1, append(previousRecords, newRecord), opt)
nextRecords, tc, err := TXT(ctx, b, zone, state1, append(previousRecords, newRecord), opt)
if tc {
truncated = true
}
if err == nil {
// Not only have we found something we should add the CNAME and the IP addresses.
if len(nextRecords) > 0 {
@@ -386,13 +400,13 @@ func TXT(ctx context.Context, b ServiceBackend, zone string, state request.Reque
case dns.TypeTXT:
if _, ok := dup[serv.Host]; !ok {
dup[serv.Host] = struct{}{}
return append(records, serv.NewTXT(state.QName())), nil
return append(records, serv.NewTXT(state.QName())), truncated, nil
}
}
}
return records, nil
return records, truncated, nil
}
// PTR returns the PTR records from the backend, only services that have a domain name as host are included.