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consul
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Don't generate TXT records just to discard them (#5272) 

* Don't generate TXT records just to discard them

* Add unit test for formatNodeRecord to ensure it prevents returning TXT records
This commit is contained in:
Matt Keeler 2019-01-28 14:59:58 -05:00 committed by GitHub
parent ae1fdaa4c2
commit 1736e24fb3
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 48 additions and 11 deletions
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40
agent/dns.go
View File

@ -457,7 +457,7 @@ func (d *DNSServer) nameservers(edns bool, maxRecursionLevel int) (ns []dns.RR,
}
ns = append(ns, nsrr)
glue, meta := d.formatNodeRecord(nil, addr, fqdn, dns.TypeANY, d.config.NodeTTL, edns, maxRecursionLevel)
glue, meta := d.formatNodeRecord(nil, addr, fqdn, dns.TypeANY, d.config.NodeTTL, edns, maxRecursionLevel, d.config.NodeMetaTXT)
extra = append(extra, glue...)
if meta != nil && d.config.NodeMetaTXT {
extra = append(extra, meta...)
@ -681,17 +681,26 @@ RPC:
return
}
generateMeta := false
metaInAnswer := false
if qType == dns.TypeANY || qType == dns.TypeTXT {
generateMeta = true
metaInAnswer = true
} else if d.config.NodeMetaTXT {
generateMeta = true
}
// Add the node record
n := out.NodeServices.Node
edns := req.IsEdns0() != nil
addr := d.agent.TranslateAddress(datacenter, n.Address, n.TaggedAddresses)
records, meta := d.formatNodeRecord(out.NodeServices.Node, addr, req.Question[0].Name, qType, d.config.NodeTTL, edns, maxRecursionLevel)
records, meta := d.formatNodeRecord(out.NodeServices.Node, addr, req.Question[0].Name, qType, d.config.NodeTTL, edns, maxRecursionLevel, generateMeta)
if records != nil {
resp.Answer = append(resp.Answer, records...)
}
if meta != nil && (qType == dns.TypeANY || qType == dns.TypeTXT) {
if meta != nil && metaInAnswer && generateMeta {
resp.Answer = append(resp.Answer, meta...)
} else if meta != nil && d.config.NodeMetaTXT {
} else if meta != nil && generateMeta {
resp.Extra = append(resp.Extra, meta...)
}
}
@ -722,7 +731,7 @@ func encodeKVasRFC1464(key, value string) (txt string) {
// The return value is two slices. The first slice is the main answer slice (containing the A, AAAA, CNAME) RRs for the node
// and the second slice contains any TXT RRs created from the node metadata. It is up to the caller to determine where the
// generated RRs should go and if they should be used at all.
func (d *DNSServer) formatNodeRecord(node *structs.Node, addr, qName string, qType uint16, ttl time.Duration, edns bool, maxRecursionLevel int) (records, meta []dns.RR) {
func (d *DNSServer) formatNodeRecord(node *structs.Node, addr, qName string, qType uint16, ttl time.Duration, edns bool, maxRecursionLevel int, generateMeta bool) (records, meta []dns.RR) {
// Parse the IP
ip := net.ParseIP(addr)
var ipv4 net.IP
@ -783,7 +792,7 @@ func (d *DNSServer) formatNodeRecord(node *structs.Node, addr, qName string, qTy
}
}
if node != nil {
if node != nil && generateMeta {
for key, value := range node.Meta {
txt := value
if !strings.HasPrefix(strings.ToLower(key), "rfc1035-") {
@ -1016,7 +1025,7 @@ func (d *DNSServer) lookupServiceNodes(datacenter, service, tag string, connect
Connect: connect,
Datacenter: datacenter,
ServiceName: service,
ServiceTags: []string{tag},
ServiceTags: []string{tag},
TagFilter: tag != "",
QueryOptions: structs.QueryOptions{
Token: d.agent.tokens.UserToken(),
@ -1246,9 +1255,18 @@ func (d *DNSServer) serviceNodeRecords(dc string, nodes structs.CheckServiceNode
}
handled[addr] = struct{}{}
generateMeta := false
metaInAnswer := false
if qType == dns.TypeANY || qType == dns.TypeTXT {
generateMeta = true
metaInAnswer = true
} else if d.config.NodeMetaTXT {
generateMeta = true
}
// Add the node record
had_answer := false
records, meta := d.formatNodeRecord(node.Node, addr, qName, qType, ttl, edns, maxRecursionLevel)
records, meta := d.formatNodeRecord(node.Node, addr, qName, qType, ttl, edns, maxRecursionLevel, generateMeta)
if records != nil {
switch records[0].(type) {
case *dns.CNAME:
@ -1263,10 +1281,10 @@ func (d *DNSServer) serviceNodeRecords(dc string, nodes structs.CheckServiceNode
}
}
if meta != nil && (qType == dns.TypeANY || qType == dns.TypeTXT) {
if meta != nil && generateMeta && metaInAnswer {
resp.Answer = append(resp.Answer, meta...)
had_answer = true
} else if meta != nil && d.config.NodeMetaTXT {
} else if meta != nil && generateMeta {
resp.Extra = append(resp.Extra, meta...)
}
@ -1367,7 +1385,7 @@ func (d *DNSServer) serviceSRVRecords(dc string, nodes structs.CheckServiceNodes
}
// Add the extra record
records, meta := d.formatNodeRecord(node.Node, addr, srvRec.Target, dns.TypeANY, ttl, edns, maxRecursionLevel)
records, meta := d.formatNodeRecord(node.Node, addr, srvRec.Target, dns.TypeANY, ttl, edns, maxRecursionLevel, d.config.NodeMetaTXT)
if len(records) > 0 {
// Use the node address if it doesn't differ from the service address
if addr == node.Node.Address {

19
agent/dns_test.go
View File

@ -6330,3 +6330,22 @@ func TestDNSInvalidRegex(t *testing.T) {
}
}
func TestDNS_formatNodeRecord(t *testing.T) {
s := &DNSServer{}
node := &structs.Node{
Meta: map[string]string{
"key": "value",
"key2": "value2",
},
}
records, meta := s.formatNodeRecord(node, "198.18.0.1", "test.node.consul", dns.TypeA, 5*time.Minute, false, 3, false)
require.Len(t, records, 1)
require.Len(t, meta, 0)
records, meta = s.formatNodeRecord(node, "198.18.0.1", "test.node.consul", dns.TypeA, 5*time.Minute, false, 3, true)
require.Len(t, records, 1)
require.Len(t, meta, 2)
}