mirror of https://github.com/status-im/consul.git
Ensure TXT RRs always end up in the Additional section except for ANY or TXT queries
This also changes where the enforcement of the enable_additional_node_meta_txt configuration gets applied. formatNodeRecord returns the main RRs and the meta/TXT RRs in separate slices. Its then up to the caller to add to the appropriate sections or not.
This commit is contained in:
Matt Keeler
parent
c8b37f0a4c
commit
cbf8f14451
60
agent/dns.go
60
agent/dns.go
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@ -376,8 +376,11 @@ func (d *DNSServer) nameservers(edns bool) (ns []dns.RR, extra []dns.RR) {
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}
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ns = append(ns, nsrr)
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glue := d.formatNodeRecord(nil, addr, fqdn, dns.TypeANY, d.config.NodeTTL, edns, false)
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glue, meta := d.formatNodeRecord(nil, addr, fqdn, dns.TypeANY, d.config.NodeTTL, edns)
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extra = append(extra, glue...)
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if meta != nil && d.config.NodeMetaTXT {
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extra = append(extra, meta...)
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}
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// don't provide more than 3 servers
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if len(ns) >= 3 {
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@ -592,10 +595,15 @@ RPC:
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n := out.NodeServices.Node
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edns := req.IsEdns0() != nil
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addr := d.agent.TranslateAddress(datacenter, n.Address, n.TaggedAddresses)
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records := d.formatNodeRecord(out.NodeServices.Node, addr, req.Question[0].Name, qType, d.config.NodeTTL, edns, true)
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records, meta := d.formatNodeRecord(out.NodeServices.Node, addr, req.Question[0].Name, qType, d.config.NodeTTL, edns)
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if records != nil {
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resp.Answer = append(resp.Answer, records...)
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}
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if meta != nil && (qType == dns.TypeANY || qType == dns.TypeTXT) {
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resp.Answer = append(resp.Answer, meta...)
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} else if meta != nil && d.config.NodeMetaTXT {
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resp.Extra = append(resp.Extra, meta...)
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}
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}
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// encodeKVasRFC1464 encodes a key-value pair according to RFC1464
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@ -619,8 +627,12 @@ func encodeKVasRFC1464(key, value string) (txt string) {
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return key + "=" + value
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}
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// formatNodeRecord takes a Node and returns an A, AAAA, TXT or CNAME record
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func (d *DNSServer) formatNodeRecord(node *structs.Node, addr, qName string, qType uint16, ttl time.Duration, edns, answer bool) (records []dns.RR) {
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// formatNodeRecord takes a Node and returns the RRs associated with that node
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//
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// The return value is two slices. The first slice is the main answer slice (containing the A, AAAA, CNAME) RRs for the node
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// and the second slice contains any TXT RRs created from the node metadata. It is up to the caller to determine where the
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// generated RRs should go and if they should be used at all.
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func (d *DNSServer) formatNodeRecord(node *structs.Node, addr, qName string, qType uint16, ttl time.Duration, edns bool) (records, meta []dns.RR) {
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// Parse the IP
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ip := net.ParseIP(addr)
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var ipv4 net.IP
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@ -681,26 +693,14 @@ func (d *DNSServer) formatNodeRecord(node *structs.Node, addr, qName string, qTy
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}
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}
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node_meta_txt := false
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if node == nil {
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node_meta_txt = false
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} else if answer {
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node_meta_txt = true
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} else {
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// Use configuration when the TXT RR would
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// end up in the Additional section of the
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// DNS response
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node_meta_txt = d.config.NodeMetaTXT
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}
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if node_meta_txt {
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if node != nil {
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for key, value := range node.Meta {
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txt := value
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if !strings.HasPrefix(strings.ToLower(key), "rfc1035-") {
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txt = encodeKVasRFC1464(key, value)
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}
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records = append(records, &dns.TXT{
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meta = append(meta, &dns.TXT{
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Hdr: dns.RR_Header{
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Name: qName,
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Rrtype: dns.TypeTXT,
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@ -712,7 +712,7 @@ func (d *DNSServer) formatNodeRecord(node *structs.Node, addr, qName string, qTy
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}
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}
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return records
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return records, meta
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}
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// indexRRs populates a map which indexes a given list of RRs by name. NOTE that
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@ -1167,9 +1167,21 @@ func (d *DNSServer) serviceNodeRecords(dc string, nodes structs.CheckServiceNode
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handled[addr] = struct{}{}
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// Add the node record
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records := d.formatNodeRecord(node.Node, addr, qName, qType, ttl, edns, true)
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had_answer := false
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records, meta := d.formatNodeRecord(node.Node, addr, qName, qType, ttl, edns)
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if records != nil {
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resp.Answer = append(resp.Answer, records...)
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had_answer = true
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}
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if meta != nil && (qType == dns.TypeANY || qType == dns.TypeTXT) {
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resp.Answer = append(resp.Answer, meta...)
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had_answer = true
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} else if meta != nil && d.config.NodeMetaTXT {
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resp.Extra = append(resp.Extra, meta...)
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}
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if had_answer {
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count++
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if count == d.config.ARecordLimit {
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// We stop only if greater than 0 or we reached the limit
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@ -1216,7 +1228,7 @@ func (d *DNSServer) serviceSRVRecords(dc string, nodes structs.CheckServiceNodes
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}
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// Add the extra record
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records := d.formatNodeRecord(node.Node, addr, srvRec.Target, dns.TypeANY, ttl, edns, false)
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records, meta := d.formatNodeRecord(node.Node, addr, srvRec.Target, dns.TypeANY, ttl, edns)
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if len(records) > 0 {
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// Use the node address if it doesn't differ from the service address
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if addr == node.Node.Address {
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@ -1246,6 +1258,10 @@ func (d *DNSServer) serviceSRVRecords(dc string, nodes structs.CheckServiceNodes
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resp.Extra = append(resp.Extra, records...)
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}
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}
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if meta != nil && d.config.NodeMetaTXT {
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resp.Extra = append(resp.Extra, meta...)
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}
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}
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}
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}
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@ -178,6 +178,9 @@ func TestDNS_NodeLookup(t *testing.T) {
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TaggedAddresses: map[string]string{
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"wan": "127.0.0.2",
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},
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NodeMeta: map[string]string{
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"key": "value",
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},
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}
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var out struct{}
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@ -190,24 +193,40 @@ func TestDNS_NodeLookup(t *testing.T) {
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c := new(dns.Client)
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in, _, err := c.Exchange(m, a.DNSAddr())
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if err != nil {
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t.Fatalf("err: %v", err)
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}
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if len(in.Answer) != 1 {
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t.Fatalf("Bad: %#v", in)
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}
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require.NoError(t, err)
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require.Len(t, in.Answer, 2)
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require.Len(t, in.Extra, 0)
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aRec, ok := in.Answer[0].(*dns.A)
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if !ok {
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t.Fatalf("Bad: %#v", in.Answer[0])
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}
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if aRec.A.String() != "127.0.0.1" {
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t.Fatalf("Bad: %#v", in.Answer[0])
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}
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if aRec.Hdr.Ttl != 0 {
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t.Fatalf("Bad: %#v", in.Answer[0])
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}
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require.True(t, ok, "First answer is not an A record")
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require.Equal(t, "127.0.0.1", aRec.A.String())
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require.Equal(t, uint32(0), aRec.Hdr.Ttl)
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txt, ok := in.Answer[1].(*dns.TXT)
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require.True(t, ok, "Second answer is not a TXT record")
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require.Len(t, txt.Txt, 1)
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require.Equal(t, "key=value", txt.Txt[0])
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// Re-do the query, but only for an A RR
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m = new(dns.Msg)
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m.SetQuestion("foo.node.consul.", dns.TypeA)
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c = new(dns.Client)
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in, _, err = c.Exchange(m, a.DNSAddr())
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require.NoError(t, err)
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require.Len(t, in.Answer, 1)
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require.Len(t, in.Extra, 1)
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aRec, ok = in.Answer[0].(*dns.A)
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require.True(t, ok, "Answer is not an A record")
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require.Equal(t, "127.0.0.1", aRec.A.String())
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require.Equal(t, uint32(0), aRec.Hdr.Ttl)
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txt, ok = in.Extra[0].(*dns.TXT)
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require.True(t, ok, "Extra record is not a TXT record")
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require.Len(t, txt.Txt, 1)
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require.Equal(t, "key=value", txt.Txt[0])
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// Re-do the query, but specify the DC
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m = new(dns.Msg)
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@ -215,24 +234,17 @@ func TestDNS_NodeLookup(t *testing.T) {
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c = new(dns.Client)
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in, _, err = c.Exchange(m, a.DNSAddr())
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if err != nil {
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t.Fatalf("err: %v", err)
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}
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if len(in.Answer) != 1 {
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t.Fatalf("Bad: %#v", in)
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}
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require.NoError(t, err)
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require.Len(t, in.Answer, 2)
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require.Len(t, in.Extra, 0)
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aRec, ok = in.Answer[0].(*dns.A)
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if !ok {
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t.Fatalf("Bad: %#v", in.Answer[0])
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}
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if aRec.A.String() != "127.0.0.1" {
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t.Fatalf("Bad: %#v", in.Answer[0])
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}
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if aRec.Hdr.Ttl != 0 {
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t.Fatalf("Bad: %#v", in.Answer[0])
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}
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require.True(t, ok, "First answer is not an A record")
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require.Equal(t, "127.0.0.1", aRec.A.String())
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require.Equal(t, uint32(0), aRec.Hdr.Ttl)
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txt, ok = in.Answer[1].(*dns.TXT)
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require.True(t, ok, "Second answer is not a TXT record")
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// lookup a non-existing node, we should receive a SOA
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m = new(dns.Msg)
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@ -240,22 +252,11 @@ func TestDNS_NodeLookup(t *testing.T) {
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c = new(dns.Client)
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in, _, err = c.Exchange(m, a.DNSAddr())
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if err != nil {
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t.Fatalf("err: %v", err)
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}
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if len(in.Ns) != 1 {
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t.Fatalf("Bad: %#v %#v", in, len(in.Answer))
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}
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require.NoError(t, err)
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require.Len(t, in.Ns, 1)
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soaRec, ok := in.Ns[0].(*dns.SOA)
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if !ok {
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t.Fatalf("Bad: %#v", in.Ns[0])
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}
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if soaRec.Hdr.Ttl != 0 {
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t.Fatalf("Bad: %#v", in.Ns[0])
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}
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require.True(t, ok, "NS RR is not a SOA record")
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require.Equal(t, uint32(0), soaRec.Hdr.Ttl)
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}
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func TestDNS_CaseInsensitiveNodeLookup(t *testing.T) {
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@ -598,6 +599,41 @@ func TestDNS_NodeLookup_ANY_DontSuppressTXT(t *testing.T) {
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verify.Values(t, "answer", in.Answer, wantAnswer)
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}
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func TestDNS_NodeLookup_A_SuppressTXT(t *testing.T) {
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a := NewTestAgent(t.Name(), `dns_config = { enable_additional_node_meta_txt = false }`)
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defer a.Shutdown()
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args := &structs.RegisterRequest{
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Datacenter: "dc1",
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Node: "bar",
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Address: "127.0.0.1",
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NodeMeta: map[string]string{
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"key": "value",
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},
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}
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var out struct{}
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require.NoError(t, a.RPC("Catalog.Register", args, &out))
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m := new(dns.Msg)
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m.SetQuestion("bar.node.consul.", dns.TypeA)
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c := new(dns.Client)
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in, _, err := c.Exchange(m, a.DNSAddr())
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require.NoError(t, err)
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wantAnswer := []dns.RR{
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&dns.A{
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Hdr: dns.RR_Header{Name: "bar.node.consul.", Rrtype: dns.TypeA, Class: dns.ClassINET, Rdlength: 0x4},
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A: []byte{0x7f, 0x0, 0x0, 0x1}, // 127.0.0.1
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},
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}
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verify.Values(t, "answer", in.Answer, wantAnswer)
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// ensure TXT RR suppression
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require.Len(t, in.Extra, 0)
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}
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func TestDNS_EDNS0(t *testing.T) {
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t.Parallel()
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a := NewTestAgent(t.Name(), "")
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