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stackexchange-dnscontrol/pkg/normalize/validate.go
Matthew Huxtable ff8ce26cee Provider support for DS records as children only (#765)
This functionality is required by the GCLOUD provider, which supports
recordsets of type DS but only for child records of the zone, to enable
further delegation. It does not support them at the apex of the zone (@)
because Google Cloud DNS is not itself a registrar which needs to model
this information.

A related change (14ff68b151, #760) was
previously introduced to enable DS support in Google, which broke
integration tests with this provider.

To cleanly support this, we introduce a new provider capability
CanUseDSForChildren and appropriate integration tests. Further, it is no
longer possible to verify a provider has the proper capabilities for a
zone simply by existence of particular records; we adapt the capability
checks to enable inspection of the individual recordsets where this is
required.

Closes #762
2020-06-18 17:24:13 -04:00

596 lines
19 KiB
Go

package normalize
import (
"fmt"
"net"
"strings"
"github.com/StackExchange/dnscontrol/v3/models"
"github.com/StackExchange/dnscontrol/v3/pkg/transform"
"github.com/StackExchange/dnscontrol/v3/providers"
"github.com/miekg/dns"
"github.com/miekg/dns/dnsutil"
)
// Returns false if target does not validate.
func checkIPv4(label string) error {
if net.ParseIP(label).To4() == nil {
return fmt.Errorf("WARNING: target (%v) is not an IPv4 address", label)
}
return nil
}
// Returns false if target does not validate.
func checkIPv6(label string) error {
if net.ParseIP(label).To16() == nil {
return fmt.Errorf("WARNING: target (%v) is not an IPv6 address", label)
}
return nil
}
// make sure target is valid reference for cnames, mx, etc.
func checkTarget(target string) error {
if target == "@" {
return nil
}
if len(target) < 1 {
return fmt.Errorf("empty target")
}
if strings.ContainsAny(target, `'" +,|!£$%&/()=?^*ç°§;:<>[]()@`) {
return fmt.Errorf("target (%v) includes invalid char", target)
}
// If it containts a ".", it must end in a ".".
if strings.ContainsRune(target, '.') && target[len(target)-1] != '.' {
return fmt.Errorf("target (%v) must end with a (.) [https://stackexchange.github.io/dnscontrol/why-the-dot]", target)
}
return nil
}
// validateRecordTypes list of valid rec.Type values. Returns true if this is a real DNS record type, false means it is a pseudo-type used internally.
func validateRecordTypes(rec *models.RecordConfig, domain string, pTypes []string) error {
var validTypes = map[string]bool{
"A": true,
"AAAA": true,
"CNAME": true,
"CAA": true,
"DS": true,
"TLSA": true,
"IMPORT_TRANSFORM": false,
"MX": true,
"SRV": true,
"SSHFP": true,
"TXT": true,
"NS": true,
"PTR": true,
"NAPTR": true,
"ALIAS": false,
}
_, ok := validTypes[rec.Type]
if !ok {
cType := providers.GetCustomRecordType(rec.Type)
if cType == nil {
return fmt.Errorf("Unsupported record type (%v) domain=%v name=%v", rec.Type, domain, rec.GetLabel())
}
for _, providerType := range pTypes {
if providerType != cType.Provider {
return fmt.Errorf("Custom record type %s is not compatible with provider type %s", rec.Type, providerType)
}
}
// it is ok. Lets replace the type with real type and add metadata to say we checked it
rec.Metadata["orig_custom_type"] = rec.Type
if cType.RealType != "" {
rec.Type = cType.RealType
}
}
return nil
}
// underscores in names are often used erroneously. They are valid for dns records, but invalid for urls.
// here we list common records expected to have underscores. Anything else containing an underscore will print a warning.
var labelUnderscores = []string{
"_acme-challenge",
"_amazonses",
"_dmarc",
"_domainconnect",
"_domainkey",
"_jabber",
"_mta-sts",
"_sip",
"_xmpp",
}
// these record types may contain underscores
var rTypeUnderscores = []string{"SRV", "TLSA", "TXT"}
func checkLabel(label string, rType string, target, domain string, meta map[string]string) error {
if label == "@" {
return nil
}
if len(label) < 1 {
return fmt.Errorf("empty %s label in %s", rType, domain)
}
if label[len(label)-1] == '.' {
return fmt.Errorf("label %s.%s ends with a (.)", label, domain)
}
if strings.HasSuffix(label, domain) {
if m := meta["skip_fqdn_check"]; m != "true" {
return fmt.Errorf(`label %s ends with domain name %s. Record names should not be fully qualified. Add {skip_fqdn_check:"true"} to this record if you really want to make %s.%s`, label, domain, label, domain)
}
}
// Underscores are permitted in labels, but we print a warning unless they
// are used in a way we consider typical. Yes, we're opinionated here.
// Don't warn for certain rtypes:
for _, ex := range rTypeUnderscores {
if rType == ex {
return nil
}
}
// Don't warn for CNAMEs if the target ends with acm-validations.aws
// See https://github.com/StackExchange/dnscontrol/issues/519
if strings.HasPrefix(label, "_") && rType == "CNAME" && strings.HasSuffix(target, ".acm-validations.aws.") {
return nil
}
// Don't warn for certain label substrings
for _, ex := range labelUnderscores {
if strings.Contains(label, ex) {
return nil
}
}
// Otherwise, warn.
if strings.ContainsRune(label, '_') {
return Warning{fmt.Errorf("label %s.%s contains an underscore", label, domain)}
}
return nil
}
// checkTargets returns true if rec.Target is valid for the rec.Type.
func checkTargets(rec *models.RecordConfig, domain string) (errs []error) {
label := rec.GetLabel()
target := rec.GetTargetField()
check := func(e error) {
if e != nil {
err := fmt.Errorf("In %s %s.%s: %s", rec.Type, rec.GetLabel(), domain, e.Error())
if _, ok := e.(Warning); ok {
err = Warning{err}
}
errs = append(errs, err)
}
}
switch rec.Type { // #rtype_variations
case "A":
check(checkIPv4(target))
case "AAAA":
check(checkIPv6(target))
case "CNAME":
check(checkTarget(target))
if label == "@" {
check(fmt.Errorf("cannot create CNAME record for bare domain"))
}
case "MX":
check(checkTarget(target))
case "NS":
check(checkTarget(target))
if label == "@" {
check(fmt.Errorf("cannot create NS record for bare domain. Use NAMESERVER instead"))
}
case "PTR":
check(checkTarget(target))
case "NAPTR":
check(checkTarget(target))
case "ALIAS":
check(checkTarget(target))
case "SOA":
check(checkTarget(target))
case "SRV":
check(checkTarget(target))
case "TXT", "IMPORT_TRANSFORM", "CAA", "SSHFP", "TLSA", "DS":
default:
if rec.Metadata["orig_custom_type"] != "" {
// it is a valid custom type. We perform no validation on target
return
}
errs = append(errs, fmt.Errorf("checkTargets: Unimplemented record type (%v) domain=%v name=%v",
rec.Type, domain, rec.GetLabel()))
}
return
}
func transformCNAME(target, oldDomain, newDomain string) string {
// Canonicalize. If it isn't a FQDN, add the newDomain.
result := dnsutil.AddOrigin(target, oldDomain)
if dns.IsFqdn(result) {
result = result[:len(result)-1]
}
return dnsutil.AddOrigin(result, newDomain) + "."
}
// import_transform imports the records of one zone into another, modifying records along the way.
func importTransform(srcDomain, dstDomain *models.DomainConfig, transforms []transform.IPConversion, ttl uint32) error {
// Read srcDomain.Records, transform, and append to dstDomain.Records:
// 1. Skip any that aren't A or CNAMEs.
// 2. Append destDomainname to the end of the label.
// 3. For CNAMEs, append destDomainname to the end of the target.
// 4. For As, change the target as described the transforms.
for _, rec := range srcDomain.Records {
if dstDomain.Records.HasRecordTypeName(rec.Type, rec.GetLabelFQDN()) {
continue
}
newRec := func() *models.RecordConfig {
rec2, _ := rec.Copy()
newlabel := rec2.GetLabelFQDN()
rec2.SetLabel(newlabel, dstDomain.Name)
if ttl != 0 {
rec2.TTL = ttl
}
return rec2
}
switch rec.Type { // #rtype_variations
case "A":
trs, err := transform.IPToList(net.ParseIP(rec.GetTargetField()), transforms)
if err != nil {
return fmt.Errorf("import_transform: TransformIP(%v, %v) returned err=%s", rec.GetTargetField(), transforms, err)
}
for _, tr := range trs {
r := newRec()
r.SetTarget(tr.String())
dstDomain.Records = append(dstDomain.Records, r)
}
case "CNAME":
r := newRec()
r.SetTarget(transformCNAME(r.GetTargetField(), srcDomain.Name, dstDomain.Name))
dstDomain.Records = append(dstDomain.Records, r)
case "MX", "NAPTR", "NS", "SOA", "SRV", "TXT", "CAA", "TLSA":
// Not imported.
continue
default:
return fmt.Errorf("import_transform: Unimplemented record type %v (%v)",
rec.Type, rec.GetLabel())
}
}
return nil
}
// deleteImportTransformRecords deletes any IMPORT_TRANSFORM records from a domain.
func deleteImportTransformRecords(domain *models.DomainConfig) {
for i := len(domain.Records) - 1; i >= 0; i-- {
rec := domain.Records[i]
if rec.Type == "IMPORT_TRANSFORM" {
domain.Records = append(domain.Records[:i], domain.Records[i+1:]...)
}
}
}
// Warning is a wrapper around error that can be used to indicate it should not
// stop execution, but is still likely a problem.
type Warning struct {
error
}
// ValidateAndNormalizeConfig performs and normalization and/or validation of the IR.
func ValidateAndNormalizeConfig(config *models.DNSConfig) (errs []error) {
for _, domain := range config.Domains {
pTypes := []string{}
txtMultiDissenters := []string{}
for _, provider := range domain.DNSProviderInstances {
pType := provider.ProviderType
// If NO_PURGE is in use, make sure this *isn't* a provider that *doesn't* support NO_PURGE.
if domain.KeepUnknown && providers.ProviderHasCapability(pType, providers.CantUseNOPURGE) {
errs = append(errs, fmt.Errorf("%s uses NO_PURGE which is not supported by %s(%s)", domain.Name, provider.Name, pType))
}
// Record if any providers do not support TXTMulti:
if !providers.ProviderHasCapability(pType, providers.CanUseTXTMulti) {
txtMultiDissenters = append(txtMultiDissenters, provider.Name)
}
}
// Normalize Nameservers.
for _, ns := range domain.Nameservers {
// NB(tlim): Like any target, NAMESERVER() is input by the user
// as a shortname or a FQDN+dot. It is stored as FQDN+dot.
// Normalize it like we do any target to assure it is FQDN+dot
ns.Name = dnsutil.AddOrigin(ns.Name, domain.Name+".")
ns.Name = strings.TrimSuffix(ns.Name, ".")
checkTarget(ns.Name)
}
// Normalize Records.
models.PostProcessRecords(domain.Records)
for _, rec := range domain.Records {
if rec.TTL == 0 {
rec.TTL = models.DefaultTTL
}
// Validate the unmodified inputs:
if err := validateRecordTypes(rec, domain.Name, pTypes); err != nil {
errs = append(errs, err)
}
if err := checkLabel(rec.GetLabel(), rec.Type, rec.GetTargetField(), domain.Name, rec.Metadata); err != nil {
errs = append(errs, err)
}
if errs2 := checkTargets(rec, domain.Name); errs2 != nil {
errs = append(errs, errs2...)
}
// Canonicalize Targets.
if rec.Type == "CNAME" || rec.Type == "MX" || rec.Type == "NAPTR" || rec.Type == "NS" || rec.Type == "SRV" {
// #rtype_variations
// These record types have a target that is a hostname.
// We normalize them to a FQDN so there is less variation to handle. If a
// provider API requires a shortname, the provider must do the shortening.
rec.SetTarget(dnsutil.AddOrigin(rec.GetTargetField(), domain.Name+"."))
} else if rec.Type == "A" || rec.Type == "AAAA" {
rec.SetTarget(net.ParseIP(rec.GetTargetField()).String())
} else if rec.Type == "PTR" {
var err error
var name string
if name, err = transform.PtrNameMagic(rec.GetLabel(), domain.Name); err != nil {
errs = append(errs, err)
}
rec.SetLabel(name, domain.Name)
} else if rec.Type == "CAA" {
if rec.CaaTag != "issue" && rec.CaaTag != "issuewild" && rec.CaaTag != "iodef" {
errs = append(errs, fmt.Errorf("CAA tag %s is invalid", rec.CaaTag))
}
} else if rec.Type == "TLSA" {
if rec.TlsaUsage < 0 || rec.TlsaUsage > 3 {
errs = append(errs, fmt.Errorf("TLSA Usage %d is invalid in record %s (domain %s)",
rec.TlsaUsage, rec.GetLabel(), domain.Name))
}
if rec.TlsaSelector < 0 || rec.TlsaSelector > 1 {
errs = append(errs, fmt.Errorf("TLSA Selector %d is invalid in record %s (domain %s)",
rec.TlsaSelector, rec.GetLabel(), domain.Name))
}
if rec.TlsaMatchingType < 0 || rec.TlsaMatchingType > 2 {
errs = append(errs, fmt.Errorf("TLSA MatchingType %d is invalid in record %s (domain %s)",
rec.TlsaMatchingType, rec.GetLabel(), domain.Name))
}
} else if rec.Type == "TXT" && len(txtMultiDissenters) != 0 && len(rec.TxtStrings) > 1 {
// There are providers that don't support TXTMulti yet there is
// a TXT record with multiple strings:
errs = append(errs,
fmt.Errorf("TXT records with multiple strings (label %v domain: %v) not supported by %s",
rec.GetLabel(), domain.Name, strings.Join(txtMultiDissenters, ",")))
}
// Populate FQDN:
rec.SetLabel(rec.GetLabel(), domain.Name)
}
}
// SPF flattening
if ers := flattenSPFs(config); len(ers) > 0 {
errs = append(errs, ers...)
}
// Process IMPORT_TRANSFORM
for _, domain := range config.Domains {
for _, rec := range domain.Records {
if rec.Type == "IMPORT_TRANSFORM" {
table, err := transform.DecodeTransformTable(rec.Metadata["transform_table"])
if err != nil {
errs = append(errs, err)
continue
}
err = importTransform(config.FindDomain(rec.GetTargetField()), domain, table, rec.TTL)
if err != nil {
errs = append(errs, err)
}
}
}
}
// Clean up:
for _, domain := range config.Domains {
deleteImportTransformRecords(domain)
}
// Run record transforms
for _, domain := range config.Domains {
if err := applyRecordTransforms(domain); err != nil {
errs = append(errs, err)
}
}
for _, d := range config.Domains {
// Check that CNAMES don't have to co-exist with any other records
errs = append(errs, checkCNAMEs(d)...)
// Check that if any advanced record types are used in a domain, every provider for that domain supports them
err := checkProviderCapabilities(d)
if err != nil {
errs = append(errs, err)
}
// Check for duplicates
errs = append(errs, checkDuplicates(d.Records)...)
// Validate FQDN consistency
for _, r := range d.Records {
if r.NameFQDN == "" || !strings.HasSuffix(r.NameFQDN, d.Name) {
errs = append(errs, fmt.Errorf("Record named '%s' does not have correct FQDN in domain '%s'. FQDN: %s", r.Name, d.Name, r.NameFQDN))
}
}
}
return errs
}
func checkCNAMEs(dc *models.DomainConfig) (errs []error) {
cnames := map[string]bool{}
for _, r := range dc.Records {
if r.Type == "CNAME" {
if cnames[r.GetLabel()] {
errs = append(errs, fmt.Errorf("Cannot have multiple CNAMEs with same name: %s", r.GetLabelFQDN()))
}
cnames[r.GetLabel()] = true
}
}
for _, r := range dc.Records {
if cnames[r.GetLabel()] && r.Type != "CNAME" {
errs = append(errs, fmt.Errorf("Cannot have CNAME and %s record with same name: %s", r.Type, r.GetLabelFQDN()))
}
}
return
}
func checkDuplicates(records []*models.RecordConfig) (errs []error) {
seen := map[string]*models.RecordConfig{}
for _, r := range records {
diffable := fmt.Sprintf("%s %s %s", r.GetLabelFQDN(), r.Type, r.ToDiffable())
if seen[diffable] != nil {
errs = append(errs, fmt.Errorf("Exact duplicate record found: %s", diffable))
}
seen[diffable] = r
}
return errs
}
// We pull this out of checkProviderCapabilities() so that it's visible within
// the package elsewhere, so that our test suite can look at the list of
// capabilities we're checking and make sure that it's up-to-date.
var providerCapabilityChecks = []pairTypeCapability{
// If a zone uses rType X, the provider must support capability Y.
//{"X", providers.Y},
capabilityCheck("ALIAS", providers.CanUseAlias),
capabilityCheck("AUTODNSSEC", providers.CanAutoDNSSEC),
capabilityCheck("CAA", providers.CanUseCAA),
capabilityCheck("NAPTR", providers.CanUseNAPTR),
capabilityCheck("PTR", providers.CanUsePTR),
capabilityCheck("R53_ALIAS", providers.CanUseRoute53Alias),
capabilityCheck("SSHFP", providers.CanUseSSHFP),
capabilityCheck("SRV", providers.CanUseSRV),
capabilityCheck("TLSA", providers.CanUseTLSA),
capabilityCheck("AZURE_ALIAS", providers.CanUseAzureAlias),
// DS needs special record-level checks
{
rType: "DS",
caps: []providers.Capability{providers.CanUseDS, providers.CanUseDSForChildren},
checkFunc: checkProviderDS,
},
}
type pairTypeCapability struct {
rType string
// Capabilities the provider must implement if any records of type rType are found
// in the zonefile. This is a disjunction - implementing at least one of the listed
// capabilities is sufficient.
caps []providers.Capability
// checkFunc provides additional checks of each provider. This function should be
// called if records of type rType are found in the zonefile.
checkFunc func(pType string, _ models.Records) error
}
func capabilityCheck(rType string, caps ...providers.Capability) pairTypeCapability {
return pairTypeCapability{
rType: rType,
caps: caps,
}
}
func providerHasAtLeastOneCapability(pType string, caps ...providers.Capability) bool {
for _, cap := range caps {
if providers.ProviderHasCapability(pType, cap) {
return true
}
}
return false
}
func checkProviderDS(pType string, records models.Records) error {
switch {
case providers.ProviderHasCapability(pType, providers.CanUseDS):
// The provider can use DS records anywhere, including at the root
return nil
case !providers.ProviderHasCapability(pType, providers.CanUseDSForChildren):
// Provider has no support for DS records
return fmt.Errorf("provider %s uses DS records but does not support them", pType)
default:
// Provider supports DS records but not at the root
for _, record := range records {
if record.Type == "DS" && record.Name == "@" {
return fmt.Errorf(
"provider %s only supports child DS records, but zone had a record at the root (@)",
pType,
)
}
}
}
return nil
}
func checkProviderCapabilities(dc *models.DomainConfig) error {
// Check if the zone uses a capability that the provider doesn't
// support.
for _, ty := range providerCapabilityChecks {
hasAny := false
switch ty.rType {
case "AUTODNSSEC":
if dc.AutoDNSSEC {
hasAny = true
}
default:
for _, r := range dc.Records {
if r.Type == ty.rType {
hasAny = true
break
}
}
}
if !hasAny {
continue
}
for _, provider := range dc.DNSProviderInstances {
// fmt.Printf(" (checking if %q can %q for domain %q)\n", provider.ProviderType, ty.rType, dc.Name)
if !providerHasAtLeastOneCapability(provider.ProviderType, ty.caps...) {
return fmt.Errorf("Domain %s uses %s records, but DNS provider type %s does not support them", dc.Name, ty.rType, provider.ProviderType)
}
if ty.checkFunc != nil {
checkErr := ty.checkFunc(provider.ProviderType, dc.Records)
if checkErr != nil {
return fmt.Errorf("while checking %s records in domain %s: %w", ty.rType, dc.Name, checkErr)
}
}
}
}
return nil
}
func applyRecordTransforms(domain *models.DomainConfig) error {
for _, rec := range domain.Records {
if rec.Type != "A" {
continue
}
tt, ok := rec.Metadata["transform"]
if !ok {
continue
}
table, err := transform.DecodeTransformTable(tt)
if err != nil {
return err
}
ip := net.ParseIP(rec.GetTargetField()) // ip already validated above
newIPs, err := transform.IPToList(net.ParseIP(rec.GetTargetField()), table)
if err != nil {
return err
}
for i, newIP := range newIPs {
if i == 0 && !newIP.Equal(ip) {
rec.SetTarget(newIP.String()) // replace target of first record if different
} else if i > 0 {
// any additional ips need identical records with the alternate ip added to the domain
copy, err := rec.Copy()
if err != nil {
return err
}
copy.SetTarget(newIP.String())
domain.Records = append(domain.Records, copy)
}
}
}
return nil
}