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backend.go
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backend.go
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package backend
import "github.com/miekg/dns"
import "github.com/golang/groupcache/lru"
import "gopkg.in/hlandau/madns.v2/merr"
import "github.com/namecoin/ncdns/namecoin"
import "github.com/namecoin/ncdns/util"
import "github.com/namecoin/ncdns/ncdomain"
import "github.com/namecoin/ncdns/tlshook"
import "github.com/hlandau/xlog"
import "sync"
import "fmt"
import "net"
import "net/mail"
import "strings"
import "time"
// Provides an abstract zone file for the Namecoin .bit TLD.
type Backend struct {
//s *Server
nc *namecoin.Client
// caches map keys are stream isolation ID's; items are of type *Domain
caches map[string]*lru.Cache
cacheMutex sync.Mutex
cfg Config
}
var log, Log = xlog.New("ncdns.backend")
// Backend configuration.
type Config struct {
NamecoinConn *namecoin.Client
// Timeout (in milliseconds) for Namecoin RPC requests
NamecoinTimeout int
// Maximum entries to permit in name cache.
CacheMaxEntries int
// Nameservers to advertise at zone apex. The first is considered the primary.
// If empty, a pseudo-hostname resolvable to SelfIP is used.
CanonicalNameservers []string
// Vanity IPs to place at the zone apex.
VanityIPs []net.IP
// Used only if CanonicalNameservers is left blank. An IP which the internal
// pseudo-hostname should resolve to. This should be the public IP of the
// nameserver serving the zone expressed by this backend.
SelfIP string
// Hostmaster in e. mail form (e.g. "hostmaster@example.com").
Hostmaster string
// Map names (like "d/example") to strings containing JSON values. Used to provide
// fake names for testing purposes. You don't need to use this.
FakeNames map[string]string
}
// Creates a new Namecoin backend.
func New(cfg *Config) (backend *Backend, err error) {
b := &Backend{}
b.cfg = *cfg
b.nc = b.cfg.NamecoinConn
b.caches = make(map[string]*lru.Cache)
hostmaster, err := convertEmail(b.cfg.Hostmaster)
if err != nil {
return
}
b.cfg.Hostmaster = hostmaster
backend = b
return
}
func convertEmail(email string) (string, error) {
if email == "" {
return ".", nil
}
if util.ValidateHostName(email) {
return email, nil
}
addr, err := mail.ParseAddress(email)
if err != nil {
return "", err
}
email = addr.Address
parts := strings.SplitN(email, "@", 2)
if len(parts) < 2 {
return "", fmt.Errorf("invalid e. mail address specified")
}
return dns.Fqdn(parts[0] + "." + parts[1]), nil
}
// Do low-level queries against an abstract zone file. This is the per-query
// entrypoint from madns.
func (b *Backend) Lookup(qname, streamIsolationID string) (rrs []dns.RR, err error) {
err = lookupReadyError()
if err != nil {
return
}
btx := &btx{}
btx.b = b
btx.qname = qname
btx.streamIsolationID = streamIsolationID
return btx.Do()
}
// Things to keep track of while processing a query.
type btx struct {
b *Backend
qname string
streamIsolationID string
subname, basename, rootname string
}
func (tx *btx) Do() (rrs []dns.RR, err error) {
// Split the domain up. 'rootname' is the TLD and everything after it,
// basename is the name directly before that, and subname is every name
// before that. So "a.b.example.bit.suffix.xyz." would have a subname
// of "a.b", a basename of "example" and a rootname of "bit.suffix.xyz".
tx.subname, tx.basename, tx.rootname, err = tx.determineDomain()
if err != nil {
// We get an error if '.bit.' does not appear anywhere. In that case
// we're not authoritative for the query in question and error out.
return
}
if tx.rootname == "" {
// REFUSED
return nil, merr.ErrNotInZone
}
// If subname and basename are "", this means the query was for a root name
// such as "bit." or "bit.suffix.xyz." directly. Serve SOA, NS records, etc.
// as requested.
if tx.subname == "" && tx.basename == "" {
return tx.doRootDomain()
}
// Where ncdns has not been configured with a hostname to identify itself by,
// it generates one under a special meta domain "x--nmc". This domain is not
// a valid Namecoin domain name, so it does not confict with the Namecoin
// domain name namespace.
if tx.basename == "x--nmc" && len(tx.b.cfg.CanonicalNameservers) == 0 {
return tx.doMetaDomain()
}
// If we have reached this point the query must be a normal user query.
rrs, err = tx.doUserDomain()
return
}
func (tx *btx) determineDomain() (subname, basename, rootname string, err error) {
return util.SplitDomainByFloatingAnchor(tx.qname, "bit")
}
func (tx *btx) doRootDomain() (rrs []dns.RR, err error) {
nss := tx.b.cfg.CanonicalNameservers
if len(tx.b.cfg.CanonicalNameservers) == 0 {
nss = []string{dns.Fqdn("this.x--nmc." + tx.rootname)}
}
soa := &dns.SOA{
Hdr: dns.RR_Header{
Name: dns.Fqdn(tx.rootname),
Ttl: 86400,
Class: dns.ClassINET,
Rrtype: dns.TypeSOA,
},
Ns: nss[0],
Mbox: tx.b.cfg.Hostmaster,
Serial: 1,
Refresh: 600,
Retry: 600,
Expire: 7200,
Minttl: 600,
}
rrs = make([]dns.RR, 0, 1+len(nss)+len(tx.b.cfg.VanityIPs))
rrs = append(rrs, soa)
for _, cn := range nss {
ns := &dns.NS{
Hdr: dns.RR_Header{
Name: dns.Fqdn(tx.rootname),
Ttl: 86400,
Class: dns.ClassINET,
Rrtype: dns.TypeNS,
},
Ns: dns.Fqdn(cn),
}
rrs = append(rrs, ns)
}
for _, ip := range tx.b.cfg.VanityIPs {
if ip.To4() != nil {
a := &dns.A{
Hdr: dns.RR_Header{
Name: dns.Fqdn(tx.rootname),
Ttl: 86400,
Class: dns.ClassINET,
Rrtype: dns.TypeA,
},
A: ip,
}
rrs = append(rrs, a)
} else {
a := &dns.AAAA{
Hdr: dns.RR_Header{
Name: dns.Fqdn(tx.rootname),
Ttl: 86400,
Class: dns.ClassINET,
Rrtype: dns.TypeAAAA,
},
AAAA: ip,
}
rrs = append(rrs, a)
}
}
return
}
func (tx *btx) doMetaDomain() (rrs []dns.RR, err error) {
ip := net.ParseIP(tx.b.cfg.SelfIP)
if ip == nil || ip.To4() == nil {
return nil, fmt.Errorf("invalid value specified for SelfIP")
}
switch tx.subname {
case "this":
rrs = []dns.RR{
&dns.A{
Hdr: dns.RR_Header{
Name: dns.Fqdn("this." + tx.basename + "." + tx.rootname),
Ttl: 86400,
Class: dns.ClassINET,
Rrtype: dns.TypeA,
},
A: ip,
},
}
case "aia":
// TODO: Make AIA address configurable (currently hardcoded to "this.x--nmc.bit")
rrs = []dns.RR{
&dns.CNAME{
Hdr: dns.RR_Header{
Name: dns.Fqdn("aia." + tx.basename + "." + tx.rootname),
Ttl: 86400,
Class: dns.ClassINET,
Rrtype: dns.TypeCNAME,
},
Target: dns.Fqdn("this." + tx.basename + "." + tx.rootname),
},
}
default:
}
return
}
func (tx *btx) doUserDomain() (rrs []dns.RR, err error) {
ncname, err := util.BasenameToNamecoinKey(tx.basename)
if err != nil {
return
}
d, err := tx.b.getNamecoinEntry(ncname, tx.streamIsolationID)
if err != nil {
return nil, err
}
rrs, err = tx.doUnderDomain(d)
if err != nil {
return nil, err
}
return rrs, nil
}
// Keep domains in parsed format.
type domain struct {
ncv *ncdomain.Value
}
func (b *Backend) resolveNameCache(name, streamIsolationID string) *string {
b.cacheMutex.Lock()
defer b.cacheMutex.Unlock()
cache, ok := b.caches[streamIsolationID]
if !ok {
return nil
}
if dd, ok := cache.Get(name); ok {
v := dd.(*string)
return v
}
return nil
}
func (b *Backend) addNamecoinJSONToCache(name string, jsonValue *string, streamIsolationID string) {
b.cacheMutex.Lock()
defer b.cacheMutex.Unlock()
cache, ok := b.caches[streamIsolationID]
if !ok {
b.caches[streamIsolationID] = &lru.Cache{
MaxEntries: b.cfg.CacheMaxEntries,
}
cache = b.caches[streamIsolationID]
}
cache.Add(name, jsonValue)
}
func (b *Backend) getNamecoinEntry(name, streamIsolationID string) (*domain, error) {
// Try the cache first
v := b.resolveNameCache(name, streamIsolationID)
// If the cache misses, resolve it via namecoind
if v == nil {
vv, err := b.resolveName(name, streamIsolationID)
if err != nil {
return nil, err
}
v = &vv
b.addNamecoinJSONToCache(name, v, streamIsolationID)
}
d, err := b.jsonToDomain(name, *v, streamIsolationID)
if err != nil {
return nil, err
}
return d, nil
}
func (b *Backend) resolveName(name, streamIsolationID string) (jsonValue string, err error) {
if fv, ok := b.cfg.FakeNames[name]; ok {
if fv == "NX" {
return "", merr.ErrNoSuchDomain
}
return fv, nil
}
// The rpcclient package has quite a long timeout, far in excess of standard
// DNS timeouts. We need to return an error response rapidly if we can't
// query the backend. Be generous with the timeout as responses from the
// Namecoin JSON-RPC seem sluggish sometimes.
result := make(chan struct{}, 1)
go func() {
jsonValue, err = b.nc.NameQuery(name, streamIsolationID)
log.Errore(err, "failed to query namecoin")
result <- struct{}{}
}()
select {
case <-result:
return
case <-time.After(time.Duration(b.cfg.NamecoinTimeout) * time.Millisecond):
return "", fmt.Errorf("timeout")
}
}
func (b *Backend) jsonToDomain(name, jsonValue, streamIsolationID string) (*domain, error) {
d := &domain{}
resolveExtraIsolated := func(n string) (string, error) {
return b.resolveExtraName(n, streamIsolationID)
}
v := ncdomain.ParseValue(name, jsonValue, resolveExtraIsolated, nil)
if v == nil {
return nil, fmt.Errorf("couldn't parse value")
}
d.ncv = v
return d, nil
}
func (b *Backend) resolveExtraName(name, streamIsolationID string) (jsonValue string, err error) {
return b.resolveName(name, streamIsolationID)
}
func (tx *btx) doUnderDomain(d *domain) (rrs []dns.RR, err error) {
rrs, err = tx.addAnswersUnderNCValue(d.ncv, tx.subname)
if err == merr.ErrNoResults {
err = nil
}
return
}
func (tx *btx) addAnswersUnderNCValue(rncv *ncdomain.Value, subname string) (rrs []dns.RR, err error) {
ncv, sn, err := tx.findNCValue(rncv, subname, nil /*hasNS*/)
if err != nil {
return
}
return tx.addAnswersUnderNCValueActual(ncv, sn)
}
func (tx *btx) findNCValue(ncv *ncdomain.Value, subname string, shortCircuitFunc func(curNCV *ncdomain.Value) bool) (xncv *ncdomain.Value, sn string, err error) {
return tx._findNCValue(ncv, subname, "", 0, shortCircuitFunc)
}
func (tx *btx) _findNCValue(ncv *ncdomain.Value, isubname, subname string, depth int,
shortCircuitFunc func(curNCV *ncdomain.Value) bool) (xncv *ncdomain.Value, sn string, err error) {
if shortCircuitFunc != nil && shortCircuitFunc(ncv) {
return ncv, subname, nil
}
if isubname != "" {
head, rest := util.SplitDomainHead(isubname)
sub, ok := ncv.Map[head]
if !ok {
sub, ok = ncv.Map["*"]
if !ok {
return nil, "", merr.ErrNoSuchDomain
}
}
return tx._findNCValue(sub, rest, head+"."+subname, depth+1, shortCircuitFunc)
}
if shortCircuitFunc != nil {
return nil, subname, merr.ErrNoSuchDomain
}
return ncv, subname, nil
}
func (tx *btx) addAnswersUnderNCValueActual(ncv *ncdomain.Value, sn string) (rrs []dns.RR, err error) {
rrs, err = ncv.RRs(nil, dns.Fqdn(tx.qname), dns.Fqdn(tx.basename+"."+tx.rootname))
// TODO: add callback variable "OnValueReferencedFunc" to backend options so that we don't pollute this function with every hook that we want
// might need to add the other attributes of tx, and sn, to the callback variable for flexibility's sake
// This doesn't normally return errors, but any errors during execution will be logged.
_ = tlshook.DomainValueHookTLS(tx.qname, ncv)
return
}
// a.b.c.d.e.f.g.zzz.bit
// f("a.b.c.d.e.f.g", "zzz.bit")
// f[g]("a.b.c.d.e.f", "g.zzz.bit")
// f[f]("a.b.c.d.e", "f.g.zzz.bit")
// f[e]("a.b.c.d", "e.f.g.zzz.bit")
// f[d]("a.b.c", "d.e.f.g.zzz.bit")
// f[c]("a.b", "c.d.e.f.g.zzz.bit")
// f[b]("a", "b.c.d.e.f.g.zzz.bit")
// f[a]("", "a.b.c.d.e.f.g.zzz.bit")
// © 2014 Hugo Landau <hlandau@devever.net> GPLv3 or later