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main.go
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main.go
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package main
import (
"bytes"
"crypto/tls"
"crypto/x509"
"encoding/pem"
"errors"
"flag"
"fmt"
"github.com/buffrr/hsig0"
"github.com/buffrr/letsdane"
rs "github.com/buffrr/letsdane/resolver"
"github.com/miekg/dns"
"io/ioutil"
"log"
"net"
"net/url"
"os"
"path"
"strings"
"time"
)
const KSK2017 = `. IN DS 20326 8 2 E06D44B80B8F1D39A95C0B0D7C65D08458E880409BBC683457104237C7F8EC8D`
var (
raddr = flag.String("r", "", "dns resolvers to use (default: /etc/resolv.conf)")
output = flag.String("o", "", "path to export the public CA file")
conf = flag.String("conf", "", "dir path to store configuration (default: ~/.letsdane)")
addr = flag.String("addr", ":8080", "host:port of the proxy")
certPath = flag.String("cert", "", "filepath to custom CA")
keyPath = flag.String("key", "", "filepath to the CA's private key")
pass = flag.String("pass", "", "CA passphrase or use DANE_CA_PASS environment variable to decrypt CA file (if encrypted)")
anchor = flag.String("anchor", "", "path to trust anchor file (default: hardcoded 2017 KSK)")
verbose = flag.Bool("verbose", false, "verbose output for debugging")
ad = flag.Bool("skip-dnssec", false, "check ad flag only without dnssec validation")
skipICANN = flag.Bool("skip-icann", false, "skip TLSA lookups for ICANN tlds and include them in the CA name constraints extension")
validity = flag.Duration("validity", time.Hour, "window of time generated DANE certificates are valid")
skipNameChecks = flag.Bool("skip-namechecks", false, "disable name checks when matching DANE-EE TLSA reocrds.")
version = flag.Bool("version", false, "Show version")
)
func getConfPath() string {
if *conf != "" {
return *conf
}
home, err := os.UserHomeDir()
if err != nil {
log.Fatalf("failed to get home dir: %v", err)
}
p := path.Join(home, ".letsdane")
if _, err := os.Stat(p); err != nil {
if err := os.Mkdir(p, 0700); err != nil {
log.Fatalf("failed to create conf dir: %v", err)
}
}
return p
}
func getOrCreateCA() (string, string) {
if *certPath != "" && *keyPath != "" {
return *certPath, *keyPath
}
p := getConfPath()
certPath := path.Join(p, "cert.crt")
keyPath := path.Join(p, "cert.key")
if _, err := os.Stat(certPath); err != nil {
if _, err := os.Stat(keyPath); err != nil {
ca, priv, err := letsdane.NewAuthority("DNSSEC", "DNSSEC", 365*24*time.Hour, nameConstraints)
if err != nil {
log.Fatalf("couldn't generate CA: %v", err)
}
certOut, err := os.OpenFile(certPath, os.O_CREATE|os.O_WRONLY, 0644)
if err != nil {
log.Fatalf("couldn't create CA file: %v", err)
}
defer certOut.Close()
pem.Encode(certOut, &pem.Block{
Type: "CERTIFICATE",
Bytes: ca.Raw,
})
privOut := bytes.NewBuffer([]byte{})
pem.Encode(privOut, &pem.Block{
Type: "RSA PRIVATE KEY",
Bytes: x509.MarshalPKCS1PrivateKey(priv),
})
kOut, err := os.OpenFile(keyPath, os.O_CREATE|os.O_WRONLY, 0600)
if err != nil {
log.Fatalf("couldn't create CA private key file: %v", err)
}
defer kOut.Close()
kOut.Write(privOut.Bytes())
return certPath, keyPath
}
}
return certPath, keyPath
}
func loadX509KeyPair(certFile, keyFile string) (tls.Certificate, error) {
certPEMBlock, err := ioutil.ReadFile(certFile)
if err != nil {
return tls.Certificate{}, err
}
keyPEMBlock, err := ioutil.ReadFile(keyFile)
if err != nil {
return tls.Certificate{}, err
}
block, _ := pem.Decode(keyPEMBlock)
var decryptedBlock []byte
if x509.IsEncryptedPEMBlock(block) {
if *pass == "" {
*pass = os.Getenv("DANE_CA_PASS")
}
decryptedBlock, err = x509.DecryptPEMBlock(block, []byte(*pass))
if err != nil {
log.Fatalf("decryption failed: %v", err)
}
} else {
decryptedBlock = keyPEMBlock
}
return tls.X509KeyPair(certPEMBlock, decryptedBlock)
}
func loadCA() (*x509.Certificate, interface{}) {
var x509c *x509.Certificate
var priv interface{}
*certPath, *keyPath = getOrCreateCA()
if *certPath != "" && *keyPath != "" {
cert, err := loadX509KeyPair(*certPath, *keyPath)
if err != nil {
log.Fatal(err)
}
priv = cert.PrivateKey
x509c, err = x509.ParseCertificate(cert.Certificate[0])
if err != nil {
log.Fatal(err)
}
return x509c, priv
}
return nil, nil
}
func isLoopback(r string) bool {
var ip net.IP
host, _, err := net.SplitHostPort(r)
if err == nil {
ip = net.ParseIP(host)
} else {
ip = net.ParseIP(r)
}
return ip != nil && ip.IsLoopback()
}
func exportCA() {
b, err := ioutil.ReadFile(*certPath)
if err != nil {
log.Fatal(err)
}
if err := ioutil.WriteFile(*output, b, 0600); err != nil {
log.Fatal(err)
}
}
func setupUnbound() (u *rs.Recursive, err error) {
u, err = rs.NewRecursive()
if err == rs.ErrUnboundNotAvail {
return nil, errors.New("letsdane has not been compiled with unbound. " +
"if you have a local dnssec capable resolver, run with -skip-dnssec")
}
if err != nil {
return
}
defer func() {
if u != nil && err != nil {
u.Destroy()
}
}()
if *anchor != "" {
if err := u.AddTAFile(*anchor); err != nil {
return nil, err
}
} else {
// add hardcoded ksk if no anchor is specified
if err := u.AddTA(KSK2017); err != nil {
return nil, err
}
}
if *raddr != "" {
addrs := strings.Split(*raddr, " ")
for _, r := range addrs {
r = strings.TrimSpace(r)
if r == "" {
continue
}
ip, port, err := net.SplitHostPort(r)
if err != nil {
port = "53"
ip = r
}
if err := u.SetFwd(ip + "@" + port); err != nil {
return nil, err
}
}
return
}
// falls back to root hints if no /etc/resolv.conf
_ = u.ResolvConf("/etc/resolv.conf")
return
}
var errNoKey = errors.New("no key found")
// parses hsd format: key@host:port
func splitHostPortKey(addr string) (hostport string, key *hsig0.PublicKey, err error) {
s := strings.Split(strings.TrimSpace(addr), "@")
if len(s) != 2 {
return "", nil, errNoKey
}
hostport = s[1]
key, err = hsig0.ParsePublicKey(s[0])
return
}
func main() {
flag.Parse()
if *version {
fmt.Printf("Version %s\n", letsdane.Version)
return
}
if !*skipICANN {
nameConstraints = nil
}
ca, priv := loadCA()
if *output != "" {
exportCA()
return
}
var resolver rs.Resolver
var sig0, secure bool
hostport, key, err := splitHostPortKey(*raddr)
switch err {
case errNoKey:
sig0 = false
u, err := url.Parse(*raddr)
if err == nil {
secure = u.Scheme == "https" || u.Scheme == "tls"
}
case nil:
sig0 = true
*ad = true
*raddr = hostport
default:
log.Fatal(err)
}
if *ad {
if !sig0 && !secure && !isLoopback(*raddr) {
log.Printf("You must have a local dnssec capable resolver to use letsdane securely")
log.Printf("'%s' is not a loopback address (insecure)!", *raddr)
}
ad, err := rs.NewStub(*raddr)
if err != nil {
log.Fatal(err)
}
if sig0 {
ad.Verify = func(m *dns.Msg) error {
return hsig0.Verify(m, key)
}
}
resolver = ad
} else {
u, err := setupUnbound()
if err != nil {
log.Fatalf("unbound: %v", err)
}
defer u.Destroy()
resolver = u
}
c := &letsdane.Config{
Certificate: ca,
PrivateKey: priv,
Validity: *validity,
Resolver: resolver,
Constraints: nameConstraints,
SkipNameChecks: *skipNameChecks,
Verbose: *verbose,
}
log.Printf("Listening on %s", *addr)
log.Fatal(c.Run(*addr))
}