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dnscrypt/cmd/convert_dnscrypt_wrapper.go
Sam Therapy 3459b621a6
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Signed-off-by: Sam Therapy <sam@samtherapy.net>
2023-03-06 23:26:40 +01:00

108 lines
3.5 KiB
Go

package main
import (
"crypto/ed25519"
"fmt"
"os"
"time"
"dns.froth.zone/dnscrypt"
"github.com/AdguardTeam/golibs/log"
"golang.org/x/crypto/curve25519"
"gopkg.in/yaml.v3"
)
// ConvertWrapperArgs is the "convert-dnscrypt-wrapper" command arguments structure
type ConvertWrapperArgs struct {
PrivateKeyFile string `short:"p" long:"private-key" description:"Path to the DNSCrypt resolver private key file that is used for signing certificates. Param is required." required:"true"`
ResolverSkFile string `short:"r" long:"resolver-secret" description:"Path to the Short-term privacy key file for encrypting/decrypting DNS queries. If not specified, resolver_secret and resolver_public will be randomly generated."`
ProviderName string `short:"n" long:"provider-name" description:"DNSCrypt provider name. Param is required." required:"true"`
Out string `short:"o" long:"out" description:"Path to the resulting config file. Param is required." required:"true"`
CertificateTTL int `short:"t" long:"ttl" description:"Certificate time-to-live (seconds)"`
}
// convertWrapper generates DNSCrypt configuration from both dnscrypt and server private keys
func convertWrapper(args ConvertWrapperArgs) {
log.Info("Generating configuration for %s", args.ProviderName)
var rc = dnscrypt.ResolverConfig{
EsVersion: dnscrypt.XSalsa20Poly1305,
CertificateTTL: time.Duration(args.CertificateTTL) * time.Second,
ProviderName: args.ProviderName,
}
// make PrivateKey
var privateKey ed25519.PrivateKey
privateKey = getFileContent(args.PrivateKeyFile)
if len(privateKey) != ed25519.PrivateKeySize {
log.Fatal("Invalid private key.")
}
rc.PrivateKey = dnscrypt.HexEncodeKey(privateKey)
// make PublicKey
publicKey := privateKey.Public().(ed25519.PublicKey)
rc.PublicKey = dnscrypt.HexEncodeKey(publicKey)
// make ResolverSk
var resolverSecret ed25519.PrivateKey
resolverSecret = getFileContent(args.ResolverSkFile)
if len(resolverSecret) != 32 {
log.Fatal("Invalid resolver secret key.")
}
rc.ResolverSk = dnscrypt.HexEncodeKey(resolverSecret)
// make ResolverPk
resolverPublic := getResolverPk(resolverSecret)
rc.ResolverPk = dnscrypt.HexEncodeKey(resolverPublic)
if err := validateRc(rc, publicKey); err != nil {
log.Fatalf("Failed to validate resolver config, err: %s", err.Error())
}
out, err := yaml.Marshal(rc)
if err != nil {
log.Fatalf("Failed to marshall output config, err: %s", err.Error())
}
err = os.WriteFile(args.Out, out, 0600)
if err != nil {
log.Fatalf("Failed to write file, err: %s", err.Error())
}
}
// validateRc verifies that the certificate is correctly
// created and validated for this resolver config. if rc valid returns nil.
func validateRc(rc dnscrypt.ResolverConfig, publicKey ed25519.PublicKey) error {
cert, err := rc.CreateCert()
if err != nil {
return fmt.Errorf("failed to validate cert, err: %s", err.Error())
}
if cert == nil {
return fmt.Errorf("created cert is empty")
}
if !cert.VerifyDate() {
return fmt.Errorf("cert date is not valid")
}
if !cert.VerifySignature(publicKey) {
return fmt.Errorf("cert signed incorrectly")
}
return nil
}
// getResolverPk calculates public key from private key
func getResolverPk(private ed25519.PrivateKey) ed25519.PublicKey {
resolverSk := [32]byte{}
resolverPk := [32]byte{}
copy(resolverSk[:], private)
curve25519.ScalarBaseMult(&resolverPk, &resolverSk)
return resolverPk[:]
}
func getFileContent(fname string) []byte {
bytes, err := os.ReadFile(fname)
if err != nil {
log.Fatalf("Fail read key file %s, err: %s", fname, err.Error())
}
return bytes
}