cmd/ca-signed: clean up the codebase

This commit is contained in:
2025-11-18 23:01:58 -08:00
parent 7f3f513bdd
commit ff34eb4eff
2 changed files with 81 additions and 199 deletions

View File

@@ -1,157 +1,22 @@
package main
import (
"bytes"
"crypto/x509"
"embed"
"errors"
"flag"
"fmt"
"os"
"path/filepath"
"time"
"git.wntrmute.dev/kyle/goutils/certlib"
"git.wntrmute.dev/kyle/goutils/certlib/verify"
"git.wntrmute.dev/kyle/goutils/die"
"git.wntrmute.dev/kyle/goutils/lib"
)
// loadCertsFromFile attempts to parse certificates from a file that may be in
// PEM or DER/PKCS#7 format. Returns the parsed certificates or an error.
func loadCertsFromFile(path string) ([]*x509.Certificate, error) {
var certs []*x509.Certificate
data, err := os.ReadFile(path)
if err != nil {
return nil, err
}
if certs, err = certlib.ParseCertificatesPEM(data); err == nil {
return certs, nil
}
if certs, _, err = certlib.ParseCertificatesDER(data, ""); err == nil {
return certs, nil
}
return nil, err
}
func makePoolFromFile(path string) (*x509.CertPool, error) {
// Try PEM via helper (it builds a pool)
if pool, err := certlib.LoadPEMCertPool(path); err == nil && pool != nil {
return pool, nil
}
// Fallback: read as DER(s), add to a new pool
certs, err := loadCertsFromFile(path)
if err != nil || len(certs) == 0 {
return nil, fmt.Errorf("failed to load CA certificates from %s", path)
}
pool := x509.NewCertPool()
for _, c := range certs {
pool.AddCert(c)
}
return pool, nil
}
//go:embed testdata/*.pem
var embeddedTestdata embed.FS
// loadCertsFromBytes attempts to parse certificates from bytes that may be in
// PEM or DER/PKCS#7 format.
func loadCertsFromBytes(data []byte) ([]*x509.Certificate, error) {
certs, err := certlib.ParseCertificatesPEM(data)
if err == nil {
return certs, nil
}
certs, _, err = certlib.ParseCertificatesDER(data, "")
if err == nil {
return certs, nil
}
return nil, err
}
func makePoolFromBytes(data []byte) (*x509.CertPool, error) {
certs, err := loadCertsFromBytes(data)
if err != nil || len(certs) == 0 {
return nil, errors.New("failed to load CA certificates from embedded bytes")
}
pool := x509.NewCertPool()
for _, c := range certs {
pool.AddCert(c)
}
return pool, nil
}
// isSelfSigned returns true if the given certificate is self-signed.
// It checks that the subject and issuer match and that the certificate's
// signature verifies against its own public key.
func isSelfSigned(cert *x509.Certificate) bool {
if cert == nil {
return false
}
// Quick check: subject and issuer match
if cert.Subject.String() != cert.Issuer.String() {
return false
}
// Cryptographic check: the certificate is signed by itself
if err := cert.CheckSignatureFrom(cert); err != nil {
return false
}
return true
}
func verifyAgainstCA(caPool *x509.CertPool, path string) (bool, string) {
certs, err := loadCertsFromFile(path)
if err != nil || len(certs) == 0 {
return false, ""
}
leaf := certs[0]
ints := x509.NewCertPool()
if len(certs) > 1 {
for _, ic := range certs[1:] {
ints.AddCert(ic)
}
}
opts := x509.VerifyOptions{
Roots: caPool,
Intermediates: ints,
KeyUsages: []x509.ExtKeyUsage{x509.ExtKeyUsageAny},
}
if _, err = leaf.Verify(opts); err != nil {
return false, ""
}
return true, leaf.NotAfter.Format("2006-01-02")
}
func verifyAgainstCABytes(caPool *x509.CertPool, certData []byte) (bool, string) {
certs, err := loadCertsFromBytes(certData)
if err != nil || len(certs) == 0 {
return false, ""
}
leaf := certs[0]
ints := x509.NewCertPool()
if len(certs) > 1 {
for _, ic := range certs[1:] {
ints.AddCert(ic)
}
}
opts := x509.VerifyOptions{
Roots: caPool,
Intermediates: ints,
KeyUsages: []x509.ExtKeyUsage{x509.ExtKeyUsageAny},
}
if _, err = leaf.Verify(opts); err != nil {
return false, ""
}
return true, leaf.NotAfter.Format("2006-01-02")
}
type testCase struct {
name string
caFile string
@@ -170,18 +35,25 @@ func (tc testCase) Run() error {
return fmt.Errorf("selftest: failed to read embedded %s: %w", tc.certFile, err)
}
pool, err := makePoolFromBytes(caBytes)
pool, err := certlib.PoolFromBytes(caBytes)
if err != nil || pool == nil {
return fmt.Errorf("selftest: failed to build CA pool for %s: %w", tc.caFile, err)
}
ok, exp := verifyAgainstCABytes(pool, certBytes)
cert, _, err := certlib.ReadCertificate(certBytes)
if err != nil {
return fmt.Errorf("selftest: failed to parse certificate from %s: %w", tc.certFile, err)
}
_, err = verify.CertWith(cert, pool, nil, false)
ok := err == nil
if ok != tc.expectOK {
return fmt.Errorf("%s: unexpected result: got %v, want %v", tc.name, ok, tc.expectOK)
}
if ok {
fmt.Printf("%s: OK (expires %s)\n", tc.name, exp)
fmt.Printf("%s: OK (expires %s)\n", tc.name, cert.NotAfter.Format(lib.DateShortFormat))
}
fmt.Printf("%s: INVALID (as expected)\n", tc.name)
@@ -237,14 +109,16 @@ func selftest() int {
failures++
continue
}
certs, err := loadCertsFromBytes(b)
certs, err := certlib.ReadCertificates(b)
if err != nil || len(certs) == 0 {
fmt.Fprintf(os.Stderr, "selftest: failed to parse cert(s) from %s: %v\n", root, err)
failures++
continue
}
leaf := certs[0]
if isSelfSigned(leaf) {
if len(leaf.AuthorityKeyId) == 0 || bytes.Equal(leaf.AuthorityKeyId, leaf.SubjectKeyId) {
fmt.Printf("%s: SELF-SIGNED (as expected)\n", root)
} else {
fmt.Printf("%s: expected SELF-SIGNED, but was not detected as such\n", root)
@@ -260,66 +134,58 @@ func selftest() int {
return 1
}
// expiryString returns a YYYY-MM-DD date string to display for certificate
// expiry. If an explicit exp string is provided, it is used. Otherwise, if a
// leaf certificate is available, its NotAfter is formatted. As a last resort,
// it falls back to today's date (should not normally happen).
func expiryString(leaf *x509.Certificate, exp string) string {
if exp != "" {
return exp
}
if leaf != nil {
return leaf.NotAfter.Format("2006-01-02")
}
return time.Now().Format("2006-01-02")
}
// processCert verifies a single certificate file against the provided CA pool
// and prints the result in the required format, handling self-signed
// certificates specially.
func processCert(caPool *x509.CertPool, certPath string) {
ok, exp := verifyAgainstCA(caPool, certPath)
name := filepath.Base(certPath)
// Try to load the leaf cert for self-signed detection and expiry fallback
var leaf *x509.Certificate
if certs, err := loadCertsFromFile(certPath); err == nil && len(certs) > 0 {
leaf = certs[0]
}
// Prefer the SELF-SIGNED label if applicable
if isSelfSigned(leaf) {
fmt.Printf("%s: SELF-SIGNED\n", name)
return
}
if ok {
fmt.Printf("%s: OK (expires %s)\n", name, expiryString(leaf, exp))
return
}
fmt.Printf("%s: INVALID\n", name)
}
func main() {
// Special selftest mode: single argument "selftest"
if len(os.Args) == 2 && os.Args[1] == "selftest" {
var skipVerify, useStrict bool
lib.StrictTLSFlag(&useStrict)
flag.BoolVar(&skipVerify, "k", false, "don't verify certificates")
flag.Parse()
tcfg, err := lib.BaselineTLSConfig(skipVerify, useStrict)
die.If(err)
args := flag.Args()
if len(args) == 1 && args[0] == "selftest" {
os.Exit(selftest())
}
if len(os.Args) < 3 {
prog := filepath.Base(os.Args[0])
fmt.Fprintf(os.Stderr, "Usage:\n %s ca.pem cert1.pem cert2.pem ...\n %s selftest\n", prog, prog)
os.Exit(2)
}
caPath := os.Args[1]
caPool, err := makePoolFromFile(caPath)
if err != nil || caPool == nil {
fmt.Fprintf(os.Stderr, "failed to load CA certificate(s): %v\n", err)
if len(args) < 2 {
fmt.Println("No certificates to check.")
os.Exit(1)
}
for _, certPath := range os.Args[2:] {
processCert(caPool, certPath)
caFile := args[0]
args = args[1:]
caCert, err := certlib.LoadCertificates(caFile)
die.If(err)
if len(caCert) != 1 {
die.With("only one CA certificate should be presented.")
}
roots := x509.NewCertPool()
roots.AddCert(caCert[0])
for _, arg := range args {
var cert *x509.Certificate
cert, err = lib.GetCertificate(arg, tcfg)
if err != nil {
lib.Warn(err, "while parsing certificate from %s", arg)
continue
}
if bytes.Equal(cert.AuthorityKeyId, caCert[0].AuthorityKeyId) {
fmt.Printf("%s: SELF-SIGNED\n", arg)
continue
}
if _, err := verify.CertWith(cert, roots, nil, false); err != nil {
fmt.Printf("%s: INVALID\n", arg)
} else {
fmt.Printf("%s: OK (expires %s)\n", arg, cert.NotAfter.Format(lib.DateShortFormat))
}
}
}