add cert-revcheck

cmd/cert-revcheck/README.txt

@@ -0,0 +1,36 @@
+cert-revcheck: check certificate expiry and revocation
+-----------------------------------------------------
+
+Description
+  cert-revcheck accepts a list of certificate files (PEM or DER) or
+  site addresses (host[:port]) and checks whether the leaf certificate
+  is expired or revoked. Revocation checks use CRL and OCSP via the
+  certlib/revoke package.
+
+Usage
+  cert-revcheck [options] <target> [<target>...]
+
+Options
+  -hardfail       treat revocation check failures as fatal (default: false)
+  -timeout dur    HTTP/OCSP/CRL timeout for network operations (default: 10s)
+  -v              verbose output
+
+Targets
+  - File paths to certificates in PEM or DER format.
+  - Site addresses in the form host or host:port. If no port is
+    provided, 443 is assumed.
+
+Examples
+  # Check a PEM file
+  cert-revcheck ./server.pem
+
+  # Check a DER (single) certificate
+  cert-revcheck ./server.der
+
+  # Check a live site (leaf certificate)
+  cert-revcheck example.com:443
+
+Notes
+  - For sites, only the leaf certificate is checked.
+  - When -hardfail is set, network issues during OCSP/CRL fetch will
+    cause the check to fail (treated as revoked).

cmd/cert-revcheck/main.go

@@ -0,0 +1,139 @@
+package main
+
+import (
+	"crypto/tls"
+	"crypto/x509"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"net"
+	"os"
+	"time"
+
+	"git.wntrmute.dev/kyle/goutils/certlib"
+	hosts "git.wntrmute.dev/kyle/goutils/certlib/hosts"
+	"git.wntrmute.dev/kyle/goutils/certlib/revoke"
+	"git.wntrmute.dev/kyle/goutils/fileutil"
+)
+
+var (
+	hardfail bool
+	timeout  time.Duration
+	verbose  bool
+)
+
+func main() {
+	flag.BoolVar(&hardfail, "hardfail", false, "treat revocation check failures as fatal")
+	flag.DurationVar(&timeout, "timeout", 10*time.Second, "network timeout for OCSP/CRL fetches and TLS site connects")
+	flag.BoolVar(&verbose, "v", false, "verbose output")
+	flag.Parse()
+
+	revoke.HardFail = hardfail
+	// Set HTTP client timeout for revocation library
+	revoke.HTTPClient.Timeout = timeout
+
+	if flag.NArg() == 0 {
+		fmt.Fprintf(os.Stderr, "Usage: %s [options] <target> [<target>...]\n", os.Args[0])
+		os.Exit(2)
+	}
+
+	exitCode := 0
+	for _, target := range flag.Args() {
+		status, err := processTarget(target)
+		switch status {
+		case "OK":
+			fmt.Printf("%s: OK\n", target)
+		case "EXPIRED":
+			fmt.Printf("%s: EXPIRED: %v\n", target, err)
+			exitCode = 1
+		case "REVOKED":
+			fmt.Printf("%s: REVOKED\n", target)
+			exitCode = 1
+		case "UNKNOWN":
+			fmt.Printf("%s: UNKNOWN: %v\n", target, err)
+			if hardfail {
+				// In hardfail, treat unknown as failure
+				exitCode = 1
+			}
+		}
+	}
+
+	os.Exit(exitCode)
+}
+
+func processTarget(target string) (string, error) {
+	if fileutil.FileDoesExist(target) {
+		return checkFile(target)
+	}
+
+	// Not a file; treat as site
+	return checkSite(target)
+}
+
+func checkFile(path string) (string, error) {
+	in, err := ioutil.ReadFile(path)
+	if err != nil {
+		return "UNKNOWN", err
+	}
+
+	// Try PEM first; if that fails, try single DER cert
+	certs, err := certlib.ReadCertificates(in)
+	if err != nil || len(certs) == 0 {
+		cert, _, derr := certlib.ReadCertificate(in)
+		if derr != nil || cert == nil {
+			if err == nil {
+				err = derr
+			}
+			return "UNKNOWN", err
+		}
+		return evaluateCert(cert)
+	}
+
+	// Evaluate the first certificate (leaf) by default
+	return evaluateCert(certs[0])
+}
+
+func checkSite(hostport string) (string, error) {
+	// Use certlib/hosts to parse host/port (supports https URLs and host:port)
+	target, err := hosts.ParseHost(hostport)
+	if err != nil {
+		return "UNKNOWN", err
+	}
+
+	d := &net.Dialer{Timeout: timeout}
+	conn, err := tls.DialWithDialer(d, "tcp", target.String(), &tls.Config{InsecureSkipVerify: true, ServerName: target.Host})
+	if err != nil {
+		return "UNKNOWN", err
+	}
+	defer conn.Close()
+
+	state := conn.ConnectionState()
+	if len(state.PeerCertificates) == 0 {
+		return "UNKNOWN", fmt.Errorf("no peer certificates presented")
+	}
+	return evaluateCert(state.PeerCertificates[0])
+}
+
+func evaluateCert(cert *x509.Certificate) (string, error) {
+	// Expiry check
+	now := time.Now()
+	if !now.Before(cert.NotAfter) {
+		return "EXPIRED", fmt.Errorf("expired at %s", cert.NotAfter)
+	}
+	if !now.After(cert.NotBefore) {
+		return "EXPIRED", fmt.Errorf("not valid until %s", cert.NotBefore)
+	}
+
+	// Revocation check using certlib/revoke
+	revoked, ok, err := revoke.VerifyCertificateError(cert)
+	if revoked {
+		// If revoked is true, ok will be true per implementation, err may describe why
+		return "REVOKED", err
+	}
+	if !ok {
+		// Revocation status could not be determined
+		return "UNKNOWN", err
+	}
+
+	return "OK", nil
+}