1 files changed, 35 insertions, 0 deletions
diff --git a/tls-getcerts.go b/tls-getcerts.go
new file mode 100644
index 0000000..b0d4533
--- /dev/null
+++ b/tls-getcerts.go
@@ -0,0 +1,35 @@
+package main
+
+import (
+	"crypto/tls"
+	"crypto/x509"
+	"fmt"
+	"os"
+	"encoding/pem"
+)
+
+func getcert(server string) (*x509.Certificate, error){
+	conn, err := tls.Dial("tcp", fmt.Sprintf("%s:443", server), &tls.Config{ServerName: server})
+	if err != nil {
+		return nil, err
+	}
+	defer conn.Close()
+	chain := conn.ConnectionState().PeerCertificates
+	return chain[len(chain)-2], nil
+}
+
+func main() {
+	for _, server := range os.Args[1:] {
+		cert, err := getcert(server)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Could not get certificate from server %q: %q\n", server, err)
+			os.Exit(1)
+		}
+		block := pem.Block{
+			Type: "CERTIFICATE",
+			Headers: nil,
+			Bytes: cert.Raw,
+		}
+		pem.Encode(os.Stdout, &block)
+	}
+}