From b524161802d261f7de7a5a3feb252b69f746679b Mon Sep 17 00:00:00 2001
From: Jeannie Kidd <jkidd@miteksystems.com>
Date: Fri, 17 Apr 2020 09:44:23 -0700
Subject: [PATCH] implement asn1 parsing

---
 asn1.go | 33 +++++++++++++++++++++++++++++++++
 shim.h  |  1 +
 2 files changed, 34 insertions(+)
 create mode 100644 asn1.go

diff --git a/asn1.go b/asn1.go
new file mode 100644
index 00000000..fdcff435
--- /dev/null
+++ b/asn1.go
@@ -0,0 +1,33 @@
+package openssl
+
+// #include "shim.h"
+import "C"
+
+import (
+	"errors"
+	"io/ioutil"
+)
+
+// ASN1Parse parses and extracts ASN.1 structure and returns the data in text format
+func ASN1Parse(asn1 []byte) (string, error) {
+	if len(asn1) == 0 {
+		return "", errors.New("empty asn1 structure")
+	}
+
+	out := C.BIO_new(C.BIO_s_mem())
+	if out == nil {
+		return "", errors.New("failed allocating output buffer")
+	}
+	defer C.BIO_free(out)
+
+	if int(C.ASN1_parse_dump(out, (*C.uchar)(&asn1[0]), C.long(len(asn1)), 1, 0)) == 0 {
+		return "", errors.New("failed to parse asn1 data")
+	}
+
+	parsed, err := ioutil.ReadAll(asAnyBio(out))
+	if err != nil {
+		return "", errors.New("failed to read bio data as bytes")
+	}
+
+	return string(parsed), nil
+}
diff --git a/shim.h b/shim.h
index c77a0a7d..2837d6d7 100644
--- a/shim.h
+++ b/shim.h
@@ -32,6 +32,7 @@
 #include <openssl/objects.h>
 #include <openssl/obj_mac.h>
 #include <openssl/cms.h>
+#include <openssl/asn1.h>
 
 #ifndef SSL_MODE_RELEASE_BUFFERS
 #define SSL_MODE_RELEASE_BUFFERS 0