Document support status of the legacy ASN.1 code.

Change-Id: Ie0565b8b819b9fd837caf723d035866facc9543c
Reviewed-on: https://boringssl-review.googlesource.com/17026
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>

include/openssl/asn1.h

diff --git a/include/openssl/asn1.h b/include/openssl/asn1.h
index 63e4d9e..8ee5b0c 100644
--- a/include/openssl/asn1.h
+++ b/include/openssl/asn1.h
@@ -71,6 +71,14 @@
 extern "C" {
 #endif
 
+
+/* Legacy ASN.1 library.
+ *
+ * This header is part of OpenSSL's ASN.1 implementation. It is retained for
+ * compatibility but otherwise underdocumented and not actively maintained. Use
+ * the new |CBS| and |CBB| library in <openssl/bytestring.h> instead. */
+
+
 #define V_ASN1_UNIVERSAL		0x00
 #define	V_ASN1_APPLICATION		0x40
 #define V_ASN1_CONTEXT_SPECIFIC		0x80

include/openssl/asn1t.h

diff --git a/include/openssl/asn1t.h b/include/openssl/asn1t.h
index 03c07fb..ae507ea 100644
--- a/include/openssl/asn1t.h
+++ b/include/openssl/asn1t.h
@@ -60,18 +60,18 @@
 #include <openssl/base.h>
 #include <openssl/asn1.h>
 
-#ifdef OPENSSL_BUILD_SHLIBCRYPTO
-# undef OPENSSL_EXTERN
-# define OPENSSL_EXTERN OPENSSL_EXPORT
-#endif
-
-/* ASN1 template defines, structures and functions */
-
 #ifdef  __cplusplus
 extern "C" {
 #endif
 
 
+/* Legacy ASN.1 library template definitions.
+ *
+ * This header is used to define new types in OpenSSL's ASN.1 implementation. It
+ * is deprecated and will be unexported from the library. Use the new |CBS| and
+ * |CBB| library in <openssl/bytestring.h> instead. */
+
+
 /* Macro to obtain ASN1_ADB pointer from a type (only used internally) */
 #define ASN1_ADB_ptr(iptr) ((const ASN1_ADB *)(iptr))
 

include/openssl/x509.h

diff --git a/include/openssl/x509.h b/include/openssl/x509.h
index f416045..cc1432d 100644
--- a/include/openssl/x509.h
+++ b/include/openssl/x509.h
@@ -89,6 +89,14 @@
 #endif
 
 
+/* Legacy X.509 library.
+ *
+ * This header is part of OpenSSL's X.509 implementation. It is retained for
+ * compatibility but otherwise underdocumented and not actively maintained. In
+ * the future, a replacement library will be available. Meanwhile, minimize
+ * dependencies on this header where possible. */
+
+
 #define X509_FILETYPE_PEM	1
 #define X509_FILETYPE_ASN1	2
 #define X509_FILETYPE_DEFAULT	3

include/openssl/x509_vfy.h

diff --git a/include/openssl/x509_vfy.h b/include/openssl/x509_vfy.h
index 85aa1f9..4c36570 100644
--- a/include/openssl/x509_vfy.h
+++ b/include/openssl/x509_vfy.h
@@ -72,6 +72,14 @@
 extern "C" {
 #endif
 
+/* Legacy X.509 library.
+ *
+ * This header is part of OpenSSL's X.509 implementation. It is retained for
+ * compatibility but otherwise underdocumented and not actively maintained. In
+ * the future, a replacement library will be available. Meanwhile, minimize
+ * dependencies on this header where possible. */
+
+
 #if 0
 /* Outer object */
 typedef struct x509_hash_dir_st

include/openssl/x509v3.h

diff --git a/include/openssl/x509v3.h b/include/openssl/x509v3.h
index 243798b..e6e8f01 100644
--- a/include/openssl/x509v3.h
+++ b/include/openssl/x509v3.h
@@ -63,6 +63,15 @@
 extern "C" {
 #endif
 
+
+/* Legacy X.509 library.
+ *
+ * This header is part of OpenSSL's X.509 implementation. It is retained for
+ * compatibility but otherwise underdocumented and not actively maintained. In
+ * the future, a replacement library will be available. Meanwhile, minimize
+ * dependencies on this header where possible. */
+
+
 /* Forward reference */
 struct v3_ext_method;
 struct v3_ext_ctx;