Unexport ASN1_LONG_UNDEF

This is another one of these weird magic values that nothing outside
of libcrypto uses. Fix a confusing comment in long_i2c() while there.
The skipping behavior is used in particular for omitting the optional
length value in the non-standard OpenSSL-specific DHparam() ASN.1
encoding.

ok jsing kenjiro

2 files changed, 8 insertions, 7 deletions

diff --git a/src/lib/libcrypto/asn1/asn1.h b/src/lib/libcrypto/asn1/asn1.h
index 7285ad0590..2b19f58717 100644
--- a/src/lib/libcrypto/asn1/asn1.h
+++ b/src/lib/libcrypto/asn1/asn1.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: asn1.h,v 1.94 2025/12/31 13:48:00 tb Exp $ */
+/* $OpenBSD: asn1.h,v 1.95 2026/01/02 08:03:02 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -199,9 +199,6 @@ typedef struct ASN1_ENCODING_st {
         int modified;            /* set to 1 if 'enc' is invalid */
 } ASN1_ENCODING;
 
-/* Used with ASN1 LONG type: if a long is set to this it is omitted */
-#define ASN1_LONG_UNDEF 0x7fffffffL
-
 /* Used by security/xca */
 #define STABLE_NO_MASK          0x02
 
diff --git a/src/lib/libcrypto/asn1/x_long.c b/src/lib/libcrypto/asn1/x_long.c
index a72411f30c..ed463bf7c5 100644
--- a/src/lib/libcrypto/asn1/x_long.c
+++ b/src/lib/libcrypto/asn1/x_long.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: x_long.c,v 1.22 2025/05/10 05:54:38 tb Exp $ */
+/* $OpenBSD: x_long.c,v 1.23 2026/01/02 08:03:02 tb Exp $ */
 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
  * project 2000.
  */
@@ -70,6 +70,9 @@
  * ASN1_INTEGER and a long directly.
  */
 
+/* Used with ASN1 LONG type: if a long is set to this it is omitted */
+#define ASN1_LONG_UNDEF 0x7fffffffL
+
 static int long_new(ASN1_VALUE **pval, const ASN1_ITEM *it);
 static void long_free(ASN1_VALUE **pval, const ASN1_ITEM *it);
 static void long_clear(ASN1_VALUE **pval, const ASN1_ITEM *it);
@@ -159,8 +162,9 @@ long_i2c(ASN1_VALUE **pval, unsigned char *content, int *putype,
         long_get(pval, &val);
 
         /*
-         * The zero value for this type (stored in the overloaded it->size
-         * field) is considered to be invalid.
+         * Omit this field if it has the zero value for this type (stored
+         * in the overloaded it->size field) - asn1_i2d_ex_primitive()
+         * specifically checks for a -1 return value.
          */
         if (val == it->size)
                 return -1;