https://bugs.gentoo.org/985099
https://github.com/libesmtp/libESMTP/pull/34

From f74ac43fcd2af19dac28901bfb9dd1e62a8ec7b0 Mon Sep 17 00:00:00 2001
From: Ravi Kant Sharma <ravi.kant.sharma@canonical.com>
Date: Tue, 28 Jul 2026 20:35:48 +0200
Subject: [PATCH] Fix build with OpenSSL 4.0 opaque ASN1_STRING

OpenSSL 4.0 made ASN1_STRING opaque, so direct access to ->data and
->length fields no longer compiles. Use ASN1_STRING_get0_data() and
ASN1_STRING_length() accessors which are available since OpenSSL 1.1.0.

Fixes #33
---
 smtp-tls.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/smtp-tls.c b/smtp-tls.c
index 9f3e50e..981284e 100644
--- a/smtp-tls.c
+++ b/smtp-tls.c
@@ -599,8 +599,8 @@ check_acceptable_security (smtp_session_t session, SSL *ssl)
 
 	      if (name->type == GEN_DNS)
 		{
-		  const char *ia5str = (const char *) name->d.ia5->data;
-		  size_t ia5len = name->d.ia5->length;
+		  const char *ia5str = (const char *) ASN1_STRING_get0_data(name->d.ia5);
+		  size_t ia5len = ASN1_STRING_length(name->d.ia5);
 
 		  hasaltname = 1;
 		  if (strlen (ia5str) == ia5len && match_domain (host, ia5str))