https://sourceforge.net/p/isync/bugs/89/
https://sourceforge.net/p/isync/isync/merge-requests/10/

--- a/src/socket.c
+++ b/src/socket.c
@@ -24,6 +24,7 @@
 	|| (defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x2070100fL)
 #  define X509_OBJECT_get0_X509(o) ((o)->data.x509)
 #  define X509_STORE_get0_objects(o) ((o)->objs)
+#  define ASN1_STRING_get0_data(s) ((const unsigned char *)ASN1_STRING_data(s))
 # endif
 #endif
 
@@ -141,8 +142,8 @@
 		for (i = 0; i < num_subj_alt_names; i++) {
 			GENERAL_NAME *subj_alt_name = sk_GENERAL_NAME_value( subj_alt_names, i );
 			if (subj_alt_name->type == GEN_DNS &&
-			    strlen( (const char *)subj_alt_name->d.ia5->data ) == (size_t)subj_alt_name->d.ia5->length &&
-			    host_matches( hostname, (const char *)(subj_alt_name->d.ia5->data) ))
+			    strlen( (const char *)ASN1_STRING_get0_data( subj_alt_name->d.ia5 ) ) == (size_t)ASN1_STRING_length( subj_alt_name->d.ia5 ) &&
+			    host_matches( hostname, (const char *)ASN1_STRING_get0_data( subj_alt_name->d.ia5 ) ))
 			{
 				found = 1;
 				break;