1 files changed, 26 insertions, 0 deletions
diff --git a/Cryptlib/OpenSSL/crypto/asn1/a_bitstr.c b/Cryptlib/OpenSSL/crypto/asn1/a_bitstr.c
index ef1caa4e..f906188b 100644
--- a/Cryptlib/OpenSSL/crypto/asn1/a_bitstr.c
+++ b/Cryptlib/OpenSSL/crypto/asn1/a_bitstr.c
@@ -234,3 +234,29 @@ int ASN1_BIT_STRING_get_bit(ASN1_BIT_STRING *a, int n)
         return (0);
     return ((a->data[w] & v) != 0);
 }
+
+/*
+ * Checks if the given bit string contains only bits specified by
+ * the flags vector. Returns 0 if there is at least one bit set in 'a'
+ * which is not specified in 'flags', 1 otherwise.
+ * 'len' is the length of 'flags'.
+ */
+int ASN1_BIT_STRING_check(ASN1_BIT_STRING *a,
+                          unsigned char *flags, int flags_len)
+{
+    int i, ok;
+    /* Check if there is one bit set at all. */
+    if (!a || !a->data)
+        return 1;
+
+    /*
+     * Check each byte of the internal representation of the bit string.
+     */
+    ok = 1;
+    for (i = 0; i < a->length && ok; ++i) {
+        unsigned char mask = i < flags_len ? ~flags[i] : 0xff;
+        /* We are done if there is an unneeded bit set. */
+        ok = (a->data[i] & mask) == 0;
+    }
+    return ok;
+}