Simplify make_addressPrefix()

In order to set the BIT STRING containing an address prefix, use existing
helper functions from the ASN.1 code instead of redoing everything by
hand. Make the function single exit and rename a few variables to make
it clearer what is being done.

ok jsing

1 files changed, 23 insertions, 21 deletions

diff --git a/src/lib/libcrypto/x509/x509_addr.c b/src/lib/libcrypto/x509/x509_addr.c
index b1ff93d4d0..ba5aaff7e6 100644
--- a/src/lib/libcrypto/x509/x509_addr.c
+++ b/src/lib/libcrypto/x509/x509_addr.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: x509_addr.c,v 1.80 2022/04/21 05:06:07 tb Exp $ */
+/*      $OpenBSD: x509_addr.c,v 1.81 2022/05/17 07:50:59 tb Exp $ */
 /*
  * Contributed to the OpenSSL Project by the American Registry for
  * Internet Numbers ("ARIN").
@@ -73,6 +73,7 @@
 #include <openssl/x509.h>
 #include <openssl/x509v3.h>
 
+#include "asn1_locl.h"
 #include "bytestring.h"
 #include "x509_lcl.h"
 
@@ -847,44 +848,45 @@ range_should_be_prefix(const unsigned char *min, const unsigned char *max,
 }
 
 /*
- * Construct a prefix.
+ * Fill IPAddressOrRange with bit string encoding of a prefix - RFC 3779, 2.1.1.
  */
 static int
-make_addressPrefix(IPAddressOrRange **result, unsigned char *addr,
-    unsigned int afi, int prefix_len)
+make_addressPrefix(IPAddressOrRange **out_aor, uint8_t *addr, uint32_t afi,
+    int prefix_len)
 {
-        IPAddressOrRange *aor;
-        int afi_len, byte_len, bit_len, max_len;
+        IPAddressOrRange *aor = NULL;
+        int afi_len, max_len, num_bits, num_octets;
+        uint8_t unused_bits;
 
         if (prefix_len < 0)
-                return 0;
+                goto err;
 
         max_len = 16;
         if ((afi_len = length_from_afi(afi)) > 0)
                 max_len = afi_len;
         if (prefix_len > 8 * max_len)
-                return 0;
+                goto err;
+
+        num_octets = (prefix_len + 7) / 8;
+        num_bits = prefix_len % 8;
 
-        byte_len = (prefix_len + 7) / 8;
-        bit_len = prefix_len % 8;
+        unused_bits = 0;
+        if (num_bits > 0)
+                unused_bits = 8 - num_bits;
 
         if ((aor = IPAddressOrRange_new()) == NULL)
-                return 0;
+                goto err;
+
         aor->type = IPAddressOrRange_addressPrefix;
+
         if ((aor->u.addressPrefix = ASN1_BIT_STRING_new()) == NULL)
                 goto err;
-
-        if (!ASN1_BIT_STRING_set(aor->u.addressPrefix, addr, byte_len))
+        if (!ASN1_BIT_STRING_set(aor->u.addressPrefix, addr, num_octets))
+                goto err;
+        if (!asn1_abs_set_unused_bits(aor->u.addressPrefix, unused_bits))
                 goto err;
 
-        aor->u.addressPrefix->flags &= ~7;
-        aor->u.addressPrefix->flags |= ASN1_STRING_FLAG_BITS_LEFT;
-        if (bit_len > 0) {
-                aor->u.addressPrefix->data[byte_len - 1] &= ~(0xff >> bit_len);
-                aor->u.addressPrefix->flags |= 8 - bit_len;
-        }
-
-        *result = aor;
+        *out_aor = aor;
         return 1;
 
  err: