libcli:auth: Implment a common create_pw_buffer_from_blob()

Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>

diff --git a/libcli/auth/smbencrypt.c b/libcli/auth/smbencrypt.c
index 8384581c2bdea9efb8095eb199964581f062d9d2..666ff3145239381b7e4c8d3bdf94674d95019bc7 100644 (file)
--- a/libcli/auth/smbencrypt.c
+++ b/libcli/auth/smbencrypt.c
@@ -1080,21 +1080,54 @@ NTSTATUS decode_rc4_passwd_buffer(const DATA_BLOB *psession_key,
  encode a password buffer with an already unicode password.  The
  rest of the buffer is filled with random data to make it harder to attack.
 ************************************************************/
-bool set_pw_in_buffer(uint8_t buffer[516], const DATA_BLOB *password)
+
+static bool create_pw_buffer_from_blob(uint8_t buffer[512],
+                                      const DATA_BLOB *in_password,
+                                      enum encode_order order)
 {
-       if (password->length > 512) {
+       size_t pwd_pos = 0;
+       size_t random_pos = 0;
+       size_t random_len = 0;
+
+       if (in_password->length > 512) {
                return false;
        }
 
-       memcpy(&buffer[512 - password->length], password->data, password->length);
+       switch (order) {
+       case ENCODE_ORDER_PASSWORD_FIRST:
+               pwd_pos = 0;
+               random_pos = in_password->length;
+               break;
+       case ENCODE_ORDER_PASSWORD_LAST:
+               pwd_pos = PASSWORD_BUFFER_LEN - in_password->length;
+               random_pos = 0;
+               break;
+       }
+       random_len = PASSWORD_BUFFER_LEN - in_password->length;
+
+       memcpy(buffer + pwd_pos, in_password->data, in_password->length);
+       generate_random_buffer(buffer + random_pos, random_len);
+
+       return true;
+}
+
+bool set_pw_in_buffer(uint8_t buffer[516], const DATA_BLOB *password)
+{
+       bool ok;
 
-       generate_random_buffer(buffer, 512 - password->length);
+       ok = create_pw_buffer_from_blob(buffer,
+                                       password,
+                                       ENCODE_ORDER_PASSWORD_LAST);
+       if (!ok) {
+               return false;
+       }
 
        /*
         * The length of the new password is in the last 4 bytes of
         * the data buffer.
         */
-       SIVAL(buffer, 512, password->length);
+       PUSH_LE_U32(buffer, PASSWORD_BUFFER_LEN, password->length);
+
        return true;
 }