libcli:auth: Implement a generic encode_pwd_buffer_from_str()

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 fe20fe4e2a3cefb2f1c46076136e57134e8d8c2b..c89ac243ba4ec7e42e926b8a0cc7b60fe9150dd1 100644 (file)
--- a/libcli/auth/smbencrypt.c
+++ b/libcli/auth/smbencrypt.c
@@ -856,35 +856,76 @@ NTSTATUS NTLMv2_RESPONSE_verify_netlogon_creds(const char *account_name,
        return NT_STATUS_OK;
 }
 
+enum encode_order {
+       ENCODE_ORDER_PASSWORD_FIRST,
+       ENCODE_ORDER_PASSWORD_LAST,
+};
+
+#define PASSWORD_BUFFER_LEN 512
+
+static ssize_t _encode_pwd_buffer_from_str(uint8_t buf[PASSWORD_BUFFER_LEN],
+                                          const char *password,
+                                          int string_flags,
+                                          enum encode_order order)
+{
+       ssize_t new_pw_len;
+       size_t pw_pos = 0;
+       size_t random_pos = 0;
+       size_t random_len = 0;
+
+       /* The incoming buffer can be any alignment. */
+       string_flags |= STR_NOALIGN;
+
+       new_pw_len = push_string(buf,
+                                password,
+                                PASSWORD_BUFFER_LEN,
+                                string_flags);
+       if (new_pw_len < 0) {
+               BURN_DATA_SIZE(buf, PASSWORD_BUFFER_LEN);
+               return -1;
+       }
+
+       if (new_pw_len == PASSWORD_BUFFER_LEN) {
+               return new_pw_len;
+       }
+
+       switch (order) {
+       case ENCODE_ORDER_PASSWORD_FIRST:
+               pw_pos = 0;
+               random_pos = new_pw_len;
+               random_len = PASSWORD_BUFFER_LEN - random_pos;
+               break;
+       case ENCODE_ORDER_PASSWORD_LAST:
+               pw_pos = PASSWORD_BUFFER_LEN - new_pw_len;
+               random_pos = 0;
+               random_len = pw_pos;
+               memmove(buf + pw_pos, buf, new_pw_len);
+               break;
+       }
+
+       generate_random_buffer(buf + random_pos, random_len);
+
+       return new_pw_len;
+}
+
 /***********************************************************
  encode a password buffer with a unicode password.  The buffer
  is filled with random data to make it harder to attack.
 ************************************************************/
 bool encode_pw_buffer(uint8_t buffer[516], const char *password, int string_flags)
 {
-       uint8_t new_pw[512];
-       ssize_t new_pw_len;
-
-       /* the incoming buffer can be any alignment. */
-       string_flags |= STR_NOALIGN;
+       ssize_t pw_len;
 
-       new_pw_len = push_string(new_pw,
-                                password,
-                                sizeof(new_pw), string_flags);
-       if (new_pw_len == -1) {
+       pw_len = _encode_pwd_buffer_from_str(buffer,
+                                            password,
+                                            string_flags,
+                                            ENCODE_ORDER_PASSWORD_LAST);
+       if (pw_len < 0 || pw_len > PASSWORD_BUFFER_LEN) {
                return false;
        }
 
-       memcpy(&buffer[512 - new_pw_len], new_pw, new_pw_len);
-
-       generate_random_buffer(buffer, 512 - new_pw_len);
+       PUSH_LE_U32(buffer, PASSWORD_BUFFER_LEN, pw_len);
 
-       /*
-        * The length of the new password is in the last 4 bytes of
-        * the data buffer.
-        */
-       SIVAL(buffer, 512, new_pw_len);
-       ZERO_STRUCT(new_pw);
        return true;
 }