Function native_password_authenticate

phx_percona/percona/sql/sql_acl.cc:11770–11854

MySQL Server Password Authentication Plugin In the MySQL authentication protocol: 1. the server sends the random scramble to the client 2. client sends the encrypted password back to the server 3. the server checks the password. */

  3. the server checks the password.
*/
static int native_password_authenticate(MYSQL_PLUGIN_VIO *vio,
                                        MYSQL_SERVER_AUTH_INFO *info)
{
  uchar *pkt;
  int pkt_len;
  MPVIO_EXT *mpvio= (MPVIO_EXT *) vio;

  DBUG_ENTER("native_password_authenticate");

  /* generate the scramble, or reuse the old one */
  if (mpvio->scramble[SCRAMBLE_LENGTH])
    create_random_string(mpvio->scramble, SCRAMBLE_LENGTH, mpvio->rand);

  /* send it to the client */
  if (mpvio->write_packet(mpvio, (uchar*) mpvio->scramble, SCRAMBLE_LENGTH + 1))
    DBUG_RETURN(CR_AUTH_HANDSHAKE);

  /* reply and authenticate */

  /*
    <digression>
      This is more complex than it looks.

      The plugin (we) may be called right after the client was connected -
      and will need to send a scramble, read reply, authenticate.

      Or the plugin may be called after another plugin has sent a scramble,
      and read the reply. If the client has used the correct client-plugin,
      we won't need to read anything here from the client, the client
      has already sent a reply with everything we need for authentication.

      Or the plugin may be called after another plugin has sent a scramble,
      and read the reply, but the client has used the wrong client-plugin.
      We'll need to sent a "switch to another plugin" packet to the
      client and read the reply. "Use the short scramble" packet is a special
      case of "switch to another plugin" packet.

      Or, perhaps, the plugin may be called after another plugin has
      done the handshake but did not send a useful scramble. We'll need
      to send a scramble (and perhaps a "switch to another plugin" packet)
      and read the reply.

      Besides, a client may be an old one, that doesn't understand plugins.
      Or doesn't even understand 4.0 scramble.

      And we want to keep the same protocol on the wire  unless non-native
      plugins are involved.

      Anyway, it still looks simple from a plugin point of view:
      "send the scramble, read the reply and authenticate"
      All the magic is transparently handled by the server.
    </digression>
  */

  /* read the reply with the encrypted password */
  if ((pkt_len= mpvio->read_packet(mpvio, &pkt)) < 0)
    DBUG_RETURN(CR_AUTH_HANDSHAKE);
  DBUG_PRINT("info", ("reply read : pkt_len=%d", pkt_len));