No ability to send arbitrary commands to ftp server like 'quote' command in ftp.  Trivial addition.  Also ftp_exec and ftp_site seem redundant.  The former does a 'SITE EXEC' in front of command the latter does 'SITE' in front of command.

The patch is trivial and available at:
http://linuxap.ksmith.com/archive/misc/php-4.3.1-ftp_quote.patch

I also include it here to 4.3.1.  It should probably patch other versions as well:

diff -urN php-4.3.1/ext/ftp/ftp.c php-4.3.1.new/ext/ftp/ftp.c
--- php-4.3.1/ext/ftp/ftp.c     2002-10-12 18:40:46.000000000 -0700
+++ php-4.3.1.new/ext/ftp/ftp.c 2003-03-30 20:28:35.000000000 -0700
@@ -417,6 +417,22 @@
 }
 /* }}} */

+/* {{{ ftp_quote
+ */
+int
+ftp_quote(ftpbuf_t *ftp, const char *cmd)
+{
+       if (ftp == NULL)
+               return 0;
+       if (!ftp_putcmd(ftp, cmd, NULL))
+               return 0;
+       if (!ftp_getresp(ftp) || ftp->resp != 200)
+               return 0;
+
+       return 1;
+}
+/* }}} */
+
 /* {{{ ftp_chdir
  */
 int
diff -urN php-4.3.1/ext/ftp/ftp.h php-4.3.1.new/ext/ftp/ftp.h
--- php-4.3.1/ext/ftp/ftp.h     2002-10-03 05:16:44.000000000 -0700
+++ php-4.3.1.new/ext/ftp/ftp.h 2003-03-30 20:45:03.000000000 -0700
@@ -179,6 +179,9 @@
 /* sends a SITE command to the server */
 int            ftp_site(ftpbuf_t *ftp, const char *cmd);

+/* sends an arbitrary command string to the server */
+int            ftp_quote(ftpbuf_t *ftp, const char *cmd);
+
 /* retrieves part of a file and saves its contents to outfp
  * returns true on success, false on error
  */
diff -urN php-4.3.1/ext/ftp/php_ftp.c php-4.3.1.new/ext/ftp/php_ftp.c
--- php-4.3.1/ext/ftp/php_ftp.c 2002-12-05 23:08:21.000000000 -0700
+++ php-4.3.1.new/ext/ftp/php_ftp.c     2003-03-30 20:47:55.000000000 -0700
@@ -71,6 +71,7 @@
        PHP_FE(ftp_rename,                      NULL)
        PHP_FE(ftp_delete,                      NULL)
        PHP_FE(ftp_site,                        NULL)
+       PHP_FE(ftp_quote,                       NULL)
        PHP_FE(ftp_close,                       NULL)
        PHP_FE(ftp_set_option,          NULL)
        PHP_FE(ftp_get_option,          NULL)
@@ -1055,6 +1056,31 @@
 }
 /* }}} */

+/* {{{ proto bool ftp_quote(resource stream, string cmd)
+   Sends an arbitrary command to the server */
+PHP_FUNCTION(ftp_quote)
+{
+       zval            *z_ftp;
+       ftpbuf_t        *ftp;
+       char            *cmd;
+       int                     cmd_len;
+
+       if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "rs", &z_ftp, &cmd, &cmd_len) == FAILURE) {
+               return;
+       }
+
+       ZEND_FETCH_RESOURCE(ftp, ftpbuf_t*, &z_ftp, -1, le_ftpbuf_name, le_ftpbuf);
+
+       /* send the command */
+       if (!ftp_quote(ftp, cmd)) {
+               php_error_docref(NULL TSRMLS_CC, E_WARNING, "%s", ftp->inbuf);
+               RETURN_FALSE;
+       }
+
+       RETURN_TRUE;
+}
+/* }}} */
+
 /* {{{ proto void ftp_close(resource stream)
    Closes the FTP stream */
 PHP_FUNCTION(ftp_close)
diff -urN php-4.3.1/ext/ftp/php_ftp.h php-4.3.1.new/ext/ftp/php_ftp.h
--- php-4.3.1/ext/ftp/php_ftp.h 2002-10-03 04:33:05.000000000 -0700
+++ php-4.3.1.new/ext/ftp/php_ftp.h     2003-03-30 20:48:15.000000000 -0700
@@ -58,6 +58,7 @@
 PHP_FUNCTION(ftp_rename);
 PHP_FUNCTION(ftp_delete);
 PHP_FUNCTION(ftp_site);
+PHP_FUNCTION(ftp_quote);
 PHP_FUNCTION(ftp_close);
 PHP_FUNCTION(ftp_set_option);
 PHP_FUNCTION(ftp_get_option);