{"id":252,"date":"2011-02-07T16:26:59","date_gmt":"2011-02-07T14:26:59","guid":{"rendered":"http:\/\/blog.ansuz.nl\/?p=252"},"modified":"2011-02-11T15:45:00","modified_gmt":"2011-02-11T13:45:00","slug":"flex-ftp-epsv-support","status":"publish","type":"post","link":"http:\/\/blog.ansuz.nl\/index.php\/2011\/02\/07\/flex-ftp-epsv-support\/","title":{"rendered":"Flex FTP EPSV support"},"content":{"rendered":"

Still working with Flex FTP<\/a> and this time I was missing EPSV support. EPSV is roughly the same as PASV, exect that you only get a port number to connect to back and not an IP address. You can read up on RFC 2428 “FTP Extensions for IPv6 and NATs”<\/a> if you want more details.<\/p>\n

The first thing I did to add support for EPSV in Flex FTP is adding a response to the Responses class.<\/p>\n

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code<\/div>\n\n\t\t\n\t\t
\n\n\t<\/div>\n\t\n\t
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  1. public static const ENTERING_EPSV:int = 229; \/\/Entering Extended Passive Mode.<\/div><\/li>\n<\/ol>\t<\/div>\n\n<\/div>\n\n

    Second was the commands class, where I added the following line:<\/p>\n

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    code<\/div>\n\n\t\t\n\t\t
    \n\n\t<\/div>\n\t\n\t
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    1. public static const EPSV:String = "EPSV";<\/div><\/li>\n<\/ol>\t<\/div>\n\n<\/div>\n\n

      Then I added an extra argument to the FTPClient class’ constructor that will indicate whether or not to use ESPV.<\/p>\n

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      code<\/div>\n\n\t\t\n\t\t
      \n\n\t<\/div>\n\t\n\t
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      1. public function FTPClient (host:String="", port:int=21, useEpsv:Boolean = false)<\/div><\/li>\n<\/ol>\t<\/div>\n\n<\/div>\n\n

        I store the value internally and use a getter method to determine if an Invoker class (i.e ListInv) needs to use EPSV.<\/p>\n

        Based on the client epsv setting any invoker can be updated to send the EPSV command instead of the PASV command when needed, i.e. my implementation of ListInv’s startSequence method:<\/p>\n

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        code<\/div>\n\n\t\t\n\t\t
        \n\n\t<\/div>\n\t\n\t
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        1. override protected function startSequence ():void {<\/div><\/li>\n
        2. if(client.useEpsv) {<\/div><\/li>\n
        3. sendCommand(new FTPCommand(Commands.EPSV));<\/div><\/li>\n
        4. } else {<\/div><\/li>\n
        5. sendCommand(new FTPCommand(Commands.PASV));<\/div><\/li>\n
        6. }<\/div><\/li>\n
        7. }<\/div><\/li>\n<\/ol>\t<\/div>\n\n<\/div>\n\n

          I also update the responseHandler method in ListInv to include the following case:<\/p>\n

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          code<\/div>\n\n\t\t\n\t\t
          \n\n\t<\/div>\n\t\n\t
          \n\t\t
          1. case Responses.ENTERING_EPSV:<\/div><\/li>\n
          2. passiveSocket =\u00c2\u00a0\u00c2\u00a0\u00c2\u00a0 PassiveSocketInfo.createPassiveSocket(evt.response.message,<\/div><\/li>\n
          3. handlePassiveConnect,<\/div><\/li>\n
          4. handleListing, ioErrorHandler,<\/div><\/li>\n
          5. null, true, client.hostname);<\/div><\/li>\n
          6. break;<\/div><\/li>\n<\/ol>\t<\/div>\n\n<\/div>\n\n

            On top of that I made some tweaks to the PassiveSocketInfo class.
            \nThe parseFromResponse method now looks like this:<\/p>\n

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            code<\/div>\n\n\t\t\n\t\t
            \n\n\t<\/div>\n\t\n\t
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            1. public static function parseFromResponse (pasvResponse:String, usingEpsv:Boolean = false, hostName:String = ""):PassiveSocketInfo {<\/div><\/li>\n
            2. var host:String;<\/div><\/li>\n
            3. var port:int;<\/div><\/li>\n
            4.  <\/div><\/li>\n
            5. if (usingEpsv) {<\/div><\/li>\n
            6. host = hostName;<\/div><\/li>\n
            7. port = pasvResponse.match(\/\\d+\/)[0];<\/div><\/li>\n
            8. } else {<\/div><\/li>\n
            9. var match:Array = pasvResponse.match(\/(\\d{1,3},){5}\\d{1,3}\/);<\/div><\/li>\n
            10. if (match == null)<\/div><\/li>\n
            11. throw new Error("Error parsing passive port! (Response: "+pasvResponse+")");<\/div><\/li>\n
            12. var data:Array = match[0].split(",");<\/div><\/li>\n
            13. host = data.slice(0,4).join(".");<\/div><\/li>\n
            14. port = parseInt(data[4])*256+parseInt(data[5]);<\/div><\/li>\n
            15. }<\/div><\/li>\n
            16. return new PassiveSocketInfo(host, port);<\/div><\/li>\n
            17. }<\/div><\/li>\n<\/ol>\t<\/div>\n\n<\/div>\n\n

              The createPassiveSocket method now takes two extra optional arguments (usingEpsv:Boolean and host:String) and just passes those on to the parseFromResponse method.<\/p>\n

              Hope this helps anybody looking for EPSV support for Flex FTP<\/a>.<\/p>\n

              PS: It’s been a while since I added EPSV support, so let me know about any gaps.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

              Still working with Flex FTP and this time I was missing EPSV support. EPSV is roughly the same as PASV, exect that you only get a port number to connect to back and not an IP address. You can read … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8,65],"tags":[97,99],"class_list":["post-252","post","type-post","status-publish","format-standard","hentry","category-actionscript-30","category-flex","tag-flex-ftp","tag-flexftp"],"_links":{"self":[{"href":"http:\/\/blog.ansuz.nl\/index.php\/wp-json\/wp\/v2\/posts\/252","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/blog.ansuz.nl\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/blog.ansuz.nl\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/blog.ansuz.nl\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/blog.ansuz.nl\/index.php\/wp-json\/wp\/v2\/comments?post=252"}],"version-history":[{"count":8,"href":"http:\/\/blog.ansuz.nl\/index.php\/wp-json\/wp\/v2\/posts\/252\/revisions"}],"predecessor-version":[{"id":269,"href":"http:\/\/blog.ansuz.nl\/index.php\/wp-json\/wp\/v2\/posts\/252\/revisions\/269"}],"wp:attachment":[{"href":"http:\/\/blog.ansuz.nl\/index.php\/wp-json\/wp\/v2\/media?parent=252"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/blog.ansuz.nl\/index.php\/wp-json\/wp\/v2\/categories?post=252"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/blog.ansuz.nl\/index.php\/wp-json\/wp\/v2\/tags?post=252"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}