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hostavailable - always .T.

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  • #31
    Re: hostavailable - always .T.

    Originally posted by CALocklin View Post
    I wonder if my ISP (Charter) is doing this to me. Here's an example of what I often get in the browser when this happens.[ATTACH]20677[/ATTACH]
    And, to the best of my knowledge, I don't have any Yahoo toolbar, etc. on my system. That's not to say it isn't there but, if it is, I can't find it.
    Yes, that is exactly the problem! No matter what host you request, Charter is giving a valid HTTP response. Normally a connection to a non-existent host should fail. hostavailable() simply checks to see if a connection can be opened to the specified host, and Charter ensures that it always can be.

    In your case, you will need to try to detect something specific about the response that indicates it is one of these "helpful" pages instead of a response from the real server. I would examine the full headers and body of the response and see if you can find something unique enough. If all that you want to know is if the host is available, I recommend not just looking for a 404 status code because a mistyped page name or temporarily removed page could result in a 404 being sent back from the real server which is available. If you do want to really know that the specific page is available on the remote server, looking at the status code would be a good way to go. A status >= 400 indicates an error condition (page not found, permissions issue, server-side code error, etc.).

    Lenny Forziati
    Vice President, Internet Products and Technical Services
    Alpha Software Corporation

    Comment


    • #32
      Re: hostavailable - always .T.

      It is not Charter or what ISP you use.. It's the BROWSER and how it resolves the URL.

      Comment


      • #33
        Re: hostavailable - always .T.

        Cal,

        If you are trying to test that your server is available from your customers' system before you start a download could not create a simple html page that you fetch to make sure your customer has a good connection to your server.
        Code:
        ?http_get("www.alanderservices.com/testconnection.html").body
        = <html>
        <body>
        GOOD CONNECTION
        </body>
        </html>
        The page is still up in anyone wants to do testing
        Jeff Ryder

        Comment


        • #34
          Re: hostavailable - always .T.

          Originally posted by Lenny Forziati View Post
          Yes, that is exactly the problem! No matter what host you request, Charter is giving a valid HTTP response. Normally a connection to a non-existent host should fail.

          In this case you, you will need to try to detect something specific about the response that indicates it is one of these "helpful" pages instead of a real response. I would examine the full headers and body of the response and see if you can find something unique enough. If all that you want to know is if the host is available, I recommend not just looking for a 404 status code because a mistyped page name or temporarily removed page could result in a 404 being sent back from the real server which is available.
          I think that clarifies it. For my purposes, the 404 should do the trick. In this case anyway. It's my own app that's trying to reach my own web page and I just want to know that it's up and running. If they can't get to my page, there's a problem.

          The big concern is for the future. I can build something to test special cases on my system or even for an individual customer. But, what happens for generic apps and for the customer who changes something without telling me? It doesn't look like there will be any easy answer to those issues.

          Since this seems to be done by the ISP, there's probably no hope but I'll ask anyway - anyone know of a way to turn the "feature" off?

          <rant>
          I'm really getting tired of stupid people. As a result of their stupidity, developers, engineers, and any other "creators" that you can think of try to make it easier for them. As a result, it often becomes more difficult for those of us who know what we are doing.

          By the way, Lenny. When are you guys going to fix/commonize all the places where I can get a list of fields for a table? Apparently somebody complained a long time ago and suggested that they should be alphabetized. So, most of them were alphabetized. Then I complained about not having the option to still see them in natural order and a few were made optional. As it is now, some are still ONLY available as alphabetized lists, some are only available in natural order, and some give you the option. For me, alphabetized is nice occasionally but most times I prefer the natural order. It's more common to have to fix something to do with the last field added to the table than it is to fix something to do with one of the original fields and I often don't remember the name of the last field - I just know it was the last field. It's also fairly common to group fields by "category" - such as all address info together. The use of alphabetic order has sometimes forced me into closing what I was doing, opening the table structure to find out the field name, then going back to what I was doing - a real PITA for me just to make someone else happy.

          This isn't the only place this type of thing has happened. I hope there will be more thought put into these kinds of things in the future. When someone suggests that "this would make it easier", think long and hard about whether or not it would make it easier for everyone. Maybe even do a quick survey here on the message board.
          </rant>

          Comment


          • #35
            Re: hostavailable - always .T.

            Originally posted by CALocklin View Post
            Since this seems to be done by the ISP, there's probably no hope but I'll ask anyway - anyone know of a way to turn the "feature" off?
            Again.. it is not Charter, it's the browser. In Firefox you can check a box: Warn me when websites try to redirect.. but it does not seem to make any difference. IE probably has similar feature.

            Comment


            • #36
              Re: hostavailable - always .T.

              Originally posted by G Gabriel View Post
              Again.. it is not Charter, it's the browser. In Firefox you can check a box: Warn me when websites try to redirect.. but it does not seem to make any difference. IE probably has similar feature.
              Gabe, I'm sorry but you are wrong. There is no browser involved when using hostavailable() or http_get(). The ISP is capturing DNS lookups and instead of returning a response indicating that there is no known IP address for the requested host name, it is returning a specific IP address for one of their servers. That server then answers all requests, regardless of which hostname you used.

              Lenny Forziati
              Vice President, Internet Products and Technical Services
              Alpha Software Corporation

              Comment


              • #37
                Re: hostavailable - always .T.

                OK Lenny.. then how do you explain the fact that you get a different response when you use different browsers?

                Comment


                • #38
                  Re: hostavailable - always .T.

                  Cal

                  Try changing your DNS to a public DNS - Doing a bit of googling, Charter is known to cause this problem - something I had not thought of.

                  Try one of these public DNS servers:-

                  199.166.28.10 (PS0.NS2.VRX.NET) - Atlanta, Ga
                  199.166.29.3 (nl.public.rootfix.net) - Nederlands
                  199.166.31.3 (NS1.QUASAR.NET) - Orlando, FL, USA
                  204.57.55.100 (NS1.JERKY.NET) - Boston, MA, USA
                  199.5.157.128 (ASLAN.OPEN-RSC.ORG) - Detroit, MI, USA

                  P.S. OpenDNS also redirects to advertising pages.
                  If It Works First Time, There's Something Wrong!!!

                  Comment


                  • #39
                    Re: hostavailable - always .T.

                    Cal:
                    Here is another idea, it seems to work but warrants more testing.
                    Code:
                    ?hostavailable("157.166.226.26")
                    = .T.
                    The above IP is that of cnn.com

                    What I am saying is, instead of testing the connection to your web page using the web page URL, use the actual IP of the page that way you avoid any improper DNS resolution.
                    P.S.:
                    If you do not know the IP of your page, post it here or send it to me and and I will give you the IP address.

                    Lenny:
                    Of course you are correct, but for the life of me I can't understand why when typing a phony address in Firefox it takes me to charter's default page, but when doing the same thing in IE it took me to google ! I thought perhaps DNS resolution occurs both at ISP as well as the browser level, or maybe the DNS was cached differently in IE. At any rate, I turned the computer off to completely clear the cache, turned it back on and Lo and Behold, both browsers now take me to the default charter's search page !!

                    Comment

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