HTTP Web Server and GET Request

This is a discussion on HTTP Web Server and GET Request within the C Programming forums, part of the General Programming Boards category; Hi, I am new around here but was hoping I may receive some guidance. I have limited experience with C ...

  1. #1
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    Question HTTP Web Server and GET Request

    Hi, I am new around here but was hoping I may receive some guidance. I have limited experience with C as well as network programming but nevertheless I have a project in which I am trying to simulate a browser requesting a video file. Knowing that creating an HTTP server might be pretty involved so I used some sample code namely the Tiny Web server code (tiny.tar) from CS:APP2e, Bryant and O'Hallaron. When I tried running said code on an unix server. i get the following

    Open_listenfd error: Permission denied
    This is what the function open_listenfd does:

    Code:
    int open_listenfd(int port) 
    {
        int listenfd, optval=1;
        struct sockaddr_in serveraddr;
      
        /* Create a socket descriptor */
        if ((listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
        return -1;
     
        /* Eliminates "Address already in use" error from bind. */
        if (setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, 
               (const void *)&optval , sizeof(int)) < 0)
        return -1;
    
        /* Listenfd will be an endpoint for all requests to port
           on any IP address for this host */
        bzero((char *) &serveraddr, sizeof(serveraddr));
        serveraddr.sin_family = AF_INET; 
        serveraddr.sin_addr.s_addr = htonl(INADDR_ANY); 
        serveraddr.sin_port = htons((unsigned short)port); 
        if (bind(listenfd, (SA *)&serveraddr, sizeof(serveraddr)) < 0)
        return -1;
    
        /* Make it a listening socket ready to accept connection requests */
        if (listen(listenfd, LISTENQ) < 0)
        return -1;
        return listenfd;
    }
    /* $end open_listenfd */
    So my understanding is that open_listenfd merely opens/create a listening socket. Please let me know what might be preventing me from doing so (do I need to create my own listen socket code or if I need to use a specific port?). I just want to see how a HTTP server works and then determine how to create an HTTP GET request for a video file. Also please feel free to direct me to any resources that might help me accomplishing this endeavor.

    Thanks!

  2. #2
    a_capitalist_story
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    Ports < 1024 are privileged, so if you're listening on one of those, you must start the application as a privileged user, like root.

  3. #3
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    Quote Originally Posted by rags_to_riches View Post
    Ports < 1024 are privileged, so if you're listening on one of those, you must start the application as a privileged user, like root.
    Ah thanks for pointing that out. I will use ports > 1024 then. Getting past the error, I tried running the code and confirmed through telnet that I am able to establish connection. Now I am trying to see how I can create an HTTP GET request in C. Now to request a file is it simply creating and sending a string similar to below to request for the file on the server?

    GET /filename HTTP/1.0

  4. #4
    Stoned Witch Barney McGrew's Avatar
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    Quote Originally Posted by ytakeru12 View Post
    Also please feel free to direct me to any resources that might help me accomplishing this endeavor.
    Beej's Guide to Network Programming

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