Beej's Guide to Network Programming - The Diigo Meta page

• 23 May 09
  

  PoSheng Hsu

  networking

• 29 Apr 09
  

  Isk Aldur

  todo network-programming

• 

  trasck :)

  programming

• 

  Joel Liu

  network programming

• 

  Ankit Mishra

  Networking

• 

  Damon Snyder

  programing networking network

• 09 Nov 08
  

  Henrik Akselsen
  • You'll see that the ai_addr field in the struct
    addrinfo is a pointer to a struct sockaddr. This is where we start getting
    into the nitty-gritty details of what's inside an IP address
    structure.
  • oftentimes,
    a call to getaddrinfo() to fill out your struct
    addrinfo for you is all you'll need. You will,
    however, have to peer inside these structs to get the
    values out, so I'm presenting them here.
  • 27 more annotations...
  • • So if you have declared
      ina to be of type struct sockaddr_in, then
      ina.sin_addr.s_addr references the 4-byte IP address (in
      Network Byte Order).
    • destination address
    • And this is the important bit: a pointer to a struct
      sockaddr_in can be cast to a pointer to a struct
      sockaddr and vice-versa. So even though connect()
      wants a struct sockaddr*, you can still use a struct
      sockaddr_in and cast it at the last minute!
    • sin_port must be
      in Network Byte Order (by using htons()
    • struct
      sockaddr_storage that is designed
      to be large enough to hold both IPv4 and IPv6 structures.
    • What's important is that you can see the address family in the
      ss_family field—check this to see if it's
      AF_INET or AF_INET6 (for IPv4 or
      IPv6). Then you can cast it to a struct sockaddr_in or
      struct sockaddr_in6 if you wanna.
    • bunch of functions that allow you to
      manipulate IP addresses.
    • inet_pton(), converts an IP address in numbers-and-dots
      notation into either a struct in_addr or a struct
      in6_addr
    • inet_ntop()
    • try to use getaddrinfo() to get all the
      struct sockaddr info, instead of packing the structures by
      hand.
    • The place most people get stuck around here is what order to call
      these things in.
    • getaddrinfo()
    • It helps set up the
      structs you need later on.

    • You give this function three input parameters, and it gives you a
      pointer to a linked-list, res, of results.

      
      
      

    • The node parameter is the host name to connect to, or
      an IP address.
    • Next is the parameter service, which can be a port
      number, like "80", or the name of a particular service
    • Finally, the hints parameter points to a struct
      addrinfo that you've already filled out with relevant
      information.
    • getaddrinfo(NULL, "3490", &hints, &servinfo)
    • servinfo now points to a linked list of 1 or more struct addrinfos
    • Also, you'll see the AI_PASSIVE flag in there; this
      tells getaddrinfo() to assign the address of my local host
      to the socket structures. This is nice because then you don't have to
      hardcode it.
    • getaddrinfo(argv[1], NULL, &hints, &res
    • What you really want to do is use the values
      from the results of the call to getaddrinfo(), and feed
      them into socket() directly like this
    • (This
      is commonly done if you're going to listen() for incoming connections on a
      specific port
    • Once you have a socket, you might have to associate
      that socket with a port on your local machine
    • The port number is used by
      the kernel to match an incoming packet to a certain process's socket
      descriptor.
    • If you're going to only be doing a connect() (because you're the client, not
      the server), this is probably be unnecessary.
    • bind(sockfd, res->ai_addr, res->ai_addrlen);
• 13 Feb 08
  

  WittyGuy

  interview network programming

• 24 Jan 08
  

  wawilson

  c programming

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