Thread: getaddrinfo : who is right?

  1. #1
    Registered User
    Join Date
    Dec 2010

    getaddrinfo : who is right?

    My man says that both
    The gethostbyname*() and gethostbyaddr*() functions are obsolete.
    So i decided to change them to getaddrinfo. So i tried to run

    l_error=getaddrinfo(host, NULL, NULL, ServerSocketAddresses);
    where host="" and
    static struct addrinfo **ServerSocketAddresses=NULL;
    Program crushes:
    Breakpoint 1, set_server_info (host=0x7fffffffe38e "", port=80, addr_len=0x7fffffffdf1c) at socket_ip_client.c:38
    38 l_error=getaddrinfo(host, NULL, NULL, ServerSocketAddresses);
    (gdb) p host
    $1 = 0x7fffffffe38e ""
    (gdb) n

    Program received signal SIGSEGV, Segmentation fault.
    0x00007ffff7ae9d1a in getaddrinfo () from /lib/x86_64-linux-gnu/
    From documentation it seems that every parameter under rule and memory for ServerSocketAddresses supposed to be allocated inside call (that's why we have freeaddrinfo for later...)
    Am i doing smth wrong or glibc does so?

  2. #2
    Registered User
    Join Date
    Sep 2007
    getaddrinfo() will point a struct addrinfo* to the head of a linked list of results. As such, it needs a pointer to that pointer so it can modify it (in exactly the same way that you must pass an int* to a function that is meant to modify the int).

    What you're doing is passing a null pointer instead of the address of a struct addrinfo*. What you want is something like:
    struct addrinfo *res;
    getaddrinfo(host, NULL, NULL, &res);
    Now res points to the head of the list (or is NULL if the lookup was unsuccessful).

  3. #3
    Registered User
    Join Date
    Dec 2010
    yep, thanks, found it too.

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