[c] How do I find the current machine's full hostname in C (hostname and domain information)?

In a C project (POSIX), how do I get the fully qualified name for the current system?

For example, I can get just the hostname of my machine by doing gethostname() from unistd.h. This might give me machine3 in return, but I'm actually looking for machine3.somedomain.com for example.

How do I go about getting this information? I do not want to use a call to system() to do this, if possible.

My solution:

#ifdef WIN32
    #include <Windows.h>
    #include <tchar.h>
#else
    #include <unistd.h>
#endif

void GetMachineName(char machineName[150])
{
    char Name[150];
    int i=0;

    #ifdef WIN32
        TCHAR infoBuf[150];
        DWORD bufCharCount = 150;
        memset(Name, 0, 150);
        if( GetComputerName( infoBuf, &bufCharCount ) )
        {
            for(i=0; i<150; i++)
            {
                Name[i] = infoBuf[i];
            }
        }
        else
        {
            strcpy(Name, "Unknown_Host_Name");
        }
    #else
        memset(Name, 0, 150);
        gethostname(Name, 150);
    #endif
    strncpy(machineName,Name, 150);
}

The easy way, try uname()

If that does not work, use gethostname() then gethostbyname() and finally gethostbyaddr()

The h_name of hostent{} should be your FQDN

I believe you are looking for:

gethostbyaddress

Just pass it the localhost IP.

There is also a gethostbyname function, that is also usefull.

gethostname() is POSIX way to get local host name. Check out man.

BSD function getdomainname() can give you domain name so you can build fully qualified hostname. There is no POSIX way to get a domain I'm afraid.

I believe you are looking for:

gethostbyaddress

Just pass it the localhost IP.

There is also a gethostbyname function, that is also usefull.

My solution:

#ifdef WIN32
    #include <Windows.h>
    #include <tchar.h>
#else
    #include <unistd.h>
#endif

void GetMachineName(char machineName[150])
{
    char Name[150];
    int i=0;

    #ifdef WIN32
        TCHAR infoBuf[150];
        DWORD bufCharCount = 150;
        memset(Name, 0, 150);
        if( GetComputerName( infoBuf, &bufCharCount ) )
        {
            for(i=0; i<150; i++)
            {
                Name[i] = infoBuf[i];
            }
        }
        else
        {
            strcpy(Name, "Unknown_Host_Name");
        }
    #else
        memset(Name, 0, 150);
        gethostname(Name, 150);
    #endif
    strncpy(machineName,Name, 150);
}

gethostname() is POSIX way to get local host name. Check out man.

BSD function getdomainname() can give you domain name so you can build fully qualified hostname. There is no POSIX way to get a domain I'm afraid.

I believe you are looking for:

gethostbyaddress

Just pass it the localhost IP.

There is also a gethostbyname function, that is also usefull.

gethostname() is POSIX way to get local host name. Check out man.

BSD function getdomainname() can give you domain name so you can build fully qualified hostname. There is no POSIX way to get a domain I'm afraid.

I believe you are looking for:

gethostbyaddress

Just pass it the localhost IP.

There is also a gethostbyname function, that is also usefull.

The easy way, try uname()

If that does not work, use gethostname() then gethostbyname() and finally gethostbyaddr()

The h_name of hostent{} should be your FQDN

gethostname() is POSIX way to get local host name. Check out man.

BSD function getdomainname() can give you domain name so you can build fully qualified hostname. There is no POSIX way to get a domain I'm afraid.