How to get the IP Address of a LINUX machine programmatically

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dode
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How to get the IP Address of a LINUX machine programmatically

Post by dode » Tue May 31, 2016 7:04 pm

Code: Select all

#include <wx/wfstream.h>
#include <wx/txtstrm.h>
#include <wx/tokenzr.h>

// Lambda get IP Address
auto getIPAddress = [&]()
{
    // Locate first device ...
    uint iLineCount = 0;
    wxString deviceName = wxEmptyString;
    wxFileInputStream input(wxT("/proc/net/route"));
    wxTextInputStream text(input, wxT("\x09"), wxConvUTF8);
    while(input.IsOk() && !input.Eof())
    {
        wxString line = text.ReadLine();
        if(iLineCount++)
        {
            wxStringTokenizer tokenizer(line, wxDEFAULT_DELIMITERS);
            while(tokenizer.HasMoreTokens())
            {
                deviceName = tokenizer.GetNextToken();
                break;
            }
        }

        if(!deviceName.IsEmpty())
            break;
    }

    // Run ifconfig on device
    wxString ipAddress = wxEmptyString;
    wxArrayString output, errors;
    wxExecute(wxT("ifconfig ") + deviceName, output, errors);
    if(!output.IsEmpty() && errors.isEmpty())
    {
        wxString ipLine = output.Item(1);
        ipAddress = ipLine.SubString(ipLine.Find(wxT(":")) + 1, ipLine.Find(wxT("Bcast:")) - 2);
    }
    return ipAddress;
};

DavidHart
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Re: How to get the IP Address of a LINUX machine programmatically

Post by DavidHart » Wed Jun 01, 2016 11:56 am

Hi,

I tested this. First, in the line:
if(!output.IsEmpty() && errors.isEmpty())
the isEmpty needs an initial I, not i.

It then failed to give an output. I'm using debian as non-root, so /sbin/ isn't in my $PATH. It worked if I hard-coded /sbin/ifconfig.

However that gave the expected result: 192:168:0:2, which is the local IP address of this machine. Was that your intention? I suspect most people reading the topic title will have been expecting to see the IP address supplied by their ISP. AFAIK it's not possible to obtain that without looking outside the box.

Regards,

David

dode
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Re: How to get the IP Address of a LINUX machine programmatically

Post by dode » Wed Jun 01, 2016 2:17 pm

Yes that was the general Idea.
I used that with lUbuntu, and opensuse and the result was ok ...

Regards
Dode

DavidHart
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Re: How to get the IP Address of a LINUX machine programmatically

Post by DavidHart » Wed Jun 01, 2016 3:59 pm

Yes that was the general Idea.
Which? To get the local address? If so, I suggest you alter the topic's title to say that.
I used that with lUbuntu, and opensuse and the result was ok ...
It is for me with ubuntu too, but in openSUSE 42.1 typing 'ifconfig' in a terminal gives:
Absolute path to ifconfig is /sbin/ifconfig, so running it may require superuser privileges (eg. root).
Typing /sbin/ifconfig worked OK though.

Perhaps your code should check if /sbin/ is in the $PATH and, If not, use the filepath rather than the filename. Or, better, always use /sbin/ifconfig if it exists.

dode
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Re: How to get the IP Address of a LINUX machine programmatically

Post by dode » Wed Jun 01, 2016 5:32 pm

Ok,

Here is the corrected Version

Code: Select all

// Lambda get IP Address
auto getIPAddress = [&]()
{
    // Locate first device ...
    uint iLineCount = 0;
    wxString deviceName = wxEmptyString;
    wxFileInputStream input(wxT("/proc/net/route"));
    wxTextInputStream text(input, wxT("\x09"), wxConvUTF8);
    while(input.IsOk() && !input.Eof())
    {
        wxString line = text.ReadLine();
        if(iLineCount++)
        {
            wxStringTokenizer tokenizer(line, wxDEFAULT_DELIMITERS);
            while(tokenizer.HasMoreTokens())
            {
                deviceName = tokenizer.GetNextToken();
                break;
            }
        }

        if(!deviceName.IsEmpty())
            break;
    }

    // Run ifconfig on device
    wxString ipAddress = wxEmptyString;
    wxArrayString output, errors;
    if(!deviceName.IsEmpty())
        wxExecute(wxT("/sbin/ifconfig ") + deviceName, output, errors);
    if(!output.IsEmpty() && errors.IsEmpty())
    {
        wxString ipLine = output.Item(1);
        ipAddress = ipLine.SubString(ipLine.Find(wxT(":")) + 1, ipLine.Find(wxT("Bcast:")) - 2);
    }
    return ipAddress;
};

dode
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Re: How to get the IP Address of a LINUX machine programmatically

Post by dode » Wed Jun 01, 2016 5:46 pm

Under lUbuntu

env | grep sbin

shows PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
(default installation no manual additon to the PATH ...)

Regards,
Dode

iwbnwif
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Re: How to get the IP Address of a LINUX machine programmatically

Post by iwbnwif » Wed Jun 01, 2016 8:51 pm

Out of interest, did you try the suggestions on this page:

https://wiki.wxwidgets.org/Getting_IP_Address_Of_Host

I just did and they both work on Ubuntu 14.04. The link on the bottom of the Wiki page points to code that appears to do exactly what you want?

Maybe its also worth looking at getifaddrs?
wxWidgets 3.1.2, MinGW64 8.1.0, g++ 8.1.0, Ubuntu 19.04, Windows 10, CodeLite + wxCrafter
Some people, when confronted with a GUI problem, think "I know, I'll use Eclipse RCP". Now they have two problems.

dode
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Re: How to get the IP Address of a LINUX machine programmatically

Post by dode » Thu Jun 02, 2016 7:25 am

Following:

Code: Select all

wxIPV4address addr;
addr.Hostname(wxGetFullHostName());
wxString ipAddr = addr.IPAddress();
Under lUbuntu 16.04 returns "0.0.0.0"

as for the :

Code: Select all

 wxIPV4address remote;
 remote.Hostname(_T("www.wxwidgets.org"));
 remote.Service(80);
 
 wxIPV4address local;
 
 wxSocketClient client;
 if(client.Connect(remote)) client.GetLocal(local);
 
 wxString ipAddr=local.IPAddress();
might be ok (although never tried ) but i need that to work also in a closed environment where only LAN exists ...

Regards
Dode.

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