linux c 检测网络状态

转自：http://stackoverflow.com/questions/808560/how-to-detect-the-physical-connected-state-of-a-network-cable-connector

You want to look at the nodes in

/sys/class/net/

I experimented with mine:

Wire Plugged in:

eth0/carrier:1
eth0/operstate:unknown

Wire Removed:

eth0/carrier:0
eth0/operstate:down

Wire Plugged in Again:

eth0/operstate:up
eth0/carrier:1

GTK 程序 检测 网线是否连接 本地网络状态 C语言实现

 转自：http://blog.csdn.net/a954423389/article/details/7327950

主程序创建一个进程, 每2秒查看一下网络状态,然后打印输出

         通过检查文件

        /sys/class/net/wlan0/operstate  (无线网络)

        /sys/class/net/eth0/operstate (有线网络)

      通过检查文件的内容   判断当前网络是否连接 

       值为up的时候,是连接 值为down的时候 是断开

       

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <gtk/gtk.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>


#define WIRELESS

#ifdef WIRELESS
#define INTERNET_STATUS_FILE "/sys/class/net/wlan0/operstate"
#else
#define INTERNET_STATUS_FILE "/sys/class/net/eth0/operstate"
#endif

#include <sys/wait.h>

static GtkWidget *fixed;
static GtkWidget *button1;
static GtkWidget *button2;
int running = 1;



void ring()
{
    GtkWidget *window;
    GtkWidget *table;
    GtkWidget *button_cancel;
    GtkWidget *label;

    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_default_size (GTK_WINDOW(window),100,100);
    gtk_window_set_position (GTK_WINDOW(window),GTK_WIN_POS_CENTER_ALWAYS);
    table = gtk_table_new(10,10,TRUE);
    gtk_container_add (GTK_CONTAINER (window),table);
    label = gtk_label_new("ring");
    button_cancel = gtk_button_new_with_label ("quit");
    gtk_table_attach_defaults (GTK_TABLE(table),button_cancel,2,4,7,9);


    gtk_widget_show_all(window);


}


void www_connect_check_real ()
{
    int ret = -2;
    while (1)
    {
        //一定要只读模式打开,读写模式打开不可以
        ret = open ("/sys/class/net/wlan0/operstate",O_RDONLY);

        if (ret<0) {
        printf("open file operstate failure%d
",ret);
        return;
        }
        char status[3]="wl";
        //printf("%s",status);
        read (ret,status,2);
        status[3] = '';
        if (0== strcmp("up",status))
        {
            printf("on line now 
");
        }
        else if (0== strcmp("do",status))
        {
            printf("off off 
");
        }
        else
        printf("unknow error
");
        close (ret);

        sleep (5);
    }

}






int main(int argc,char* argv[])
{
    GtkWidget *window,*view;
    GtkWidget *vbox,*button,*label;


    /*线程初始化*/
    if (!g_thread_supported())
    g_thread_init(NULL);

    gdk_threads_init();






    gtk_init(&argc,&argv);
    window=gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_title(GTK_WINDOW(window),"thread apllication");



    vbox=gtk_vbox_new(FALSE,0);
    gtk_container_add(GTK_CONTAINER(window),vbox);

    label=gtk_label_new("Notice! Button is moving");
    gtk_box_pack_start(GTK_BOX(vbox),label,FALSE,FALSE,0);
    view=gtk_viewport_new(NULL,NULL);
    gtk_box_pack_start(GTK_BOX(vbox),view,FALSE,FALSE,0);
    fixed=gtk_fixed_new();
    gtk_widget_set_usize(fixed,330,330);
    gtk_container_add(GTK_CONTAINER(view),fixed);
    button1=gtk_button_new_with_label("1");
    button2=gtk_button_new_with_label("2");
    gtk_fixed_put(GTK_FIXED(fixed),button1,10,10);
    gtk_fixed_put(GTK_FIXED(fixed),button2,40,40);


    GtkWidget *button_ring = gtk_button_new_with_label ("ring");
    gtk_box_pack_start(GTK_BOX(vbox),button_ring,FALSE,FALSE,5);
    g_signal_connect (button_ring,"clicked",G_CALLBACK(ring),NULL);

    /*创建线程*/
    g_thread_create((GThreadFunc)www_connect_check_real,NULL,FALSE,NULL);




    gtk_widget_show_all(window);
    g_signal_connect(G_OBJECT(window),"delete_event",G_CALLBACK(gtk_main_quit),NULL);
    gtk_container_set_border_width(GTK_CONTAINER(window),10);
    gdk_threads_enter();
    gtk_main();
    gdk_threads_leave();




    return FALSE;
}

 注意:

          1,ubuntu 10.04上,当使用静态IP的时候,即使 连接着网络, 文件的值也不up 而是unknown, 这是驱动上的bug,ubuntu 11.10上就正常

 http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/5.7_Technical_Notes/kernel.html

          2,相关链接

 http://stackoverflow.com/questions/808560/how-to-detect-the-physical-connected-state-of-a-network-cable-connector

http://www.linuxforums.org/forum/programming-scripting/142431-how-write-program-c-detect-ethernet-cable.html

           3,也可以使用shell脚本来检测,网上例子很多

           4,也可以编写一个内核模块来检测,后期再说,先找工作

http://stackoverflow.com/questions/7225888/how-can-i-monitor-the-nic-statusup-down-in-a-c-program-without-polling-the-ker

           5,

 [cpp] view plain copy

 

//RFC 2863操作状态
unsigned char       operstate;
/* operstate的可能取值如下：
enum {
    IF_OPER_UNKNOWN,
    IF_OPER_NOTPRESENT,
    IF_OPER_DOWN,
    IF_OPER_LOWERLAYERDOWN,
    IF_OPER_TESTING,
    IF_OPER_DORMANT,
    IF_OPER_UP,
};
 **/
//映射到RFC2863兼容状态的策略
unsigned char       link_mode;
/* link_mode的可能取值如下：
enum {
    IF_LINK_MODE_DEFAULT,
    IF_LINK_MODE_DORMANT,
};
 **/

我们检测的文件内容,其实是这个成员变变量的值,返回值比较多,程序中只是判断了前两个字符

http://blog.csdn.net/npy_lp/article/details/7056903

linux c 检测网络状态

转自：https://blog.csdn.net/linqiongjun86/article/details/48393807

获取wifi网络状态

#include <string.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <sys/types.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>


void connect_check_real ()  
{  
        int ret;  
    int fp;
    char status[10];  
        //一定要只读模式打开,读写模式打开不可以  
    ///sys/class/net/wlan0/carrier  0:down 1:up 
        fp = open ("/sys/class/net/wlan0/operstate",O_RDONLY);  
  
        if (fp<0) {  
        printf("open file operstate failure%d ",fp);  
        return;  
        }  
        
    memset(status,0,sizeof(status));
        ret = read (fp,status,10);   
    printf("status:%s ",status);
        if (NULL != strstr(status,"up"))  
        {  
            printf("on line now ");  
        }  
        else if (NULL != strstr(status,"down"))  
        {  
            printf("off off ");  
        }  
        else   
        printf("unknow error ");  
        close (fp);      
}