获取 Linux 上接口的 IP 地址

小开

最佳答案

试试这个:

#include <stdio.h>
#include <unistd.h>
#include <string.h> /* for strncpy */


#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <net/if.h>
#include <arpa/inet.h>


int
main()
{
int fd;
struct ifreq ifr;


fd = socket(AF_INET, SOCK_DGRAM, 0);


/* I want to get an IPv4 IP address */
ifr.ifr_addr.sa_family = AF_INET;


/* I want IP address attached to "eth0" */
strncpy(ifr.ifr_name, "eth0", IFNAMSIZ-1);


ioctl(fd, SIOCGIFADDR, &ifr);


close(fd);


/* display result */
printf("%s\n", inet_ntoa(((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr));


return 0;
}

代码示例取自给你。

小开

除了 Filip 演示的 ioctl ()方法之外，您还可以使用 ()。在手册页的底部有一个示例程序。

小开

如果您正在查找特定接口的地址(IPv4) ，请输入 Wlan0 请尝试使用 ()的代码:

#include <arpa/inet.h>
#include <sys/socket.h>
#include <netdb.h>
#include <ifaddrs.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
int main(int argc, char *argv[])
{
struct ifaddrs *ifaddr, *ifa;
int family, s;
char host[NI_MAXHOST];


if (getifaddrs(&ifaddr) == -1)
{
perror("getifaddrs");
exit(EXIT_FAILURE);
}




for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next)
{
if (ifa->ifa_addr == NULL)
continue;


s=getnameinfo(ifa->ifa_addr,sizeof(struct sockaddr_in),host, NI_MAXHOST, NULL, 0, NI_NUMERICHOST);


if((strcmp(ifa->ifa_name,"wlan0")==0)&&(ifa->ifa_addr->sa_family==AF_INET))
{
if (s != 0)
{
printf("getnameinfo() failed: %s\n", gai_strerror(s));
exit(EXIT_FAILURE);
}
printf("\tInterface : <%s>\n",ifa->ifa_name );
printf("\t  Address : <%s>\n", host);
}
}


freeifaddrs(ifaddr);
exit(EXIT_SUCCESS);
}

您可以将 Wlan0替换为用于以太网的乙醇和用于本地环回的瞧。

数据结构的结构和详细说明可以找到给你。

要了解更多关于 C 语言中的链表，这个呼叫将是一个很好的起点。

小开

我的建议是: 同样的代码即使在 iOS 上也可以工作:

#include <arpa/inet.h>
#include <sys/socket.h>
#include <netdb.h>
#include <ifaddrs.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>






#import "ViewController.h"


@interface ViewController ()


@end


@implementation ViewController


- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
showIP();
}






void showIP()
{
struct ifaddrs *ifaddr, *ifa;
int family, s;
char host[NI_MAXHOST];


if (getifaddrs(&ifaddr) == -1)
{
perror("getifaddrs");
exit(EXIT_FAILURE);
}




for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next)
{
if (ifa->ifa_addr == NULL)
continue;


s=getnameinfo(ifa->ifa_addr,sizeof(struct sockaddr_in),host, NI_MAXHOST, NULL, 0, NI_NUMERICHOST);


if( /*(strcmp(ifa->ifa_name,"wlan0")==0)&&( */ ifa->ifa_addr->sa_family==AF_INET) // )
{
if (s != 0)
{
printf("getnameinfo() failed: %s\n", gai_strerror(s));
exit(EXIT_FAILURE);
}
printf("\tInterface : <%s>\n",ifa->ifa_name );
printf("\t  Address : <%s>\n", host);
}
}


freeifaddrs(ifaddr);
}




@end

我只是删除了针对 wlan0的测试以查看数据。你可以删除“家庭”

小开

如果不介意二进制大小，可以使用 iprote2作为库。

Iprote2-as-lib

优点:

不需要编写套接字层代码。
可以获得更多关于网络接口的信息。
简单的 API 接口。

缺点:

Iprote2-as-lib 库大小很大。 ~ 500kb。

小开

我最近也遇到过同样的问题，这是我编写的代码，它可以工作。确保使用网络接口的名称，完全与您的名称一致(可以是“ eth0”或者其他)。

必须事先检查 ifconfigcommand 是否获得接口名称并在 C 中使用它。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <unistd.h>
#include <linux/if.h>
#include <errno.h>
#include <ifaddrs.h>
#include <netinet/in.h>
#include <arpa/inet.h>
    



void extract_ipaddress()
{
//create an ifreq struct for passing data in and out of ioctl
struct ifreq my_struct;
     

//declare and define the variable containing the name of the interface
char *interface_name="enp0s3";   //a very frequent interface name is "eth0";
     

//the ifreq structure should initially contains the name of the interface to be queried. Which should be copied into the ifr_name field.
//Since this is a fixed length buffer, one should ensure that the name does not cause an overrun
size_t interface_name_len=strlen(interface_name);
     

if(interface_name_len<sizeof(my_struct.ifr_name))
{
memcpy(my_struct.ifr_name,interface_name,interface_name_len);
my_struct.ifr_name[interface_name_len]=0;
}
else
{
perror("Copy name of interface to ifreq struct");
printf("The name you provided for the interface is too long...\n");
}
     

//provide an open socket descriptor with the address family AF_INET
/* ***************************************************************
* All ioctl call needs a file descriptor to act on. In the case of SIOCGIFADDR this must refer to a socket file descriptor. This socket must be in the address family that you wish to obtain (AF_INET for IPv4)
* ***************************************************************
*/
     

int file_descriptor=socket(AF_INET, SOCK_DGRAM,0);
     

if(file_descriptor==-1)
{
perror("Socket file descriptor");
printf("The construction of the socket file descriptor was unsuccessful.\n");
return -1;
}
     

//invoke ioctl() because the socket file descriptor exists and also the struct 'ifreq' exists
int myioctl_call=ioctl(file_descriptor,SIOCGIFADDR,&my_struct);
     

if (myioctl_call==-1)
{
perror("ioctl");
printf("Ooops, error when invoking ioctl() system call.\n");
close(file_descriptor);
return -1;
}
     

close(file_descriptor);
     

/* **********************************************************************
* If this completes without error , then the hardware address of the interface should have been returned in the  'my_struct.ifr_addr' which is types as struct sockaddr_in.
* ***********************************************************************/
     

//extract the IP Address (IPv4) from the my_struct.ifr_addr which has the type 'ifreq'
     

/* *** Cast the returned address to a struct 'sockaddr_in' *** */
struct sockaddr_in * ipaddress= (struct sockaddr_in *)&my_struct.ifr_addr;
/* *** Extract the 'sin_addr' field from the data type (struct) to obtain a struct 'in_addr' *** */
printf("IP Address is %s.\n", inet_ntoa(ipaddress->sin_addr));


}

小开

我找到了一个获取 ip 的简单方法，利用 bash 命令:

hostname -I

但是使用“ hostname-I”会在屏幕上打印结果，我们需要使用“ popen ()”将结果读出并保存到一个字符串中，下面是 c 代码:

#include <stdio.h> // popen
#include "ip_common_def.h"


const char * get_ip()
{
// Read out "hostname -I" command output
FILE *fd = popen("hostname -I", "r");
if(fd == NULL) {
fprintf(stderr, "Could not open pipe.\n");
return NULL;
}
// Put output into a string (static memory)
static char buffer[IP_BUFFER_LEN];
fgets(buffer, IP_BUFFER_LEN, fd);


// Only keep the first ip.
for (int i = 0; i < IP_BUFFER_LEN; ++i)
{
if (buffer[i] == ' ')
{
buffer[i] = '\0';
break;
}
}


char *ret = malloc(strlen(buffer) + 1);
memcpy(ret, buffer, strlen(buffer));
ret[strlen(buffer)] = '\0';
printf("%s\n", ret);
return ret;
}