在Linux上使用C语言编程获取IPv4地址及子网掩码

在Linux上(如Ubuntu或CentOS), 获取某个Network Interface比如eth0的IP地址等信息，我们可以使用ifconfig或者ip addr show命令。

$ ifconfig eth0
eth0      Link encap:Ethernet  HWaddr :::ba:8d:be
          inet addr:192.168.1.102  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80:::64ff:feba:8dbe/ Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:  Metric:
          RX packets: errors: dropped: overruns: frame:
          TX packets: errors: dropped: overruns: carrier:
          collisions: txqueuelen:
          RX bytes: (29.1 MB)  TX bytes: (4.0 MB)
          Interrupt:
 
$ ip addr show eth0
: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu  qdisc mq state UP group default qlen
    link/ether :::ba:8d:be brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.102/ brd 192.168.1.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80:::64ff:feba:8dbe/ scope link
       valid_lft forever preferred_lft forever

那么用C语言编程怎么实现呢？先用strace工具观察一下ifconfig eth0的运行内幕。

$ strace ifconfig eth0
execve("/sbin/ifconfig", ["ifconfig", "eth0"], [/* 71 vars */]) = 0
brk(0)                                  = 0x9565000
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
mmap2(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb76fe000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=114965, ...}) = 0
mmap2(NULL, 114965, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb76e1000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/i386-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0P\234\1\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=1763068, ...}) = 0
mmap2(NULL, 1772156, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7530000
mmap2(0xb76db000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1aa000) = 0xb76db000
mmap2(0xb76de000, 10876, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb76de000
close(3)                                = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb752f000
set_thread_area({entry_number:-1 -> 6, base_addr:0xb752f940, limit:1048575, seg_32bit:1, contents:0, read_exec_only:0, limit_in_pages:1, seg_not_present:0, useable:1}) = 0
mprotect(0xb76db000, 8192, PROT_READ)   = 0
mprotect(0x8058000, 4096, PROT_READ)    = 0
mprotect(0xb7724000, 4096, PROT_READ)   = 0
munmap(0xb76e1000, 114965)              = 0
brk(0)                                  = 0x9565000
brk(0x9586000)                          = 0x9586000
open("/usr/lib/locale/locale-archive", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=8752496, ...}) = 0
mmap2(NULL, 2097152, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb732f000
mmap2(NULL, 4096, PROT_READ, MAP_PRIVATE, 3, 0x855000) = 0xb76fd000
close(3)                                = 0
uname({sys="Linux", node="idorax", ...}) = 0
access("/proc/net", R_OK)               = 0
access("/proc/net/unix", R_OK)          = 0
socket(PF_LOCAL, SOCK_DGRAM, 0)         = 3
socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 4
access("/proc/net/if_inet6", R_OK)      = 0
socket(PF_INET6, SOCK_DGRAM, IPPROTO_IP) = 5
access("/proc/net/ax25", R_OK)          = -1 ENOENT (No such file or directory)
access("/proc/net/nr", R_OK)            = -1 ENOENT (No such file or directory)
access("/proc/net/rose", R_OK)          = -1 ENOENT (No such file or directory)
access("/proc/net/ipx", R_OK)           = -1 ENOENT (No such file or directory)
access("/proc/net/appletalk", R_OK)     = -1 ENOENT (No such file or directory)
access("/proc/sys/net/econet", R_OK)    = -1 ENOENT (No such file or directory)
access("/proc/sys/net/ash", R_OK)       = -1 ENOENT (No such file or directory)
access("/proc/net/x25", R_OK)           = -1 ENOENT (No such file or directory)
open("/proc/net/dev", O_RDONLY)         = 6
fstat64(6, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb76fc000
read(6, "Inter-|   Receive               "..., 1024) = 447
close(6)                                = 0
munmap(0xb76fc000, 4096)                = 0
ioctl(5, SIOCGIFFLAGS, {ifr_name="eth0", ifr_flags=IFF_UP|IFF_BROADCAST|IFF_RUNNING|IFF_MULTICAST}) = 0
ioctl(5, SIOCGIFHWADDR, {ifr_name="eth0", ifr_hwaddr=00:25:64:ba:8d:be}) = 0
ioctl(5, SIOCGIFMETRIC, {ifr_name="eth0", ifr_metric=0}) = 0
ioctl(5, SIOCGIFMTU, {ifr_name="eth0", ifr_mtu=1500}) = 0
ioctl(5, SIOCGIFMAP, {ifr_name="eth0", ifr_map={mem_start=0, mem_end=0, base_addr=0, irq=16, dma=0, port=0}}) = 0
ioctl(5, SIOCGIFMAP, {ifr_name="eth0", ifr_map={mem_start=0, mem_end=0, base_addr=0, irq=16, dma=0, port=0}}) = 0
ioctl(5, SIOCGIFTXQLEN, {ifr_name="eth0", ifr_qlen=1000}) = 0
open("/usr/share/locale/locale.alias", O_RDONLY|O_CLOEXEC) = 6
fstat64(6, {st_mode=S_IFREG|0644, st_size=2570, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb76fc000
read(6, "# Locale name alias data base.\n#"..., 4096) = 2570
read(6, "", 4096)                       = 0
close(6)                                = 0
munmap(0xb76fc000, 4096)                = 0
open("/usr/share/locale/en_US/LC_MESSAGES/net-tools.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/net-tools.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en_US/LC_MESSAGES/net-tools.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale-langpack/en/LC_MESSAGES/net-tools.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
ioctl(4, SIOCGIFADDR, {ifr_name="eth0", ifr_addr={AF_INET, inet_addr("192.168.1.102")}}) = 0
ioctl(4, SIOCGIFDSTADDR, {ifr_name="eth0", ifr_dstaddr={AF_INET, inet_addr("192.168.1.102")}}) = 0
ioctl(4, SIOCGIFBRDADDR, {ifr_name="eth0", ifr_broadaddr={AF_INET, inet_addr("192.168.1.255")}}) = 0
ioctl(4, SIOCGIFNETMASK, {ifr_name="eth0", ifr_netmask={AF_INET, inet_addr("255.255.255.0")}}) = 0
fstat64(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 6), ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb76fc000
write(1, "eth0      Link encap:Ethernet  H"..., 58eth0      Link encap:Ethernet  HWaddr 00:25:64:ba:8d:be
) = 58
write(1, "          inet addr:192.168.1.10"..., 75          inet addr:192.168.1.102  Bcast:192.168.1.255  Mask:255.255.255.0
) = 75
open("/proc/net/if_inet6", O_RDONLY)    = 6
fstat64(6, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb76fb000
read(6, "00000000000000000000000000000001"..., 1024) = 108
read(6, "", 1024)                       = 0
write(1, "          inet6 addr: fe80::225:"..., 61          inet6 addr: fe80::225:64ff:feba:8dbe/64 Scope:Link
) = 61
read(6, "", 1024)                       = 0
close(6)                                = 0
munmap(0xb76fb000, 4096)                = 0
write(1, "          UP BROADCAST RUNNING M"..., 61          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
) = 61
write(1, "          RX packets:31318 error"..., 65          RX packets:31318 errors:0 dropped:0 overruns:0 frame:0
) = 65
write(1, "          TX packets:29503 error"..., 67          TX packets:29503 errors:0 dropped:0 overruns:0 carrier:0
) = 67
write(1, "          collisions:0 txqueuele"..., 40          collisions:0 txqueuelen:1000
) = 40
write(1, "          RX bytes:29127563 (29."..., 65          RX bytes:29127563 (29.1 MB)  TX bytes:4104503 (4.1 MB)
) = 65
write(1, "          Interrupt:16 \n", 24          Interrupt:16
) = 24
write(1, "\n", 1
)                       = 1
close(5)                                = 0
exit_group(0)                           = ?
+++ exited with 0 +++

注意上面的socket()和ioctl(), 我们不难发现如下关键调用，

socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 4
ioctl(4, SIOCGIFADDR, {ifr_name="eth0", ifr_addr={AF_INET, inet_addr("192.168.1.102")}}) = 0
ioctl(4, SIOCGIFNETMASK, {ifr_name="eth0", ifr_netmask={AF_INET, inet_addr("255.255.255.0")}}) = 0

好了，现在可以上C代码了，(foo_get.c)

 /**
  * get IPv4 address and subnet mask of a network interface
  */
 #include <stdio.h>
 #include <unistd.h>
 #include <string.h>
 #include <sys/socket.h>
 #include <sys/ioctl.h>
 #include <net/if.h>
 #include <arpa/inet.h>
 
 int
 main(int argc, char *argv[])
 {
         int rc = ;
         struct sockaddr_in *addr = NULL;
 
         if (argc != ) {
                 fprintf(stderr, "Usage: %s <ifname>\n", argv[]);
                 return -;
         }
 
         char *ifname = argv[];
 
         struct ifreq ifr;
         memset(&ifr, , sizeof(struct ifreq));
 
         /* 0. create a socket */
         int fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
         if (fd == -)
                 return -;
 
         /* 1. set type of address to retrieve : IPv4 */
         ifr.ifr_addr.sa_family = AF_INET;
 
         /* 2. copy interface name to ifreq structure */
         strncpy(ifr.ifr_name, ifname, IFNAMSIZ - );
 
         /* 3. get the IP address */
         if ((rc = ioctl(fd, SIOCGIFADDR, &ifr)) != )
                 goto done;
 
         char ipv4[] = {  };
         addr = (struct sockaddr_in *)&ifr.ifr_addr;
         strncpy(ipv4, inet_ntoa(addr->sin_addr), sizeof(ipv4));
 
         /* 4. get the mask */
         if ((rc = ioctl(fd, SIOCGIFNETMASK, &ifr)) != )
                 goto done;
 
         char mask[] = {  };
         addr = (struct sockaddr_in *)&ifr.ifr_addr;
         strncpy(mask, inet_ntoa(addr->sin_addr), sizeof(mask));
 
         /* 5. display */
         printf("IFNAME:IPv4:MASK\n");
         printf("%s:%s:%s\n", ifname, ipv4, mask);
 
         /* 6. close the socket */
 done:
         close(fd);
 
         return rc;
 }

编译并测试，

$ gcc -g -Wall -std=gnu99 -o foo_get foo_get.c
 
$ ./foo_get eth0
IFNAME:IPv4:MASK
eth0:192.168.1.102:255.255.255.0
 
$ ./foo_get lo
IFNAME:IPv4:MASK
lo:127.0.0.1:255.0.0.0

参考资料：

NETDEVICE(7)
INET(3)
https://stackoverflow.com/questions/6652384/how-to-set-the-ip-address-from-c-in-linux

在Linux上使用C语言编程获取IPv4地址及子网掩码的更多相关文章

linux 操作系统下c语言编程入门
2)Linux程序设计入门--进程介绍 3)Linux程序设计入门--文件操作 4)Linux程序设计入门--时间概念 5)Linux程序设计入门--信号处理 6)Linux程序设计入门--消息管理 ...
[转] linux操作系统下c语言编程入门--基础知识
点击阅读原文这篇文章介绍在LINUX下进行C语言编程所需要的基础知识.在这篇文章当中,我们将会学到以下内容: 1. 源程序编译 2. Makefile的编写 3. 程序库 ...
linux下的c语言编程学习笔记
视频参看csdn学院王阳和下面的linux环境下c语言编程基础相当的经典,其中王阳的视频讲的很好,相当的经典编译hellogcc.c需要依赖/home目录下的头文件为了避免同一个文件被includ ...
Linux下的C语言编程
一.在Linux下的C语言编程所需工具(下面所列举的都是我编程所用的工具) 1.文本编辑器 Vim 2.编译链接工具 gcc 3.调试器 gdb 4.项目管理工具 make和makefile 二.VI ...
Linux下的C Socket编程 -- 获取对方IP地址
Linux下的C Socket编程(二) 获取域名对应的IP地址经过上面的讨论,如果我们想要连接到远程的服务器,我们需要知道对方的IP地址,系统函数gethostbyname便能够实现这个目的.它能 ...
windows下C语言编程获取磁盘(分区)使用情况
windows下编程获取磁盘(分区)使用情况 windows下编程获取磁盘(分区)使用情况 GetLogicalDriveStrings函数使用示例获取需要的缓冲区长度示例获取所有驱动器号示例 ...
实验四 Linux系统搭建C语言编程环境
项目内容这个作业属于那个课程 <班级课程的主页链接> 这个作业的要求在哪里 <作业要求链接地址> 学号-姓名 17043220-万文文作业学习目标 1).Linux系统下 ...
Centos7（Linux）网络配置，自动获取ip地址
Centos7.0 Vmware 网络桥接配置,利用DHCP自动获取ip地址首先要将Vmware10.0.3设置为桥接模式. CentOS 7.0默认安装好之后是没有自动开启网络连接的! cd / ...
Hadoop 上使用C 语言编程【转】
转自:https://www.linuxidc.com/Linux/2012-04/58991.htm 今天尝试用C语言在Hadoop上编写统计单词的程序,具体过程如下: 一.编写map和reduce ...

随机推荐

[转发]RTH试用手记之“外场应用”
年初,罗德与施瓦茨公司(Rohde & Schwarz)推出了第一款的手持示波器,从指标上看,该示波器打破了传统手持器功能简单.指标水平低.结构粗糙的印象,取而代之达到了主流台式数字示波器的性 ...
makefile文件。批处理文件。
makefile文件: NAME=XXX #要编译的文件名 OBJS=$(NAME).obj #指定输出的目标文件名 ML_FLAG=/C /COF ...
C#集合总结
1.为什么引入集合? 因为数组长度是固定的,为了建立一个动态的"数组",所以引入了集合. 2.为什么引入ArrayList 非泛型集合? ArrayList可以填补数组的不足,进行 ...
java invoke(转摘)
JAVA反射机制是在运行状态中,对于任意一个类,都能够知道这个类的所有属性和方法:对于任意一个对象,都能够调用它的任意一个方法:这种动态获取的以及动态调用对象的方法的功能称为java语言的反射机制 ...
Message Loop 原理及应用
此文已由作者王荣涛授权网易云社区发布. 欢迎访问网易云社区,了解更多网易技术产品运营经验. Message loop,即消息循环,在不同系统或者机制下叫法也不尽相同,有被叫做event loop,也有 ...
2018-2019-2 20165219《网络对抗技术》Exp4 恶意代码分析
基础问题回答实验目的监控系统的运行状态,看有没有可疑的程序在运行分析一个恶意软件,就分析Exp2或Exp3中生成后门软件:分析工具尽量使用原生指令或sysinternals,systracer套 ...
小A的旅行（绿豆蛙的归宿）【期望ＤＰ】
Description 给出一个有向无环的连通图,起点为1,终点为N,每条边都有一个长度.小A从起点出发,走向终点.到达每一个顶点时,如果有K条离开该点的道路,小A可以选择任意一条道路离开该点,并且走 ...
[CSS3] 二级下拉导航
<!DOCTYPE html> <html lang="zh-cn"> <head> <meta charset="utf-8& ...
[Objective-C语言教程]数据封装（27）
所有Objective-C程序都由以下两个基本要素组成 - 程序语句(代码) - 这是执行操作的程序的一部分,它们被称为方法(函数). 程序数据 - 数据是受程序功能影响的程序信息. 封装是一种面向对 ...
关闭tomcat端口号
一. CentOS 关闭tomcat端口号 1. 首先保证liunx下 ps -ef | grep java 2. 会显示如下信息我使用的是IDEA打包的war包.tomcat是自带的 3. 查看未 ...

在Linux上使用C语言编程获取IPv4地址及子网掩码

在Linux上使用C语言编程获取IPv4地址及子网掩码的更多相关文章

随机推荐

热门专题