诚石

Linux下面的socket编程,如何获得本机IP地址                                      

代码:
#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>

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

        inet_sock = socket(AF_INET, SOCK_DGRAM, 0);
        strcpy(ifr.ifr_name, "eth0");
        if (ioctl(inet_sock, SIOCGIFADDR, &ifr) < 0)
                perror("ioctl");
        printf("%s\n", inet_ntoa(((struct sockaddr_in*)&(ifr.ifr_addr))->sin_addr));

        return 0;
}

Illidan     05-10-31 16:21
如果网卡不止一块，还可以用ioctl还做吗？
怎么知道网卡的数量呢？

小锁     05-10-31 18:38
代码:
#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>

int main()
{
        int inet_sock;
        struct ifreq ifr;
        FILE *net_devs;
        char buf[1024];
        char interface[32];

        net_devs = fopen("/proc/net/dev", "r");
        if(net_devs == NULL){
                perror("Can't open /proc/net/dev for reading");
                exit(1);
        }

        inet_sock = socket(AF_INET, SOCK_DGRAM, 0);
        while(1){
                if(fscanf(net_devs, "%32s %1024[^\n]", interface, buf) <= 0){
                        break;
                }
                if(interface[strlen(interface) - 1] != ':'){
                        continue; // skip the comment
                }else{
                        interface[strlen(interface) - 1] = '#CONTENT#';
                }
                strcpy(ifr.ifr_name, interface);
                if (ioctl(inet_sock, SIOCGIFADDR, &ifr) < 0)
                        perror("ioctl");
                printf("%s:%s\n", interface,
                                inet_ntoa(((struct sockaddr_in*)&(ifr.ifr_addr))->sin_addr));
        }
        close(inet_sock);

        return 0;
}

Illidan     05-11-01 15:42

试改如下，好像可以得到需要的结果：
代码:
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <arpa/inet.h>

int main()
{
        int inet_sock;
        struct ifreq ifr;
        FILE *net_devs;
        char buf[1024];
        char interface[32];
        int index;

        net_devs = fopen("/proc/net/dev", "r");
        if(net_devs == NULL){
                perror("Can't open /proc/net/dev for reading");
                exit(1);
        }

        inet_sock = socket(AF_INET, SOCK_DGRAM, 0);
        while(1){
                if(fscanf(net_devs, "%32s %1024[^\n]", interface, buf) <= 0){
                        break;
                }
                index = 0;
                while ( index<32 && interface[index] != ':' ) {
                        index++;
                }
                if (index>=32)
                        continue;
                interface[index] = '#CONTENT#';
                strcpy(ifr.ifr_name, interface);
                if (ioctl(inet_sock, SIOCGIFADDR, &ifr) < 0)
                        perror("ioctl");
                printf("%s:\t%s\n", interface,
                                inet_ntoa(((struct sockaddr_in*)&(ifr.ifr_addr))->sin_addr));
        }
        close(inet_sock);

        return 0;
}