C语言+shell 实现linux网卡状态检测和C语言实现linux网卡连接检测 2文的方法各有缺陷，比如有些系统执行ifconfig需要root权限，要不就不支持ioctl(fd, SIOCGMIIPHY, &ifr)这样的操作。以下给出了C语言实现linux网卡连接检测 的改进版实现与C语言+shell 实现linux网卡状态检测 同样的功能。

#include <stdlib.h>#include <stdio.h>#include <string.h>#include <unistd.h> #include <sys/socket.h>#include <sys/ioctl.h>#include <linux/if.h>#include <linux/mii.h>#include <linux/sockios.h>#include <errno.h> #include <ifaddrs.h>#include <arpa/inet.h> #include <linux/ethtool.h> int cshell_netlink_status(char *if_name){ char buffer[BUFSIZ]; char cmd[100]; FILE *read_fp; int chars_read; int ret =0; memset( buffer, 0, BUFSIZ ); memset( cmd, 0, 100 ); sprintf(cmd, "ifconfig -a | grep %s",if_name); read_fp = popen(cmd, "r"); if ( read_fp != NULL ) { chars_read = fread(buffer, sizeof(char), BUFSIZ-1, read_fp); pclose(read_fp); if (chars_read > 0) { ret = 1; } else { fprintf(stderr, "DEVICE_NONE\r\n"); return 0; } } if(ret == 1) { memset( buffer, 0, BUFSIZ ); memset( cmd, 0, 100 ); sprintf(cmd, "ifconfig |grep %s",if_name); read_fp = popen(cmd, "r"); if ( read_fp != NULL ) { chars_read = fread(buffer, sizeof(char), BUFSIZ-1, read_fp); pclose(read_fp); if (chars_read > 0) { ret = 2; } else { fprintf(stderr, "DEVICE_DOWN\r\n"); return 1; } } } if(ret == 2) { memset( buffer, 0, BUFSIZ ); memset( cmd, 0, 100 ); sprintf(cmd, "ifconfig %s | grep RUNNING | awk '{print $3}'",if_name); read_fp = popen(cmd, "r"); if ( read_fp != NULL ) { chars_read = fread(buffer, sizeof(char), BUFSIZ-1, read_fp); pclose(read_fp); if (chars_read > 0) { fprintf(stderr, "DEVICE_LINKED\r\n"); return 3; } else { fprintf(stderr, "DEVICE_UNPLUGGED\r\n"); return 2; } } } return -1;} int c_netlink_status(const char *if_name ){ int fd = -1; struct ifreq ifr; struct ifconf ifc; struct ifreq ifrs_buf[100]; int if_number =0; int i; if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { fprintf(stderr, "%s: socket error [%d] %s\r\n",if_name, errno, strerror(errno)); close(fd); return -1; } ifc.ifc_len = sizeof(ifrs_buf); ifc.ifc_buf = (caddr_t)ifrs_buf; if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) <0) { fprintf(stderr, "%s: ioctl SIOCGIFCONF error [%d] %s\r\n",if_name, errno, strerror(errno)); close(fd); return -1; } if_number = ifc.ifc_len / sizeof(struct ifreq); for(i=0; i< if_number; i++) { if(strcmp(if_name,ifrs_buf[i].ifr_name ) == 0) { break; } } if(i >= if_number) { close(fd); fprintf(stderr, "DEVICE_NONE\r\n"); return 0; } bzero(&ifr, sizeof(ifr)); strncpy(ifr.ifr_name, if_name, IFNAMSIZ-1); ifr.ifr_name[IFNAMSIZ-1] = 0; if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifr) <0) { fprintf(stderr, "%s: ioctl SIOCGIFFLAGS error [%d] %s\r\n",if_name, errno, strerror(errno)); close(fd); return -1; }#if 1 if(!(ifr.ifr_flags & IFF_UP)) { close(fd); fprintf(stderr, "DEVICE_DOWN\r\n"); return 1; } if(!(ifr.ifr_flags & IFF_RUNNING)) { close(fd); fprintf(stderr, "DEVICE_UNPLUGGED\r\n"); return 2 ; } fprintf(stderr, "DEVICE_LINKED\r\n"); return 3; #else{ struct ethtool_value edata; if(!(ifr.ifr_flags & IFF_UP) || !(ifr.ifr_flags & IFF_RUNNING)) { close(fd); fprintf(stderr, "%s: DOWN\r\n",if_name); return 1; } edata.cmd = ETHTOOL_GLINK; edata.data = 0; ifr.ifr_data = (char *) &edata; if(ioctl( fd, SIOCETHTOOL, &ifr ) < 0) { fprintf(stderr, "%s: ioctl SIOCETHTOOL error [%d] %s\r\n",if_name, errno, strerror(errno)); close(fd); return -1; } if(edata.data == 0) { fprintf(stderr, "DEVICE_UNPLUGGED\r\n"); return 2; } else { fprintf(stderr, "DEVICE_LINKED\r\n"); return 3; }}#endif} int main(int argc, char* argv[]){ int i=0; if(argc != 2) { fprintf(stderr, "usage: %s <ethname>\r\n", argv[0]); return -1; } i = cshell_netlink_status(argv[1]); printf( "cshell_netlink_status if_status = %d\n", i ); i = c_netlink_status(argv[1]); printf( "c_netlink_status if_status = %d\n", i ); return 0;}

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