linux下里面如何获取网卡的实时网速

#include "tspeed.h" int get_if_dbytes(struct if_info* ndev) { assert(ndev); struct ifaddrs *ifa_list = NULL; struct ifaddrs *ifa = NULL; struct if_data *ifd = NULL; int ret = 0; ret = getifaddrs(&ifa_list); if(ret < 0) { perror("Get Interface Address Fail:"); goto end; } for(ifa=ifa_list; ifa; ifa=ifa->ifa_next){ if(!(ifa->ifa_flags & IFF_UP) && !(ifa->ifa_flags & IFF_RUNNING)) continue; if(ifa->ifa_data == 0) continue; ret = strcmp(ifa->ifa_name,ndev->ifi_name); if(ret == 0){ ifd = (struct if_data *)ifa->ifa_data; ndev->ifi_ibytes = ifd->ifi_ibytes; ndev->ifi_obytes = ifd->ifi_obytes; break; } } freeifaddrs(ifa_list); end: return (ret ? -1 : 0); } int get_if_speed(struct if_speed *ndev) { assert(ndev); struct if_info *p1=NULL,*p2=NULL; p1 = (struct if_info *)malloc(sizeof(struct if_info)); p2 = (struct if_info *)malloc(sizeof(struct if_info)); bzero(p1,sizeof(struct if_info)); bzero(p2,sizeof(struct if_info)); strncpy(p1->ifi_name,ndev->ifs_name,strlen(ndev->ifs_name)); strncpy(p2->ifi_name,ndev->ifs_name,strlen(ndev->ifs_name)); int ret = 0; ret = get_if_dbytes(p1); if(ret < 0) goto end; usleep(ndev->ifs_us); ret = get_if_dbytes(p2); if(ret < 0) goto end; ndev->ifs_ispeed = p2->ifi_ibytes - p1->ifi_ibytes; ndev->ifs_ospeed = p2->ifi_obytes - p1->ifi_obytes; end: free(p1); free(p2); return 0; }