网络编程 UDP 主机网络信息取得

1，if_nametoindex 通过网卡名字取得网卡编号

2，if_indextoname 通过网卡编号取得网卡名字

#include <stdio.h>
#include <string.h>
#include <net/if.h>
int main(){
  int index;
  char buf[128];
  //根据名字取得编号
  index = if_nametoindex("enp0s3");
  if(index == 0){
    perror("if_nametoindex");
    return 1;
  }
  printf("index:%d\n", index);
  memset(buf, 0, sizeof(buf));
  //根据编号取得名字
  if(if_indextoname(index, buf) == NULL){
    perror("if_indextoname");
    return 1;
  }
  printf("name:%s\n", buf);
  return 0;
}

github源代码

3，getifaddrs 取得网卡的名字，取得网卡的flags，取得IP地址，取得netmask

#include <stdio.h>
#include <string.h>
#include <ifaddrs.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
int main(){
  ifaddrs *ifa_list;
  ifaddrs *ifa;
  int n;
  char addrstr[256], netmaskstr[256];
  n = getifaddrs(&ifa_list);
  if(n != 0){
    return 1;
  }
  for(ifa = ifa_list; ifa != NULL; ifa = ifa->ifa_next){
    printf("ifa_name:%s\n", ifa->ifa_name);
    printf("ifa_flags:  0x%.8x\n", ifa->ifa_flags);
    memset(addrstr, 0, sizeof(addrstr));
    memset(netmaskstr, 0, sizeof(netmaskstr));
    //IPv4
    if(ifa->ifa_addr->sa_family == AF_INET){
      //IP
      inet_ntop(AF_INET,
        &((sockaddr_in*)ifa->ifa_addr)->sin_addr,
        addrstr, sizeof(addrstr));
      //mask
      inet_ntop(AF_INET,
        &((sockaddr_in*)ifa->ifa_netmask)->sin_addr,
        netmaskstr, sizeof(netmaskstr));
      printf("   IPv4: %s netmask : %s\n", addrstr, netmaskstr);
    }
    //IPv6
    else if(ifa->ifa_addr->sa_family == AF_INET6){
      //IP
      inet_ntop(AF_INET6,
        &((sockaddr_in6*)ifa->ifa_addr)->sin6_addr,
        addrstr, sizeof(addrstr));
      //mask
      inet_ntop(AF_INET6,
        &((sockaddr_in6*)ifa->ifa_netmask)->sin6_addr,
        netmaskstr, sizeof(netmaskstr));
      printf("   IPv6: %s netmask : %s\n", addrstr, netmaskstr);
    }
    else if(ifa->ifa_addr->sa_family == AF_PACKET){
      printf("  af_packet:%d\n", ifa->ifa_addr->sa_family);
    }
    else{
      printf("  else:%d\n", ifa->ifa_addr->sa_family);
    }
    printf("\n");
  }
  freeifaddrs(ifa_list);
  return 0;
}