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;

}

github源代码

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