linux - 用于多个以太网端口的多个 udp 套接字

Question

我的 Linux 运行在一个带有多以太网端口的设备上，我已经设置了每个端口，现在我的 UDP 回显服务器运行在我的 Linux 上。我已经从 packetsender 应用程序发送数据包并从同一端口接收回来。具体如下:

192.168.1.100

192.168.1.101

192.168.1.102

192.168.1.103 是 4 个以太网端口

当我将数据包发送到 192.168.1.100 并从该端口返回回声时，当我为第二个端口设置网络并将数据包发送到 192.168.1.101 时，我从 192.168.1.100 收到回声虽然它们是在 192.168.1.101 交付的，但我知道套接字被内核绑定(bind)到第一个端口，如果我想让我的多端口将每个套接字绑定(bind)到端口。要做什么？这是代码套接字的单端口绑定(bind)。我应该使用 select() 并进行相同的绑定(bind)，说明每个端口的 IP 地址吗？内核正在分配自己选择的套接字绑定(bind)。

#include <stdio.h>

int main(int argc, char **argv)
{
    printf("Hello World!\n");

    return 0;
}
*/


#include <stdio.h>      /* standard C i/o facilities */
#include <stdlib.h>     /* needed for atoi() */
#include <unistd.h>     /* defines STDIN_FILENO, system calls,etc */
#include <sys/types.h>  /* system data type definitions */
#include <sys/socket.h> /* socket specific definitions */
#include <netinet/in.h> /* INET constants and stuff */
#include <arpa/inet.h>  /* IP address conversion stuff */
#include <netdb.h>      /* gethostbyname */



/* this routine echos any messages (UDP datagrams) received */

#define MAXBUF 1024*1024

void echo( int sd ) {
    int len,n;
    char bufin[MAXBUF];
    struct sockaddr_in remote;

    /* need to know how big address struct is, len must be set before the
       call to recvfrom!!! */

    len = sizeof(remote);

    while (1) {
      /* read a datagram from the socket (put result in bufin) */
      n=recvfrom(sd,bufin,MAXBUF,0,(struct sockaddr *)&remote,&len);

      /* print out the address of the sender */
      printf("Got a datagram from %s port %d\n",
             inet_ntoa(remote.sin_addr), ntohs(remote.sin_port));

      if (n<0) {
        perror("Error receiving data");
      } else {
        printf("GOT %d BYTES\n",n);
    printf("%s\n",bufin);
        /* Got something, just send it back */

        sendto(sd,bufin,n,0,(struct sockaddr *)&remote,len);
    // ClUSTERING
      }
    }
}

/* server main routine */

int main() {
  int ld;
  struct sockaddr_in skaddr;
  int length;

  /* create a socket
     IP protocol family (PF_INET)
     UDP protocol (SOCK_DGRAM)
  */

  if ((ld = socket( PF_INET, SOCK_DGRAM, 0 )) < 0) {
    printf("Problem creating socket\n");
    exit(1);
  }

  /* establish our address
     address family is AF_INET
     our IP address is INADDR_ANY (any of our IP addresses)
     the port number is assigned by the kernel
  */

  skaddr.sin_family = AF_INET;
  skaddr.sin_addr.s_addr = htonl(INADDR_ANY);
  skaddr.sin_port = htons(0);

  if (bind(ld, (struct sockaddr *) &skaddr, sizeof(skaddr))<0) {
    printf("Problem binding\n");
    exit(0);
  }

  /* find out what port we were assigned and print it out */

  length = sizeof( skaddr );
  if (getsockname(ld, (struct sockaddr *) &skaddr, &length)<0) {
    printf("Error getsockname\n");
    exit(1);
  }

  /* port number's are network byte order, we have to convert to
     host byte order before printing !
  */
  printf("The server UDP port number is %d\n",ntohs(skaddr.sin_port));

  /* Go echo every datagram we get */
  echo(ld);
  return(0);
}

Answer 1

您将套接字绑定(bind)到 INADDR_ANY，这意味着任何 IP 地址。如果这不是您想要的，请将其绑定(bind)到特定的 IP 地址。但是那样你需要多个套接字。你现在拥有它的方式，你没有。