getaddrinfo 未获取 ipv6 地址

Question

我正在尝试获取 ipv4 和 ipv6 地址并使用它们连接到服务器，但我只能使用 ipv4 地址连接。它实际上是一个标准代码。 当我运行服务器和客户端时， ipv4 和 ipv6 地址都在 /etc/hosts 中，

192.155.112.18 hostname.site hostname
fe80::a00:28ff:fe23:47a0 hostname.site hostname

输出是 服务器：

usage: showip hostname
server: waiting for connections...
server: got connection from 192.155.112.18

客户端：

client: connecting to 192.155.112.18
client: connecting to 192.155.112.18
client: received 'Hello, world!'

getaddrinfo 也获取 ipv6 地址，但没有我需要获取的接口 fe80::a00:28ff:fe23:47a0%eth0 之类的。我怎样才能制作一个标准代码获取ipv4和ipv6（带接口）

#include <unistd.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <errno.h>
#include <netinet/in.h>
#include <sys/wait.h>
#include <signal.h>
#include <ifaddrs.h>

#define PORT "3490"  // the port users will be connecting to

void error(const char *msg)
{
    perror(msg);
    exit(1);
}
int gHostIP;
#define BACKLOG 10     // how many pending connections queue will hold

void sigchld_handler(int s)
{
   while(waitpid(-1, NULL, WNOHANG) > 0);
}

// get sockaddr, IPv4 or IPv6:
void *get_in_addr(struct sockaddr *sa)
{
  if (sa->sa_family == AF_INET) 
  {
    return &(((struct sockaddr_in*)sa)->sin_addr);
   }

   return &(((struct sockaddr_in6*)sa)->sin6_addr);
}

int main()
{
   int sockfd, new_fd;  // listen on sock_fd, new connection on new_fd
   struct addrinfo hints, *servinfo, *p;
   struct sockaddr_storage their_addr; // connector's address information
   socklen_t sin_size;
   struct sigaction sa;
   int yes=1;
   char s[INET6_ADDRSTRLEN];
   int rv;
       char *arg;

       arg = (char*)malloc(20*sizeof(char));

       fprintf(stderr,"usage: showip hostname\n");

       memset(&hints, 0, sizeof(hints));
       hints.ai_family = AF_UNSPEC; // AF_INET or AF_INET6 to force version
       hints.ai_socktype = SOCK_STREAM;


       if ((rv = getaddrinfo("myhostname", PORT, &hints, &servinfo)) != 0) {
         fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
         return 1;
       }
       for(p = servinfo; p != NULL; p = p->ai_next) {
          if ((sockfd = socket(p->ai_family, p->ai_socktype,
                  p->ai_protocol)) == -1) {
              perror("server: socket");
            continue;
          }

          if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes,
                  sizeof(int)) == -1) {
              perror("setsockopt");
              exit(1);
          }
           /*if(p->ai_family == AF_INET6)
              strcat(p->ai_addr,"%eth3");*/
           if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
              close(sockfd);
              perror("server: bind");
              continue;
            }

          break;
       }

    if (p == NULL)  {
      fprintf(stderr, "server: failed to bind\n");
      return 2;
     }

     freeaddrinfo(servinfo); // all done with this structure

     if (listen(sockfd, BACKLOG) == -1) {
    perror("listen");
    exit(1);
     }

    sa.sa_handler = sigchld_handler; // reap all dead processes
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = SA_RESTART;
    if (sigaction(SIGCHLD, &sa, NULL) == -1) {
      perror("sigaction");
      exit(1);
    }

    printf("server: waiting for connections...\n");

    while(1)
    {  // main accept() loop
      sin_size = sizeof their_addr;
      new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size);
      if (new_fd == -1) {
          perror("accept");
          continue;
      }

      inet_ntop(their_addr.ss_family,
          get_in_addr((struct sockaddr *)&their_addr),
          s, sizeof s);
      printf("server: got connection from %s\n", s);

      if (!fork()) { // this is the child process
          close(sockfd); // child doesn't need the listener
          if (send(new_fd, "Hello, world!", 13, 0) == -1)
            perror("send");
          close(new_fd);
          exit(0);
      }
      close(new_fd);  // parent doesn't need this
     }

     return 0;
}

client.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/resource.h>
#include <sched.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <errno.h>
#include <netinet/in.h>
#include <sys/wait.h>
#include <signal.h>
#include <ifaddrs.h>

#define PORT "3490" // the port client will be connecting to

#define MAXDATASIZE 100 // max number of bytes we can get at once
int gHostIP;

// get sockaddr, IPv4 or IPv6:
void *get_in_addr(struct sockaddr *sa)
{
    if (sa->sa_family == AF_INET) {
        return &(((struct sockaddr_in*)sa)->sin_addr);
    }

    return &(((struct sockaddr_in6*)sa)->sin6_addr);
}



int main(int argc, char *argv[])
{
    int sockfd, numbytes;
    char buf[MAXDATASIZE];
    struct addrinfo hints, *servinfo, *p;
    int rv;
    char s[INET6_ADDRSTRLEN];
    char *arg;
    arg = (char*)malloc(20*sizeof(char));

    struct ifaddrs *ifaddr, *ifa;
    int family, s1;
    char host[NI_MAXHOST];


    memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;


    if ((rv = getaddrinfo("myhostname", PORT, &hints, &servinfo)) != 0)
    {
      fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
      return 1;
    }


    for (p = servinfo; p != NULL; p = p->ai_next)
    {
        if ((sockfd = socket(p->ai_family, p->ai_socktype,
            p->ai_protocol)) == -1) {
        perror("client: socket");
        continue;
        } 
        inet_ntop(p->ai_family, get_in_addr((struct sockaddr *)p->ai_addr),
               s, sizeof s);
         printf("\nclient: connecting to %s\n", s);
         if (connect(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
        close(sockfd);
        perror("\nclient: connect");
        continue;
         }

         break;
    }

    if (p == NULL) {
        fprintf(stderr, "client: failed to connect\n");
        return 2;
    }

    inet_ntop(p->ai_family, get_in_addr((struct sockaddr *)p->ai_addr),
        s, sizeof s);
    printf("client: connecting to %s\n", s);

    freeaddrinfo(servinfo);

    if ((numbytes = recv(sockfd, buf, MAXDATASIZE-1, 0)) == -1) {
            perror("recv");
            exit(1);
    }

    buf[numbytes] = '\0';

    printf("client: received '%s'\n",buf);

    close(sockfd);

    return 0;
}

Answer 1

您正在使用链接本地地址作为您的 ipv6 地址，最好使用像 2001:db8:1::1/64 这样的全球单播地址，而不是

以下命令作为 root 添加它：

ip -6 addr add 2001:db8:1::1/64 dev eth0

使用 客户：

ip -6 addr add 2001:db8:1::2/64 dev eth0

Answer 2

如果您的服务器绑定在 ipv4 地址上，那么您只能接受 ipv4 客户端。

问题是你的 getaddrinfo() 首先返回 ipv4 。 （有人工作得很好，因为他们的 getaddrinfo() 首先返回 ipv6）

所以你可以将代码更改为

for (p = res; p!= NULL; p = p->ai_next) {
    if (p->ai_family == AF_INET6 && (sock = socket(p->ai_family, p-
        ai_socktype, p->ai_protocol)) < 0
    ) {}
}