demo_ipv6

demo_ipv6.c

/* demo_ipv6.c */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <libgen.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <arpa/inet.h>
#include <net/if.h>

struct in6_ifreq {
  struct in6_addr ifr6_addr;
  u_int32_t ifr6_prefixlen;
  unsigned int ifr6_ifindex;
};

#define retval_if(expr, retval, runcode) \
  if ((expr)) { \
    { runcode ; } \
    return (retval); \
  }

#define init_ifindex(ifr) \
  memset(&ifr, 0, sizeof(struct ifreq)); \
  strncpy(ifr.ifr_name, argv[0], IFNAMSIZ-1); \
  retval_if( ioctl(fd, SIOGIFINDEX, &ifr), -3 /* 253 */, NULL );

static int cmd_add(int fd, int argc, char *argv[])
{
  struct in6_ifreq req;
  struct ifreq ifr;

  init_ifindex(ifr);

  /* Set a random IPv6 address */
  inet_pton(AF_INET6, argv[1], &req.ifr6_addr);
  req.ifr6_prefixlen = 64;
  req.ifr6_ifindex = ifr.ifr_ifindex;
  retval_if( ioctl(fd, SIOCSIFADDR, &req), -4 /* 252 */, NULL );

  return 0;
}

static int cmd_get(int fd, int argc, char *argv[])
{
  char buf[256] = { 0, };
  struct in6_ifreq req;
  struct ifreq ifr;
  uint64_t *index = &((uint64_t*)&req.ifr6_addr)[1];

  init_ifindex(ifr);

  memset(&req, 0, sizeof(struct in6_ifreq));
  /* Set index of nth address on the interface */
  *index = (argc == 1) ? 0 : atoi(argv[1]);
  req.ifr6_prefixlen = 64;
  req.ifr6_ifindex = ifr.ifr_ifindex;
  retval_if( ioctl(fd, SIOCGIFADDR, &req), -5 /* 251 */, NULL );

  inet_ntop(AF_INET6, &req.ifr6_addr, buf, sizeof(buf));
  printf("interface (%s) addr (%s)\n", argv[0], buf);

  return 0;
}

int main(int argc, char *argv[])
{
  int ret = 0, fd;

  retval_if( argc < 3, -1 /* 255 */,
             fprintf(stderr, "usage: %s <command>\n\n"
                             "- command\n"
                             "    add : <ifname> <ipv6 address>\n"
                             "    get : <ifname> [index]\n\n",
                             basename(argv[0])) );

  retval_if( ((fd = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP)), fd < 0),
             -2 /* 254 */, NULL );

  if (!strcmp(argv[1], "add"))
    ret = cmd_add(fd, argc-2, argv+2);
  else if (!strcmp(argv[1], "get"))
    ret = cmd_get(fd, argc-2, argv+2);
  
  close(fd);
  return ret;
}