XPORTを探すプログラム

/*

    This program is free software: you can redistribute it and/or modify

    it under the terms of the GNU General Public License as published by

    the Free Software Foundation, either version 2 of the License, or

    (at your option) any later version.

    This program is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of

    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License

    along with this program.  If not, see <http://www.gnu.org/licenses/>.

*/

#include <stdio.h>

#include <unistd.h>

#include <pthread.h>

#include <string.h>

#include <netdb.h>

#include <stdlib.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <unistd.h>

#include <fcntl.h>

#include <errno.h>

#include <sys/time.h>

#include <arpa/inet.h>

const int rport = 30718;

int sock;

struct sockaddr_in saddr, caddr;

int mkbroadsend(int port, struct sockaddr_in *caddr){

  int sock = 0;

  int sockopt = 1;

  if((sock = socket(AF_INET, SOCK_DGRAM,0)) < 0){

    perror("mkbroadsend: Can't make udp socket.\n");

    return 0;

  }

  setsockopt(sock, SOL_SOCKET, SO_REUSEADDR | SO_BROADCAST, 

       &sockopt, sizeof(sockopt));

  caddr->sin_family = AF_INET;

  caddr->sin_port = htons(port);

  caddr->sin_addr.s_addr = inet_addr("255.255.255.255");

  return sock;

}

void getipfromsockaddr(struct sockaddr_in caddr, unsigned char *ip){

  unsigned int v;

  v = caddr.sin_addr.s_addr;

  ip[0] = v & 0xff;

  ip[1] = (v >> 8) & 0xff;

  ip[2] = (v >> 16) & 0xff;

  ip[3] = (v >> 24) & 0xff;

}

void udprecv(void){

  unsigned char data[256];

  int magic;

  unsigned char ip[4];

  int clen, sz;

  struct sockaddr_in caddr;

  struct hostent *host;

  while(1){

    sz = recvfrom(sock, (char *)data, sizeof(data), 0,

       (struct sockaddr *)&caddr, (socklen_t*)&clen);

    getipfromsockaddr(caddr, ip);

    memcpy((char *)&magic, data, 4);

    if(magic == 0xf7000000){

      printf("------------------\n");

      printf("IP   = %u.%u.%u.%u\n", ip[0],ip[1],ip[2],ip[3]);

      printf("Ver  = %c%c\n", data[8],data[9]);

      printf("MAC  = %02X-%02X-%02X-%02X-%02X-%02X\n",

      data[24],data[25],data[26],data[27],

      data[28],data[29]);

      host = gethostbyaddr(&caddr.sin_addr.s_addr,

      sizeof(caddr.sin_addr.s_addr), AF_INET);

      printf("Host = %s\n", host->h_name);

      printf("------------------\n\n");

    }

  }

}

int main(int argc, char *argv[]){

  pthread_t udpthread;

  char com[4];

  unsigned int t = 1;

  sock = mkbroadsend(rport, &saddr);

  pthread_create(&udpthread, NULL, (void *)udprecv, NULL);

  pthread_detach(udpthread);

  com[0] = 0x00;

  com[1] = 0x00;

  com[2] = 0x00;

  com[3] = 0xf6;

  sendto(sock, com, 4, 0, (struct sockaddr *)&saddr, sizeof(saddr));

  if(argc > 1){

    t = strtoul(argv[1], NULL, 0);

    printf("Wait %u seconds\n", t);

  }

  sleep(t);

  return 0;

}