control.c

   1 #include <stdio.h>
   2 #include <arpa/inet.h>
   3 #include <errno.h>
   4 #include <fcntl.h>
   5 #include <malloc.h>
   6 #include <netdb.h>
   7 #include <string.h>
   8 #include <sys/time.h>
   9 #include <sys/types.h>
  10 #include <sys/socket.h>
  11 #include <netinet/in.h>
  12 #include <signal.h>
  13 #include <stdarg.h>
  14 #include <stdlib.h>
  15 #include <unistd.h>
  16 #include <time.h>
  17 #include "control.h"
  18
  19 int new_packet(short type, char *packet)
  20 {
  21         int id = (time(NULL) ^ (rand() * 1024*1024));
  22
  23         *(short *)(packet + 0) = ntohs(0x9012);
  24         *(short *)(packet + 2) = ntohs(type);
  25         *(int *)(packet + 6) = ntohl(id);
  26
  27         return 10;
  28 }
  29
  30 int send_packet(int sockfd, int dest_ip, int dest_port, char *packet, int len)
  31 {
  32         struct sockaddr_in addr;
  33
  34         *(short *)(packet + 4) = ntohs(len);
  35
  36         memset(&addr, 0, sizeof(addr));
  37         addr.sin_family = AF_INET;
  38         *(int*)&addr.sin_addr = htonl(dest_ip);
  39         addr.sin_port = htons(dest_port);
  40         if (sendto(sockfd, packet, len, 0, (void *) &addr, sizeof(addr)) < 0)
  41         {
  42                 perror("sendto");
  43                 return 0;
  44         }
  45         return 1;
  46 }
  47
  48 int read_packet(int sockfd, char *packet)
  49 {
  50         struct sockaddr_in addr;
  51         int alen = sizeof(addr);
  52         memset(&addr, 0, sizeof(addr));
  53         return recvfrom(sockfd, packet, 1400, 0, (void *) &addr, &alen);
  54 }
  55
  56 void dump_packet(char *packet, FILE *stream)
  57 {
  58         if (htons(*(short *)(packet + 0)) != 0x9012)
  59         {
  60                 fprintf(stream, "Invalid packet identifier %x\n", htons(*(short *)(packet + 0)));
  61                 return;
  62         }
  63         fprintf(stream, "Control packet:\n");
  64         fprintf(stream, "       Type: %d\n", htons(*(short *)(packet + 2)));
  65         fprintf(stream, "       Length: %d\n", htons(*(short *)(packet + 4)));
  66         fprintf(stream, "       Identifier: %x\n", htonl(*(int *)(packet + 6)));
  67         fprintf(stream, "\n");
  68 }
  69
  70