/* UDP Scanner (with protocol probes)
  By: fryxar
  Compile: gcc scanudp.c -o scanudp
*/
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <unistd.h>
#include <signal.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <netdb.h>


#define VERSION "1.0"
#define MAXBUF 1400
#define MAXSCAN 100
#define TIMEOUT 6

typedef struct config {
  int timeout;
} config;

typedef struct scan {
  u_int16_t number;// Number of udp port
    char *name;// Name of udp port
    char *outstring;// String to send (protocol dependent)
    int outstringlen;// Len above
    char *instring;// String to wait (protocol dependent, NULL for anything)
    int instringlen;// Len above
  char match;// Does port match? Allways initialized to 0
} scan;

// Port scanning probes definitions (protocol dependent)
struct scan port[] = {

  7, "echo", 
    "probe", 5, "probe", 5, 0,

    13, "daytime", 
    "\x0a", 1, NULL, 0, 0,

    19, "chargen", 
    "\x0a", 1, NULL, 0, 0,

  // dig @ip localhost A
    53, "dns", 
    "\x68\x6c\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\x09\x6c\x6f\x63\x61\x6c\x68\x6f\x73\x74\x00\x00\x01\x00\x01", 27, NULL, 0, 0,

  // echo "get a" | tftp ip
    69, "tftp", 
    "\x00\x01\x61\x00\x6e\x65\x74\x61\x73\x63\x69\x69\x00", 13, NULL, 0, 0,

  // ntpq -p ip
    123, "ntp", 
    "\x16\x01\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00", 13, NULL, 1, 0,

  // nbtstat -A ip
    137, "ns-netbios", 
    "\x98\x38\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x20\x43\x4b\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x41\x00\x00\x21\00\01", 50, NULL, 1, 0,

  // snmpwalk ip ILMI
    161, "snmp(ILMI)", 
    "\x30\x24\x02\x01\x00\x04\x04\x49\x4c\x4d\x49\xa1\x19\x02\x04\x18\x39\x99\xcd\x02\x01\x00\x02\x01\x00\x30\x0b\x30\x09\x06\x05\x2b\x06\x01\x02\x01\x05\x00", 38, NULL, 0, 0,

  // snmpwalk ip public
    161, "snmp(public)", 
    "\x30\x26\x02\x01\x00\x04\x06\x70\x75\x62\x6c\x69\x63\xa1\x19\x02\x04\x2c\x60\x2d\xb6\x02\x01\x00\x02\x01\x00\x30\x0b\x30\x09\x06\x05\x2b\x06\x01\x02\x01\x05\x00", 40, NULL, 0, 0,

   0, NULL, NULL, 0, NULL, 0, 0
};

void usage(char *program) {
int i;

  fprintf( stderr,
  "%s v"VERSION" - by: Franco Pieressa\n"
  "usage: %s [options] <host>\n\n"
  "options:\n"
  " -t <timeout> Set port scanning timeout\n"
  "\nSupported protocol:\n"
  , program, program);

  for( i=0; port[i].number; i++)
    fprintf( stderr, "%s ", port[i].name );
  fprintf( stderr, "\n\n" );

exit(-1);
}

struct config conf;

int main(int argc, char *argv[]) {
charbuf[MAXBUF], opt, *host;
int fd[MAXSCAN], nread, i, j, maxfd, repeat;
struct timevaltv;
struct sockaddr_indest_addr;
fd_setfdset;
structhostent *he;


// Set defaults
  conf.timeout = 10;

  if(argc < 2) usage( argv[0] );

  while((opt = getopt(argc, argv, "t:")) != -1) {
    switch(opt) {
      case 't':
        if(strlen(optarg) == 0) usage(argv[0]);
            conf.timeout = atoi(optarg);
            break;

      default:
        usage(argv[0]);
        break;
    }
  }

  host = argv[argc-1];

  if( (he = gethostbyname(host)) == NULL) {
    fprintf(stderr, "Error: Cannot resolve %s!\n", host);
    exit(-1);
  }


  FD_ZERO( &fdset );
    maxfd = 0;

  for( i = 0; port[i].number; i++ ) {
      if((fd[i] = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
      perror(NULL);
      exit(2);
    }
    if( maxfd < fd[i] ) maxfd = fd[i];
    FD_SET( fd[i], &fdset );

    dest_addr.sin_family = AF_INET;
    dest_addr.sin_addr = *((struct in_addr *)he->h_addr);
    dest_addr.sin_port =htons(port[i].number);

    if( connect(fd[i], (struct sockaddr *)&dest_addr, sizeof(dest_addr)) < 0 ) {
      perror(NULL);
      close(fd[i]);
      exit(4);
    }

    memcpy( buf, port[i].outstring, port[i].outstringlen );
    if( send(fd[i], buf, port[i].outstringlen, 0) < 0 ) {
      perror(NULL);
      close(fd[i]);
      exit(5);
    }
  }

  // Wait for timeout
  sleep( conf.timeout );

  tv.tv_sec= 0;
  tv.tv_usec = 0;

  if( select( maxfd+1, &fdset, NULL, NULL, &tv ) < 0 ) {
    perror(NULL);
    exit(6);
  }

  for( i = 0; port[i].number; i++ ) {
    if( !FD_ISSET( fd[i], &fdset ) ) {
      close( fd[i] );
      continue;
    }

    if( (nread = recv(fd[i], buf, MAXBUF, 0)) <= 0 ) {
      close( fd[i] );
      continue;
    }

    if( port[i].instring == NULL || !memcmp( buf, port[i].instring, port[i].instringlen ) ) {
      for( repeat = 0, j = 0; j < i; j++ ) 
      if( port[i].number == port[j].number && port[j].match > 0 ) repeat = 1;

      if( !repeat ) {
        printf( "%s\t%d/udp\n", host, port[i].number );
        port[i].match++;
      }
      close( fd[i] );
    }
  }

exit(0);
}