/* Created by: Giorgos Kappes                                   */
/* Year of first version: 2008                                  */
/* For any question mail to: g_kappes@hotmail.com               */
/* This is open source software                                 */
/****************************************************************/
/* Compile: gcc tcpscan.c -o tcpscan                            */
/****************************************************************/
#include <errno.h>                        /* perror() and errno */
#include <netdb.h>              /* required by getprotobyname() */
#include <sys/types.h>
#include <sys/socket.h>            /* both required by socket() */
#include <netinet/in.h>                   /* define sockaddr_in */
#include <unistd.h>                         /* memset()         */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>

#define PORT_MAX 65535                   /* Max port number     */
#define TIMEOUT_TIME 2                  /* Timeout time        */


extern int errno;
extern int h_errno;


void PrintHelp()
{
     printf("-------------------------------------------------------------\n");
     printf("                     TCPSCAN VERSION: 1.0\n");
     printf("-------------------------------------------------------------\n");
     printf("Created by: Giorgos Kappes\n");
     printf("Year of first version: 2008\n");
     printf("For any question mail to: g_kappes@hotmail.com\n");
     printf("This is open source software\n");
     printf("-------------------------------------------------------------\n");
     printf("                         SOME HELP\n");
     printf("-------------------------------------------------------------\n");
     printf("SYNTAX\n--> tcpscan [host name/ ip address]\n");
     printf("EXAMPLES\ntcpscan 85.167.12.10 \n");
     printf("tcpscan scylla.cs.uoi.gr \n");
     printf("-------------------------------------------------------------\n");
}     

main(int argc, char *argv[])
{
   /* VARIABLES                                                   */
    int sd;  /* our socket descriptor                             */
    int rval;  /* our connect descriptor                          */
    int port;  /* the connection port                             */
    int flags;
    fd_set myset;
    struct timeval tv;
    socklen_t lon; 
    int valopt;
    int lp,hp,ans,open=0,t_time=TIMEOUT_TIME;
    
    /* Structure to store pointer to protocol name in /etc/protocol*/ 
    struct protoent *protocol;
    /* structure to store ip address and port for connection       */
    struct sockaddr_in  socketaddr;
    /* structure to setup the address of the remote host           */
    struct hostent *hostaddr;    
    /* ----------------------------------------------------------- */
    /* CHECK PROGRAM RUN                                           */
    
    /* Check The arguments                                         */
    if (argc<2) {     /* No arguments given. We must print program */
        PrintHelp();  /* information                               */
        exit(0);
    }    
    else if (argc<2) {                                 
        printf("ERROR - Missing argument.\n");         
        exit(0);
    }
    else if (argc>2) {                               
        printf("ERROR - Too much arguments.\n");
        exit(0);
    } 

    /* ----------------------------------------------------------- */   
    /* INITIALIZE PROTOCOL - SOCKET AND CONNECT                    */
    
    /* initialize the protocol pointer by calling getprotobyname    */  
    protocol = getprotobyname( "tcp" );
    if ( !protocol )
    {
      perror( "getprotobyname()" );
      return (errno);
    }
    printf("Ports to scan: 0 - %d\n",PORT_MAX);
    lp = 0;
    hp = PORT_MAX;
    ans = 2;
    while (ans!=1) {
        printf("\n1. Contiune\n2. Specify new port range\n3. Scan a single port\n4. Set Timeout time\n\n> ");
        scanf("%d",&ans);
        while(ans<1 || ans > 4) {
            printf("\nWrong answer! Try Again!\n\n");
            printf("\n1. Contiune\n2. Specify new port range\n3. Scan a single port\n4. Set Timeout time\n\n> ");
            scanf("%d",&ans);
        }
        if (ans == 2) {
            printf("Lower port: ");
            scanf("%d",&lp);
            printf("Highest port: ");
            scanf("%d",&hp);
        }
        else if (ans == 3) {
            printf("Port: ");
            scanf("%d",&hp);
            lp=hp;
        }
        else if (ans == 4){
            printf("Timeout time: The default is 2 sec. For lower time the program will be faster, but for higher time the results may be more accurate\n");
            printf("Timeout time [1-10]: ");
            scanf("%d",&t_time);
            while (t_time<1 || t_time > 10) {
                printf("Wrong time. Try again.\n");
                printf("Timeout time [1-10]: ");
                scanf("%d",&t_time); 
            }
            printf("\nTimeout time set to: %d sec\n",t_time);
         }
    }
    printf("\nPorts to scan: %d - %d\n",lp,hp);
    printf("\nPort Scanning: %s. . .\n\n",argv[1]);
    printf("-------------------------------------------\n");
    printf("                 RESULTS\n");
    printf("-------------------------------------------\n");
    for (port=lp;port<=hp;port++) {
        /* build our socket                                            */      
        sd = socket( PF_INET, SOCK_STREAM, protocol->p_proto );
        if ( sd == -1 )
        {
          perror( "socket()" );
          return (errno);
        }
        /* make our socket non blocking to let us handle timeout        */
        fcntl(sd, F_SETFL, (flags = fcntl(sd,F_GETFL)) | O_NONBLOCK );
    
        /* At this point, all we have done is created a means for        *
         * communicating on the network, but we are not connected to     *
         * anyone at this point. Before we can do that, we must decide   *
         * who it is we want to talk to and establish a connection.      */
     
      
        /* Initialize socketaddr                                         */

        memset( &socketaddr, 0, sizeof(socketaddr)); /* initialize it    */  
        socketaddr.sin_family = AF_INET; /* set the fam type to Internet */
        socketaddr.sin_port = htons( port );  /* set port to argv[2]     */ 
        
        hostaddr = gethostbyname(argv[1]);
        if ( !hostaddr )
        {
            fprintf( stderr, "gethostbyname(): %s\n", hstrerror(h_errno) );
            return (h_errno);
        }     
     
        /* Now we'll use memcpy() to place it in our sockaddr_in struct: */
    
        memcpy( &socketaddr.sin_addr, hostaddr->h_addr, hostaddr->h_length );  
    
        /* At this point, we're ready to connect to the remote host:     */

        rval = connect( sd, (struct sockaddr *) &socketaddr, sizeof(socketaddr) );
        
        
        if (rval<0) {
        
            if (errno == EINPROGRESS) { 
                tv.tv_sec = t_time; 
                tv.tv_usec = 0; 
                FD_ZERO(&myset); 
                FD_SET(sd, &myset); 
                if (select(sd+1, NULL, &myset, NULL, &tv) > 0) { 
                    lon = sizeof(int); 
                    getsockopt(sd, SOL_SOCKET, SO_ERROR, (void*)(&valopt), &lon);
                    if (!valopt) {
                        printf("--- Found OPEN Port: %d  [TCP]\n",port); 
                        open++;
                        
                    }  
                } 
                else { 
                    printf("------ TIMEOUT on port: %d\n",port);
                    
                } 
             } 
             else { 
                printf("error\n");
                exit(0); 
             } 
        }
        close(sd);
    }
    printf("-------------------------------------------\n");
    printf("Open TCP ports: %d\n",open);
    printf("-------------------------------------------\n");
    printf("\nPort scanning on %s completed!\n\n",argv[1]);
    return(0);
    
}