FILE *f;    struct pcap_file_header pfh;    struct pcap_pkthdr pkh;    struct timeval tv;    int n;    if( opt.cap_out == NULL )    {        printf("Please specify an output file (-w).\n");        return 1;    }    if( ( f = fopen( opt.cap_out, "wb+" ) ) == NULL )    {        fprintf( stderr, "failed: fopen(%s,wb+)\n", opt.cap_out );        return( 1 );    }    pfh.magic           = TCPDUMP_MAGIC;    pfh.version_major   = PCAP_VERSION_MAJOR;    pfh.version_minor   = PCAP_VERSION_MINOR;    pfh.thiszone        = 0;    pfh.sigfigs         = 0;    pfh.snaplen         = 65535;    pfh.linktype        = LINKTYPE_IEEE802_11;    n = sizeof( struct pcap_file_header );    if( fwrite( &pfh, 1, n, f ) != (size_t) n )    {        fprintf( stderr, "failed: fwrite(pcap file header)\n" );        return( 1 );    }    gettimeofday( &tv, NULL );    pkh.tv_sec  = tv.tv_sec;    pkh.tv_usec = tv.tv_usec;    pkh.len     = length;    pkh.caplen  = length;    n = sizeof( pkh );    if( fwrite( &pkh, 1, n, f ) != (size_t) n )    {        fprintf( stderr, "fwrite(packet header) failed\n" );        return( 1 );    }    n = length;    if( fwrite( packet, 1, n, f ) != (size_t) n )    {        fprintf( stderr, "fwrite(packet data) failed\n");        return( 1 );    }    return 0;}int read_prga(unsigned char **dest, char *file){    FILE *f;    int size;    if(file == NULL) return( 1 );    if(*dest == NULL) *dest = (unsigned char*) malloc(1501);    f = fopen(file, "r");    if(f == NULL)    {         printf("Error opening %s\n", file);         return( 1 );    }    fseek(f, 0, SEEK_END);    size = ftell(f);    rewind(f);    if(size > 1500) size = 1500;    if( fread( (*dest), size, 1, f ) != 1 )    {        fprintf( stderr, "fread failed\n" );        return( 1 );    }    opt.prgalen = size;    fclose(f);    return( 0 );}int forge_arp(){    /* use arp request */    opt.pktlen = 60;    memcpy( h80211, ARP_REQ, opt.pktlen );    memcpy( opt.dmac, "\xFF\xFF\xFF\xFF\xFF\xFF", 6 );    if( set_tofromds(h80211) != 0 ) return 1;    if( set_bssid(h80211)    != 0 ) return 1;    if( set_smac(h80211)     != 0 ) return 1;    if( set_dmac(h80211)     != 0 ) return 1;    memcpy( h80211 + 40, opt.smac, 6 );    if( set_dip(h80211, 56)  != 0 ) return 1;    if( set_sip(h80211, 46)  != 0 ) return 1;    return 0;}int forge_udp(){    unsigned short chksum;    opt.pktlen = 61;    memcpy(h80211, UDP_PACKET, opt.pktlen);    if( set_tofromds(h80211) != 0 ) return 1;    if( set_bssid(h80211)    != 0 ) return 1;    if( set_smac(h80211)     != 0 ) return 1;    if( set_dmac(h80211)     != 0 ) return 1;    if( set_dip(h80211, 48)  != 0 ) return 1;    if( set_sip(h80211, 44)  != 0 ) return 1;    /* set udp length */    h80211[57] = '\x09';    /* generate + set ip checksum */    chksum = ip_chksum((unsigned short*)(h80211+32), 20);    memcpy(h80211+42, &chksum, 2);    return 0;}int forge_icmp(){    unsigned short chksum;    opt.pktlen = 60;    memcpy(h80211, ICMP_PACKET, opt.pktlen);    if(memcmp(opt.dmac, NULL_MAC, 6) == 0)    {        memcpy( opt.dmac, "\xFF\xFF\xFF\xFF\xFF\xFF", 6 );    }    if( set_tofromds(h80211) != 0 ) return 1;    if( set_bssid(h80211)    != 0 ) return 1;    if( set_smac(h80211)     != 0 ) return 1;    if( set_dmac(h80211)     != 0 ) return 1;    if( set_dip(h80211, 48)  != 0 ) return 1;    if( set_sip(h80211, 44)  != 0 ) return 1;    /* generate + set ip checksum */    chksum = ip_chksum((unsigned short*)(h80211+32), 20);    memcpy(h80211+42, &chksum, 2);    return 0;}int forge_custom(){    if(read_raw_packet(h80211, opt.raw_file, opt.pktlen) != 0) return 1;    if( set_tofromds(h80211) != 0 ) return 1;    if(memcmp(opt.bssid, NULL_MAC, 6) != 0)    {        if( set_bssid(h80211) != 0 ) return 1;    }    if(memcmp(opt.dmac, NULL_MAC, 6) != 0)    {        if( set_dmac(h80211) != 0 ) return 1;    }    if(memcmp(opt.smac, NULL_MAC, 6) != 0)    {        if( set_smac(h80211) != 0 ) return 1;    }    return 0;}void print_usage(void){    printf(usage, getVersion("Packetforge-ng", _MAJ, _MIN, _SUB_MIN, _BETA) );}int main(int argc, char* argv[]){    int arg;    int option_index;    memset( &opt, 0, sizeof( opt ) );    /* initialise global options */    memset(opt.bssid, '\x00', 6);    memset(opt.dmac,  '\x00', 6);    memset(opt.smac,  '\x00', 6);    memset(opt.dip,   '\x00', 4);    memset(opt.sip,   '\x00', 4);    memset(opt.fctrl, '\x00', 2);    opt.prga     = NULL;    opt.cap_out  = NULL;    opt.raw_file = NULL;    opt.mode    = -1;    opt.pktlen  = -1;    opt.prgalen = -1;    opt.sport   = -1;    opt.dport   = -1;    opt.tods    =  1;    opt.fromds  =  0;    opt.encrypt =  1;    while( 1 )    {        option_index = 0;        static struct option long_options[] = {            {"arp",      0, 0, '0'},            {"udp",      0, 0, '1'},            {"icmp",     0, 0, '2'},            {"custom",   1, 0, '9'},            {0,          0, 0,  0 }        };        int option = getopt_long( argc, argv,                        "p:a:c:h:jok:l:j:r:y:0129:w:e",                        long_options, &option_index );        if( option < 0 ) break;        switch( option )        {            case 0 :                break;            case 'p' :                sscanf( optarg, "%x", &arg );                if( arg < 0 || arg > 65355 )                {                    printf( "Invalid frame control word.\n" );                    return( 1 );                }                opt.fctrl[0]=((arg>>8)&0xFF);                opt.fctrl[1]=(arg&0xFF);                break;            case 'a' :                if( getmac( optarg, 1, opt.bssid ) != 0 )                {                    printf( "Invalid AP MAC address.\n" );                    return( 1 );                }                break;            case 'c' :                if( getmac( optarg, 1, opt.dmac ) != 0 )                {                    printf( "Invalid destination MAC address.\n" );                    return( 1 );                }                break;            case 'h' :                if( getmac( optarg, 1, opt.smac ) != 0 )                {                    printf( "Invalid source MAC address.\n" );                    return( 1 );                }                break;            case 'j' :                opt.fromds = 1;                break;            case 'o' :                opt.tods = 0;                break;            case 'e' :                opt.encrypt = 0;                break;            case 'r' :                if( opt.raw_file != NULL )                {                    printf( "Packet source already specified.\n" );                    return( 1 );                }                opt.raw_file = optarg;                break;            case 'y' :                if( opt.prga != NULL )                {                    printf( "PRGA file already specified.\n" );                    return( 1 );                }                if( read_prga(&(opt.prga), optarg) != 0 )                {                    return( 1 );                }                break;            case 'w' :                if( opt.cap_out != NULL )                {                    printf( "Output file already specified.\n" );                    return( 1 );                }                opt.cap_out = optarg;                break;            case 'k' :                if( getip(optarg, opt.dip, &(opt.dport)) != 0 )                {                    printf( "Invalid destination IP address.\n" );                    return 1;                }                break;            case 'l' :                if( getip(optarg, opt.sip, &(opt.sport)) != 0 )                {                    printf( "Invalid source IP address.\n" );                    return 1;                }                break;            case '0' :                if( opt.mode != -1 )                {                    printf( "Mode already specified.\n" );                    return( 1 );                }                opt.mode = 0;                break;            case '1' :                if( opt.mode != -1 )                {                    printf( "Mode already specified.\n" );                    return( 1 );                }                opt.mode = 1;                break;            case '2' :                if( opt.mode != -1 )                {                    printf( "Mode already specified.\n" );                    return( 1 );                }                opt.mode = 2;                break;            case '9' :                if( opt.mode != -1 )                {                    printf( "Mode already specified.\n" );                    return( 1 );                }                opt.pktlen = atoi(optarg);                if(opt.pktlen < 24 || opt.pktlen > 2048)                {                    printf( "Invalid packet length.\n" );                    return 1;                }                opt.mode = 9;                break;            default :                if(opt.mode != -1)break;                print_usage();                return 1;        }    }	switch (opt.mode)	{		case 0:		        if( forge_arp() != 0 )		        {		            printf("Error building an ARP packet.\n");		            return 1;        		}        		break;        case 1:				if( forge_udp() != 0 )				{					printf("Error building an UDP packet.\n");					return 1;				}        		break;        case 2:                if( forge_icmp() != 0 )				{					printf("Error building an ICMP packet.\n");					return 1;				}				break;		case 9:		        if( forge_custom() != 0 )		        {		            printf("Error building a custom packet.\n");		            return 1;        		}		default:		        print_usage();		        printf("Please specify a mode.\n");        		return 1;	}    if(opt.encrypt)    {        if( create_wep_packet(h80211, &(opt.pktlen)) != 0 )         	return 1;    }    else    {        /* set WEP bit = 0 */        h80211[1] = h80211[1] & 0xBF;    }    if( write_cap_packet(h80211, opt.pktlen) != 0 )    {        printf("Error writing pcap file %s.\n", opt.cap_out);        return 1;    }    return 0;}