snifdump.cpp

/*
	Original code by realmonster
	
	Updated 2020.08.01 by dzik
	- updated console output formatting
	- created build.bat file to automate build process
*/

#include "pcap.h"

/* 4 bytes IP address */
typedef struct ip_address{
    u_char byte1;
    u_char byte2;
    u_char byte3;
    u_char byte4;
}ip_address;

/* IPv4 header */
typedef struct ip_header{
    u_char  ver_ihl;        // Version (4 bits) + Internet header length (4 bits)
    u_char  tos;            // Type of service 
    u_short tlen;           // Total length 
    u_short identification; // Identification
    u_short flags_fo;       // Flags (3 bits) + Fragment offset (13 bits)
    u_char  ttl;            // Time to live
    u_char  proto;          // Protocol
    u_short crc;            // Header checksum
    ip_address  saddr;      // Source address
    ip_address  daddr;      // Destination address
    u_int   op_pad;         // Option + Padding
}ip_header;

/* UDP header*/
typedef struct udp_header{
    u_short sport;          // Source port
    u_short dport;          // Destination port
    u_short len;            // Datagram length
    u_short crc;            // Checksum
}udp_header;

/* UDP header*/
typedef struct tcp_header{
    u_short sport;          // Source port
    u_short dport;          // Destination port
    u_int seqn;             // Sequence Number
    u_int ackn;             // Acknowledgement Number
    u_char hlen;            // Header Length
    u_char flags;           // Control Bits
    u_short window;         // Window
    u_short crc;            // Checksum
    u_short uptr;           // Urgent Pointer
    u_int   op_pad;         // Option + Padding
}tcp_header;


/* prototype of the packet handler */
void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data);

FILE *f;

int main()
{
	pcap_if_t *alldevs;
	pcap_if_t *d;
	int inum;
	int i=0;
	pcap_t *adhandle;
	char errbuf[PCAP_ERRBUF_SIZE];
	u_int netmask;
	char packet_filter[] = "ip and tcp and (port 6112 or port 4000)"; 	//All Bnet Connections
	struct bpf_program fcode;

	f = fopen("d2dump.bin","wb");
    /* Retrieve the device list */
    if (pcap_findalldevs_ex(PCAP_SRC_IF_STRING, NULL, &alldevs, errbuf) == -1)
    {
        fprintf(stderr,"Error in pcap_findalldevs: %s\n", errbuf);
        exit(1);
    }
    
    /* Print the list */
    for(d=alldevs; d; d=d->next)
    {
        printf("%d. %s", ++i, d->name);
        if (d->description)
            printf(" (%s)\n", d->description);
        else
            printf(" (No description available)\n");
    }

    if(i==0)
    {
        printf("\nNo interfaces found! Make sure WinPcap is installed.\n");
        return -1;
    }
    
    printf("Enter the interface number (1-%d):",i);
    scanf_s("%d", &inum);
    
    if(inum < 1 || inum > i)
    {
        printf("\nInterface number out of range.\n");
        /* Free the device list */
        pcap_freealldevs(alldevs);
        return -1;
    }

    /* Jump to the selected adapter */
    for(d=alldevs, i=0; i< inum-1 ;d=d->next, i++);
    
    /* Open the adapter */
    if ( (adhandle= pcap_open(d->name,  // name of the device
                             65536,     // portion of the packet to capture. 
                                        // 65536 grants that the whole packet will be captured on all the MACs.
                             PCAP_OPENFLAG_PROMISCUOUS,         // promiscuous mode
                             1000,      // read timeout
                             NULL,      // remote authentication
                             errbuf     // error buffer
                             ) ) == NULL)
    {
        fprintf(stderr,"\nUnable to open the adapter. %s is not supported by WinPcap\n", d->name);
        /* Free the device list */
        pcap_freealldevs(alldevs);
        return -1;
    }
    
    /* Check the link layer. We support only Ethernet for simplicity. */
    if(pcap_datalink(adhandle) != DLT_EN10MB)
    {
        fprintf(stderr,"\nThis program works only on Ethernet networks.\n");
        /* Free the device list */
        pcap_freealldevs(alldevs);
        return -1;
    }
    
    if(d->addresses != NULL)
        /* Retrieve the mask of the first address of the interface */
        netmask=((struct sockaddr_in *)(d->addresses->netmask))->sin_addr.S_un.S_addr;
    else
        /* If the interface is without addresses we suppose to be in a C class network */
        netmask=0xffffff; 


    //compile the filter
    if (pcap_compile(adhandle, &fcode, packet_filter, 1, netmask) <0 )
    {
        fprintf(stderr,"\nUnable to compile the packet filter. Check the syntax.\n");
        /* Free the device list */
        pcap_freealldevs(alldevs);
        return -1;
    }
    
    //set the filter
    if (pcap_setfilter(adhandle, &fcode)<0)
    {
        fprintf(stderr,"\nError setting the filter.\n");
        /* Free the device list */
        pcap_freealldevs(alldevs);
        return -1;
    }
    
    printf("\nlistening on %s...\n", d->description);
    
    /* At this point, we don't need any more the device list. Free it */
    pcap_freealldevs(alldevs);
    
    /* start the capture */
    pcap_loop(adhandle, 0, packet_handler, NULL);
    
    return 0;
}

/* Callback function invoked by libpcap for every incoming packet */
void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data)
{
    struct tm ltime;
    char timestr[16];
    ip_header *ih;
    tcp_header *uh;
    u_int ip_len;
    u_int tcp_len;
    u_int d_len;
    u_short sport, dport, window, crc, uptr;
	u_int seqn, ackn;
    time_t local_tv_sec;
    const u_char *data;

    /*
     * Unused variable
     */
    (VOID)(param);

    /* convert the timestamp to readable format */
    local_tv_sec = header->ts.tv_sec;
    localtime_s(&ltime, &local_tv_sec);
    strftime( timestr, sizeof timestr, "%H:%M:%S", &ltime);

    /* retireve the position of the ip header */
    ih = (ip_header *) (pkt_data +
        14); //length of ethernet header

    /* retireve the position of the tcp header */
    ip_len = (ih->ver_ihl & 0xf) * 4;
    uh = (tcp_header *) ((u_char*)ih + ip_len);

    tcp_len = (uh->hlen >> 4) * 4;
    data = (u_char*)uh + tcp_len;

    d_len = ntohs(ih->tlen) - ip_len - tcp_len;
	
    /* convert from network byte order to host byte order */
    sport = ntohs( uh->sport );
    dport = ntohs( uh->dport );
	seqn = ntohl(uh->seqn);
	ackn = ntohl(uh->ackn);
	window = ntohs(uh->window);
	crc = ntohs(uh->crc);
	uptr = ntohs(uh->uptr);
	
	HANDLE hConsole = GetStdHandle(STD_OUTPUT_HANDLE);
	if (d_len > 0) 
	{
		SetConsoleTextAttribute(hConsole, 12); // red
		/* print timestamp and length of the packet */
		printf("%s.%.6d\t", timestr, header->ts.tv_usec);
		
		SetConsoleTextAttribute(hConsole, 10); // green
		printf("len:%d\t", d_len);
		
		if (data[0] == 0xFF) 
		{
			SetConsoleTextAttribute(hConsole, 2); //
			printf("SID\t");
		}
		else if (sport == 6112 || dport == 6112) 
		{
			SetConsoleTextAttribute(hConsole, 5); //
			printf("MCP\t");
		}
		else if (sport == 4000 || dport == 4000) 
		{
			SetConsoleTextAttribute(hConsole, 6); //
			printf("D2GS\t");
		}
		else
		{
			SetConsoleTextAttribute(hConsole, 3); //
			printf("UNKNOWN\t");
		}
		
		SetConsoleTextAttribute(hConsole, 11); // magenta
		printf("%d.%d.%d.%d:%d\t", ih->saddr.byte1, ih->saddr.byte2, ih->saddr.byte3, ih->saddr.byte4, sport);
		printf("->\t");
		printf("%d.%d.%d.%d:%d\t", ih->daddr.byte1, ih->daddr.byte2, ih->daddr.byte3, ih->daddr.byte4, dport);
			
		printf("\n");
		
		SetConsoleTextAttribute(hConsole, 7); // white
		printf("\t");
		
		for (int i = 0; i < d_len; i++) {
			printf("%02x ", data[i]);
		}
		printf("\n");
	}

    /* print ip addresses and tcp ports */
	fwrite(&ih->saddr.byte1,1,1,f);
	fwrite(&ih->saddr.byte2,1,1,f);
	fwrite(&ih->saddr.byte3,1,1,f);
	fwrite(&ih->saddr.byte4,1,1,f);
	fwrite(&sport,1,2,f);
    fwrite(&ih->daddr.byte1,1,1,f);
	fwrite(&ih->daddr.byte2,1,1,f);
	fwrite(&ih->daddr.byte3,1,1,f);
	fwrite(&ih->daddr.byte4,1,1,f);
	fwrite(&dport,1,2,f);
	fwrite(&seqn,1,4,f); // Sequence Number
	fwrite(&ackn,1,4,f); // Acknowledgement Number
	fwrite(&uh->hlen,1,1,f); // Header Length
	fwrite(&uh->flags,1,1,f); // Control Bits
	fwrite(&window,1,2,f); // Window
	fwrite(&crc,1,2,f); // Checksum
	fwrite(&uptr,1,2,f); // Urgent Pointer
	fwrite(&d_len,1,4,f);
	fwrite(data,d_len,1,f);
	fflush(f);
}