/* obreader.c by Sec <sec@42.org>
 * vim:set cin sm ts=4:
 * 
 * Do whatever you want with this code, but give credit
 *
 * This program reads packets from an USB-Serial R0ket
 * and sends them off via TCP/UDP to a central host
 *
 */

#include <sys/types.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <sys/uio.h>
#include <unistd.h>
#include <stdio.h>
#include <time.h>
#include <string.h>
#include <pwd.h>
#include <stdlib.h>

#define INTERVAL 1

#define BUFSIZE 100
#define PORT 2342
char *SRV_IP="127.0.0.1";

#define TYPE_UDP
#undef TYPE_TCP

/* rotating buffer */
#define ELEMSIZE 32
unsigned int bufstart=0,bufend=0; /* rotating buffer */
#define BUFIDX(a) (a*ELEMSIZE)
#define BUFPUSH() do{ bufend++; if(bufend==BUFSIZE){ bufend=0; }; if(bufend==bufstart){ BUFPOP();}; }while(0)
#define BUFPOP() do{ bufstart++; if(bufstart==BUFSIZE){ bufstart=0; }; }while(0)
unsigned char buffer[BUFIDX(BUFSIZE)];

time_t the_time;

static u_int16_t
crc16 (const unsigned char *buffer, int size)
{
        u_int16_t crc = 0xFFFF;

        if (buffer && size)
                while (size--)
                {
                        crc = (crc >> 8) | (crc << 8);
                        crc ^= *buffer++;
                        crc ^= ((unsigned char) crc) >> 4;
                        crc ^= crc << 12;
                        crc ^= (crc & 0xFF) << 5;
                }

        return crc;
}

void setnonblocking(int fd) {
	int opts;

	opts = fcntl(fd,F_GETFL);
	if (opts < 0) {
		perror("fcntl(F_GETFL)");
		exit(EXIT_FAILURE);
	}
	opts = (opts | O_NONBLOCK);
	if (fcntl(fd,F_SETFL,opts) < 0) {
		perror("fcntl(F_SETFL)");
		exit(EXIT_FAILURE);
	}
	return;
}

/* Reference is https://r0ket.badge.events.ccc.de/tracking:reader */
void pkt_cleanup(int idx){
    static u_int32_t ctr;

    buffer[BUFIDX(idx)+2]=1; // BEACONLOG_SIGHTING
    buffer[BUFIDX(idx)+3]=0; // interface 0
    *(u_int16_t*)(buffer+BUFIDX(idx)+4)=htons(1234); // reader id
    *(u_int16_t*)(buffer+BUFIDX(idx)+6)=htons(32);   // size
    *(u_int32_t*)(buffer+BUFIDX(idx)+8)=htonl(ctr++);
    *(u_int32_t*)(buffer+BUFIDX(idx)+12)=htonl(the_time);

    *(u_int16_t*)(buffer+BUFIDX(idx)+0)=htons(0xffff ^ crc16(buffer+BUFIDX(idx)+2,30));
}

void write_r0ket(int fd,char * buf,int len){
    int r;
    r=write(fd,buf,len);
    if(r!=len){
        printf("wrote only %d bytes of %d to device\n",r,len);
        exit(EXIT_FAILURE);
    };
}

void setup_r0ket(int fd){
    unsigned char buf[256];
    int x,r;
    u_int32_t uuid=0;

    write_r0ket(fd,"\\7\\0",4);                     /* Get UUID    */
    write_r0ket(fd,"\\4\001\002\003\002\001\\0",9); /* Set rx_mac  */
    write_r0ket(fd,"\\5\x51\\0",5);                 /* Set channel */
    write_r0ket(fd,"\\6\x10\\0",5);                 /* Set rx_len  */

    usleep(100000); /* wait 100ms for an answer */
    r=read(fd,buf,sizeof(buf));
    /* try to find uuid in reply. Could be nicer, but it works. */
    if(r>7){
        for(x=0;x<r-7;x++){
            if(buf[x]=='\\' && buf[x+1]=='7' &&
                    buf[x+6]=='\\' && buf[x+7] == '0'){
                uuid=ntohl(*(u_int32_t*)(buf+x+2));
                break;
            };
        };
    };
    if(uuid){
        printf("uuid=%x\n",uuid);
        return;
    }else{
        printf("No uuid?\n");
        exit(EXIT_FAILURE);
    };
};

signed int read_r0ket(int fd){
	int r,t,o,x;
	static unsigned char data[64];
    static unsigned char offset=0;
    static unsigned char firstread=1;

	r=read(fd,data+offset,sizeof(data)-offset);
	if(r<0){
		perror("read(device)");
		exit(EXIT_FAILURE);
	};
    if(r==0){
        printf("eof(device)");
        close(fd);
        return -1;
    };
#if 0
    for(t=offset;t<offset+r;t++){
        printf("%02x",data[t]);
    };
    printf (" read %d bytes, offset was %d\n",r,offset);
#endif
    r+=offset;
    offset=0;

    /* find frame start */
    while(data[0] != '\\' && r>0){
        if(!firstread)
            printf("ignoring garbage: %02X\n",data[0]);
        memmove(data,data+1,sizeof(data)-1);
        r--;
    };
    if(r==0){ /* no data left */
        return 0;
    };

    if(data[1]=='1'){
        firstread=0;
        /* find frame end */
        for(x=2;x<r-1;x++){
            if(data[x]=='\\' && data[x+1]=='0')
                break;
        }
        if(x>=r-1){ /* no EOF found */
            if(r>60){
                printf("serial frame content overflow\n");
                return 0;
            };
            offset=r; /* keep unused data for next round */
            return 0;
        };

//        printf("consume %d: ",x);
        o=16;
        BUFPUSH();
        for(t=2;t<x;t++){
            if(o>=ELEMSIZE) /* "buffer" overflow protection */
                break;
            buffer[BUFIDX(bufend)+o]=data[t];
            if(data[t]!='\\')
                o++;
//            printf("%02x",data[t]);
        };
        pkt_cleanup(bufend);
        x+=2; /* also consume end of frame marker */
//        printf("\n");
    }else if(data[1]=='7'){ /* beaconid frame */
        /* find frame end */
        for(x=2;x<r-1;x++){
            if(data[x]=='\\' && data[x+1]=='0')
                break;
        }
        if(x>=r-1){ /* no EOF found */
            if(r>60){
                printf("serial frame content overflow\n");
                return 0;
            };
            offset=r; /* keep unused data for next round */
            return 0;
        };
        /* XXX: do something with beaconid */
        BUFPUSH();
        for(t=0;t<16;t++){ /* clear buffer */
            buffer[BUFIDX(bufend)+16+t]=0;
        };
        buffer[BUFIDX(bufend)+16]=22; // RFBPROTO_READER_ANNOUNCE
        *(u_int16_t*)(buffer+BUFIDX(bufend)+16+14)= \
            htons(crc16(buffer+BUFIDX(bufend)+16,14));
        pkt_cleanup(bufend);
        x=8;
    }else if(data[1]=='2'){ /* command ack frame */
        x=4; /* just consume, and do nothing */
    }else{
        if(!firstread)
            printf("invalid frame type: %02x\n",data[1]);
        x=2;
    };
    if(x==r) /* all data consumed */
        return 0;
    /* keep unconsumed data */
    memmove(data,data+x,r-x);
    offset=r-x;
	return 0;
}

void write_socket(int sockfd){
    BUFPOP();
    if (send(sockfd, buffer+BUFIDX(bufstart), ELEMSIZE, 0)==-1){
        perror("send");
//        exit(EXIT_FAILURE);
    };
}

int main(int argc, char ** argv){
	int c;					/* getopt return value */
	char *device="/dev/ttyACM0";
	int devfd=-1,sockfd=-1,listenfd=-1;		/* FD for device & socket */
	int maxfd=0;
	int cnt;
	fd_set rset,wset;	        /* file descriptors for select() */
	struct timeval timeout;	    /* Timeout for select */
    struct sockaddr_in si_other; /* target socket */
    time_t ot,heartbeat=0;

    time(&ot);

	/* The big getopt loop */
	while ((c = getopt(argc, argv, "s:d:")) != EOF)
		switch (c)
		{
			case 'd':
				device=(char *)malloc(strlen(optarg)+2);
				strcpy(device,optarg);
				break;

			case 's':
				SRV_IP=(char *)malloc(strlen(optarg)+2);
				strcpy(SRV_IP,optarg);
				break;

			default:
				fprintf(stderr, "Usage: %s [options] \n\n\
This program reads packets from an USB-Serial R0ket\n\
and sends them off via TCP/UDP to a central host\n\n\
   -d <device>	Open a different device instead of '%s'\n\
   -h           This help\n",
					argv[0],
					device
					);
				exit(255);
		}

/*	argc -= optind; argv += optind; *//* only if we want more args */

	/* Open & prep input device */
	if((devfd=open(device,O_RDWR)) == -1){
		perror("open(device)");
        exit(EXIT_FAILURE);
    };
	setnonblocking(devfd);
    setup_r0ket(devfd);

	/* Open & prep outout device */
#ifdef TYPE_UDP
    if ((sockfd=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP))==-1){
        perror("socket(udp)");
        exit(EXIT_FAILURE);
    };
    memset((char *) &si_other, 0, sizeof(si_other));
    si_other.sin_family = AF_INET;
    si_other.sin_port = htons(PORT);
    if (inet_aton(SRV_IP, &si_other.sin_addr)==0) {
        perror("inet_aton()");
        exit(EXIT_FAILURE);
    }
    if(connect(sockfd,(struct sockaddr*)&si_other,sizeof(si_other))<0){
        perror("connect");
        exit(EXIT_FAILURE);
    };
	setnonblocking(sockfd);
#endif
#ifdef TYPE_TCP
    if((listenfd = socket(AF_INET, SOCK_STREAM, 0))<0){
        perror("socket(tcpserver)");
        exit(EXIT_FAILURE);
    };
    memset((char *) &si_other, 0, sizeof(si_other));
    si_other.sin_family = AF_INET;
    si_other.sin_addr.s_addr = INADDR_ANY;
    si_other.sin_port = htons(PORT);
    if(bind(listenfd,(struct sockaddr*)&si_other,sizeof(si_other))<0){
        perror("bind");
        exit(EXIT_FAILURE);
    };
    if(listen(listenfd,1)!=0){
        perror("listen");
        exit(EXIT_FAILURE);
    };
#endif

	while(1){
        /* prepare stuff for select */
        timeout.tv_sec = 1;
        timeout.tv_usec = 0;

        if(devfd>maxfd)
            maxfd=devfd;
        if(sockfd>maxfd)
            maxfd=sockfd;
        if(listenfd>maxfd)
            maxfd=listenfd;

        FD_ZERO(&rset);
        if(devfd==-1){
            fprintf(stderr,"Can't yet deal with disappearing device\n");
            exit(EXIT_FAILURE);
        };
        FD_SET(devfd,&rset);
        if(sockfd!=-1){
#ifdef TYPE_TCP
            FD_SET(sockfd,&rset);
#endif
        }else if(listenfd!=-1){
            FD_SET(listenfd,&rset);
        };

        FD_ZERO(&wset);
        if(bufstart!=bufend && sockfd!=-1){
            FD_SET(sockfd,&wset);
        };

		cnt = select(maxfd+1, &rset, &wset, NULL, &timeout);


        /* First run timer stuff */
        time(&the_time);
        if(the_time-ot>=INTERVAL){
            ot=the_time;
            printf("[running: buf=%d, sockfd=%d]\n",(BUFSIZE+bufend-bufstart)%BUFSIZE,sockfd);
        };

        if(the_time-heartbeat>=1){
            heartbeat=the_time;
            write_r0ket(devfd,"\\7\\0",4); /* Get UUID    */
        };

        /* Now check select / fds*/
		if (cnt<0){
			perror("select");
			exit(EXIT_FAILURE);
		};

		if (cnt==0){ /* timeout */
			printf("[timeout]\n");
            continue;
		};

		if (FD_ISSET(devfd,&rset)){
			if(read_r0ket(devfd)<0){
                close(devfd);
                devfd=-1;
            };
            if(--cnt ==0) continue;
        };

		if (sockfd!=-1 && FD_ISSET(sockfd,&rset)){
            int r;
            unsigned char dummy[32];
            r=read(sockfd,dummy,32);
            if(r<0){
                perror("read(socket)");
                exit(EXIT_FAILURE);
            };
            if(r==0){
                printf("eof() on socket\n");
                close(sockfd);
                sockfd=-1;
            };
            if(r>0){
                printf("read [%d] bytes from socket and ignored them.\n",r);
            };

            if(--cnt ==0) continue;
        };

		if (sockfd!=-1 && FD_ISSET(sockfd,&wset)){
			write_socket(sockfd);
            if(--cnt ==0) continue;
        };

		if (listenfd!=-1 && FD_ISSET(listenfd,&rset)){
            if(sockfd!=-1){ // close old connection
                close(sockfd);
            };
            unsigned int size=sizeof(si_other);
            if((sockfd=accept(listenfd,(struct sockaddr*)&si_other,&size))<0){
                perror("accept");
                continue; // Do not exit, we can handle this :-)
            };
            printf("New connection from %s (fd %d)\n", inet_ntoa(si_other.sin_addr), sockfd);
            if(--cnt ==0) continue;
        };

        printf("unknwon select left over: cnt=%d, ",cnt);
        printf("rset: ");
        for(cnt=0;cnt<maxfd+1;cnt++){
            printf(FD_ISSET(cnt,&rset)?"1":"0");
        };
        printf("wset: ");
        for(cnt=0;cnt<maxfd+1;cnt++){
            printf(FD_ISSET(cnt,&wset)?"1":"0");
        };
        printf("\n");
	};
    return(0);
}