dvbo.cpp

Example Dreambox CAM source code

//===========================================================
// DVB object (C++)
// Handles all DVB stream analysis, in particular PSI data
// Code is independent of encryption scheme used
// (c) Aug 2008 by Dirktator
//===========================================================

#include "dvbo.h"
#include "/data/dreambox/tuxbox-bb/build/tmp/staging/powerpc-linux/include/ost/dmx.h"	
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/poll.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <stropts.h>	
#include <sys/un.h>
#include <unistd.h>
#include <errno.h>

//Constructor method, initializes the required variables
dvbo_handler::dvbo_handler(int progid, int dmx_fd, int debug)
{
	int i;

	fd 			= dmx_fd;						//just forward the demux file handle into an object-wide variable, saves a lot of passing of variables via function params!
	dbg			= debug;						//idem for debug flag
	ECMpidcount = 0;
	lock		= 0;							//We start with a state where no valid cardserver/EMU was identified 

	for (i=0;i<20;i++) 							//clean ECMpids array
	{ 
		ECMpids[i].CA_PID		= 0; 
		ECMpids[i].CA_System_ID	= 0;
	}
}

//Filter using the demux device; DVB API 1
//return 0 on error, nonzero on ok
int dvbo_handler::Set_Filter(int pid, char filt, char mask)
{
	struct dmxSctFilterParams sFP;

	if (dbg) printf("Set filter pid:%d, value:%d...",pid, filt);
	memset(&sFP,0,sizeof(sFP));
  	sFP.pid     			= pid;
  	sFP.timeout 			= 5000;		//wait max 5 seconds for ECM message
  	sFP.flags   			= DMX_IMMEDIATE_START;
  	sFP.filter.filter[0] 	= filt;
  	sFP.filter.mask[0] 		= mask;
    
  	if (ioctl(fd, DMX_SET_FILTER, &sFP) < 0)  
  	{
    	perror(" Status");
    	return 0;
  	}
	if (dbg) printf(" success!\n");
	return 1;
}

//Stop filtering
int dvbo_handler::Stop_Filter(void)
{
	if (dbg) printf("Stopping filtering...");
  	if (ioctl(fd,DMX_STOP)<0)
	{
		perror(" Stop filter");
		return 0;
	}
	if (dbg) printf(" success!\n");
	return 1;
}

//Read and analyze the Program Allocation Table (id=0)
//input: 	program number and demux device handler
//returns: 	Program Map Table (PMT) id
int dvbo_handler::Parse_PAT(int prognr)
{
	char 	buffer[4096];
	int 	i, j, n, seclen;
	char 	nib1, nib2;		//nibble1 and 2
	int		pnr, pmtnr;

	//General fields
	printf("Parsing PAT, searching for PMT of SID %d\n",prognr);
	n=read(fd,buffer,4096);
	
	if (dbg) 
	{
		printf("\tRead %d bytes\n",n);
		for (j=0;j<n;j+=16)							//dump PAT data
		{
			printf("\t%04x: ",j);
			for (i=0;i<16;i++) printf("%02x ",buffer[j*16+i]);
			printf("\n");
		}
		printf("\ttable_id:%d\n",buffer[0]);		//8bit
	}

	nib2=(buffer[1]&0xF)<<4;	
	seclen=nib2; seclen=(seclen<<4)+buffer[2];		//12bit
	if (dbg) printf("\tsection_length:%d\n",seclen);
	
	//PMT entries start as of byte 8
	//Each entry consists of:
	i=8; pnr=0; pmtnr=0;
	while (i<seclen)								//section counter
	{	
		pnr=buffer[i]<<8;
		pnr+=buffer[i+1];
		if (pnr==prognr) 							//Found it! Now read 13 PMT id bits
		{
			pmtnr=((buffer[i+2]<<8) + buffer[i+3])&0x1fff; //13 bits masking, skip first 3 bits
			printf("\tPMTid: %04x(%04d)\n",pmtnr,pmtnr);	
			break;
		}
		i+=4;						//next section
	}
	if (pnr!=prognr)
	{
		perror("\tPMT id not found!");
		return 0;
	}
	else return pmtnr;
}

//Read a CA descriptor section from the stream, buffer is the streambuffer, i is the index to start parsing
//input:	pointer to data from the PMT containing CA data, length of the buffer
//returns: 	nothing
void dvbo_handler::Parse_CA_Descriptor_Section(char *buf, int cplen)
{
	char cabuf[4096];
	int  x, j, capid, ptr=0;
	
	cabuf[0]=0;
	for (x=0;x<cplen+2;x++) cabuf[x]=buf[x];	//just bluntly copy all data in buf to the local buffer....
	
	if (dbg)
	{
		printf("\t\tCA Descr Section: ");
		for (j=0;j<cplen;j++) printf("%02x ",cabuf[j]); 
	}
	
	int 	casys=(cabuf[2]<<8)+cabuf[3];
	char 	caSys[255];
	if (dbg) 
		switch (casys&0xff00)
		{
			case 0x600: 	sprintf(caSys,"Irdeto"); break;
			case 0x100: 	sprintf(caSys,"Seca"); break;
			case 0x1700: 	sprintf(caSys,"Betacrypt"); break; 
			case 0x1800: 	sprintf(caSys,"Nagra (Kudelski)"); break;
			case 0x0900:	sprintf(caSys,"News Datacom - VideoGuard"); break;
			case 0x0b00:	sprintf(caSys,"Conax"); break;
			case 0x0d00: 	sprintf(caSys,"Philips Cryptoworks"); break;
			default:		sprintf(caSys,"Unknown (%04x)", casys);
		}
	capid=((cabuf[4]<<8) + cabuf[5])&0x1fff; 	//13 bits masking, skip first 4 bits
	
	//now update global ECMpids array	
	ECMpids[ECMpidcount].CA_PID=capid;			//add the PID
	ECMpids[ECMpidcount].CA_System_ID=casys;	//add the system id
	ECMpidcount++;

	if (dbg) printf("\n\t\t\t=> CA PID[%d]: %04x (%d), type: %04x (%s)\n",ECMpidcount, capid, capid, casys,caSys);	
}

//Read the PMT and get the CA pid
//	CA sections are indicated by a value of 0x09 in the program_info field or 0x09 in the ES_info field
//  returns the amount of CA descriptors read;
int dvbo_handler::Parse_PMT(int prognr)
{
	char 	buffer[4096];
	int 	i,j,n;
	int 	capid, eslen, seclen, stype;

	//Object property variable maintenance
	ECMpidcount=0;		//when Parse_PMT is called we need to fill the ECMpids table from scratch!

	printf("Parsing PMT to find CA pid\n");
	n=read(fd,buffer,4096);		//read the data from the stream
	if (dbg) 
	{
		printf("\tRead %d bytes\n",n);

		//dump hex table
		for (j=0;j<n;j+=16)	
		{
			printf("\t%04x: ",j);
			for (i=0;i<16;i++) printf("%02x ",buffer[j+i]);
			printf("\n");
		}
	}
	
	//section length
	seclen=((buffer[1]<<8) + buffer[2])&0x0fff;	//12 bits masking
	if (dbg) printf("\tSection length: %d\n", seclen);

	//Program_Info_Length
	int pil=0;	
	pil= ( (buffer[10]<<8) + buffer[11])&0x0fff; 		//12 bits masking, skip first 4 bits
	if (dbg) printf("\tProgram Info Section (length: %d)\n",pil);

	//program_info section
	int cnt=12;  //start of pil subsections
	while(cnt<pil+17)
	{
		int dtag=buffer[cnt]; 		//printf("\t\tDtag: %02x ",dtag);
		int delen=buffer[cnt+1]; 	//printf("Des length: %d\n",delen);
		if (delen==0)
		{
			printf("Error\n");				
			break;
		} 
		if (dtag==0x09) Parse_CA_Descriptor_Section(&buffer[cnt],delen);
		cnt+=(delen+2);
	}

	//Video stream descriptor sections
	if (dbg) printf("\tES Info Section\n");
	int sec_start=12+pil;			//first section
	while (sec_start<(seclen-4))   	//note 4 last bytes are CRC, so do not try to read these!
	{
		//streamtype
		stype=buffer[sec_start];
		//if (stype==0x02) printf("\tStreamtype: video (0x02)\n");		
		//if (stype==0x04) printf("\tStreamtype: audio (0x04)\n");
		eslen=((buffer[sec_start+3]<<8)+buffer[sec_start+4])&0x0fff;	//12 bits
		//printf("\tStreamtype: %02x; ES length: %d\n",stype, eslen);

		//anaylyse ES info length section, can contain multiple subsections
		int cnt=sec_start+5;
		while(cnt<(eslen+sec_start+5))
		{
			int dtag=buffer[cnt]; 		//printf("\t\tDtag: %02x ",dtag);
			int delen=buffer[cnt+1]; 	//printf("Des length: %d\n",delen);
			if (delen==0)
			{
				printf("Error\n");
				break;
			} 
			//dtag=0x09 is CA information, streamtype=0x02 is video
			if ((stype==0x02)&&(dtag==0x09)) Parse_CA_Descriptor_Section(&buffer[cnt],delen);	//for now only consider VIDEO ECM messages!!!
			cnt+=(delen+2);
		}

		sec_start+=(eslen+5); 
	}
	return(ECMpidcount);
}

//Parse the CA section, goal: to retrieve the buffer that contains the control words
//Inputs:	demux file handler; the capid is just passed for debug reasons
//Output:	sets the object property ECMbuffer which contains the encrypted ECM packet and returns the providerid found in the ECM
int dvbo_handler::Parse_ECM(int capid)
{
	char 	ch;
	int 	n,j,i, calen, ecmlen, provid;
	
	if (dbg) printf("Parsing CA pid %04x (%04d)\n",capid,capid);

	for (i=0;i<4096;i++) 
		ECMbuffer[i]=0;
	
	ECMbufsize = read(fd,ECMbuffer,184);				//read the data from the stream, set the object property ECMbufsize
	if (dbg) 
	{	
		printf("\tRead %d bytes\n",ECMbufsize);
		printf("\tTable-id: %02x\n",ECMbuffer[0]);
	}
	calen=((ECMbuffer[1]<<8)+ECMbuffer[2])&0x0fff;		//12 bits, useless data at the moment, maybe when we start building EMU's....
	if (dbg) printf("\tCA section length: %d\n",calen);

	//Now parse the SECA specific data
	provid=(ECMbuffer[3]<<8)+ECMbuffer[4];
	if (dbg) printf("\t\tProvider ID:%04x\n",provid);
	
	return(provid);

}