capmt.cpp

Example Dreambox CAM source code

//===========================================================
// CAPMT object (C++)
// Handles some CAMPT and CA I/O
// Code is independent of encryption scheme used
// (c) Aug 2008 by Dirktator
//===========================================================

#include "capmt.h"
#include "/data/dreambox/tuxbox-bb/build/tmp/staging/powerpc-linux/include/ost/ca.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, basically just passed debug information
ca_handler::ca_handler(int debug)
{
	dbg = debug;		//after the object is created, set the dbg value as defined by the command line parameter, one of these silly C++ syntax things
}

//the Linux DVB API does not provide a mechanism to read the program the user is watching
//thus we must read the CAPMT device to receive this info from Enigma
//inputs: 	none
//returns:	
int ca_handler::Read_CAPMT(void)
{
	int i, s,t, len;
	struct sockaddr_un remote;
	unsigned char buffer[8192];

	if (dbg) printf("Reading CAPMT device\n");
	if ((s=socket(AF_UNIX,SOCK_STREAM,0))==-1)	//We need a local socket to read the data from Enigma! This is client code (PLi)
	{
		perror("\tCAPMT socket");
		return 0;
	}

	if (dbg) printf("\tTrying to connect...\n");
	remote.sun_family = AF_UNIX;			//internal Unix socket (non-IP)
    strcpy(remote.sun_path, CAPMTNAME);		//set the local socket path, something like /tmp/.listen.camd.socket or something
	len = strlen(remote.sun_path) + sizeof(remote.sun_family);
    
	if (connect(s, (struct sockaddr *)&remote, len) == -1) 	//connect to the socket
	{
    	perror("connect");
		close(s);
        return 0;
    }
	if (dbg) printf("\tConnected.\n");
	
	if ((t=recv(s,buffer,100,0))>0)			//receive data from the socket
	{
		i=(buffer[7]<<8)+buffer[8];
		if (dbg) printf("\tSID:%04x (%04d)\n",i,i);	
	}	
	else perror("\tCAPMT recv");
	close(s);
	return(i);
}

//Unscramble the video stream by writing both control words to the CA device
//inputs:	ca device file handler, 2 control word buffers (8 bytes each) and some index which's function is unclear
//Returns:	nothing, drives the Dreambox's unscrambling
void ca_handler::write_control_words(unsigned int ca, unsigned char *cw_0, unsigned char *cw_1, int index)
{
  	ca_descr_t ca_descr;
  	long long ecw,ocw;
  	int i;

	static char lastcw0[8], lastcw1[8];	
	
	if (memcmp(cw_0,lastcw0,8))
	{
		printf("write control words\nCW0:");
		for (i=0;i<8;i++) printf("%02x ",cw_0[i]);
		printf("\n");
		
		ca_descr.index = index;
	  	ca_descr.parity = 0;
		memcpy(lastcw0,cw_0,8);
		memcpy(ca_descr.cw,cw_0,8);	
		if (ioctl(ca,CA_SET_DESCR,&ca_descr) < 0) perror("CA_SET_DESCR");
		else printf("\t written CW0 to CA device\n");
	}

  	if (memcmp(cw_1,lastcw1,8))
	{
		printf("write control words\nCW1:");
		for (i=0;i<8;i++) printf("%02x ",cw_1[i]);
		printf("\n");
		
		ca_descr.index = index;
	  	ca_descr.parity = 1;
		memcpy(lastcw1,cw_1,8);
		memcpy(ca_descr.cw,cw_1,8);
		if (ioctl(ca,CA_SET_DESCR,&ca_descr) < 0) perror("CA_SET_DESCR");
		else printf("\t written CW1 to CA device\n");
	}
}