Datakomm_1/link.cpp

#include "physlayer.h"
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include "link_signal.h"
#include "link.h" 
#include "student.h"


const CONTROL_FRAME_SIZE = 14;
int PSOCK_FD;
int USOCK_FD;

typedef enum state{IDLE, UICON, UOCON, DATA, UIDCON, UODCON}state; 
state LINK_STATE = IDLE; 
 
static action ALIST[] = { 
{ L_DATA_REQUEST             , DataRequest          }, 
{ L_DATA_INDICATION          , DataIndication       }, 
{ L_CONNECT_REQUEST          , ConnectRequest       }, 
{ L_CONNECT_INDICATION       , ConnectIndication    }, 
{ L_CONNECT_RESPONSE         , ConnectResponse      }, 
{ L_CONNECT_CONFIRM          , ConnectConfirm       }, 
{ L_DISCONNECT_REQUEST       , DisconnectRequest    }, 
{ L_DISCONNECT_INDICATION    , DisconnectIndication }, 
{ L_DISCONNECT_RESPONSE      , DisconnectResponse   }, 
{ L_DISCONNECT_CONFIRM       , DisconnectConfirm    }, 
{ L_ABORT_REQUEST            , AbortRequest         }, 
{ L_ABORT_INDICATION         , AbortIndication      }, 
{ SYSTEM_FAILURE             , SystemError          }, 
{ DEFAULT                    , Default              }, 
}; 

int incoming_frame_status = 0, incoming_frame_index = 0;  // global!
int incoming_frame_length = 0;
struct Frame
{
   char start_header[6];
   short control;
   short length;
   short cc;
   char *data;
   char end_header[6];
};

Frame incoming_frame;  // global! (tillfälligt).

int ConnectRequest(void)
{
	int return_value;

   if(LINK_STATE == IDLE)
   {
   	return_value = WriteSignaltoSocket(PSOCK_FD, F_CONNECT_REQUEST, SIG_LEN);
   	if(return_value < 0)
      	return SYSTEM_FAILURE;

      LINK_STATE = UOCON;
   }
   else
   {
   	return_value = Abort(BO);
		if(return_value < 0)
      	return SYSTEM_FAILURE;
   }

   return SUCCESS;
}

int ConnectIndication(void)
{
	int return_value;

   if(LINK_STATE == IDLE)
   {
   	return_value = WriteSignaltoSocket(PSOCK_FD, F_CONNECT_RESPONSE, SIG_LEN);
   	if(return_value < 0)
      	return SYSTEM_FAILURE;

      LINK_STATE = UICON;
   }
   else
   {
   	return_value = Abort(BO);
		if(return_value < 0)
      	return SYSTEM_FAILURE;
   }

   return SUCCESS;
}


int ConnectConfirm(void)
{
	Frame frame;
	int return_value, frame_length;

   if(LINK_STATE == IDLE)
   {
   	return_value = Abort(SP);
		if(return_value < 0)
      	return SYSTEM_FAILURE;
   }
   else if(LINK_STATE == UOCON)
   {
   	frame_length = PutDataInFrame("", 0, &frame, SABM);
   	if(frame_length == -10)
      	return SYSTEM_FAILURE;

      return_value = SendFrame(&frame, PSOCK_FD);
      if(return_value < 0)
      	return SYSTEM_FAILURE;
   }
   else
   {
   	return_value = Abort(BO);
		if(return_value < 0)
      	return SYSTEM_FAILURE;
   }

   return SUCCESS;
}

int ConnectResponse(void)
{
	Frame frame;
	int return_value, frame_length;

   if(LINK_STATE == IDLE)
   {
   	return_value = Abort(SU);
		if(return_value < 0)
      	return SYSTEM_FAILURE;
   }
   else if(LINK_STATE == UICON)
   {
   	frame_length = PutDataInFrame("", 0, &frame, UA);
   	if(frame_length == -10)
      	return SYSTEM_FAILURE;

      return_value = SendFrame(&frame, PSOCK_FD);
      if(return_value < 0)
      	return SYSTEM_FAILURE;

      LINK_STATE = DATA;
   }
   else
   {
   	return_value = Abort(BO);
		if(return_value < 0)
      	return SYSTEM_FAILURE;
   }

   return SUCCESS;
}

int DisconnectRequest(void)
{
	Frame frame;
	int return_value, frame_length;

   if(LINK_STATE == IDLE)
   {
   	return_value = Abort(SU);
		if(return_value < 0)
      	return SYSTEM_FAILURE;

      LINK_STATE = IDLE;
   }
   else if(LINK_STATE == DATA)
   {
   	frame_length = PutDataInFrame("", 0, &frame, DISC);
   	if(frame_length == -10)
      	return SYSTEM_FAILURE;

      return_value = SendFrame(&frame, PSOCK_FD);
      if(return_value < 0)
      	return SYSTEM_FAILURE;

      LINK_STATE = UODCON;
   }
   else
   {
   	return_value = Abort(BO);
		if(return_value < 0)
      	return SYSTEM_FAILURE;
   }

   return SUCCESS;
}

int DisconnectIndication(void)
{
	int return_value;

   if(LINK_STATE == IDLE)
   {
   	return_value = Abort(SP);
		if(return_value < 0)
      	return SYSTEM_FAILURE;
   }
   else if(LINK_STATE == UIDCON)
   {
   	return_value = WriteSignaltoSocket(PSOCK_FD, F_DISCONNECT_RESPONSE, SIG_LEN);
	 	if(return_value < 0)
      	return SYSTEM_FAILURE;

      LINK_STATE = IDLE;
   }
   else
   {
   	return_value = Abort(BO);
		if(return_value < 0)
      	return SYSTEM_FAILURE;
   }

   return SUCCESS;
}

int DisconnectResponse(void)
{
	Frame frame;
	int return_value, frame_length;

   if(LINK_STATE == IDLE)
   {
   	return_value = Abort(SU);
		if(return_value < 0)
      	return SYSTEM_FAILURE;

      LINK_STATE = IDLE;
   }
   else if(LINK_STATE == UIDCON)
   {
   	frame_length = PutDataInFrame("", 0, &frame, UA);
   	if(frame_length == -10)
      	return SYSTEM_FAILURE;

      return_value = SendFrame(&frame, PSOCK_FD);
      if(return_value < 0)
      	return SYSTEM_FAILURE;
   }
   else
   {
   	return_value = Abort(BO);
		if(return_value < 0)
      	return SYSTEM_FAILURE;
   }

   return SUCCESS;
}

int DisconnectConfirm(void)
{
 	int return_value;

   if(LINK_STATE == IDLE)
   {
   	return_value = Abort(SP);
		if(return_value < 0)
      	return SYSTEM_FAILURE;
   }
   else if(LINK_STATE == UODCON)
      LINK_STATE = IDLE;
   else
   {
   	return_value = Abort(BO);
		if(return_value < 0)
      	return SYSTEM_FAILURE;
   }

   return SUCCESS;
}

int AbortRequest(void)
{
	int return_value;

   if(LINK_STATE == IDLE)
   // Do nothing.
   ;
   else
   {
   	return_value = Abort(SP);
		if(return_value < 0)
      	return SYSTEM_FAILURE;
   }

   return SUCCESS;
}

int AbortIndication(void)
{
	int return_value;

   if(LINK_STATE == IDLE)
   ;// Do nothing.

   else
   {
   	return_value = Abort(SU);
		if(return_value < 0)
      	return SYSTEM_FAILURE;
   }

   return SUCCESS;
}

int Status(void)
{
	int return_value;
   char frame_status;

   frame_status = CheckFrame(&incoming_frame);

   return_value = WriteSignaltoSocket(USOCK_FD, L_STATUS, SIG_LEN);
	if(return_value < 0)
     	return SYSTEM_FAILURE;

   return_value = WriteDatatoSocket(USOCK_FD, &frame_status, sizeof(char));
	 	if(return_value < 0)
      	return SYSTEM_FAILURE;

   return SUCCESS;
}

int Abort(short who)
{
	int return_value;

   if((who == SU) || (who == BO))
   {
      return_value = WriteSignaltoSocket(USOCK_FD, L_ABORT_INDICATION, SIG_LEN);
      if(return_value < 0)
			return SYSTEM_FAILURE;
   }
   if((who == SP) || (who == BO))
   {
      return_value = WriteSignaltoSocket(PSOCK_FD, F_ABORT_REQUEST, SIG_LEN);
      if(return_value < 0)
			return SYSTEM_FAILURE;
   }

   LINK_STATE = IDLE;

   return SUCCESS;
}

int Checksum(int data_length)
{
	int sum;

   // Vet ej varför, men det står i laborationshäftet.
   sum = data_length % 128;

   return sum;
}

int PutDataInFrame(char *data, short data_length, Frame *frame, short control)
{
	int frame_length, cc = 0;

   strcat(frame->start_header, "DLEST");
   frame->start_header[5] = 'X';

   frame->control = control;
   frame->length = data_length;

   if(control == I)
   	cc = Checksum(data_length);
	else
   {
   	frame->cc = cc;
      data_length = sizeof(frame->data);
   }

   frame->data = data;

   strcat(frame->start_header, "DLEET");
   frame->end_header[5] = 'X';

   frame_length = 6 + 6 + 2 + 2 + 2 + data_length;

   return frame_length;
}

int ClearFrame(Frame *frame)
{
	frame->start_header[0] = 0;
   frame->end_header[0] = 0;
   frame->control = 0;
   frame->length = 0;
   frame->cc = 0;
   if(frame->data != NULL)
   {
   	delete[] frame->data;
      frame->data = NULL;
   }

   incoming_frame_status = 0;  // Global variabel.
   incoming_frame_index = 0;   // Global variabel.
}

int FillInFrame(Frame *frame, char data, char *charframe)
{
	int status;

	if(CheckFrame(frame) == -1)
   	return FRAME_ERROR;

   if(incoming_frame_status)
   	return FRAME_IS_FULL;

   if(incoming_frame_index == 12)
   {
   	if(frame->control == I)
   	{
       	frame->data = new char[frame->length];
         if(frame->data == NULL)
          	return SYSTEM_FAILURE;

         charframe[incoming_frame_index] = data;
         incoming_frame_index++;
      }
   }
   else
   {
   	charframe[incoming_frame_index] = data;
      incoming_frame_index++;
   }

   return CheckFrame(frame);
}

int CheckFrame(Frame *frame)
{
	int start, end, cc;

	if(incoming_frame_index == 10) //   HEADER_LENGTH = 22
   	incoming_frame_length = HEADER_LENGTH + frame->length;

   if(incoming_frame_index >= 10)
   {
		if(incoming_frame_index == incoming_frame_length)
		{
      	start = CheckStartHeader((char*)frame);
         end = CheckEndHeader((char*)frame);
         cc = CheckCC(frame);
         FixFrameData(frame);  // tar bort de onödiga DLE om det behövs.

         if(start == 0 && end == 0 && cc == 0)
         {
         	incoming_frame_status = 1;
         	return FRAME_IS_FULL;  // frame_is_full = 1
         }
         else
         	return FRAME_ERROR;  // frame_error = -1
      }
   }

   return FRAME_NOT_READY; // frame_not_ready = 0
}

int CheckStartHeader(char *frame)
{
	int index;
	char start[7];
   start[7] = '\0';

   for(index = 0; index < 6; index++)
   	start[index] = (char)frame[index];

   return strcmp(start, "DLESTX");
}

int CheckEndHeader(char *frame)
{
	if(incoming_frame_status != 1)
   	return FRAME_ERROR;

	int index;
	char start[7];
   start[7] = '\0';

   for(index = 0; index < 6; index++)
   	start[index] = (char)frame[incoming_frame_index - 5 + index];

   return strcmp(start, "DLEETX");
}

int CheckCC(Frame *frame)
{
	int cc;
   cc = Checksum(frame->length);

   if(cc == frame->cc)
   	return 0;

   return FRAME_ERROR;
}

int FixFrameData(Frame *frame)
{
	char *tmp;
	int length, index, tmpindex, before = 0;
   length = frame->length;

   for(index = 0; index < frame->length; index++)
	{
   	if(frame->data[index] == 'D' && frame->data[index+1] == 'L' && frame->data[index+2]
== 'E')
       {
			if(before == 1)
         	{ length--; before = 0; }
         else
         	before = 1;
      }
   }

   if(length == frame->length)
   	return SUCCESS;

   tmp = new char[length];
   if(tmp == NULL)
   	return SYSTEM_FAILURE;

   for(index = 0, tmpindex = 0; index < frame->length; index++, tmpindex++)
	{
   	if(frame->data[index] == 'D' && frame->data[index+1] == 'L' && frame->data[index+2] == 'E')
      {
			if(before == 1)
         	{ before = 0; index += 3; }
         else
         	before = 1;
      }

      if(index < frame->length)
      	tmp[tmpindex];
   }

   delete[] frame->data;
   frame->data = tmp;
   frame->length = length;
   return SUCCESS;
}

int SendFrame(Frame *frame, int socket_id)
{
	int frame_length, index = 0, return_value;
   frame_length = GetFrameLength(frame);

	if(socket_id == USOCK_FD)
   {
   	return_value = WriteSignaltoSocket(USOCK_FD, L_DATA_INDICATION, SIG_LEN);
		if(return_value < 0)
     		return SYSTEM_FAILURE;

   	return_value = WriteDatatoSocket(USOCK_FD, frame->data,
frame->length);
 	 	if(return_value < 0)
      	return SYSTEM_FAILURE;
   }
   else if(socket_id == PSOCK_FD)
   {
   	for(index = 0; index < frame_length; index++)
      {
   		return_value = WriteSignaltoSocket(PSOCK_FD, F_DATA_REQUEST, SIG_LEN);
			if(return_value < 0)
     			return SYSTEM_FAILURE;

   		return_value = WriteDatatoSocket(PSOCK_FD, (char
*)&frame[index], sizeof(char));
 	 		if(return_value < 0)
 
      	return SYSTEM_FAILURE;
       }
   }
   else
   	return SYSTEM_FAILURE;

   return SUCCESS;
}

int DataIndication(void)
{
	/*Frame *frame;
	char temp = 'a';
	int return_value, frame_length;

   if(LINK_STATE == IDLE)
   	Abort(SP);
   else if(LINK_STATE == UICON)
   {
   	return_value = ReadDatafromSocket(PSOCK_FD, &temp, TWO_BYTES);
   	if(return_value < 0)
      	return SYSTEM_FAILURE;

      return_value = ReadDatafromSocket(PSOCK_FD, temp, BYTE_LEN);
   	if(return_value < 0)
      return SYSTEM_FAILURE;
   }
   else
   {
   	return_value = Abort(BO);
		if(return_value < 0)
      	return SYSTEM_FAILURE;
   }

   if(frame != NULL)
   	delete[] frame;
*/

   return SUCCESS;

}

void main(int argc, char *argv[])
{
	int tmp_fd1, PSOCK;
	printf("LINK_LAYER har startat...\n");

   if((PSOCK = CreateUnixClientSocket(UPATH)) < 0)
   {
   	fprintf(stderr, "Can't create unix client signal socket 111\n");
      exit(1);
   }

   printf("LINK_LAYER har skapat FTP_LAYER Socket...\n");
   if((tmp_fd1 = CreateUnixServerSocket(PPATH)) < 0)
   {
   	fprintf(stderr, "Can't create unix server signal socket.\n");
      exit(1);
   }

   printf("LINK_LAYER har skapat PHYS_LAYER Socket...\n");
   switch(fork())
   {
   	case -1:
      			fprintf(stderr, "Fork failed.\n");

      case  0:
		printf("Fuck you\n\n");
      			close(PSOCK_FD);
               close(USOCK_FD);
               execv("./phys_layer", argv);
               exit(1);

      default:
      			if((PSOCK = AcceptConnection(tmp_fd1)) < 0)
               {
               	fprintf(stderr, "Can't accept unix client signal socket.\n");
                  exit(1);
               }

               MainLoop();
               exit(1);
   }
}

void MainLoop(void)
{
	int return_value;
	do
   {
		return_value = PollSocket(PSOCK_FD, USOCK_FD, NULL);
      if(return_value < 0)
      	return;

      return_value = ReadSignalfromSocket(return_value - 1, SIG_LEN);
      return_value = (* FindAction(return_value, ALIST))();
		if(return_value < 0)
			return ;

   } while(return_value >= 0);

}

int DataRequest(void)
{
	return 10;
}

int Default(void)
{
	return 10;
}


int GetFrameLength(Frame *frame)
{
	return frame->length;
}

int SystemError(void)
{
	return 108;
}