Startpunkten

2026-03-05 13:37:25 +01:00
commit 00233de938
22 changed files with 4613 additions and 0 deletions
--- a/link.cpp
+++ b/link.cpp
@@ -0,0 +1,689 @@
+#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)