server.c

/******************************************************************************
* myServer.c
* 
* Writen by Prof. Smith, updated Jan 2023
* Use at your own risk.  
*
*****************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/uio.h>
#include <sys/time.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <strings.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdint.h>

#include "networks.h"
#include "safeUtil.h"
#include "PDUTransmit.h"
#include "pollLib.h"
#include "serverMessageHandler.h"
#include "handleTable.h"

#define MAXUSERDATA 200	//Users can send messages of at most 200 bytes (199 + NULL Byte)
#define PDUHEADERLEN 3	//
#define DEBUG_FLAG 1

int recvFromClient(int clientSocket);
int checkArgs(int argc, char *argv[]);

//these functions already existed in the demo code, i dont see any reason we shouldnt be able to use them :)
void addNewSocket(int mainServerSocket, int debugFlag){
	int clientSocket= tcpAccept(mainServerSocket, DEBUG_FLAG);
	addToPollSet(clientSocket);
}
void processClient(int clientSocket){
	int msgLen=recvFromClient(clientSocket);

	if(msgLen==0){	//client is closed
		handleTable_removeBySocket(clientSocket);	//remove them from handle table and pollset
		removeFromPollSet(clientSocket);
		close(clientSocket);		//close the file descriptor
		// printf("Socket %d: Connection closed by other side\n", clientSocket);	
	}
}
void serverControl(int mainServerSocket){
	int pollRet=pollCall(-1);
	if(pollRet==mainServerSocket){
		addNewSocket(mainServerSocket, DEBUG_FLAG);		//performs TCP actions needed for adding a new client
	}else{
		processClient(pollRet);		//handles all messages recieved from clients (aside from initial setup)
	}
}
int main(int argc, char *argv[]){
	int mainServerSocket = 0;   						//socket descriptor for the server socket
	int portNumber = checkArgs(argc, argv);				//parse the users intended port number for server if one is provided
	mainServerSocket = tcpServerSetup(portNumber);		//create the server socket
	setupPollSet();										//create pollSet
	addToPollSet(mainServerSocket);						
	handleTable_setup();	//create a new handler table
	while(1){
		serverControl(mainServerSocket);	//handle client connections
	}
	close(mainServerSocket);
	return 0;
}


int recvFromClient(int clientSocket)
{
	uint8_t dataBuffer[MaxIPMsgSize];
	int dataLength = 0;	//includes the flag, and then the user message
	//now get the data from the client_socket
	if ((dataLength = recvPDU(clientSocket, dataBuffer, MaxIPMsgSize)) < 0)
	{
		perror("recv call");
		exit(-1);
	}
	if (dataLength > 0)
	{
		// printf("Sock %d: Message received, length: %d Data: %s\n", clientSocket, dataLength, dataBuffer);
		
		handleMessage(clientSocket, (struct PDUMsg*) dataBuffer);	
	}
	return dataLength;	//0 for connection closed, otherwise non-zero (message length)
}



int checkArgs(int argc, char *argv[])
{
	// Checks args and returns port number
	int portNumber = 0;

	if (argc > 2)
	{
		fprintf(stderr, "Usage %s [optional port number]\n", argv[0]);
		exit(-1);
	}
	
	if (argc == 2)
	{
		portNumber = atoi(argv[1]);
	}
	
	return portNumber;
}