MyServer.c

//159.334 assignment1

#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <winsock.h>
#include <dirent.h>
#include <sys/types.h>
#include <time.h>
#define WSVERS MAKEWORD(2,0) 
//for wsastartup() use only, make 2 byte -> 16bit word
WSADATA wsadata;


#define BUFFERSIZE 200
#define SEGMENTSIZE 198

static const char USER[] = "admin";
static const char PW[] = "admin";
void str_cut(char* output_string, const char* input_string, int start, int end);
int recv_msg(char* receive_buffer,int ns);
char rfc[20][4];



main(int argc, char *argv[]){
	strcpy(rfc[0],"SYST");
	strcpy(rfc[1],"USER");
	strcpy(rfc[2],"PASS");
	strcpy(rfc[3],"QUIT");
	
	const char username[] = "admin";
	const char password[] = "admin";
	const int cport = 1234;
	struct sockaddr_in localaddr,remoteaddr,data_addr_act;
	SOCKET s, ns, s_data_act;
	
	char send_buffer[BUFFERSIZE],receive_buffer[BUFFERSIZE];
	char temp[BUFFERSIZE];
	char bool;
	memset(&send_buffer,0,BUFFERSIZE);
	memset(&receive_buffer,0,BUFFERSIZE);	//init buffers
	
	int n,bytes,addrlen;
	memset(&localaddr,0,sizeof(localaddr));
	memset(&remoteaddr,0,sizeof(remoteaddr));	//init local and remote addresses
	
	


	//winsock init	
	printf("\nSERVER : Initialising Winsock ...\n");
	if(WSAStartup(WSVERS, &wsadata) != 0){
		WSACleanup();
		printf("WSAStartup failed. Error Code : %d", WSAGetLastError());
		exit(1);
	}
	printf("SERVER : Initialised.\n");

	//SOCKET
	s = socket(PF_INET, SOCK_STREAM, 0);	//init s socket(A/P family[PF_INET for tcp] , transport[SOCK_STREAM for tcp] , protocol specified [0 for no specification])
	if (s < 0) {
		printf("SERVER : socket failed\n");
		exit(1);
	}
	localaddr.sin_family = AF_INET;	//address family set for tcp
	if (argc == 2) {	//decision on using specified port or default port
		localaddr.sin_port = htons((u_short)atoi(argv[1]));
		printf("SERVER : Communication port is specified to %s. \n",argv[1]);
	}else{
		localaddr.sin_port = htons(cport);
		printf("SERVER : No port specified, use default port %d.\n",cport);
	}
	localaddr.sin_addr.s_addr = INADDR_ANY;	//s_addr, 32 bit unsigned long IP addr, INADDR_ANY -> 0,0,0,0 local
	
	//BIND: bind socket with local address
	if (bind(s,(struct sockaddr *)(&localaddr),sizeof(localaddr))!=0){
		printf("SERVER : Bind failed!\n");
		exit(0);
	}
	printf("SERVER : binding succeeded.\n");

	//LISTEN
	listen(s,5);
	printf("SERVER : Listening...\n");

	//infinite loop
	while(1){
		addrlen = sizeof(remoteaddr);
		ns = accept(s,(struct sockaddr *)(&remoteaddr),&addrlen);
		if (ns < 0){
			sprintf(send_buffer,"421 Service not available, closing control connection\r\n");
			break;
		}
		printf("SERVER : accepted a connection from client IP %s port %d \n",inet_ntoa(remoteaddr.sin_addr),ntohs(localaddr.sin_port));
		//inet_ntoa converts Ipv4 address into ASCII string in internet standard dotted-decimal format
		//ntohs converts a u_short from TCP/IP network byte order to host byte order (format conversion blah blah)

		//system info feed if 421 not happen
		sprintf(send_buffer,"220 Microsoft FTP service\r\n");
		bytes = send(ns,send_buffer,strlen(send_buffer),0);
		if(bytes<0)break;

		while(1){
			memset(&receive_buffer,0,BUFFERSIZE);
			bytes = recv_msg(receive_buffer,ns);
			if(bytes < 0)break;
			memset(&send_buffer,0,BUFFERSIZE);
			
			if(strncmp(receive_buffer,"USER",4) && strncmp(receive_buffer,"PASS",4) && strncmp(receive_buffer,"SYST",4) 
				&&strncmp(receive_buffer,"PORT",4) && strncmp(receive_buffer,"STOR",4) && strncmp(receive_buffer,"RETR",4)
				&&strncmp(receive_buffer,"LIST",4) && strncmp(receive_buffer,"QUIT",4)){
                sprintf(send_buffer,"202 Command not implemented, superfluous at this site. \r\n");
                bytes = send(ns,send_buffer,strlen(send_buffer),0);
            }
			
			if(strncmp(receive_buffer,"USER",4) == 0){
				sprintf(send_buffer,"331 password required\r\n");
				bytes = send(ns,send_buffer,strlen(send_buffer),0);
				if(bytes < 0)break;
			}
			
			if(strncmp(receive_buffer,"PASS",4) == 0){
				sprintf(send_buffer,"230 logged in\r\n");
				bytes = send(ns,send_buffer,strlen(send_buffer),0);
				if(bytes < 0)break;
			}
			
			if(strncmp(receive_buffer,"QUIT",4) == 0){
				sprintf(send_buffer,"221 Service closing control connection\r\n");
				bytes = send(ns,send_buffer,strlen(send_buffer),0);
				if(bytes < 0)break;
				exit(1);
			}
	
			if(strncmp(receive_buffer,"PORT",4) == 0){
				int act_ip[6], port_dec, connect_result;
				unsigned char act_port[2];
				char data_addr[20];
				
				sscanf(receive_buffer,"PORT %d,%d,%d,%d,%d,%d",&act_ip[0],&act_ip[1],&act_ip[2],&act_ip[3],&act_port[0],&act_port[1]);
				sscanf(receive_buffer,"PORT %d,%d,%d,%d,%d,%d",&act_ip[0],&act_ip[1],&act_ip[2],&act_ip[3],&act_ip[4],&act_ip[5]);
				sprintf(data_addr,"%d.%d.%d.%d",act_ip[0],act_ip[1],act_ip[2],act_ip[3]);
				port_dec = (act_port[0] << 8) + act_port[1];
				data_addr_act.sin_port = htons(port_dec);			
				data_addr_act.sin_addr.s_addr = inet_addr(data_addr);
				data_addr_act.sin_family = AF_INET;
				s_data_act = socket(AF_INET, SOCK_STREAM, 0);
				if(s_data_act == INVALID_SOCKET){
					printf("SERVER : socket function failed with error:%d \n",WSAGetLastError());
					WSACleanup();
					return 1;
				}
				connect_result = connect(s_data_act, (struct sockaddr *) & data_addr_act, sizeof(data_addr_act));
				if(connect_result == SOCKET_ERROR){
					printf("SERVER : connect function failed with error:%d \n",WSAGetLastError());
					connect_result == closesocket(s_data_act);
					if(connect_result == SOCKET_ERROR)
						printf("SERVER : close socket function failed with error:%d \n",WSAGetLastError());
					WSACleanup();
					return 1;
				}
				printf("SERVER : data connection established.\n");
				sprintf(send_buffer,"200 PORT command successful\n");
				bytes = send(ns,send_buffer,strlen(send_buffer),0);
				if(bytes < 0) break;
			}

			if(strncmp(receive_buffer,"LIST",4) == 0){
				DIR *dp;
				struct dirent *ep;
				sprintf(send_buffer,"125 data connection already open, transfer starting\r\n");
				bytes = send(ns,send_buffer,strlen(send_buffer),0);
				if(bytes < 0) break;
				dp = opendir("./");
				if(dp != NULL){
					while(ep = readdir(dp)){
						//puts(ep->d_name);
						sprintf(temp,"200\t");
						strcat(temp,ep->d_name);
						strcat(temp,"\r\n");
						sprintf(send_buffer,temp);
						bytes = send(s_data_act, send_buffer,strlen(send_buffer),0);
						if(bytes < 0) break;						
					}
					(void) closedir (dp);
				}else
					perror("SERVER : couldn't open the directory.");
				closesocket(s_data_act);
				sprintf(send_buffer,"226 closing data connection. Requested file action successful.\r\n");
				bytes = send(ns,send_buffer,strlen(send_buffer),0);
				if(bytes < 0) break;
			}
			
			if(strncmp(receive_buffer,"STOR",4) == 0){
				char filename[100];
				char data_buffer[BUFFERSIZE];
				FILE *fout;
				sprintf(send_buffer,"125 data connection already open, transfer starting\r\n");
				bytes = send(ns,send_buffer,strlen(send_buffer),0);
				str_cut(filename,receive_buffer,5,strlen(receive_buffer));
				fout=fopen(filename,"w");
				while(1){
					bytes = recv_msg(data_buffer,s_data_act);
					printf("%s\n",data_buffer);
					if(bytes<=0)break;
					fprintf(fout,"%s\r\n",data_buffer);
				}
				fclose(fout);
				closesocket(s_data_act);
				sprintf(send_buffer,"226 file uploaded.\r\n");
				bytes = send(ns,send_buffer,strlen(send_buffer),0);
				if(bytes<0)break;
			}
			
			if(strncmp(receive_buffer,"RETR",4) == 0){
				char filename[100];
				char data_buffer[BUFFERSIZE]; 	
				FILE *fin;
				sprintf(send_buffer,"125 data connection already open, transfer starting\r\n");
				bytes = send(ns,send_buffer,strlen(send_buffer),0);
				if(bytes<0)break;
				str_cut(filename,receive_buffer,5,strlen(receive_buffer));
				fin = fopen(filename,"r");
				if(fin == NULL){
					printf("Server: cannot open %s",filename);
					break;
				}
				//while(fscanf(fin, "   %s   ", data_buffer) != EOF){
				while(fgets(data_buffer,BUFFERSIZE,fin)!=NULL){
					//fscanf(fin,"%s\r\n",data_buffer);
					//fgets(data_buffer,BUFFERSIZE,fin);
					//printf(data_buffer);
					sprintf(send_buffer,"%s\n",data_buffer);
					bytes = send(s_data_act,send_buffer,strlen(send_buffer),0);
					if(bytes<=0) break;
				}
				fclose(fin);
				closesocket(s_data_act);
				sprintf(send_buffer,"226 file downloaded.\r\n");
				bytes = send(ns,send_buffer,strlen(send_buffer),0);
				if(bytes < 0)break;
				
			}
			
			if(strncmp(receive_buffer,"SYST",4 == 0)){
				char filename[] = "syst_info.txt";
				FILE *fin;
				char data_buffer[BUFFERSIZE];
				sprintf(send_buffer,"125 data connection already open, transfer starting\r\n");
				bytes = send(ns,send_buffer,strlen(send_buffer),0);
				if(bytes<0)break;
				fin = fopen (filename,"r");
				if(fin == NULL){
					printf("Server: cannot open %s",filename);
					break;
				}
				while(fgets(data_buffer,BUFFERSIZE,fin)!=NULL){
					//printf(data_buffer);
					bytes = send(s_data_act,send_buffer,strlen(send_buffer),0);
					if(bytes<0) break;
				}
				fclose(fin);
				closesocket(s_data_act);
				sprintf(send_buffer,"226 system info done.\r\n");
				bytes = send(ns,send_buffer,strlen(send_buffer),0);
				if(bytes<0)break;
			}
			
			
		}



		closesocket(ns);
		printf("SERVER : disconnected from %s \r\n", inet_ntoa(remoteaddr.sin_addr));
		printf("SERVER : exit?(y/n)");
		bool = getchar();
		if(bool=='y')exit(1);
		
	}
	closesocket(s);
	return 0;
}














void str_cut(char* output_string, const char* input_string, int start, int end){
	int i = 0;
	int j = 0;
	for(j = start; j <= end; j++){
		output_string[i] = input_string[j];
		i++;
	}
}

int recv_msg(char* receive_buffer,int ns){
	int n = 0;
	int bytes = 0;
	while(1){
		bytes = recv(ns,&receive_buffer[n],1,0);
		if(bytes<=0) break;
		if(receive_buffer[n] == '\n'){
			receive_buffer[n] = '\0';
			break;
		}
		if(receive_buffer[n] != '\r') n++;
	}
	//if(bytes <= 0) break;
	printf("-->Debug: message reads from client <%s>\r\n", receive_buffer);
	return bytes;
}