problem closing a socket

This is a discussion on problem closing a socket within the C Programming forums, part of the General Programming Boards category; I can't close the socket of my server! It does everything as it should but this I have this code ...

  1. #1
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    problem closing a socket

    I can't close the socket of my server! It does everything as it should but this


    I have this code for my client (which works just fine):

    Code:
    #include <sys/types.h>   /* required include files */
    #include <sys/socket.h>
    #include <netinet/in.h>  /* bind in internet domain */
    #include <netdb.h>
    #include <string.h>
    #include <stdio.h>
    #include <stdlib.h>
    #include <unistd.h>
    
    
    #define SOCKET_ERROR        -1
    #define STRGLEN 100  /* message string length */
    const int APORT = 1234;   /* chosen port number */
    
    
    
    // FUNCTIONS
    
    
    /*	Function send_file
    		send the content of one file to the server	*/
    void send_file(int s, char* namefile){
    	FILE* p;
    	int i;
    	char ch;
    	char length[100],text[1000];
    
    	p=fopen(namefile,"r");
    	i=0;
    	ch = getc(p);  /* read 1st character in file */
    	while( ch != EOF){ /* keep going until end of file */
    		text[i]=ch;
    		ch = getc(p);  /* read next character in in-file */
    		i++;
    	}
    	fclose(p);
    	text[i]='\0';
    	sprintf(length, "%d", i);
    	send(s, length, strlen(length), 0);
    	send(s, text, i, 0);
    }
    
     
    /*	Function main	*/
    main(int argc, char *argv[]){  /* argv[1] is server hostname argv[2] is port */
    	char string[STRGLEN];  /* message string */
    	register int s;   /* created socket (index to unix descriptor table) */
    	struct hostent *hp;  /* pointer to host structure */
    	struct sockaddr_in sin;  /* socket structure */
    	float number;
    	int i;   /* loop counter */
    	int selection;	/* menu choice */
    	int num, server_port;
    	char c;
    	
    	
    	/*  look up the network address of server hostname */
    	hp = gethostbyname(argv[1]);
    	if( hp==0 ){  
    		fprintf(stderr, "unknown host %s\n", argv[1]);
    		exit(1);
    	}
    	
    	/* create socket in the Internet domain(AF_INET) that will
    	be connection oriented SOCK_STREAM. (connectionless is 
    	SOCK_DGRAM) 3rd argument indicated default TCP/IP protocol */
    	if( (s = socket(AF_INET, SOCK_STREAM, 0)) <0 ){ 
    		perror("client: socket"); 
    		exit(1); 
    	}
    	
    	/* Create the address we will be connecting to We use port
    	1234 but put it into network byte order.
    	Also we use bcopy to copy the network number */
    	sin.sin_family = AF_INET;
    
    	server_port=atoi(argv[2]);
    	sin.sin_port = htons(server_port);
    	bcopy(hp->h_addr, &sin.sin_addr, hp->h_length);
    	
    	/* Try to connect to the address.
    	For this to succeed, the server must already have bound
    	this address, and must have issued a listen() request. */
    	if(connect(s, (struct sockaddr *)&sin, sizeof(sin)) < 0){
    		perror("client: connect");
    		exit(1); 
    	}
    	
    	//Save a file
    				printf("Enter file's name:\t");
    				scanf("%[^\n]", string);
    				printf("%s", string);
    				send(s, string, STRGLEN, 0);
    				//send_file(s, string);
    				
     
    
       /* close connection, since were finished on both sides */
    
       close(s);
    
    }


    and this for my server:

    Code:
    #include <sys/types.h>  /* required include files */
    #include <sys/socket.h>
    #include <netinet/in.h>
    #include <netdb.h>
    #include <stdlib.h>
    #include <stdio.h>
    #include <string.h>
    #include <ctype.h>
    #include <unistd.h>
    
    
    #define SOCKET_ERROR        -1
    #define STRGLEN 100  /* message string length */
    const int APORT = 1235;  /* port number */
    
    
    
    
    //DATA STRUCTURES
    
    typedef struct{
    	char nameUser[100];
    	int numUser;
    }user;
    
    
    typedef struct userStruct{
    	user u;
    	struct userStruct* next;
    }userknot;
    
    typedef struct{
    	userknot* start;
    	userknot* end;
    	int totalUsers;
    }userslist;
    
    typedef struct{
    	char nameFile[100];
    	int numFile;
    	int numUser;
    	//time_t t;
    }textFile;
    
    typedef struct fileStruct{
    	textFile tf;
    	struct fileStruct* next;
    }fileknot;
    
    typedef struct{
    	fileknot* start;
    	fileknot* end;
    	int totalFiles;
    }fileslist;
    
    
    
    //FUNCTIONS
    
    
    /*   Function create_users_list
    		This function initializes the users list */
    userslist* create_users_list(userslist* list){
    	if(list==NULL)return NULL;
    	list->start=list->end=NULL;
    	list->totalUsers=0;
    	return list;
    }
    
    
    /*   Function create_files_list
    		This function initializes the files list */
    fileslist* create_files_list(fileslist* list){
    	if(list==NULL)return NULL;
    	list->start=list->end=NULL;
    	list->totalFiles=0;
    	return list;
    }
    
    
    /*	Function add_file
    		add a new file */
    void add_file(char* name_file, int nFile, int nUser, fileslist* flist){
    	fileknot* fk;
    	fk=(fileknot*)malloc(sizeof(fileknot));
    	if(fk==NULL){
    		printf("Can't add a new file");
    		exit(-1);
    	}
    	else{
    		strcpy(fk->tf.nameFile, name_file);
    		fk->tf.numFile=nFile;
    		fk->tf.numUser=nUser;
    		if(flist->totalFiles==0){
    			flist->end=flist->start=fk;
    		}
    		else{
    			flist->end->next=fk;
    			flist->end=fk;
    		}
    		flist->end->next=NULL;
    		flist->totalFiles++;
    	}
    }
    
    
    /*	Function get_savings
    		This function gets back the data that has been saved previously */
    void get_savings(FILE* p, userslist* ul, fileslist* fl)
    {
    	userknot* uk;
    	fileknot* fk;
    	int i, length;
    	char string[100];
    
    	fgets(string, STRGLEN, p); 
    	sscanf(string, "%d", &(ul->totalUsers));	//read the total number of users
    	uk=(userknot*)malloc(sizeof(userknot));
    	if(uk==NULL){
    		printf("Couldn't allocate a userknot\n");
    		exit(-1);
    	}
    	if(ul->totalUsers!=0){
    		ul->start=uk;
    		fgets(string, STRGLEN, p);	//read the name of the user
    		sscanf(string, "%[^\n]", uk->u.nameUser);
    		length=strlen(string);
    		uk->u.nameUser[length-1]='\0';
    		fgets(string, STRGLEN, p);	//read the number of the user
    		sscanf(string, "%d", &(uk->u.numUser));
    		i=1;
    		while(i<ul->totalUsers){
    			uk->next=(userknot*)malloc(sizeof(userknot));
    			uk=uk->next;
    			fgets(string, STRGLEN, p);	//read the name of the user
    			sscanf(string, "%[^\n]", uk->u.nameUser);
    			length=strlen(string);
    			uk->u.nameUser[length-1]='\0';
    			fgets(string, STRGLEN, p);	//read the number of the user
    			sscanf(string, "%d", &(uk->u.numUser));
    			i++;
    		}
    		uk->next=NULL;
    		ul->end=uk;
    	}
    
    	fgets(string, STRGLEN, p); 
    	sscanf(string, "%d", &(fl->totalFiles));	//read the total number of users
    	fk=(fileknot*)malloc(sizeof(fileknot));
    	if(fk==NULL){
    		printf("Couldn't allocate a userknot\n");
    		exit(-1);
    	}
    	if(fl->totalFiles!=0){
    		fl->start=fk;
    		fgets(string, STRGLEN, p);	//read the name of the file
    		sscanf(string, "%[^\n]", fk->tf.nameFile);
    		length=strlen(string);
    		fk->tf.nameFile[length-1]='\0';
    		fgets(string, STRGLEN, p);	//read the number of the file
    		sscanf(string, "%d", &(fk->tf.numFile));
    		fgets(string, STRGLEN, p);	//read the number of the user
    		sscanf(string, "%d", &(fk->tf.numUser));
    		i=1;
    		while(i<fl->totalFiles){
    			fk->next=(fileknot*)malloc(sizeof(fileknot));
    			fk=fk->next;
    			fgets(string, STRGLEN, p);	//read the name of the file
    			sscanf(string, "%[^\n]", fk->tf.nameFile);
    			length=strlen(string);
    			fk->tf.nameFile[length-1]='\0';
    			fgets(string, STRGLEN, p);	//read the number of the file
    			sscanf(string, "%d", &(fk->tf.numFile));
    			fgets(string, STRGLEN, p);	//read the number of the user
    			sscanf(string, "%d", &(fk->tf.numUser));
    			i++;
    		}
    		fk->next=NULL;
    		fl->end=fk;
    	}
    }
    
    
    /*	Function print_all_files
    		this function prints the list of all the files of one user  */
    void print_all_files(int num_user, fileslist* fl){
    	fileknot* fk;
    	char string[STRGLEN];
    	int num, n=0, go_on, nSentFiles=0;
    	fk=(fileknot*)malloc(sizeof(fileknot));
    	num=fl->totalFiles;
    	sprintf(string, "%d", num);
    	printf("nb of files: %d\n", num);	/* send the total number of files */
    	if(num!=0){
    		fk=fl->start;
    		while(n<num){
    			if(fk->tf.numUser==num_user){
    				strcpy(string, fk->tf.nameFile);
    				printf("%s\n", string);
    				nSentFiles++;
    			}
    			fk=fk->next;
    			n++;
    		}
    		printf("nSentfiles: %d\n", nSentFiles);
    	}
    }
    
    
    /*	Function save_file	
    		receive the content of one file from the client, encode it and save 
    		it on the server	*/
    void save_file(int s, char* namefile){
    	int max, total = 0, i;
    	const int bsize = 1024;
    	char c, length[bsize+1], buffer[bsize+1],text[bsize+1];
    	int read = bsize;
    	FILE* p;
     
    	length[0]=0;	//initialize length
    	recv(s, length, bsize, 0);
    	sscanf(length, "%d", &max);
    	text[0] = 0; // initialize for strcat()
    	while(read == bsize){
    		read = recv(s, buffer, bsize, 0);
    		if(read < 0){
    			printf("Server: Error while receiving file\n"); // error, bail out
    			exit(-1);
    		}
    		total += read;
    		if(total > max){
    			printf("Error: overflow\n"); // overflowv
    			exit(-1);
    		}
    		buffer[read] = 0;
    		strcat(text, buffer);	/* in case the string is too long and need more than one read */
        }
    	total=strlen(text);
    	printf("debug: %s\n", text);
    	i=0;
    	p=fopen(namefile, "w");
    	while(i<total-1){
    		c=(char)(text[i]+5);
    		putc(c, p);
    		i++;
    	}
    	fclose(p);
    }
    
    
    /*	Function main */
    main(void){
    	char string[STRGLEN], name[STRGLEN], name_file[STRGLEN];
    	int fromlen;
    	char hostname[64]; /* local machine hostname */
    	struct hostent *hp; /* gethostbyname return ptr */
    	register int s; /* socket descriptor, or -1 if error */
    	register int ns; /* created new socket for accept */
    	struct sockaddr_in  sin; /* socket structure */
    	struct sockaddr_in fsin; /* socket str. for accept*/
    	float number=0.0;
    	int i;  /* loop counter */
    	int selection;	/* menu choice */
    	int num_user, num_file;
    	userslist* ulist;
    	fileslist* flist;
    	FILE* p;
    	char* text;
    
    
    	text=(char*)malloc(1000*sizeof(char));
    	ulist=(userslist*)malloc(sizeof(userslist));
    	flist=(fileslist*)malloc(sizeof(fileslist));
    
    	
    	/* first need to know our hostname. */
    	gethostname(hostname, sizeof(hostname));
    	
    	/* Next look up the network address of our host.*/
    	if((hp = gethostbyname(hostname)) == NULL){ 
    		fprintf(stderr, "%s: unknown host\n", hostname);
    		exit(-1); 
    	}
    	
    	/* create socket in Internet domain(AF_INET), that is 
    	connection oriented (SOCK_STREAM) rather than
    	connectionless (SOCK_DGRAM),
    	arg3=0 for default TCP/IP protocol*/
    	if(( s = socket(AF_INET, SOCK_STREAM, 0) ) < 0){ 
    		perror("server: socket"); 
    		exit(-1); 
    	}
    	
    	/* Create the address to connecting to. We use port
    	APORT but put it into network byte order.
    	Also we use bcopy to copy the network number. */
    	bzero(&sin, sizeof(sin));
    	sin.sin_family = AF_INET;  /* IP protocol */
    	/* sin.sin_addr.s_addr = INADDR_ANY;*/
    	sin.sin_port = htons(APORT);
    	bcopy(hp->h_addr, &sin.sin_addr, hp->h_length);
    	
    	/* Try to bind(address and port no.)to socket s */
    	if(bind(s, (struct sockaddr *)&sin, sizeof(sin)) < 0){ 
    		perror("server: bind"); 
    		exit(-1); 
    	}
    	
    	/* server ready, listen on socket s max 5 requests queued*/
    	if(listen(s, 5) < 0) {
    		perror("server: listen"); 
    		exit(-1); 
    	}
    
     
    
       /* Accept connections then fork ns (new socket) that
       will be connected to the client. fsin will contain
       the IP address of the client. */
    	bzero(&fsin, sizeof(fsin));
    	fromlen = sizeof(fsin);
    	if((ns = accept(s, (struct sockaddr *)&fsin, &fromlen))<0){
    		perror("server: accept"); 
    		exit(-1);
    	}
    
    	ulist=create_users_list(ulist);			//Initialization of the users list
    	if(ulist==NULL){
    		printf("Impossible to allocate a users list");
    		exit(-1);			//Exit the program
    	}
    	flist=create_files_list(flist);			//Initialization of the files list
    	if(flist==NULL){
    		printf("Impossible to allocate a files list");
    		exit(-1);			//Exit the program
    	}
    
    	/* get save file */
    	p=fopen("save.txt","r");
    	if(p!=NULL){
    		get_savings(p, ulist, flist);
    		fclose(p);
    	}
    
    	recv(ns, string, STRGLEN, 0);		//read name of the file
    	strcpy(name_file, string);
    	num_file=flist->totalFiles+1;
    	num_user=1;
    	add_file(name_file, num_file, num_user, flist);
    	print_all_files(num_user, flist);
    	//save_file(ns, name_file);
    				
    	
    	/* We can simply use close() to terminate the
    	connection, since we're done with both sides */
    	close(s);
    }

    even if I put exit() instead of close, my program still freezes after the print_all_files. Well not freezes maybe, but I don't have the command prompter as I should.
    Can anyone help me?

  2. #2
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    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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