How can I stop the while? - c

Question

I have A TCP Server-Client where I enter a number with the number of times that I want to send the word to the server. So I send correctly because I print the information on a loop(in client) but in the server shows infinitely because I put while(1) but if I don't use just print it one time. I don't want to send the number to the server.
If I enter the number 4 I want to print the word "hello" four times
This is the server, now it's printing infinitely obviously.
#define MAXPENDING 5 /* Maximum number of simultaneous connections */
#define BUFFSIZE 255 /* Size of message to be received */
void err_sys(char *mess) { perror(mess); exit(1); }
void handle_client(int sock) {
char buffer[BUFFSIZE];
int received = -1;
while (1) {
/* Read from socket */
read(sock, &buffer[0], BUFFSIZE);
printf("Message from client: %s\n", buffer);
/* Write to socket */
write(sock, buffer, strlen(buffer) + 1);
/* Close socket */
close(sock);
}
}
int main(int argc, char *argv[]) {
struct sockaddr_in echoserver, echoclient;
int serversock, clientsock;
int result;
/* Check input arguments */
if (argc != 2) {
fprintf(stderr, "Usage: %s <port>\n", argv[0]);
exit(1);
}
/* Create TCP socket */
serversock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
if (serversock < 0) {
err_sys("Error socket");
}
/* Set information for sockaddr_in structure */
memset(&echoserver, 0, sizeof(echoserver)); /* we reset memory */
echoserver.sin_family = AF_INET; /* Internet/IP */
echoserver.sin_addr.s_addr = htonl(INADDR_ANY); /* ANY address */
echoserver.sin_port = htons(atoi(argv[1])); /* server port */
/* Bind socket */
result = bind(serversock, (struct sockaddr *) &echoserver, sizeof(echoserver));
if (result < 0) {
err_sys("Error bind");
}
/* Listen socket */
result = listen(serversock, MAXPENDING);
if (result < 0) {
err_sys("Error listen");
}
while (1) {
unsigned int clientlen = sizeof(echoclient);
/* Wait for a connection from a client */
clientsock = accept(serversock, (struct sockaddr *) &echoclient, &clientlen);
if (clientsock < 0) {
err_sys("Error accept");
}
fprintf(stdout, "Client: %s\n", inet_ntoa(echoclient.sin_addr));
/* Call function to handle socket */
handle_client(clientsock);
}
}
This is the client
printf("Enter a number between 0 to 9[0 to exit]: ");
fgets(number, 100, stdin);
while(strtol(number,&pEnd,10)!=0){
while (!((strtol(number,&pEnd,10) <= 9) && (strtol(number,&pEnd,10) >= 0))) {
printf("[ERROR] The number you entered is out of range\n");
printf("Enter a number between 0 to 9[0 to exit]: ");
fgets(number, 100, stdin);
}
if(strtol(number,&pEnd,10)!=0){
printf("Enter a word: ");
fgets(buffer, 100, stdin);
for(int i=0;i<strtol(number,&pEnd,10);i++){
write(sock, buffer, strlen(buffer) + 1);
fprintf(stdout, " sent \n");
read(sock, buffer, BUFFSIZE);
fprintf(stdout, " %s ...done \n", buffer);
}
}
printf(" Enter a number between 0 to 9[0 to exit]: ");
fgets(number, 100, stdin);
}

Answer 1

There are multiple problems in you code:
you do not test if read() succeeds. You should break from the loop if it fails.
you unconditionally close the socket in the body of the loop: the next read will fail and return -1 immediately, you will print a bogus message and iterate at nauseam.
you call strlen() and printf() with a buffer that might not be null terminated, potentially causing undefined behavior.
Here is a modified version:
void handle_client(int sock) {
char buffer[BUFFSIZE];
int received = -1;
if (sock < 0)
return;
for (;;) {
/* Read from socket */
received = read(sock, buffer, sizeof(buffer) - 1);
if (received <= 0)
break;
buffer[received] = '\0';
printf("Message from client: %s\n", buffer);
/* Write to socket */
write(sock, buffer, received);
}
/* Close socket */
close(sock);
}

Answer 2

You have an infinite loop in your hands normally that is not recommended but if you need to do it then add a if statement such:
while(1){
if(clientsock < 0){/*statement that is met so that your code stops running the if */
break;
}
}