gets not working in TCP/IP chat program - c

Question

/* Server Code */
#include<stdio.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<pthread.h>
#define MAXSIZE 50
void transmit();
void Recieve();
int sockfd, newsockfd, retval;
socklen_t actuallen;
int recedbytes, sentbytes;
struct sockaddr_in serveraddr, clientaddr;
// char buff[MAXSIZE];
int a = 0, port_no;
main()
{
printf("Enter port number: ");
scanf("%d",&port_no);
sockfd=socket(AF_INET,SOCK_STREAM,0);
if(sockfd==-1) {
printf("\nSocket creation error");
exit(-1);
}
serveraddr.sin_family=AF_INET;
serveraddr.sin_port=htons(port_no);
serveraddr.sin_addr.s_addr=htonl(INADDR_ANY);
retval= bind(sockfd, (struct sockaddr*)&serveraddr, sizeof(serveraddr));
if(retval == -1) {
printf("Binding error");
close(sockfd);
exit(0);
}
retval = listen(sockfd, 1);
if (retval == -1) {
close(sockfd);
exit(0);
}
actuallen = sizeof(clientaddr);
newsockfd = accept(sockfd, (struct sockaddr*)&clientaddr, &actuallen);
if(newsockfd == -1) {
close(sockfd);
exit(0);
}
int i=1;
pid_t pid = fork();
if(pid == 0)
transmit();
else
Recieve();
close(newsockfd);
close(sockfd);
}
void Recieve()
{
char buff[50]; int f=1;
while(f)
{
recedbytes=recv(newsockfd,buff,sizeof(buff),0);
if(recedbytes == -1) {
close(sockfd);
close(newsockfd);
exit(0);
}
printf("recdbytes: %d\n", recedbytes);
if(strcmp(buff, "Stop") == 0)
{
puts("Closing");
strcpy(buff,"Stop");
sentbytes=send(newsockfd,buff,sizeof(buff),0);
if(sentbytes == -1) {
close(sockfd);
close(newsockfd);
exit(0);
}
f=0;
}
else {
char cl[]="Client: ";
strcat(cl,buff);
puts(cl);
}
}
}
void transmit()
{
char buff[50];
while(1)
{
// printf("%s","You: ");
gets(buff);
sentbytes = send(newsockfd, buff, sizeof(buff), 0);
if(sentbytes == -1) {
close(sockfd);
close(newsockfd);
exit(0);
}
}
}
/* Client Code */
#include<stdio.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<pthread.h>
#define MAXSIZE 50
void transmit();
void Recieve();
int sockfd, retval;
int recedbytes, sentbytes;
struct sockaddr_in serveraddr;
// char buff[MAXSIZE];
main()
{
int port_no;
printf("Enter port number:");
scanf("%d",&port_no);
sockfd=socket(AF_INET,SOCK_STREAM,0);
if(sockfd == -1) {
printf("\nSocket creation error");
exit(-1);
}
serveraddr.sin_family = AF_INET;
serveraddr.sin_port = htons(port_no);
serveraddr.sin_addr.s_addr = inet_addr("127.0.0.1");
retval = connect(sockfd, (struct sockaddr*)&serveraddr, sizeof(serveraddr));
if(retval == -1) {
printf("Connection error"); close(sockfd);
exit(0);
}
int i = 1;
pid_t pid = fork();
if(pid == 0)
transmit();
else
Recieve();
printf("\n");
close(sockfd);
}
void Recieve()
{
char buff[50];
int f=1;
while(f)
{
recedbytes = recv(sockfd, buff, sizeof(buff), 0);
if(recedbytes == -1) {
close(sockfd);
exit(0);
}
printf("recdbytes: %d\n",recedbytes);
if(strcmp(buff, "Stop") == 0)
{
puts("Closing");
f = 0;
strcpy(buff, "Stop");
sentbytes = send(sockfd, buff, sizeof(buff), 0);
if(sentbytes == -1) {
close(sockfd);
exit(0);
}
}
else {
char sr[] = "Server :";
strcat(sr, buff);
puts(sr);
}
}
}
void transmit()
{
char buff[50];
while(1)
{
// printf("%s","You: ");
gets(buff);
sentbytes = send(sockfd, buff, sizeof(buff), 0);
if(sentbytes == -1) {
close(sockfd);
exit(0);
}
}
}
I am trying to create a chat server/client program using TCP/IP and process creation in C (linux).
It seems like the gets(buff) in transmit function of both the Client and Server Programs is not functioning as blocking and send(..) function is transmitting an empty buff.
As a result, "Client:" or "Server:" in server program and client program respectively is being printed even if no data has actually been sent from the counterpart program.

Answer 1

recedbytes=recv(newsockfd,buff,sizeof(buff),0);
if(recedbytes == -1) {
close(sockfd);
close(newsockfd);
exit(0);
}
printf("recdbytes: %d\n", recedbytes);
if(strcmp(buff, "Stop") == 0)
How are you expecting strcmp to know the length of the received string? You never did anything with recedbytes.
You also have numerous other bugs. You are expecting recv to somehow receive messages, despite the fact that you've never implemented any message protocol.
If you want to send and receive messages, you have to do three things:
Precisely define what a "message" is.
Write code to send a message.
Write code to receive a message.
There's no evidence in the code you've done any of these things. If your definition of a message is "precisely 50 bytes, always including a zero byte that marks the end of the data the receiver should process", then you may be okay on 1 and 2, but you definitely haven't done 3.