A simple chat program in C (TCP)

tcpserver.c

 
#include"stdio.h"
#include"stdlib.h"
#include"sys/types.h"
#include"sys/socket.h"
#include"string.h"
#include"netinet/in.h"
#include"pthread.h"

#define PORT 4444
#define BUF_SIZE 2000
#define CLADDR_LEN 100

void * receiveMessage(void * socket) {
 int sockfd, ret;
 char buffer[BUF_SIZE]; 
 sockfd = (int) socket;
 memset(buffer, 0, BUF_SIZE);  
 for (;;) {
  ret = recvfrom(sockfd, buffer, BUF_SIZE, 0, NULL, NULL);  
  if (ret < 0) {  
   printf("Error receiving data!\n");    
  } else {
   printf("client: ");
   fputs(buffer, stdout);
   //printf("\n");
  }  
 }
}

void main() {
 struct sockaddr_in addr, cl_addr;
 int sockfd, len, ret, newsockfd;
 char buffer[BUF_SIZE];
 pid_t childpid;
 char clientAddr[CLADDR_LEN];
 pthread_t rThread;
 
 sockfd = socket(AF_INET, SOCK_STREAM, 0);
 if (sockfd < 0) {
  printf("Error creating socket!\n");
  exit(1);
 }
 printf("Socket created...\n");
 
 memset(&addr, 0, sizeof(addr));
 addr.sin_family = AF_INET;
 addr.sin_addr.s_addr = INADDR_ANY;
 addr.sin_port = PORT;
 
 ret = bind(sockfd, (struct sockaddr *) &addr, sizeof(addr));
 if (ret < 0) {
  printf("Error binding!\n");
  exit(1);
 }
 printf("Binding done...\n");

 printf("Waiting for a connection...\n");
 listen(sockfd, 5);


 len = sizeof(cl_addr);
 newsockfd = accept(sockfd, (struct sockaddr *) &cl_addr, &len);
 if (newsockfd < 0) {
  printf("Error accepting connection!\n");
  exit(1);
 } 

 inet_ntop(AF_INET, &(cl_addr.sin_addr), clientAddr, CLADDR_LEN);
 printf("Connection accepted from %s...\n", clientAddr); 
 
 memset(buffer, 0, BUF_SIZE);
 printf("Enter your messages one by one and press return key!\n");

 //creating a new thread for receiving messages from the client
 ret = pthread_create(&rThread, NULL, receiveMessage, (void *) newsockfd);
 if (ret) {
  printf("ERROR: Return Code from pthread_create() is %d\n", ret);
  exit(1);
 }

 while (fgets(buffer, BUF_SIZE, stdin) != NULL) {
  ret = sendto(newsockfd, buffer, BUF_SIZE, 0, (struct sockaddr *) &cl_addr, len);  
  if (ret < 0) {  
   printf("Error sending data!\n");  
   exit(1);
  }
 }   
 
 close(newsockfd);
 close(sockfd);

 pthread_exit(NULL);
 return;
}

tcpclient.c

 
#include"stdio.h"  
#include"stdlib.h"  
#include"sys/types.h"  
#include"sys/socket.h"  
#include"string.h"  
#include"netinet/in.h"  
#include"netdb.h"
#include"pthread.h"
  
#define PORT 4444 
#define BUF_SIZE 2000 
  
void * receiveMessage(void * socket) {
 int sockfd, ret;
 char buffer[BUF_SIZE]; 
 sockfd = (int) socket;
 memset(buffer, 0, BUF_SIZE);  
 for (;;) {
  ret = recvfrom(sockfd, buffer, BUF_SIZE, 0, NULL, NULL);  
  if (ret < 0) {  
   printf("Error receiving data!\n");    
  } else {
   printf("server: ");
   fputs(buffer, stdout);
   //printf("\n");
  }  
 }
}

int main(int argc, char**argv) {  
 struct sockaddr_in addr, cl_addr;  
 int sockfd, ret;  
 char buffer[BUF_SIZE]; 
 char * serverAddr;
 pthread_t rThread;

 if (argc < 2) {
  printf("usage: client < ip address >\n");
  exit(1);  
 }

 serverAddr = argv[1]; 
 
 sockfd = socket(AF_INET, SOCK_STREAM, 0);  
 if (sockfd < 0) {  
  printf("Error creating socket!\n");  
  exit(1);  
 }  
 printf("Socket created...\n");   

 memset(&addr, 0, sizeof(addr));  
 addr.sin_family = AF_INET;  
 addr.sin_addr.s_addr = inet_addr(serverAddr);
 addr.sin_port = PORT;     

 ret = connect(sockfd, (struct sockaddr *) &addr, sizeof(addr));  
 if (ret < 0) {  
  printf("Error connecting to the server!\n");  
  exit(1);  
 }  
 printf("Connected to the server...\n");  

 memset(buffer, 0, BUF_SIZE);
 printf("Enter your messages one by one and press return key!\n");

 //creating a new thread for receiving messages from the server
 ret = pthread_create(&rThread, NULL, receiveMessage, (void *) sockfd);
 if (ret) {
  printf("ERROR: Return Code from pthread_create() is %d\n", ret);
  exit(1);
 }

 while (fgets(buffer, BUF_SIZE, stdin) != NULL) {
  ret = sendto(sockfd, buffer, BUF_SIZE, 0, (struct sockaddr *) &addr, sizeof(addr));  
  if (ret < 0) {  
   printf("Error sending data!\n\t-%s", buffer);  
  }
 }

 close(sockfd);
 pthread_exit(NULL);
 
 return 0;    
}  

terminal 1 
gcc tcpserver.c -o server -pthread 
./server 
terminal 2 
gcc tcpclient.c -o client -pthread 
./client 192.168.0.4