Linux Network Programming Chat program (TCP protocol Fork process)

The implementation of the server and the client chat with each other, no order restrictions, can be carried out at the same time.

Service side: SERVER.C

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <unistd.h>
#include <arpa/inet.h>

#define MAXBUF 1024

int main (int argc, char *argv[])
{
int pid;
int SOCKFD, NEW_FD;
Socklen_t Len;
struct sockaddr_in my_addr, their_addr;
unsigned int myport, lisnum;
Char buf[maxbuf + 1];

if (argv[2])
MyPort = Atoi (argv[2]); /* Converts command line string to Integer, for Port/*
Else
MyPort = 7575; /* Set the default port * *


if (Argv[3])
Lisnum = Atoi (argv[3]); /* Listening Queue Size * *
Else
Lisnum = 5;

if ((SOCKFD = socket (af_inet, sock_stream, 0)) = = 1)/* Create socket Object * *
{
Perror ("socket");
Exit (Exit_failure);
}

Bzero (&my_addr, sizeof (MY_ADDR));
my_addr.sin_family = af_inet; /* Address Agreement * *
My_addr.sin_port = htons (MyPort); /* Address Port * *
if (Argv[1])
MY_ADDR.SIN_ADDR.S_ADDR = inet_addr (argv[1]);
Else
MY_ADDR.SIN_ADDR.S_ADDR = Inaddr_any; /* Otherwise, the default local machine arbitrary address * *

if (Bind (SOCKFD, (struct sockaddr *) &my_addr, sizeof (struct sockaddr)) = = 1)/* BIND address information * *
{
Perror ("bind");
Exit (Exit_failure);
}

if (listen (sockfd,lisnum) = = 1)//monitor Network * *
{
Perror ("Listen");
Exit (Exit_failure);
}
printf ("Wait for connect\n");
len = sizeof (struct sockaddr);
if ((New_fd =accept (SOCKFD, (struct sockaddr *) &their_addr,&len)) = = 1)
/* Blocking wait connection, the connection successfully returns the new socket descriptor, THEIR_ADDR store the client's sockaddr address information
{
Perror ("accept");
Exit (Exit_failure);
}
Else
printf ("Server:got connection from%s, port%d, socket%d\n", Inet_ntoa (THEIR_ADDR.SIN_ADDR), Ntohs (their_addr.sin_port ), NEW_FD);

if ( -1== (Pid=fork ()))/* Create a new process * *
{
Perror ("fork"); exit (Exit_failure);
}
else if (PID = = 0)/* subprocess is used to send message * *
{
while (1)
{
Bzero (buf, maxbuf + 1);
printf ("Input to send:");
Fgets (buf, Maxbuf, stdin);
if (!strncasecmp (buf, "Quit", 4))
{
printf ("I'll close the connect!\n");
Break
}
Len = Send (NEW_FD, buf, strlen (BUF)-1, 0);
if (Len < 0)
{
printf ("Message '%s ' send Failure!errno the code is%d,errno '%s ' \ n",
BUF, errno, Strerror (errno));
Break
}
}
}
else/* The parent process is used to receive the message * *
{
while (1)
{
Bzero (buf, maxbuf + 1);
Len = recv (new_fd, buf, maxbuf, 0);
if (len > 0)
printf ("Message recv successful: '%s ',%dbyte recv\n", buf, Len);
else if (Len < 0)
{
printf ("Recv failure!errno code is%d,errno '%s ' \ n",
errno, Strerror (errno));
Break
}
Else
{
printf ("The other one Close quit\n");
Break
}
}
}
Close (NEW_FD);
Close (SOCKFD);
return 0;
}


Client program: CLIENT.C
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <resolv.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

#define MAXBUF 1024

int main (int argc, char **argv)
{
int SOCKFD, Len;
struct sockaddr_in dest;
Char buffer[maxbuf + 1];
if (argc!= 3)
{
printf ("Error format,it must be:\n\t\t%s IP port\n", argv[0]);
Exit (Exit_failure);
}

if ((SOCKFD = socket (af_inet, sock_stream, 0)) < 0) {/* Create socket Object/*
Perror ("Socket");
Exit (errno);
}
printf ("Socket created\n");

Bzero (&dest, sizeof (dest)); /* Clear 0 Operation * *
dest.sin_family = af_inet; /* Address Agreement * *
Dest.sin_port = htons (atoi (argv[2)); /* Address Port * *
if (Inet_aton (argv[1), (struct in_addr *) &dest.sin_addr.s_addr) = = 0)/* IP address/
{
Perror (argv[1]); Exit (errno);
}
if (Connect (SOCKFD, (struct sockaddr *) &dest, sizeof (dest)) ==-1)/* Initiate connection * *
{
Perror ("Connect");
Exit (errno);
}
printf ("Server connected\n");

pid_t pid;
if ( -1== (Pid=fork ()))/* Create a new process * *
{
Perror ("fork"); exit (Exit_failure);
}
else if (pid==0)/* subprocess is used to receive messages, do not understand the process of their own to Baidu?
{
while (1)
{
Bzero (buffer, maxbuf + 1);
Len = recv (sockfd, buffer, maxbuf, 0);
if (len > 0)
printf ("recv Successful: '%s ',%d byte recv\n", buffer, Len);
else if (Len < 0)
{
Perror ("recv");
Break
}
Else
{
printf ("The other one close, quit\n");
Break
}
}
}
else/* The parent process is used to send a message.
{
while (1)
{
Bzero (buffer, maxbuf + 1);
printf ("Pls send message to send:");
Fgets (buffer, maxbuf, stdin);
if (!strncasecmp (buffer, "quit", 4))
{
printf ("I'll quit!\n");
Break
}
Len = Send (sockfd, buffer, strlen (buffer)-1, 0);
if (Len < 0)
{
Perror ("send");
Break
}
}
}
Close (SOCKFD);
return 0;
}

The test methods are as follows:
GCC Server.c-o Server
GCC Client.c-o Client
./server 172.16.148.114 8888/* A terminal, 172.16.148.114 is the IP address of my virtual machine * *
./client 172.16.148.114 8888/* * under another terminal


Add a knowledge point:
int shutdown (int sockfd,int how);
Shutdown can directly close the descriptor, regardless of the descriptor's reference number, you can choose to abort a direction of the connection
How there are three different ways to be
SHUT_RD (0): Turn off Read on SOCKFD, this option will not allow SOCKFD read operation.
SHUT_WR (1): Turn off the write feature of SOCKFD, this option will not allow the SOCKFD write operation.
Shut_rdwr (2): Turn off the read and write function of SOCKFD.