[Linux C]TCP通讯例程

           这个是最最最基本的例程，先开一个坑，稍后再慢慢完善。

服务端程序

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<sys/stat.h>
#include<sys/ipc.h>
#include<sys/time.h>
#include<sys/types.h>
#include<fcntl.h>
#include<errno.h>
#include<unistd.h>
#include<dirent.h>
#include<signal.h>
#include<sys/socket.h>
#include<netinet/in.h>

#define port 4006

void sigfun(int signal)
{
    while(waitpid(-1,NULL,WNOHANG));
}

int main(void)
{
	int flag = 0;
	int socket_fd,connect_fd;
	
	socket_fd = socket(AF_INET,SOCK_STREAM,0); 	//creat a socket(TCP)	

	if (socket_fd < 0)
        {
	    perror("creat a socket failed!\n");
	    return -1; 
	}

	struct sockaddr_in srv;			//creat an address struct
	bzero(&srv,sizeof(srv));

	srv.sin_family = AF_INET;	        //IPv4
 	srv.sin_port = htons(port);	        //Port ID

	srv.sin_addr.s_addr=htonl(INADDR_ANY);

	/************************
	flag = inet_pton(AF_INET,desIP,&srv.sin_addr);	//IP Address

	if (flag == 0)
	{ 
            perror("invalid IP Address!!!\n");
            return; 
        }
	else if (flag==-1)
	{ 
            perror("af does contain a valid address family!!!\n");
            return; 
        }
	*************************/
	
	bind(socket_fd,(struct sockaddr*)&srv,sizeof(srv));

	listen(socket_fd,3);	//wait and listen

	while (1)
	{
		signal(SIGCHLD,sigfun);

		connect_fd = accept(socket_fd,NULL,NULL);
	
		pid_t pid = fork();	//creat the child process

		if (pid == -1)
			perror("process creat failed!\n");
	
		else if (pid == 0)
		{	
			char* netbuff = (char*) malloc(50*sizeof(char));

			while (1)
			{
			    bzero(netbuff,50);

			    flag = read(connect_fd,netbuff,50);
				
                            if (flag == 0) 
                                break;

			    write(STDOUT_FILENO,netbuff,strlen(netbuff));
			}	
			close(connect_fd);
			free(netbuff);
			exit(0);
		}
	
		else
		    continue;
	}

	return 0;
}

客户端程序

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<sys/stat.h>
#include<sys/ipc.h>
#include<sys/types.h>
#include<fcntl.h>
#include<errno.h>
#include<unistd.h>
#include<dirent.h>
#include<signal.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<poll.h>

#define port 4006
#define desIP "192.168.1.253"

int main(void)
{
	int flag = 0;

	int sockfd = socket(AF_INET,SOCK_STREAM,0);    //creat a socket(TCP)	
	
        if (sockfd == -1)
	{ 
            perror("creat a socket failed!\n");
            return; 
        }

	struct sockaddr_in cli;		    //creat a address struct
	bzero(&cli,sizeof(cli));	    //initial

	cli.sin_family = AF_INET;           //IPv4
 	cli.sin_port = htons(port);	    //Port ID

	flag = inet_pton(AF_INET,desIP,&cli.sin_addr);	//set des IP Address
	
        if (flag == 0)
	{ 
             perror("invalid IP Address!!!\n");
             return; 
        }
	else if (flag == -1)
	{ 
             perror("af does contain a valid address family!!!\n");
             return; 
        }
	
	connect(sockfd,(struct sockaddr*)&cli,sizeof(cli));

	char* netbuff = (char*) malloc(50*sizeof(char));

	while (1)
	{
		bzero(netbuff,50);
		
		printf("you say:");
		fgets(netbuff,50,stdin);

		if (strncmp("quit",netbuff,4) == 0) 
                    break;

		write(sockfd,netbuff,strlen(netbuff));
	}	
	
	close(sockfd);
	free(netbuff);
	
	return 0;
}