其实这篇文章就是前面一篇文章的复制体，主要是今天闲着无聊，就在Ubuntu下又写了一篇这个传说中的简单Socket通信。

以下是Linux网络编程的函数说明


'socket' Function
To perform network I/O, the first thing a process must do is call the socket function,
specifying the type of communication protocol desired (TCP using IPv4, UDP using
IPv6, Unix domain stream protocol, etc.).
#include <sys/socket.h>
int socket (int family, int type, int protocol);
Returns: non-negative descriptor if OK, -1 on error
    

具体参数如下



'connect' Function
The connect function is used by a TCP client to establish a connection with a TCP
server.
#include <sys/socket.h>
int connect(int sockfd, const struct sockaddr *servaddr, socklen_t addrlen);
Returns: 0 if OK, -1 on error
其中struct sockaddr
是一个结构体。
struct sockaddr_in { sa_family_t sin_family; /* address family: AF_INET */ in_port_t sin_port; /* port in network byte order */ struct in_addr sin_addr; /* internet address */};/* Internet address. */struct in_addr { uint32_t s_addr; /* address in network byte order */};



'bind' Function
#include <sys/socket.h>
int bind (int sockfd, const struct sockaddr *myaddr, socklen_t addrlen);
Returns: 0 if OK,-1 on error



'listen' Function
#include <sys/socket.h>
#int listen (int sockfd, int backlog);
Returns: 0 if OK, -1 on error



'accept' Function
#include <sys/socket.h>
int accept (int sockfd, struct sockaddr *cliaddr, socklen_t *addrlen);
Returns: non-negative descriptor if OK, -1 on error


This function returns up to three values: an integer return code that is either a new
socket descriptor or an error indication, the protocol address of the client process
(through the cliaddr pointer), and the size of this address (through the addrlen
pointer). If we are not interested in having the protocol address of the client returned,
we set both cliaddr and addrlen to null pointers.


'close' Function
#include <unistd.h>
int close (int sockfd);
Returns: 0 if OK, -1 on error

服务器端：

#include<stdio.h>
#include<sys/socket.h>
#include<string.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<unistd.h>
#include<stdlib.h>
#define MAXN 4096 

int main(int argc ,char **argv){
	struct sockaddr_in A ,B ;
	char meg[MAXN] ;
	char rev[MAXN] ;
	socklen_t len;
	int s_socket,socket_conn;
	s_socket = socket(AF_INET,SOCK_STREAM,0);	
	if(s_socket < 0){
		printf("Faile to socket!\n");
		return 1;
	}						
	A.sin_family = AF_INET ;
	if(argv[1]){
		A.sin_port = htons(atoi(argv[1])) ;
	}
		else
	A.sin_port = htons(1234);
	A.sin_addr.s_addr = htonl(INADDR_ANY) ;	
	bind(s_socket ,(struct sockaddr *)&A,sizeof(A));		
	listen(s_socket,5);								
	printf("Server is Waiting ...\n");			
	len = sizeof(struct sockaddr_in) ;	
	socket_conn = accept(s_socket,(struct sockaddr *)&B ,&len);
	if(socket_conn >= 0){
			printf("连接成功，开始通信！\n");
			while(1){										
				fgets(meg,MAXN,stdin);	inet_ntoa(B.sin_addr);	
				len = strlen(meg);
				if(meg[len-1] == '\n')	meg[len-1] = 0 ;
				send(socket_conn,meg,strlen(meg)+1,0);			
				printf("已经成功发送%d个字节\n",len);
				if(strcmp(meg,"quit") == 0){
					printf("Server is cancelling the communication!\n");
					break ;
				}
				recv(socket_conn,rev,MAXN,0);						
				if(strcmp(rev,"quit")==0){
					printf("Client is cancelling the communication!\n");
					break ;
				}
				printf("成功接受%d个字符，字符为：%s\n",strlen(rev),rev);
	
			}
			close(socket_conn) ;						
	}
	else{
		printf("Faile to aceept!\n");
	}
	close(s_socket);								
	return 0;
}

客户端：

#include<stdio.h>
#include<string.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<unistd.h>
#include<stdlib.h>
#define MAXN 4096 

int main(int argc, char **argv){
	int c_socket ,conn;
	int len ;
	char rev[MAXN] ,buf[MAXN];
	struct sockaddr_in A ;
	c_socket = socket(AF_INET,SOCK_STREAM,0);		
	A.sin_family = AF_INET ;	
	if(argv[1]){
		A.sin_port = htons(atoi(argv[1]));
	}		
	if(argv[2]){
		A.sin_addr.s_addr = inet_addr(argv[2]);
	}
	conn = connect(c_socket,(struct sockaddr *)&A,sizeof(struct sockaddr_in));		
	if(conn >= 0){
		printf("正在进行通信！\n");
		while(1){
			recv(c_socket,rev,MAXN,0);									
			if(strcmp(rev,"quit") == 0){
				printf("Server is Cancelling the communication!\n");
				break ;

			}
                        printf("成功接收到了%d字符，字符为：%s\n",strlen(rev),rev);
			fgets(buf,MAXN,stdin);
			len = strlen(buf) ;
			if(buf[len-1] == '\n')	buf[len-1] = 0 ;
			send(c_socket,buf,strlen(buf)+1,0);			
			if(strcmp(buf,"quit") == 0){
				printf("Client is Cancelling the communication!\n");
				break ;
			}
		}
		printf("Communication is Done!\n");
	}
	else{
		printf("Faile to connet\n");	
		return 1;
	}
	close(c_socket);					
	return 0;
}

GCC编译过程：

gcc -Wal -o Server Server.c

./Server 1234

gcc -Wall -o Client Client.c

./Client  1234 127.0.0.1