socket通信，server与多客户端通信-白红宇

近日研究socket 通信，学习了如下的一篇文章：

http://blog.csdn.net/dlutcat/article/details/1813933

(向作者致敬)

感觉很好，但还有一点不过瘾，就想着能否加点料:增加多个客户端，让他们一起和服务器端通信。

为了区别各个客户端，把客户端里加入了识别自身hostname的一段。

修改后的代码如下：

server ：

复制代码

#include<netinet/in.h>

#include<sys/types.h>

#include<sys/socket.h>

#include<stdio.h>

#include<stdlib.h>

#include<string.h>

#include<unistd.h>

#include<sys/signal.h>

#include<sys/wait.h>

#define HELLO_WORLD_SERVER_PORT 6666

#define LENGTH_OF_LISTEN_QUEUE 20

#define BUFFER_SIZE 1024

void reaper(int sig){

int status;

while( wait3(&status,WNOHANG,(struct rusage*)0) >=0 )

;

}

int main(int argc, char **argv)

{

struct sockaddr_in server_addr;

bzero(&server_addr,sizeof(server_addr));

server_addr.sin_family = AF_INET;

server_addr.sin_addr.s_addr = htons(INADDR_ANY);

server_addr.sin_port = htons(HELLO_WORLD_SERVER_PORT);

int server_socket = socket(AF_INET,SOCK_STREAM,0);

if( server_socket < 0){

printf("Create Socket Failed!");

exit(1);

}

if( bind(server_socket,(struct sockaddr*)&server_addr,sizeof(server_addr))){

printf("Server Bind Port : %d Failed!", HELLO_WORLD_SERVER_PORT);

exit(1);

}

fprintf(stderr,"Before Main Process listen.\n");

if ( listen(server_socket, LENGTH_OF_LISTEN_QUEUE) ){

printf("Server Listen Failed!");

exit(1);

}

fprintf(stderr, "After Main Process listen.\n");

(void)signal(SIGCHLD,reaper);

while (1){

struct sockaddr_in client_addr;

socklen_t length = sizeof(client_addr);

fprintf(stderr,"Before accept. In %d.\n",getpid());

int new_server_socket =

accept(server_socket,(struct sockaddr*)&client_addr,&length);

if ( new_server_socket < 0){

printf("Server Accept Failed!\n");

break;

}

fprintf(stderr,"After accept. In %d.\n",getpid());

int child_process_pid = fork();

if(child_process_pid == 0 ){

fprintf(stderr,"Child. %d born.\n",getpid());

close(server_socket);

char buffer[BUFFER_SIZE];

bzero(buffer, BUFFER_SIZE);

strcpy(buffer,"Hello,World! FromServer! ");

int pd;

pd=getpid();

char cpd[10];

sprintf(cpd,"%d",pd);

strcat(buffer,cpd);

strcat(buffer,"\n");

send(new_server_socket,buffer,BUFFER_SIZE,0);

bzero(buffer,BUFFER_SIZE);

length = recv(new_server_socket,buffer,BUFFER_SIZE,0);

if (length < 0){

printf("Server Recieve Data Failed!\n");

exit(1);

}

fprintf(stderr,"got: %s in %d\n",buffer,getpid());

close(new_server_socket);

exit(0);

}

else if(child_process_pid > 0)

close(new_server_socket);

}

close(server_socket);

return 0;

}

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client:

复制代码

#include <netinet/in.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#define HELLO_WORLD_SERVER_PORT 6666

#define BUFFER_SIZE 1024

void talk_to_server(char ** argv){

struct sockaddr_in client_addr;

bzero(&client_addr,sizeof(client_addr));

client_addr.sin_family = AF_INET;

client_addr.sin_addr.s_addr = htons(INADDR_ANY);

client_addr.sin_port = htons(0);

int client_socket = socket(AF_INET,SOCK_STREAM,0);

if( client_socket < 0){

printf("Create Socket Failed!\n");

exit(1);

}

if( bind(client_socket,(struct sockaddr*)&client_addr,sizeof(client_addr))){

printf("Client Bind Port Failed!\n");

exit(1);

}

struct sockaddr_in server_addr;

bzero(&server_addr,sizeof(server_addr));

server_addr.sin_family = AF_INET;

if(inet_aton(argv[1],&server_addr.sin_addr) == 0)

{

printf("Server IP Address Error!\n");

exit(1);

}

server_addr.sin_port = htons(HELLO_WORLD_SERVER_PORT);

socklen_t server_addr_length = sizeof(server_addr);

if(

connect( client_socket, (struct sockaddr*)&server_addr,

server_addr_length) < 0 ) {

printf("Can Not Connect To %s!\n",argv[1]);

exit(1);

}

char buffer[BUFFER_SIZE];

bzero(buffer,BUFFER_SIZE);

int length = recv( client_socket, buffer,BUFFER_SIZE,0);

if(length < 0){

printf("Recieve Data From Server %s Failed!\n", argv[1]);

exit(1);

}

printf("From Server %s :\t%s",argv[1],buffer);

bzero(buffer,BUFFER_SIZE);

char name[64];

gethostname(name,sizeof(name));

strcpy(buffer,name);

send(client_socket,buffer,BUFFER_SIZE,0);

close(client_socket);

}

int main(int argc, char **argv){

if (argc != 2){

printf("Usage: ./%s ServerIPAddress\n",argv[0]);

exit(1);

}

int i=0;

for(i=0; i<10000; i++){

talk_to_server(argv);

sleep(10);

}

return 0;

}

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然后，用三个机器，一个跑server,两个跑client。先运行server,再分别跑两个client，结果如下：

为了方便观察，略作整理：

Server端运行结果:

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./con-server.o

Before Main Process listen.

After Main Process listen.

Before accept. In 676.

After accept. In 676

Child 678 born.

Before accept. In 676.

got : post2.gao in 678

After accept. In 676.

Child 679 born.

Before accept. In 676.

got: post3.gao in 679.

After accept. In 676.

Child 680 born.

Before accept. In 676.

got: post2.gao in 680.

After accept. In 676.

Child. 681 born.

Before accept. In 676.

got: post3.gao in 681

......

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两个client端运行结果：

./con-client.o 192.168.66.136

From Server 192.168.66.136: Hello,World! From Server! 678

From Server 192.168.66.136: Hello,World! From Server! 680

......

./con-client.o 192.168.66.136

From Server 192.168.66.136: Hello,World! From Server! 679

From Server 192.168.66.136: Hello,World! From Server! 681

......

这样就成为多个客户端请求Server端。

此外也可以发现，listen动作不阻塞，accept动作阻塞。

服务器端主进程每当捕获到一个客户端请求，就fork一个子进程，

由子进程用 new_server_socket来send 和 recv工作。

fork子进程后，工作完毕再消除的方法未必理想，今后有机会看看能否事先开一个进程池，来提升效率。

本文转自健哥的数据花园博客园博客，原文链接：http://www.cnblogs.com/gaojian/archive/2012/08/02/2618642.html，如需转载请自行联系原作者