一：要求
1.通过一个服务器实现最多5个客户之间的信息群发。
2.服务器显示客户的登录与退出；
3.客户连接后首先发送客户名称，之后发送群聊信息；
4.客户输入bye代表退出，在线客户能显示其他客户的登录于退出。
二：提示
1、服务器端：
主线程：
定义一个全局客户信息表ent，每个元素对应一个客户，存储：socket描述符、客户名、客户IP、客户端口、状态（初值为0）。
主线程循环接收客户连接请求，在ent中查询状态为0的元素，
如果不存在状态为0的元素（即连接数超过最大连接数），向客户发送EXIT标志；
否则，修改客户信息表中该元素的socket描述符、客户IP、客户端口号，状态为1（表示socket可用）；
同时创建一个通信线程并将客户索引号index传递给通信线程。
通信线程：
首先向客户端发送OK标志
循环接收客户发来信息，若信息长度为0，表示客户端已关闭，向所有在线客户发送该用户退出；
若信息为用户名，修改全局客户信息表ent中index客户的用户名name，并显示该用户登录；
若信息为退出，修改全局客户信息表ent中index客户状态为0，并显示该用户退出，终止线程；
同时查询全局客户信息表ent，向状态为1的客户发送接收的信息。
2、客户端：
根据用户从终端输入的服务器IP地址及端口号连接到相应的服务器；
连接成功后，接收服务端发来的信息，若为EXIT，则达到最大用户量，退出；
若为OK，可以通讯，首先先发送客户名称；
主进程循环从终端输入信息，并将信息发送给服务器；
当发送给服务器为bye后，程序退出。
同时创建一个线程负责接收服务器发来的信息，并显示，当接收的长度小于等于0时终止线程；
三：程序
客户端与服务端的头文件：
ifndef _GCS_H
#define _GCS_H
#include <netinet/in.h> #define MSGLEN 1024 #define OK 1
#define EXIT 2
#define MSG 3
#define USER 4 struct CLIENTMSG {
int op;
char user[];
char buf[MSGLEN];
}; struct CLIENTS {
int sockfd;
int port;
char user[];
struct sockaddr_in client;
int stat;
};
struct CLIENTS ent[]; #endif
服务端：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ipc.h>
#include <pthread.h>
#include "group_chat_system.h" extern struct CLIENTS ent[]; void* func(void *arg);
void sever_process(int index); int main(int argc, char **argv)
{
int sever_fd,client_fd;
struct sockaddr_in sever,client;
char ip[];
int port,clientlen;
unsigned char i,index;
struct CLIENTMSG clientMSG;
pthread_t tid;
int *arg; for(i=; i<; i++) {
ent[i].stat = ;
} /***************创建服务器sockfd************/
if((sever_fd = socket(AF_INET, SOCK_STREAM, )) == -) {
perror("socket error");
exit(errno);
} /***************输入ip与端口*****************/
printf("please input ip:");
scanf("%s", ip);
printf("\nplease input port:");
scanf("%d", &port);
printf("\n"); /******************bind***********************/
bzero(&sever, sizeof(sever));
sever.sin_family = AF_INET;
sever.sin_port = htons(port);
sever.sin_addr.s_addr= inet_addr(ip);
if(bind(sever_fd, (struct sockaddr*)&sever, sizeof(struct sockaddr)) == -) {
perror("bind error");
exit(errno);
} /******************listen***********************/
if(listen(sever_fd, ) == -) {
perror("listen error");
exit(errno);
} while() {
clientlen = sizeof(client);
if((client_fd = accept(sever_fd, (struct sockaddr*)&client, &clientlen)) == -) {
perror("accept error");
exit(errno);
}
printf("accept ok\n");
index = ;
for(i=; i<; i++) {
if(ent[i].stat ==){
index = i;
break;
}
} if(index <= ) {
printf("client_fd : %d\n", client_fd);
ent[index].sockfd = client_fd;
ent[index].port = port;
ent[index].client = client;
ent[index].stat = ;
arg = malloc(sizeof(int));
*arg = index;
pthread_create(&tid, NULL, func, (void*)arg);
} else {
printf("the client already has 5\n");
bzero(&clientMSG, sizeof(clientMSG));
clientMSG.op = EXIT;
send(client_fd, &clientMSG, sizeof(clientMSG), );
close(client_fd);
} }
close(sever_fd);
return ;
} void *func(void *arg)
{
int *info;
info = (int *)arg;
sever_process(*info);
pthread_exit(NULL);
} void sever_process(int index)
{
struct CLIENTMSG sendMSG;
struct CLIENTMSG recvMSG;
int len,i; /*首先发送邋OK标志*/
sendMSG.op = OK;
send(ent[index].sockfd, &sendMSG, sizeof(sendMSG), ); while() {
bzero(&sendMSG, sizeof(sendMSG));
bzero(&recvMSG, sizeof(recvMSG)); len = recv(ent[index].sockfd, &recvMSG, sizeof(recvMSG), );
if(len == ) {
sendMSG.op = EXIT;
for(i=; i<; i++) {
if(ent[i].stat == )
send(ent[i].sockfd, &sendMSG, sizeof(sendMSG), );
}
}
if(len > ) {
if(recvMSG.op == USER) {
bcopy(recvMSG.user, ent[index].user, strlen(recvMSG.user));
printf("user %s login form ip: %s port: %d\n", ent[index].user, inet_ntoa(ent[index].client.sin_addr), ntohs(ent[index].client.sin_port));
sendMSG.op = USER;
}
if(recvMSG.op == EXIT) {
//printf("recv exit\n");
sendMSG.op = EXIT;
bcopy(ent[index].user, sendMSG.user, strlen(recvMSG.user));
for(i=; i<; i++) {
if(ent[i].stat == )
send(ent[i].sockfd, &sendMSG, sizeof(sendMSG), );
}
break;
}
if(recvMSG.op == MSG) {
//printf("recv msg\n");
//printf("%s: %s", recvMSG.user,recvMSG.buf);
sendMSG.op= MSG;
}
bcopy(recvMSG.user, sendMSG.user, strlen(recvMSG.user));
bcopy(recvMSG.buf, sendMSG.buf, strlen(recvMSG.buf));
for(i=; i<; i++) {
//printf("\n%d: %s\n", sendMSG.op, sendMSG.user);
if(ent[i].stat == ) {
if(strncmp(ent[i].user, sendMSG.user, strlen(sendMSG.user)))
send(ent[i].sockfd, &sendMSG, sizeof(sendMSG), );
} }
}
} }
客户端：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ipc.h>
#include <pthread.h>
#include "group_chat_system.h" struct client_arg {
int sockfd;
struct CLIENTMSG clientMSG;
};
struct client_arg *arg; void *func(void* arg);
void client_process(int sockfd, struct CLIENTMSG clientMSG); int main(int argc, char **argv)
{
int sockfd;
struct sockaddr_in sever;
char ip[];
unsigned int port,len;
struct CLIENTMSG sendMSG;
pthread_t tid; if((sockfd = socket(AF_INET, SOCK_STREAM, )) == -) {
perror("socket error");
exit();
} printf("please input ip:");
scanf("%s", ip);
printf("\nplease input port:");
scanf("%d", &port);
printf("\n"); bzero(&sever, sizeof(sever));
sever.sin_family = AF_INET;
sever.sin_port = htons(port);
inet_aton(ip, &sever.sin_addr);
if(connect(sockfd, (struct sockaddr*)&sever, sizeof(struct sockaddr)) == -) {
perror("connect error");
exit(errno);
} len = recv(sockfd, &sendMSG, sizeof(sendMSG), );
if(len > ){
if(sendMSG.op == EXIT) {
printf("exceed the numble of users\n");
}
if(sendMSG.op == OK) {
bzero(&sendMSG, sizeof(sendMSG));
printf("please input client name: ");
fgets(sendMSG.user, MSGLEN, stdin);
//scanf("%s", sendMSG.user);
sendMSG.op = USER;
send(sockfd, &sendMSG, sizeof(sendMSG), );
arg = (struct client_arg*)malloc(sizeof(struct client_arg));
arg->sockfd = sockfd;
pthread_create(&tid, NULL, func, (void*)arg); while() {
// bzero(&sendMSG, sizeof(sendMSG));
sendMSG.op = MSG;
//printf("waiting...");
fgets(sendMSG.buf, MSGLEN, stdin);
//scanf("%s", sendMSG.buf);
//printf("%s: %s %d\n", sendMSG.user,sendMSG.buf, sendMSG.op);
if(!strncasecmp(sendMSG.buf, "bye", )) {
sendMSG.op = EXIT;
send(sockfd, &sendMSG, sizeof(sendMSG), );
break;
}
send(sockfd, &sendMSG, sizeof(sendMSG), );
}
}
pthread_cancel(tid);
}
close(sockfd);
return ;
} void *func(void* arg)
{
struct client_arg *info;
info = (struct client_arg*)arg;
client_process(info->sockfd, info->clientMSG);
free(arg);
pthread_exit(NULL);
} void client_process(int sockfd, struct CLIENTMSG clientMSG)
{
int len;
while() {
bzero(&clientMSG, sizeof(clientMSG));
len = recv(sockfd, &clientMSG, sizeof(clientMSG), );
if(len > ) {
if(clientMSG.op==USER){
printf("the user %s is login.\n",clientMSG.user);
}else if(clientMSG.op == EXIT){
printf("the user %s is logout.\n",clientMSG.user);
}else if(clientMSG.op == MSG){
printf("%s: %s\n",clientMSG.user,clientMSG.buf);
}
}
}
}
Makefile文件：
main:sever.o client.o
gcc sever.o -o sever -lpthread
gcc client.o -o client -lpthread
sever.o:sever.c
gcc -c sever.c group_chat_system.h
gcc -c client.c group_chat_system.h
clean:
rm *.o sever client
四：现象