使用UDP協議完成一個聊天室程序的小項目,大部分代碼都有註釋,一看就能看到的.
實現的功能:
(1)查看/顯示已經登陸的用戶信息
(2)向已登陸的用戶發送消息
(3)輸出錯誤消息,給予提示
(4)退出
共有三個文件:
chat_public.h
#ifndef _CHAT_PUB_H_
#define _CHAT_PUB_H_
//chat_public.h
#include <list>
#include <algorithm>
using namespace std;
// C2S 客戶端到服務器的
#define C2S_LOGIN 0x01
#define C2S_LOGOUT 0x02
#define C2S_ONLINE_USER 0x03
#define MSG_LEN 512
// S2C 服務器到客戶端的
#define S2C_LOGIN_OK 0x01
#define S2C_ALREADY_LOGINED 0x02
#define S2C_SOMEONE_LOGIN 0x03
#define S2C_SOMEONE_LOGOUT 0x04
#define S2C_ONLINE_USER 0x05
// C2C 客戶端到客戶端的
#define C2C_CHAT 0x06
typedef struct message // 傳遞的消息結構
{
int cmd;
char body[MSG_LEN]; // 消息的內容
} MESSAGE;
typedef struct user_info // 用戶信息結構
{
char username[16]; // 用戶名
unsigned int ip; // IP地址
unsigned short port; //端口
} USER_INFO;
typedef struct chat_msg //客戶與客戶之間的消息結構
{
char username[16];
char msg[100];
}CHAT_MSG;
typedef list<USER_INFO> USER_LIST; // 用list<USER_INFO> 容器
#endif /* _PUB_H_ */
chatser.cpp
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include "chat_public.h"
#define ERR_EXIT(m) \
do \
{ \
perror(m); \
exit(EXIT_FAILURE); \
} while(0)
// 聊天室成員列表
USER_LIST client_list;
void do_login(MESSAGE& msg, int sock, struct sockaddr_in *cliaddr);
void do_logout(MESSAGE& msg, int sock, struct sockaddr_in *cliaddr);
void do_sendlist(int sock, struct sockaddr_in *cliaddr);
void chat_srv(int sock)
{
struct sockaddr_in cliaddr;
socklen_t clilen;
int n;
MESSAGE msg;
while (1)
{
memset(&msg, 0, sizeof(msg));
clilen = sizeof(cliaddr);
n = recvfrom(sock, &msg, sizeof(msg), 0, (struct sockaddr *)&cliaddr, &clilen); // 接收客戶到服務器的消息
if (n < 0)
{
if (errno == EINTR)
continue;
ERR_EXIT("recvfrom");
}
int cmd = ntohl(msg.cmd); // 將命令轉換成主機字節序
switch (cmd)// 判斷是是什麼消息
{
case C2S_LOGIN: // 登陸
do_login(msg, sock, &cliaddr);
break;
case C2S_LOGOUT: // 退出
do_logout(msg, sock, &cliaddr);
break;
case C2S_ONLINE_USER: // 點對點的客戶連接
do_sendlist(sock, &cliaddr);
break;
default:
break;
}
}
}
// 登陸函數
void do_login(MESSAGE& msg, int sock, struct sockaddr_in *cliaddr)
{
USER_INFO user; // 定義用戶結構體變量
strcpy(user.username, msg.body); // 取出用戶名
user.ip = cliaddr->sin_addr.s_addr; // ip地址
user.port = cliaddr->sin_port; // 端口號
// 查找當前登陸正在的用戶的用戶名是否在當前的用戶列表中 (防止重名)
USER_LIST::iterator it; // 定義迭代器
for (it=client_list.begin(); it != client_list.end(); ++it)
{
if (strcmp(it->username,msg.body) == 0)
{
break; // 如果找到就退出循環
}
}
if (it == client_list.end()) //遍歷到結尾,沒有找到
{
printf("has a user login : %s <-> %s:%d\n", msg.body, inet_ntoa(cliaddr->sin_addr), ntohs(cliaddr->sin_port));
client_list.push_back(user);
// 登錄成功應答
MESSAGE reply_msg;
memset(&reply_msg, 0, sizeof(reply_msg));
reply_msg.cmd = htonl(S2C_LOGIN_OK);
sendto(sock, &reply_msg, sizeof(msg), 0, (struct sockaddr *)cliaddr, sizeof(struct sockaddr_in));
int count = htonl((int)client_list.size());
// 發送在線人數
sendto(sock, &count, sizeof(int), 0, (struct sockaddr *)cliaddr, sizeof(struct sockaddr_in));
printf("sending user list information to: %s <-> %s:%d\n", msg.body, inet_ntoa(cliaddr->sin_addr), ntohs(cliaddr->sin_port));
// 發送在線列表
for (it=client_list.begin(); it != client_list.end(); ++it)
{
sendto(sock, &*it, sizeof(USER_INFO), 0, (struct sockaddr *)cliaddr, sizeof(struct sockaddr_in));
}
// 向其他用戶通知有新用戶登錄
for (it=client_list.begin(); it != client_list.end(); ++it)
{
if (strcmp(it->username,msg.body) == 0)
continue;
struct sockaddr_in peeraddr;
memset(&peeraddr, 0, sizeof(peeraddr));
peeraddr.sin_family = AF_INET;
peeraddr.sin_port = it->port;
peeraddr.sin_addr.s_addr = it->ip;
msg.cmd = htonl(S2C_SOMEONE_LOGIN);
memcpy(msg.body, &user, sizeof(user));
if (sendto(sock, &msg, sizeof(msg), 0, (struct sockaddr *)&peeraddr, sizeof(peeraddr)) < 0)
ERR_EXIT("sendto");
}
}
else // 沒有遍歷到結尾, 找到用戶
{
printf("user %s has already logined\n", msg.body);
MESSAGE reply_msg;
memset(&reply_msg, 0, sizeof(reply_msg));
reply_msg.cmd = htonl(S2C_ALREADY_LOGINED);
sendto(sock, &reply_msg, sizeof(reply_msg), 0, (struct sockaddr *)cliaddr, sizeof(struct sockaddr_in));
}
}
void do_logout(MESSAGE& msg, int sock, struct sockaddr_in *cliaddr)
{
printf("has a user logout : %s <-> %s:%d\n", msg.body, inet_ntoa(cliaddr->sin_addr), ntohs(cliaddr->sin_port));
USER_LIST::iterator it;
for (it=client_list.begin(); it != client_list.end(); ++it)
{
if (strcmp(it->username,msg.body) == 0)
break;
}
if (it != client_list.end())
client_list.erase(it);
// 向其他用戶通知有用戶登出
for (it=client_list.begin(); it != client_list.end(); ++it)
{
if (strcmp(it->username,msg.body) == 0)
continue;
struct sockaddr_in peeraddr;
memset(&peeraddr, 0, sizeof(peeraddr));
peeraddr.sin_family = AF_INET;
peeraddr.sin_port = it->port;
peeraddr.sin_addr.s_addr = it->ip;
msg.cmd = htonl(S2C_SOMEONE_LOGOUT);
if (sendto(sock, &msg, sizeof(msg), 0, (struct sockaddr *)&peeraddr, sizeof(peeraddr)) < 0)
ERR_EXIT("sendto");
}
}
void do_sendlist(int sock, struct sockaddr_in *cliaddr)
{
MESSAGE msg;
msg.cmd = htonl(S2C_ONLINE_USER);
sendto(sock, (const char*)&msg, sizeof(msg), 0, (struct sockaddr *)cliaddr, sizeof(struct sockaddr_in));
int count = htonl((int)client_list.size());
/* 發送在線用戶數 */
sendto(sock, (const char*)&count, sizeof(int), 0, (struct sockaddr *)cliaddr, sizeof(struct sockaddr_in));
/* 發送在線用戶列表 */
for (USER_LIST::iterator it=client_list.begin(); it != client_list.end(); ++it)
{
sendto(sock, &*it, sizeof(USER_INFO), 0, (struct sockaddr *)cliaddr, sizeof(struct sockaddr_in));
}
}
int main(void)
{
int sock;
if ((sock = socket(PF_INET, SOCK_DGRAM, 0)) < 0)
ERR_EXIT("socket");
struct sockaddr_in servaddr;
memset(&servaddr, 0, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(5188);
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
if (bind(sock, (struct sockaddr*)&servaddr, sizeof(servaddr)) < 0)
ERR_EXIT("bind");
chat_srv(sock);
return 0;
}
chatcli.cpp
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include "chat_public.h"
#define ERR_EXIT(m) \
do \
{ \
perror(m); \
exit(EXIT_FAILURE); \
} while(0)
// 當前用戶名
char username[16];
// 聊天室成員列表
USER_LIST client_list;
void do_someone_login(MESSAGE& msg);
void do_someone_logout(MESSAGE& msg);
void do_getlist();
void do_chat();
void parse_cmd(char* cmdline, int sock, struct sockaddr_in *servaddr);
bool sendmsgto(int sock, char* username, char* msg);
void parse_cmd(char* cmdline, int sock, struct sockaddr_in *servaddr)
{
char cmd[10]={0};
char *p;
p = strchr(cmdline, ' ');
if (p != NULL)
*p = '\0';
strcpy(cmd, cmdline);
if (strcmp(cmd, "exit") == 0) // 退出命令
{
MESSAGE msg;
memset(&msg,0,sizeof(msg));
msg.cmd = htonl(C2S_LOGOUT);
strcpy(msg.body, username);
if (sendto(sock, &msg, sizeof(msg), 0, (struct sockaddr *)servaddr, sizeof(struct sockaddr_in)) < 0)
ERR_EXIT("sendto");
printf("user %s has logout server\n", username);
exit(EXIT_SUCCESS);
}
else if (strcmp(cmd, "send") == 0) // send命令
{
char peername[16]={0};
char msg[MSG_LEN]={0};
// send user msg
while (*p++ == ' ') ;
char *p2;
//extern char *strchr(const char *s,char c);查找字符串s中首次出現字符c的位置。
p2 = strchr(p, ' ');
if (p2 == NULL)
{
printf("bad command\n");
printf("\nCommands are:\n");
printf("send username msg\n");
printf("list\n");
printf("exit\n");
printf("\n");
return;
}
*p2 = '\0';
strcpy(peername, p);
while (*p2++ == ' ') ;
strcpy(msg, p2);
sendmsgto(sock, peername, msg); // 向用戶發送消息
}
else if (strcmp(cmd, "list") == 0) // list命令
{
MESSAGE msg;
memset(&msg, 0, sizeof(msg));
msg.cmd = htonl(C2S_ONLINE_USER);
if (sendto(sock, &msg, sizeof(msg), 0, (struct sockaddr *)servaddr, sizeof(struct sockaddr_in)) < 0)
ERR_EXIT("sendto");
}
else
{
printf("bad command\n");
printf("\nCommands are:\n");
printf("send username msg\n");
printf("list\n");
printf("exit\n");
printf("\n");
}
}
bool sendmsgto(int sock, char* name, char* msg)
{
if (strcmp(name, username) == 0) // 不能向自己發送消息
{
printf("can't send message to self\n");
return false;
}
USER_LIST::iterator it;
for (it=client_list.begin(); it != client_list.end(); ++it)
{
if (strcmp(it->username,name) == 0)
break;
}
if (it == client_list.end())
{
printf("user %s has not logined server\n", name);
return false;
}
MESSAGE m;
memset(&m,0,sizeof(m));
m.cmd = htonl(C2C_CHAT);
CHAT_MSG cm;
strcpy(cm.username, username);
strcpy(cm.msg, msg);
memcpy(m.body, &cm, sizeof(cm));
//strcpy(m.body,msg);
struct sockaddr_in peeraddr;
memset(&peeraddr,0,sizeof(peeraddr));
peeraddr.sin_family = AF_INET;
peeraddr.sin_addr.s_addr = it->ip;
peeraddr.sin_port = it->port;
in_addr tmp;
tmp.s_addr = it->ip;
printf("sending message [%s] to user [%s] <-> %s:%d\n", msg, name, inet_ntoa(tmp), ntohs(it->port));
sendto(sock, (const char*)&m, sizeof(m), 0, (struct sockaddr *)&peeraddr, sizeof(peeraddr));
return true;
}
void do_getlist(int sock)
{
int count;
recvfrom(sock, &count, sizeof(int), 0, NULL, NULL);
printf("has %d users logined server\n", ntohl(count));// 打印有在線用戶人數
client_list.clear(); // 清空當前用戶列表
int n = ntohl(count);
for (int i=0; i<n; i++)// 一個個接收用戶列表信息,插入到用戶列表中
{
USER_INFO user;
recvfrom(sock,&user, sizeof(USER_INFO), 0, NULL, NULL);
client_list.push_back(user);
in_addr tmp;
tmp.s_addr = user.ip;
printf("%s <-> %s:%d\n", user.username, inet_ntoa(tmp), ntohs(user.port));
}
}
void do_someone_login(MESSAGE& msg)
{
USER_INFO *user = (USER_INFO*)msg.body;
in_addr tmp;
tmp.s_addr = user->ip;
printf("%s <-> %s:%d has logined server\n", user->username, inet_ntoa(tmp), ntohs(user->port));
client_list.push_back(*user);
}
void do_someone_logout(MESSAGE& msg)
{
USER_LIST::iterator it;
for (it=client_list.begin(); it != client_list.end(); ++it)
{
if (strcmp(it->username,msg.body) == 0)
break;
}
if (it != client_list.end())
client_list.erase(it); // 用戶列表清除
printf("user %s has logout server\n", msg.body);
}
void do_chat(const MESSAGE& msg)
{
CHAT_MSG *cm = (CHAT_MSG*)msg.body;
printf("recv a msg [%s] from [%s]\n", cm->msg, cm->username);
//recvfrom(sock, &count, sizeof(int), 0, NULL, NULL);
}
void chat_cli(int sock)
{
struct sockaddr_in servaddr;
memset(&servaddr, 0, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(5188);
servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");
struct sockaddr_in peeraddr;
socklen_t peerlen;
MESSAGE msg;
while (1)
{
memset(username,0,sizeof(username));
printf("please inpt your name:");
fflush(stdout);
scanf("%s", username);
memset(&msg, 0, sizeof(msg));
msg.cmd = htonl(C2S_LOGIN);
strcpy(msg.body, username);
sendto(sock, &msg, sizeof(msg), 0, (struct sockaddr *)&servaddr, sizeof(servaddr));
memset(&msg, 0, sizeof(msg));
recvfrom(sock, &msg, sizeof(msg), 0, NULL, NULL);
int cmd = ntohl(msg.cmd); // 轉換成主機字節序
if (cmd == S2C_ALREADY_LOGINED)
printf("user %s already logined server, please use another username\n", username);
else if (cmd == S2C_LOGIN_OK)
{
printf("user %s has logined server\n", username);
break;
}
}
int count;
recvfrom(sock, &count, sizeof(int), 0, NULL, NULL);
int n = ntohl(count);
printf("has %d users logined server\n", n);
for (int i=0; i<n; i++)
{
USER_INFO user;
recvfrom(sock, &user, sizeof(USER_INFO), 0, NULL, NULL);
client_list.push_back(user);
in_addr tmp;
tmp.s_addr = user.ip;
printf("%d %s <-> %s:%d\n", i, user.username, inet_ntoa(tmp), ntohs(user.port));
}
printf("\nCommands are:\n");
printf("send username msg\n");
printf("list\n");
printf("exit\n");
printf("\n");
fd_set rset;
FD_ZERO(&rset);
int nready;
while (1)
{
FD_SET(STDIN_FILENO, &rset);
FD_SET(sock, &rset);
nready = select(sock+1, &rset, NULL, NULL, NULL);
if (nready == -1)
ERR_EXIT("select");
if (nready == 0)
continue;
if (FD_ISSET(sock, &rset))
{
peerlen = sizeof(peeraddr);
memset(&msg,0,sizeof(msg));
recvfrom(sock, &msg, sizeof(msg), 0, (struct sockaddr *)&peeraddr, &peerlen);
int cmd = ntohl(msg.cmd);
switch (cmd)
{
case S2C_SOMEONE_LOGIN:
do_someone_login(msg);
break;
case S2C_SOMEONE_LOGOUT:
do_someone_logout(msg);
break;
case S2C_ONLINE_USER: // 用戶列表消息
do_getlist(sock);
break;
case C2C_CHAT: // 點對點聊天程序
do_chat(msg);
break;
default:
break;
}
}
if (FD_ISSET(STDIN_FILENO, &rset))
{
char cmdline[100] = {0};
if (fgets(cmdline, sizeof(cmdline), stdin) == NULL)
break;
if (cmdline[0] == '\n')
continue;
cmdline[strlen(cmdline) - 1] = '\0';
parse_cmd(cmdline, sock, &servaddr);
}
}
memset(&msg,0,sizeof(msg));
msg.cmd = htonl(C2S_LOGOUT);
strcpy(msg.body, username);
sendto(sock, (const char*)&msg, sizeof(msg), 0, (struct sockaddr *)&servaddr, sizeof(servaddr));
close(sock);
}
int main(void)
{
int sock;
if ((sock = socket(PF_INET, SOCK_DGRAM, 0)) < 0)
ERR_EXIT("socket");
chat_cli(sock);
return 0;
}
圖片展示:
服務器:
客戶1:cjl
客戶2:yzq