15.基於UDP協議的聊天室程式

使用UDP協議完成一個聊天室程式的小專案,大部分程式碼都有註釋,一看就能看到的.

實現的功能:

              (1)檢視/顯示已經登陸的使用者資訊

              (2)向已登陸的使用者傳送訊息

              (3)輸出錯誤訊息,給予提示

              (4)退出

共有三個檔案:

chat_public.h

#ifndef _CHAT_PUB_H_
#define _CHAT_PUB_H_

//chat_public.h 

#include <list>
#include <algorithm>
using namespace std;


// C2S  客戶端到伺服器的
#define C2S_LOGIN			0x01
#define C2S_LOGOUT			0x02
#define C2S_ONLINE_USER		0x03

#define MSG_LEN				512


// S2C  伺服器到客戶端的
#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  // 傳遞的訊息結構
{
	int cmd;
	char body[MSG_LEN];  // 訊息的內容
} MESSAGE;

typedef struct user_info // 使用者資訊結構
{
	char username[16];  // 使用者名稱
	unsigned int ip;    // IP地址
	unsigned short port;  //埠
} USER_INFO;

typedef struct chat_msg  //客戶與客戶之間的訊息結構
{
	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);  // 接收客戶到伺服器的訊息  
		if (n < 0)
		{
			if (errno == EINTR)
				continue;
			ERR_EXIT("recvfrom");
		}

		int cmd = ntohl(msg.cmd); // 將命令轉換成主機位元組序
		switch (cmd)// 判斷是是什麼訊息
		{
		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:  // 點對點的客戶連線
			do_sendlist(sock, &cliaddr);
			break;
		default:
			break;
		}
	}
}


// 登陸函式 
void do_login(MESSAGE& msg, int sock, struct sockaddr_in *cliaddr)
{
	USER_INFO user;  // 定義使用者結構體變數 
	strcpy(user.username, msg.body); // 取出使用者名稱 
	user.ip = cliaddr->sin_addr.s_addr; // ip地址
	user.port = cliaddr->sin_port; // 埠號 
	
	// 查詢當前登陸正在的使用者的使用者名稱是否在當前的使用者列表中 (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;  // 如果找到就退出迴圈  
		}
	}

	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);

		// 登入成功應答
		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());
		// 傳送線上人數
		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));
		// 傳送線上列表
		for (it=client_list.begin(); it != client_list.end(); ++it)
		{
			sendto(sock, &*it, sizeof(USER_INFO), 0, (struct sockaddr *)cliaddr, sizeof(struct sockaddr_in));
		}

		// 向其他使用者通知有新使用者登入
		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, 找到使用者 
	{
		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);

	// 向其他使用者通知有使用者登出
	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());
	/* 傳送線上使用者數 */
	sendto(sock, (const char*)&count, sizeof(int), 0, (struct sockaddr *)cliaddr, sizeof(struct sockaddr_in));
	/* 傳送線上使用者列表 */
	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)

// 當前使用者名稱
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);查詢字串s中首次出現字元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); // 向使用者傳送訊息
	}
	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) // 不能向自己傳送訊息
	{
		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));// 列印有線上使用者人數
	client_list.clear(); // 清空當前使用者列表

	int n = ntohl(count);
	for (int i=0; i<n; i++)// 一個個接收使用者列表資訊,插入到使用者列表中
	{
		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);  // 使用者列表清除

	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); // 轉換成主機位元組序
		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:  // 使用者列表訊息
				do_getlist(sock);
				break;
			case C2C_CHAT:  // 點對點聊天程式
				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:

伺服器:

客戶1:cjl

客戶2:yzq