Linux Linux程序练习十二（select实现QQ群聊）

Posted 2020-08-10

//头文件--helper.h
#ifndef _vzhang
#define _vzhang

#ifdef __cplusplus
extern "C"
{
#endif

#define MAX_SOCKET_NUM 1024
#define BUF_SIZE 1024

//server create socket
int server_socket(int port);

//close socket
int close_socket(int st);

//start select
int start_select(int listen_st);

//connect server
int connect_server(char * ipaddr, int port);

//thread for recv message
void * thread_recv(void *arg);

//thread for send message
void * thread_send(void *arg);

#ifdef __cplusplus
}
#endif


#endif

//辅助方法--helper.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <time.h>
#include <fcntl.h>
#include <sys/select.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include "helper.h"

//create socket
int create_socket()
{
    int st = socket(AF_INET, SOCK_STREAM, 0);
    if (st < 0)
    {
        printf("create socket failed ! error message :%s\n", strerror(errno));
        return -1;
    }
    return st;
}

//set reuseaddr
int set_reuseaddr(int st)
{
    int on = 1;
    if (setsockopt(st, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) < 0)
    {
        printf("reuseaddr failed ! error message :%s\n", strerror(errno));
        return -1;
    }
    return 0;
}

//bind IP and port
int bind_ip(int st, int port)
{
    struct sockaddr_in addr;
    memset(&addr, 0, sizeof(addr));
    //type
    addr.sin_family = AF_INET;
    //port
    addr.sin_port = htons(port);
    //address
    addr.sin_addr.s_addr = htonl(INADDR_ANY);
    if (bind(st, (struct sockaddr *) &addr, sizeof(addr)) < 0)
    {
        printf("bind failed ! error message :%s\n", strerror(errno));
        return -1;
    }
    return 0;
}

//listen
int listen_port(int st, int num)
{
    if (listen(st, num) < 0)
    {
        printf("listen failed ! error message :%s\n", strerror(errno));
        return -1;
    }
    return 0;
}

//server create socket
int server_socket(int port)
{
    int st = create_socket();
    if (st < 0)
    {
        return -1;
    }
    if (set_reuseaddr(st) < 0)
    {
        return -1;
    }
    if (bind_ip(st, port) < 0)
    {
        return -1;
    }
    if (listen_port(st, 20) < 0)
    {
        return -1;
    }
    return st;
}

//get IP address by sockaddr_in
void sockaddr_toa(const struct sockaddr_in *addr, char * ipaddr)
{
    unsigned char * p = (unsigned char *) &(addr->sin_addr.s_addr);
    sprintf(ipaddr, "%u.%u.%u.%u", p[0], p[1], p[2], p[3]);
}

//accept client
int accept_client(int st)
{
    if (st < 0)
    {
        printf("function accept_client param not correct!\n");
        return -1;
    }
    struct sockaddr_in addr;
    memset(&addr, 0, sizeof(addr));
    socklen_t len = sizeof(addr);
    int client_st = accept(st, (struct sockaddr *) &addr, &len);
    if (client_st < 0)
    {
        printf("accept failed ! error message :%s\n", strerror(errno));
        return -1;
    }
    char buf[30] = { 0 };
    sockaddr_toa(&addr, buf);
    printf("accept by %s\n", buf);
    return client_st;
}

//close socket
int close_socket(int st)
{
    if (st < 0)
    {
        printf("function close_socket param not correct!\n");
        return -1;
    }
    close(st);
    return 0;
}

//protect message
int protect_message(int st, int * starr)
{
    if (st < 0 || starr == NULL)
    {
        printf("function recv_message param not correct!\n");
        return -1;
    }
    char buf[BUF_SIZE] = { 0 };
    int i = 0;
    int rc = recv(st, buf, sizeof(buf), 0);
    if (rc < 0)
    {
        printf("recv failed ! error message :%s\n", strerror(errno));
        return -1;
    } else if (rc == 0)
    {
        printf("client is closed !\n");
        return -1;
    }
    /*
     *QQ消息处理：接收到client1的消息直接发送给client2
     */
    for (; i < MAX_SOCKET_NUM; i++)
    {
        if (starr[i] != st && starr[i] != -1)
        {
            //向其他的chient发送消息
            if (send(starr[i], buf, strlen(buf), 0) < 0)
            {
                printf("send failed ! error message :%s\n", strerror(errno));
                return -1;
            }
        }
    }
    return 0;
}

//send message
int send_message(int st, int * starr)
{
    return 0;
}

//start select
int start_select(int listen_st)
{
    if (listen_st < 0)
    {
        printf("function create_select param not correct!\n");
        return -1;
    }
    int i = 0;
    //定义select第一个参数变量
    int maxfd = 0;
    int rc = 0;
    //创建客户端socket池
    int client[MAX_SOCKET_NUM] = { 0 };
    //初始化socket池
    for (; i < MAX_SOCKET_NUM; i++)
    {
        client[i] = -1;
    }
    //定义事件数组结构
    fd_set allset;
    while (1)
    {
        //清空事件数组
        FD_ZERO(&allset);
        //将服务器端socket加入事件数组
        FD_SET(listen_st, &allset);
        //假设值最大的socket是listen_st
        maxfd = listen_st;
        //将所有客户端socket加入到事件数组
        for (i = 0; i < MAX_SOCKET_NUM; i++)
        {
            if (client[i] != -1)
            {
                FD_SET(client[i], &allset);
                if (maxfd < client[i])
                {
                    maxfd = client[i];
                }
            }
        }
        //select阻塞接收消息
        rc = select(maxfd + 1, &allset, NULL, NULL, NULL);
        //select函数报错，直接退出循环
        if (rc < 0)
        {
            printf("select failed ! error message :%s\n", strerror(errno));
            break;
        }
        if (FD_ISSET(listen_st, &allset))
        {
            rc--;
            //处理服务端socket事件
            int client_st = accept_client(listen_st);
            if (client_st < 0)
            {
                /*
                 * 如果accept失败，直接退出select,
                 * continue不太合适，因为其他的客户端事件还没有处理，这样就会丢事件
                 */
                break;
            }
            //将客户端socket放到socket池中
            for (i = 0; i < MAX_SOCKET_NUM; i++)
            {
                if (client[i] == -1)
                {
                    client[i] = client_st;
                    break;
                }
            }
            if (i == MAX_SOCKET_NUM)
            {
                printf("服务器端socket池已经满了");
                //socket池已满，关闭客户端连接
                close_socket(client_st);
            }
        }
        //处理客户端事件
        for (i = 0; i < MAX_SOCKET_NUM; i++)
        {
            //如果事件数组中的事件已经处理完成，直接进入跳出当前循环
            if (rc <= 0)
            {
                break;
            }
            if (client[i] != -1)
            {
                if (FD_ISSET(client[i], &allset))
                {
                    //该socket有事件发生
                    if (protect_message(client[i], client) < 0)
                    {
                        //接收消息失败，但是由于逻辑复杂，直接退出select
                        //关闭客户端socket
                        close_socket(client[i]);
                        //将该socket从socket池中删除
                        client[i] = -1;
                        break;
                    }
                }
            }
        }
    }
    return 0;
}

//connect server
int connect_server(char * ipaddr, int port)
{
    int st = create_socket();
    if (st < 0)
    {
        return -1;
    }
    struct sockaddr_in addr;
    memset(&addr, 0, sizeof(addr));
    //type
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = inet_addr(ipaddr);
    if (connect(st, (struct sockaddr *) &addr, sizeof(addr)) < 0)
    {
        printf("connect failed ! error message :%s\n", strerror(errno));
        return -1;
    }
    return st;
}

//thread for recv message
void * thread_recv(void *arg)
{
    int st = *(int *) arg;
    if (st < 0)
    {
        printf("function thread_recv param not correct!\n");
        return NULL;
    }
    char buf[BUF_SIZE] = { 0 };
    while (1)
    {
        if (recv(st, buf, sizeof(buf), 0) < 0)
        {
            printf("recv failed ! error message :%s\n", strerror(errno));
            break;
        }
        printf("%s", buf);
        memset(buf, 0, sizeof(buf));
    }
    return NULL;
}

//thread for send message
void * thread_send(void *arg)
{
    int st = *(int *) arg;
    if (st < 0)
    {
        printf("function thread_send param not correct!\n");
        return NULL;
    }
    char buf[BUF_SIZE] = { 0 };
    while (1)
    {
        read(STDIN_FILENO, buf, sizeof(buf));
        if (send(st, buf, sizeof(buf), 0) < 0)
        {
            printf("send failed ! error message :%s\n", strerror(errno));
            break;
        }
        memset(buf, 0, sizeof(buf));
    }
    return NULL;
}

//QQ客户端
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <unistd.h>
#include <errno.h>
#include "helper.h"

int main(int arg, char *args[])
{
    if (arg < 3)
    {
        printf("please print two param !\n");
        return -1;
    }
    int port = atoi(args[2]);
    char ipaddr[30] = { 0 };
    strcpy(ipaddr, args[1]);
    //connect server
    int st = connect_server(ipaddr, port);
    if (st < 0)
    {
        return -1;
    }
    //recv thread
    pthread_t thr1, thr2;
    if (pthread_create(&thr1, NULL, thread_recv, &st) != 0)
    {
        printf("pthread_create failed ! error message :%s\n", strerror(errno));
        return -1;
    }
    if (pthread_create(&thr2, NULL, thread_send, &st) != 0)
    {
        printf("pthread_create failed ! error message :%s\n", strerror(errno));
        return -1;
    }
    //join
    pthread_join(thr1,NULL);
    pthread_join(thr2,NULL);
    //close socket
    close_socket(st);
    return 0;
}

//QQ服务端
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "helper.h"

int main(int arg,char *args[])
{
    //服务器端需要传入端口号
    if(arg<2)
    {
        printf("please print one param !\n");
        return -1;
    }
    int port=atoi(args[1]);
    int st=server_socket(port);
    if(st<0)
    {
        return -1;
    }
    //开启select 监听事件
    start_select(st);
    //close socket
    close_socket(st);
    return 0;
}

.SUFFIXES:.c .o
CC=gcc
SRCS1=QQserver.c    helper.c
SRCS2=QQclient.c    helper.c
OBJS1=$(SRCS1:.c=.o)
OBJS2=$(SRCS2:.c=.o)
EXEC1=mserver
EXEC2=mclient

start:$(OBJS1) $(OBJS2)
    $(CC) -o $(EXEC1) $(OBJS1)
    $(CC) -o $(EXEC2) $(OBJS2) -lpthread
    @echo "-------ok-----------"
.c.o:
    $(CC) -Wall -g -o [email protected] -c $<
clean:
    rm -f $(OBJS1)
    rm -f $(EXEC1)
    rm -f $(OBJS2)
    rm -f $(EXEC2)

小结：
　　这次程序编码调试都很快，调试中第一个错误，客户端连接不上服务器，但是connect不报错，我几乎每次写网络程序都有这个问题，就目前而言有两种出错可能
出错场景1：服务端socket有问题，为0或者不是正确的socket
出错场景2：服务器端的socket没有放在select池中，没有被select监视
我暂时就只有这两种犯错场景。
调试第二个错误：“Segmentation fault”，这个错误我觉得一般都是操作内存出了问题，内存泄漏，我这边是因为在函数sockaddr_toa()中
unsigned char *p=(unsiged char *)&(addr->sin_addr.s_addr); //没有取addr->sin_addr.s_addr的地址转化成unsigned char类型，发生内存泄漏
调试第三个错误是逻辑错误，每次有客户端socket接收数据出错后，我没有从socket池中将该socket清除，导致select()函数不再阻塞，每次直接返回