linux 网络编程:使用两线程实现socket同时收发数据
来源:互联网 发布:linux编写c语言 编辑:程序博客网 时间:2024/05/16 04:57
转载:http://blog.csdn.net/li_wen01/article/details/52665505
工作中最近有使用到socket 向客户端同时发送和接收数据,因为是嵌入式linux设备,且要求只能同时一个客户端连接该端口。考虑到节省系统资源,只创建了两个线程分别实现服务端的收发数据。下面直接上代码,该代码为在PC机上程序,已作详细注释。
server.c
- #include<stdio.h>
- #include<stdlib.h>
- #include<string.h>
- #include<errno.h>
- #include<sys/types.h>
- #include<sys/socket.h>
- #include<netinet/in.h>
- #include<termios.h>
- #include<sys/types.h>
- #include<sys/stat.h>
- #include<fcntl.h>
- #include<unistd.h>
- #include<sys/ioctl.h>
- #include<signal.h>
-
- #define MAXLINE 256
- #define PORT 6666
- int listenfd;
- int connfd;
- pthread_t read_id, write_id;
-
-
-
-
-
- void stop(int signo)
- {
- printf("stop\n");
- close(connfd);
- close(listenfd);
- _exit(0);
- }
-
-
-
-
-
-
- void signal_pipe(int signo)
- {
- pthread_kill(read_id,SIGQUIT);
- pthread_join(read_id,NULL);
-
- close(connfd);
- printf("read pthread out \n");
-
- pthread_exit(0);
- }
-
-
-
-
-
- void pthread_out(int signo)
- {
- pthread_exit(0);
- }
-
-
-
-
- void* read_func(void* arg)
- {
- char readbuff[MAXLINE];
- int n = 0;
- int fd;
-
- fd = *(int*)arg;
- memset(&readbuff,0,sizeof(readbuff));
-
- signal(SIGQUIT,pthread_out);
- while(1)
- {
- n = recv(fd, readbuff, MAXLINE, 0);
- if(n > 0)
- {
- printf("server recv data: %s \n",readbuff);
- }
- };
- }
-
-
-
- void* write_func(void* arg)
- {
- char writebuff[MAXLINE];
- char* write = "I am server";
- unsigned char i = 0;
- int num = 0;
- int fd;
-
- fd = *(int*)arg;
- memset(&writebuff,0,sizeof(writebuff));
-
- signal(SIGPIPE,signal_pipe);
- while(1)
- {
- sleep(1);
- send(fd,write,strlen(write)+1,0);
- }
- }
-
- int main(int argc, char** argv)
- {
- char buff[MAXLINE];
- int num;
- int addrlen;
- struct sockaddr_in server_addr;
- struct sockaddr_in client_addr;
-
- if((listenfd = socket(AF_INET,SOCK_STREAM,0)) == -1)
- {
- printf("create socket error: %s(errno: %d)\n",strerror(errno),errno);
- exit(0);
- }
-
-
- addrlen = sizeof(struct sockaddr_in);
- memset(&server_addr, 0, addrlen);
- server_addr.sin_family = AF_INET;
- server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
- server_addr.sin_port = htons(PORT);
-
-
- if( bind(listenfd, (struct sockaddr*)&server_addr, sizeof(server_addr)) == -1)
- {
- printf("bind socket error: %s(errno: %d)\n",strerror(errno),errno);
- exit(0);
- }
-
-
- if( listen(listenfd, 1) == -1)
- {
- printf("listen socket error: %s(errno: %d)\n",strerror(errno),errno);
- exit(0);
- }
-
- signal(SIGINT,stop);
- while(1)
- {
- printf("wait client accpt \n");
- if( (connfd = accept(listenfd, (struct sockaddr*)&client_addr, &addrlen)) == -1)
- {
- printf("accept socket error: %s(errno: %d)",strerror(errno),errno);
- continue;
- }
-
- if(pthread_create(&read_id,NULL,read_func,&connfd))
- {
- printf("pthread_create read_func err\n");
- }
-
- if(pthread_create(&write_id,NULL,write_func,&connfd))
- {
- printf("pthread_create write_func err\n");
- }
-
- pthread_join(write_id,NULL);
- printf("write pthread out \n");
- }
- }
这里需要特别注意线程资源的回收,因为每次与客户端建立连接,服务端都会创建连个线程,因此我们需要在客户端断开连接时回收线程资源。在这里有两种方式来检测客户端是否已经断开连接。第一:上面server.c服务端使用的,当客户端断开连接时,send 所在的进程会收到一个SIGPIPE信号,服务端收到SIGPIPE信号就进行线程退出操作。第二:recv函数在对方断开连接它会返回参数0,根据该参数也可以知道客户端已经断开了连接。在下面你的client.c客户端测试程序使用的就是这种方式。 这里还有一个问题,signal(SIGPIPE,signal_pipe)函数的注册,我本来是把它放置在主线程main函数中,然后在signal_pipe 同时回收read 和 write线程,结果read进程可以正常回收,write线程却回收失败,具体原因也不清楚,求高人指点。于是我就是用SIGQUIT信号,在write线程收到SIGPIPE信号时,通知read线程退出,直到其退出再退出write线程。这样就实现了系统资源的回收。
client客户端测试程序:
- #include<stdio.h>
- #include<stdlib.h>
- #include<string.h>
- #include<errno.h>
- #include<sys/types.h>
- #include<sys/socket.h>
- #include<netinet/in.h>
- #include<termios.h>
- #include<sys/types.h>
- #include<sys/stat.h>
- #include<fcntl.h>
- #include<unistd.h>
- #include<sys/ioctl.h>
- #include<signal.h>
-
- #define MAXLINE 256
- #define PORT 6666
- int fd;
-
-
-
-
- void stop(int signo)
- {
- printf("client stop\n");
- close(fd);
- _exit(0);
- }
-
-
- void client_process(void)
- {
- char readbuff[MAXLINE];
- char writebuff[MAXLINE];
- charchar * write = "I am client";
- int num = 0;
-
- while(1)
- {
- num = recv(fd,readbuff,MAXLINE,0);
- if(num > 0)
- {
- printf("client read data : %s \n",readbuff);
- send(fd, write, strlen(write)+1, 0);
- }
- else if(num == 0)
- {
- stop(1);
- }
- }
- }
-
- int main(int argc, char** argv)
- {
- struct sockaddr_in server_addr;
- struct sockaddr_in client_addr;
- int ret;
-
- fd = socket(AF_INET,SOCK_STREAM,0);
- if(fd < 0)
- {
- printf("clinet socket err \n");
- }
-
-
- memset(&server_addr,0,sizeof(server_addr));
- server_addr.sin_family = AF_INET;
- server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
- server_addr.sin_port = htons(PORT);
-
- inet_pton(AF_INET,argv[1],&server_addr.sin_addr);
- connect(fd,(struct sockaddr*)&server_addr,sizeof(server_addr));
-
- signal(SIGINT,stop);
- client_process();
-
- close(fd);
- return 0;
- }
在客户端是用recv 函数的返回值判断服务端是否断开连接而不是SIGPIPE信号,主要是在这程序中,我的实现是send函数在接收到服务端的数据才发送,所以如果在这里不会触发SIGPIPE信号。如果要实现客户端的独立收发,可以模仿服务端的实现方式,这里不再现实。下面是测试执行情况:
- root@ubuntu:/home/share/Socket# ./server
- wait client accpt
- server recv data: I am client
- server recv data: I am client
- server recv data: I am client
- server recv data: I am client
- server recv data: I am client
- server recv data: I am client
- server recv data: I am client
- server recv data: I am client
- read pthread out
- write pthread out
- wait client accpt
- server recv data: I am client
- server recv data: I am client
- server recv data: I am client
- read pthread out
- write pthread out
- wait client accpt
-
-
-
- root@ubuntu:/home/share/Socket# ./client 127.0.0.1
- client read data : I am server
- client read data : I am server
- client read data : I am server
- client read data : I am server
- client read data : I am server
- client read data : I am server
- client read data : I am server
- client read data : I am server
- ^Cclient stop
- root@ubuntu:/home/share/Socket# ./client 127.0.0.1
- client read data : I am server
- client read data : I am server
- client read data : I am server
- ^Cclient stop
- root@ubuntu:/home/share/Socket#
执行服务端从程序等待客户连接,执行客户端程序与服务端建立连接,服务端每秒向客户端发送字符串:I am server,客户端接收到数据后向服务端发送字符串: I am client 。在client端按下ctrl + c 结束客户端程序,服务端检测到客户端断开连接后,关闭文件描述符,回收创建的read 和write 线程。- root@ubuntu:/home/share/Socket# ./server
- wait client accpt
- server recv data: I am client
- server recv data: I am client
- server recv data: I am client
- server recv data: I am client
- server recv data: I am client
- ^Cstop
- root@ubuntu:/home/share/Socket#
-
- root@ubuntu:/home/share/Socket# ./client 127.0.0.1
- client read data : I am server
- client read data : I am server
- client read data : I am server
- client read data : I am server
- client read data : I am server
- client stop
- root@ubuntu:/home/share/Socket#
在服务端按下ctlc + c 服务端检测到SIGINT信号,关闭文件描述符结束程序,整个进程全部退出。客户端检测到服务端断开连接后,执行退出操作。这里实现的是只有一个客户端同时连接时的处理方式,如果要处理多客户端同时连接,使用这种方式好像并不合适,可以使用多进程的方式处理。