Linux-C 本地套接字使用例子

叁歲伎倆 2023-07-03 08:13 30阅读 0赞

###                                                      Linux-C 本地套接字使用例子 ###

**一、简述**

记--简单的使用本地套接字(UNIX套接字)双向通信的例子。

源码打包：链接: https://pan.baidu.com/s/1POzM1x6Bn2iCV3nzkwphmg 提取码: 5kvp

**二、效果**

三个进程使用本地套接字进行收发消息。       ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L25hbmZlaWJ1eWk_size_16_color_FFFFFF_t_70][]

![20200204203632599.gif][]

三、工程结构

![20200204203941449.png][]

四、源文件

main.c文件

#include <stdio.h>
    #include "udsSocket.h"
    #include <string.h>
    #include <stdlib.h>
    #include <pthread.h>
    #include <unistd.h>
    #include <arpa/inet.h>
    #include <signal.h>
    
    int gSockFd = -1;
    pthread_t gRecv_thread = -1;
    void * recv_msg(void *arg);
    void releaseResource(int sigNo);
    
    int main(int argc, char* argv[])
    {
    	int ret;
    	char buf[1024] = {0};
    	char destAddr[1024] = {0};
    	
    	if(argc<2)
    	{
    		printf("eg:./main /home/liang/sock_A\n");
    		return -1;
    	}
    	
    	//绑定sock
    	printf("addr:%s,\n",argv[1]);
    	int gSockFd = udsBind(argv[1], strlen(argv[1]));
    	if(gSockFd<=0)
    	{		
    		return -1;
    	}
    	
    	//printf("gSockFd:%d,\n",gSockFd);
    	
    	//捕捉Ctrl+C信号，用来释放资源
    	signal(SIGINT, releaseResource);
    	
    	//创建接收线程	
    	pthread_create(&gRecv_thread, NULL, recv_msg, (void*)&gSockFd);
    	
    	//循环发送消息
    	while(1)
    	{
    		printf("destAddr Msg:");
    		scanf("%s %s", destAddr, buf);
    		if(strlen(buf)>0)
    		{
    			ret = udsSendMessage(gSockFd, buf, strlen(buf), destAddr);
    			printf("buf:%s, ret:%d,\n", buf, ret);
    			if(ret<=0)
    			{
    				printf("send ret：%d.\n", ret);
    			}
    		
    			if(strcmp(buf, "exit") == 0)
    			{				
    				break;
    			}
    		}		
    		
    		memset(buf, 0, sizeof(buf));
    		memset(destAddr, 0, sizeof(destAddr));
    	}
    	
    	//关闭子线程
    	if(gRecv_thread>=0)
    	{
    		pthread_cancel(gRecv_thread);
    		gRecv_thread = -1;
    	}
    	
    	printf("exit program!\n");
    	return 0;
    }
    
    //处理挂断信号--SIGINT
    void releaseResource(int sigNo)
    {
    	//关闭通信socket
    	if(gSockFd>=0)
    	{
    		close(gSockFd);
    	}
    	
    	//关闭子线程
    	if(gRecv_thread>=0)
    	{
    		pthread_cancel(gRecv_thread);
    		gRecv_thread = -1;
    	}
    	
    	printf("\nRelease resource.\n");
    	exit(0);
    }
    
    //接收线程所要执行的函数 接收消息
    void* recv_msg(void *arg)
    {
    	int ret = 0;
    	int *socket_fd = (int *)arg;//通信的socket
    	struct sockaddr_un  src_addr;  //用来存放对方(信息的发送方)的IP地址信息
    	char msg[1024] = {0};//消息缓冲区
    	char msg2[1024] = {0};//消息缓冲区
    	socklen_t sockLen = sizeof(src_addr);
    	
    	if(*socket_fd<1)
    	{
    		return (void *)-1;
    	}
    	
    	memset(&src_addr, 0, sizeof(src_addr));
    	
    	//循环接收客户发送过来的数据  
    	while(1)
    	{
    		//ret = udsRecv(*socket_fd, msg);
    		ret = recvfrom(*socket_fd, msg, sizeof(msg), 0, (struct sockaddr *)&src_addr, &sockLen);
    		if(ret>=0)
    		{
    			//printf("\n[RECV From %s:%d]%s,\n", inet_ntoa(src_addr.sin_addr), ntohs(src_addr.sin_port), msg);//打印消息发送方的ip与端口号 本地套接字都是在本机通信的，sockaddr_un结构体没有IP和端口的成员，sockaddr_in结构体有
    			printf("\n[RECV From %s]%s\n", src_addr.sun_path, msg);
    			printf("destAddr Msg:");
    			fflush(stdout);
    			if(strcmp(msg, "exit") == 0)
    			{
    				//通知主线程。。。
    				break;
    			}	
    			memset(msg, 0, sizeof(msg));//清空上次消息
    		}
    		usleep(400);			 
    	}
    	
    	//关闭通信socket
    	close(*socket_fd);
    	printf("exit program!\n");
    	exit(0);
    	return NULL;
    }

udsSocket.c文件

#include <unistd.h>
    #include <fcntl.h>
    #include <sys/types.h>
    #include <errno.h>
    #include <sys/stat.h>
    #include <stdio.h>
    #include "udsSocket.h"
    
    #define RECV_SIZE_MAX	1024
    
    enum e_ErrNo
    {
    	RETERR,
    	RETFAIL,
    	RETOK,
    	RETCONTINUE,
    	RETNUL
    };
    
    struct sockaddr_un gSrcAddr = {0};
    struct sockaddr_un gDestAddr = {0};
    socklen_t gSockLen = 0;
    int gSocketFd = 0;
    
    //绑定socket
    int udsBind(const char* _path, int _len)
    {
    	int ret;
    	int flag;
    	char path[32];
    
    	if (_len > sizeof(path))
    	{
    	    perror( "path is too long!" );
    	    return -1;
    	}
    
    	strncpy(path, _path, _len);
    	
    	if ((gSocketFd = socket(AF_UNIX, SOCK_DGRAM, 0)) < 0)
    	{
    		perror( "socket error!" );
    		return -1;
    	}
    
    	unlink(path);
    	//printf("gSocketFd:%d,\n",gSocketFd);
    
    	memset( &gSrcAddr, 0, sizeof(gSrcAddr));
    	gSrcAddr.sun_family = AF_UNIX;
    	strncpy( gSrcAddr.sun_path,  path, strlen(path));
    
    	gSockLen = strlen( gSrcAddr.sun_path ) + sizeof( gSrcAddr.sun_family);
    	
    	ret = bind(gSocketFd,(struct sockaddr*)&gSrcAddr, gSockLen);
    	if(ret < 0)
    	{
    		perror("bind err!\n");
    		return -1;
    	}
    
    	//设置为非阻塞
    #ifdef NONBLOCK
    	flag = fcntl(gSocketFd, F_GETFL, 0);
    	if(flag < 0)
    	{
    		perror("fcntl fail!\n");
    		return -1;
    	}
    	flag |= O_NONBLOCK;//非阻塞，没有读到消息立即返回不等待
    	if (fcntl(gSocketFd, F_SETFL, flag) < 0)
    	{
    		perror("fcntl fail!\n");
    		return -1;
    	}
    #endif
    	
    	chmod(path, S_IRUSR|S_IWUSR|S_IXUSR|S_IRGRP|S_IWGRP|S_IXGRP|S_IROTH|S_IWOTH|S_IXOTH);
    
        return gSocketFd;
    }
    
    
    //发送socket消息
    int udsSendMessage(int _socketFd, char* _data, int _len, const char * _destAddr)
    {
    	int ret;	
    	struct sockaddr_un destAddr;
    	if(gSocketFd>0)
    	{
    		memset( &destAddr, 0, sizeof( destAddr ) );
    		destAddr.sun_family = AF_UNIX;
    		strncpy(destAddr.sun_path, _destAddr, strlen(_destAddr));
    		
    		socklen_t sockLen = strlen(destAddr.sun_path) + sizeof(destAddr.sun_family);
    		
    		ret = sendto( gSocketFd, _data, _len, 0, (struct sockaddr *)&destAddr, sockLen);
    		if( ret < 0 )
    		{
    			perror( "write socket error!" );
    			return RETERR;
    		}
    	}	
    
    	return ret;
    }
    
    
    //接收socket消息
    int udsRecv(int _socketFd, char *sBuf) 
    {
    	int err, ret = 0;
    	char tmpbuf[RECV_SIZE_MAX];
    	
    	if(_socketFd>0)
    	{
    		memset(tmpbuf, 0, RECV_SIZE_MAX); 
    		socklen_t sockLen = strlen(gDestAddr.sun_path) + sizeof(gDestAddr.sun_family);
    		
    		errno = 0;
    		ret = recvfrom(_socketFd, tmpbuf, RECV_SIZE_MAX, 0, (struct sockaddr*)&gDestAddr, &sockLen);
    		printf("sockLen=%d,\n", sockLen);
    		err = errno;
    
    		if (ret == -1 && err != EAGAIN && err != EWOULDBLOCK)
    		{	
    			perror("recv failed.\n");
    			return RETERR;
    		}
    		else if (ret == 0 || (ret==-1 && err==EAGAIN))
    		{
    			return RETCONTINUE;
    		}
    		
    		memcpy(sBuf, tmpbuf, ret);
    	}	
    	
    	return ret;
    }

udsSocket.h文件

#ifndef __UDSSOCKET_H_
    #define __UDSSOCKET_H_
    
    #include <sys/socket.h>
    #include <sys/un.h>
    
    int udsBind(const char* _path, int _len);
    int udsSendMessage(int _socketFd, char* _data, int _len, const char * _destAddr);
    int udsRecv(int _socketFd, char *sBuf);
    
    
    #endif //__UDSSOCKET_H_

Makefile文件

#Description:For UdsSocket Test
    #Date:2020-02-04
    #Author:Genven_Liang
    
    CC=gcc
    FLAG=-lpthread -Wall
    TARGET=main
    
    SRC := $(shell ls *.c)
    OBJ := $(patsubst %.c,%.o,$(SRC))
    #OBJ=main.o udsSocket.o
    
    $(TARGET):$(OBJ)
    	@$(CC) -o $@ $^ $(FLAG)
    	@echo "make successful!!!"
    
    %.o:%.c
    	@$(CC) -c -o $@ $<
    
    .THONY:clean
    clean:
    	@rm -f $(TARGET) $(OBJ)
    	@echo "clean finish!!!"

五、总结

5.1 UDS(Unix Domain Socket) Unix域套接字

用于本地进程间通信，类似UDP。

头文件在sys/un.h, 可使用find或locate命令查找存放路径

使用find命令在/usr路径下查找un.h

![20200204205423891.png][]

使用locate命令直接查找

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L25hbmZlaWJ1eWk_size_16_color_FFFFFF_t_70 1][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L25hbmZlaWJ1eWk_size_16_color_FFFFFF_t_70 2][]

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[20200204203632599.gif]: https://img-blog.csdnimg.cn/20200204203632599.gif
[20200204203941449.png]: https://img-blog.csdnimg.cn/20200204203941449.png
[20200204205423891.png]: https://img-blog.csdnimg.cn/20200204205423891.png
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