SIGURG信号 -- 带外数据的处理

野性酷女 2022-07-26 01:45 213阅读 0赞

使用SIGURG处理带外数据程序实例：

#include <sys/socket.h>
    #include <netinet/in.h>
    #include <arpa/inet.h>
    #include <assert.h>
    #include <stdio.h>
    #include <unistd.h>
    #include <stdlib.h>
    #include <errno.h>
    #include <string.h>
    #include <signal.h
    #include <fcntl.h>
    
    #define BUFSIZE 1024
    
    static int connfd;
    
    /*SIGURG信号处理函数*/
    void sig_urg(int urg)
    {
        int save_errno = errno;
        char buffer[BUFSIZE];
        memset(buffer, '\0', BUFSIZE);
        int ret = recv(connfd, buffer, BUFSIZE-1 , MSG_OOB);/*MSG_OOB标志 接收带外数据*/
        printf("接收到%d数据:%s\n", ret, buffer);
        errno = save_errno;    
    }
    
    void addsig(int sig, void (*sig_handler)(int))
    {
        struct sigaction sa;
        memset(&sa, '\0', sizeof(sa));
        sa.sa_handler = sig_handler;
        sa.sa_flags |= SA_RESTART;
        sigfillset(&sa.sa_mask);
        assert(sigaction(sig, &sa, NULL) != -1);
    }
    
    int main(int argc, char* argv[])
    {
        if(argc <= 2)
        {
            printf("Args err");
            return 1;
        }
    
        const char* ip = argv[1];
        int port = atoi(argv[2]);
    
        struct sockaddr_in address;
        bzero(&address, sizeof(address));
        address.sin_family = AF_INET;
        inet_pton(AF_INET, ip, &address.sin_addr);
        address.sin_port = htons(port);
    
        int sock = socket(PF_INET, SOCK_STREAM, 0);
        assert(sock >= 0);
    
        int ret = bind(sock, (struct sockaddr*)&address, sizeof(address));
        assert(ret != -1);
    
        struct sockaddr_in client;
        socklen_t client_addrlength = sizeof(client);
        connfd = accept(sock, (struct sockaddr*)&client, &client_addrlength);
        if(connfd < 0)
        {
            printf("errno is %d\n", errno);
        }
        else
        {
            /*捕捉到SIGURG则执行sig_urg信号处理函数*/
            addsig(SIGURG, sig_urg);
            /*使用SIGURG信号前，必须设置socket的宿主进程或进程组，设为当前进程*/
            fcntl(connfd, F_SETOWN, getpid());
    
            char buffer[BUFSIZE];
            /*普通数据入口*/
            while(1)
            {
                memset(buffer, '\0', BUFSIZE);
    
                ret = recv(connfd, buffer, BUFSIZE-1,0);
                if(ret <= 0)
                {
                    break;
                }
                printf("接收到%d数据:%s\n", ret, buffer);
            }
            close(connfd);
        }
        close(sock);
    
        return 0;
    }

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