为什么没有scm_timestamping控制消息出现？

问题描述

我的代码由两个程序组成：TCP服务器和TCP客户端。该项目的目标是为TCP工作打上时间戳记。我查阅了this个Linux文档，但似乎找不到任何表明我的代码不起作用的内容。它说SO_TIMESTAMPING可用于流套接字。我真的在这里迷路了。还是我误解了它应该如何工作？我从未使用过linux，也从未进行过任何网络连接，因此我可能会遇到一个明显的错误，但是我没有看到它。

• client.cpp：

#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <arpa/inet.h> 
#include <linux/errqueue.h>
#include <linux/net_tstamp.h>

int port = 8989;
const char *address = "127.0.0.1";

int main(int argc,char *argv[])
{
    int sockfd = 0,n = 0;
    char recvBuff[1024];
    struct sockaddr_in serv_addr; 

    memset(recvBuff,'0',sizeof(recvBuff));
    if((sockfd = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP)) < 0)
    {
        fprintf(stderr,"\n Error : Could not create socket \n");
        return 1;
    }

    // Enable timestamping:
    int timestampingFlags = SOF_TIMESTAMPING_RX_SOFTWARE | SOF_TIMESTAMPING_SOFTWARE;
    int optRet = setsockopt(sockfd,SOL_SOCKET,SO_TIMESTAMPING,&timestampingFlags,sizeof(timestampingFlags));
    if(optRet < 0)
    {
        printf("Unable to set socket option for timestamping");
    } // OK

    memset(&serv_addr,sizeof(serv_addr)); 

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(port); 

    if(inet_pton(AF_INET,address,&serv_addr.sin_addr)<=0)
    {
        fprintf(stderr,"\n inet_pton error occured\n");
        return 1;
    } 

    if(connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr)) < 0)
    {
       fprintf(stderr,"\n Error : Connect Failed \n");
       perror(0);
       return 1;
    } 

    // Receive responses
    while ((n = read(sockfd,recvBuff,sizeof(recvBuff)-1)) > 0)
    {
        recvBuff[n] = 0;
        if(fputs(recvBuff,stdout) == EOF)
        {
            fprintf(stderr,"\n Error : Fputs error\n");
        }

        // Get and print the time stamp
        struct msghdr msgh;
        struct cmsghdr *cmsg;
        struct scm_timestamping *timeStamp;

        int flags = MSG_WAITALL | MSG_PEEK;
        int recvRet = recvmsg(sockfd,&msgh,flags);
        /* Receive auxiliary data in msgh */

        // There are no messages here
        for(cmsg = CMSG_FirsTHDR(&msgh);
            cmsg != NULL;
            cmsg = CMSG_NXTHDR(&msgh,cmsg))
        {
            printf("A control message arrived!\n");
            if (cmsg->cmsg_level == SOL_SOCKET &&
                cmsg->cmsg_type == SCM_TIMESTAMPING)
            {
                timeStamp = (struct scm_timestamping *)CMSG_DATA(cmsg);
                printf("Timestamp received: %ld.09%ld\n",timeStamp->ts[0].tv_sec,timeStamp->ts[0].tv_nsec);
                break;
            }
        }
    }

    if(n < 0)
    {
        fprintf(stderr,"\n Read error \n");
    }
    return 0;
}

-server.cpp：

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <time.h> 
#include <signal.h>

// call this function to start a nanosecond-resolution timer
struct timespec timer_start()
{
    struct timespec start_time;
    clock_gettime(CLOCK_PROCESS_cpuTIME_ID,&start_time);
    return start_time;
}

// call this function to end a timer,returning microseconds elapsed as a long
long timer_end(struct timespec start_time)
{
    struct timespec end_time;
    clock_gettime(CLOCK_PROCESS_cpuTIME_ID,&end_time);
    long diffInNanos = (end_time.tv_sec - start_time.tv_sec) * (long)1e9 + (end_time.tv_nsec - start_time.tv_nsec);
    return diffInNanos / 1000;
}

int port = 8989;

int main(int argc,char *argv[])
{
    int listenfd = 0,connfd = 0;
    struct sockaddr_in serv_addr; 

    char sendBuff[1025];
    time_t ticks; 

    listenfd = socket(AF_INET,IPPROTO_TCP);
    memset(&serv_addr,sizeof(serv_addr));

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons(port);

    bind(listenfd,(struct sockaddr*)&serv_addr,sizeof(serv_addr)); 

    printf("Now listening for a connection!\n");
    listen(listenfd,1);     
    
    // Wait for a connection from a client socket
    connfd = accept(listenfd,(struct sockaddr*)NULL,NULL);
    printf("Connected!\n");

    // Once connection is established,start sending messagess in a regular time interval
    
    long timeBetweenSendsUS = 1000*1000;
    for(struct timespec startTime = timer_start();
        true;
        startTime = timer_start())
    {
        memset(sendBuff,sizeof(sendBuff));
        ticks = time(NULL);
        snprintf(sendBuff,sizeof(sendBuff),"%.24s\r\n",ctime(&ticks));

        long elapsedUS = timer_end(startTime);
        usleep(timeBetweenSendsUS - elapsedUS);
        printf("Sending message!\n");
        write(connfd,sendBuff,strlen(sendBuff));
    }

    close(connfd);
    return 0;
}

然后我使用g++ <filename> -o <filename>分别编译每个文件，并在服务器运行时首先运行服务器二进制文件，然后运行客户机二进制文件。因此，请重复我的问题：为什么辅助数据中没有控制消息？

解决方法

暂无找到可以解决该程序问题的有效方法，小编努力寻找整理中！

如果你已经找到好的解决方法，欢迎将解决方案带上本链接一起发送给小编。

小编邮箱:dio#foxmail.com (将#修改为@）