从UDP套接字C＆＃x2B;＆＃x2B读取二进制数据

Question

我正在尝试从UDP插座读取二进制数据。数据（二进制，每个步骤递增）具有16位，并通过FPGA以太网接口发送到我的主机计算机（Ubuntu 20）。我的UDP服务器正在接收数据，但未显示。我想“ printf”函数有问题，因为当我通过终端发送（本地）文本时，它起作用。如何显示此数据？ UDP服务器的代码如下：

#include <QCoreApplication>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <iostream>
#include <string>
#include <sstream>
#include <stdio.h>
#include <stdlib.h>

#define BUFLEN 512  //Max length of buffer
#define PORT 1024   //The port on which to listen for incoming data

void die(char *s)
{
    perror(s);
    exit(1);
}

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    struct sockaddr_in si_me, si_other;
    socklen_t slen = sizeof(si_other);

    int s, i , recv_len;
    char buf[BUFLEN];

    //create a UDP socket
    if ((s=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1)
    {
        die("socket");
    }

    // zero out the structure
    memset((char *) &si_me, 0, sizeof(si_me));

    si_me.sin_family = AF_INET;
    si_me.sin_port = htons(PORT);
    si_me.sin_addr.s_addr = htonl(INADDR_ANY);

    //bind socket to port
    if( bind(s , (struct sockaddr*)&si_me, sizeof(si_me) ) == -1)
    {
        die("bind");
    }

    printf("Using port %d, ctrl + C abort\n", PORT);

    //keep listening for data
    while(1)
    {
        printf("Waiting for data...");
        fflush(stdout);

        //try to receive some data, this is a blocking call
        if ((recv_len = recvfrom(s, buf, BUFLEN, MSG_WAITALL, (struct sockaddr *) &si_other, &slen)) == -1)
        {
            die("recvfrom()");
        }

        //print details of the client/peer and the data received
        printf("Received packet from %s:%d\n", inet_ntoa(si_other.sin_addr), ntohs(si_other.sin_port));
        printf("Data: %s\n" , buf);
    }

    close(s);
    return 0;

    return a.exec();
}

解决方案： printf（）函数确实存在问题。为了打印收到的十六进制数据，我使用了此提示（问题C插座）打印数据：

#include <ctype.h>
#include <stdio.h>
void hexdumpunformatted(void *ptr, int buflen) {
  unsigned char *buf = (unsigned char*)ptr;
  int i, j;
  for (i=0; i<buflen; i++) {
    printf("%02x ", buf[i]);
    printf(" ");
  }
}