UDP套接字编程 [英] UDP Socket Programming

问题描述

我正在使用通过端口50001接收数据的UDP服务器。我使用wireshark来监控数据。我在UDP服务器缓冲区中收到的数据和wireshark中显示的数据不完全匹配。但是有些地方它完全匹配......这可能是什么原因？这是UDP服务器的接收器代码

I am using UDP Server which receives data through port 50001. I used wireshark to monitor the data. Here the data what i receive in UDP server buffer and what data is showing in wireshark is not matching fully . but some places it is matching exactly ...What could be the reason for this? here is the receiver code for UDP server

char mesg[50];


n=recvfrom(sockfd,mesg,50,0,(struct sockaddr*)&cliaddr,&len);
fwrite(mesg,1,50,fp);

来自客户端的任何值应该在3000到-3000的范围内，但在某些地方它会达到30000到-30000。在wireshark中，我绘制了它正好在3000到-3000范围内的值。但如果我绘制接收缓冲区，它给出的范围是3000到-3000，但更多的值在30000到-30000范围内

the values whatever is coming from client should be in the range of 3000 to -3000 but in some places it is going to 30000 to -30000. In wireshark i plotted that values it is coming exactly in 3000 to -3000 range. but if i plot the received buffer it is giving in the range of 3000 to -3000 but also more values are in the range of 30000 to -30000

推荐答案

你的 fwrite 调用错误，因为假设收到的消息中有50个字符。您应该使用从 recvfrom 的调用返回的值，因此：

Your fwrite call is wrong as it is assuming there are 50 characters in the received message. You should be using the value returned from the call to recvfrom thus:

n = recvfrom(sockfd, mesg, 50, 0, (struct sockaddr*)&cliaddr, &len);
fwrite(mesg, 1, n, fp);

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