本文介绍了UDP可靠的数据服务实现的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我正在尝试使用UDP实现简单的数据传输.校验和有问题,给定包含数据的数据包,我应该如何实现校验和?还知道如何实现超时,以便触发重传吗?谢谢
I'm trying to implement a simple data transfer using UDP. I have a problem for the checksum, given a packet containing the data, how should I implement the checksum? also any idea how to implement the timeouts so it will trigger the retransmission ? Thanks
推荐答案
here's one approach for the internet checksum
unsigned short checkSum() {
unsigned long sum = 0;
int i;
for(i=0; i < your packet length ; i++) {
sum += (your packet data[i] & 0xFFFF);
}
while (sum >> 16) {
sum = (sum & 0xFFFF) + (sum >> 16);
}
sum = ~sum;
return ((unsigned short) sum);
}
for the retransmission, you can set alarm to trigger timeout
when packet is loss. you can do something using
signal (SIGALRM, timeout function);
Hope it helps!
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