是否有一个pre-现有功能或code，我可以用它来计算TCP段的校验和在POSIX程序 [英] Is there a pre-existing function or code I can use to compute a TCP segment checksum in a POSIX program

问题描述

我写一个小程序POSIX，我需要计算一个TCP段的校验，我想使用现有的功能，以避免写一个自己。

I am writing a little POSIX program and I need to compute the checksum of a TCP segment, I would like use an existing function in order to avoid to writing one myself.

喜欢的东西（伪code）：

Something like (pseudocode) :

char *data = ....
u16_integer = computeChecksum(data);

我在网上搜索上，但我没有找到一个正确的答案，任何建议？

I searched on the web but I did not find a right answer, any suggestion ?

推荐答案

下面，它采取或多或少直接从RFC：

Here, it's taken more or less directly from the RFC:

uint16_t ip_calc_csum(int len, uint16_t * ptr)
{

        int sum = 0;
        unsigned short answer = 0;
        unsigned short *w = ptr;
        int nleft = len;

        while (nleft > 1) {
                sum += *w++;
                nleft -= 2;
        }

        sum = (sum >> 16) + (sum & 0xFFFF);
        sum += (sum >> 16);
        answer = ~sum;
        return (answer);
}

这篇关于是否有一个pre-现有功能或code，我可以用它来计算TCP段的校验和在POSIX程序的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！