Go Back N C语言(有ACK)

最新推荐文章于 2021-05-19 22:25:12 发布

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最新推荐文章于 2021-05-19 22:25:12 发布 · 4.1k 阅读

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#c语言

本文详细介绍了如何使用C语言实现Go Back N协议，包括其工作原理、数据包发送与接收过程，并探讨了带有ACK确认机制的实现细节，为理解网络协议提供了实践案例。

#include <stdio.h>
#include <string.h>

#include "protocol.h"
#include "datalink.h"

#define DATA_TIMER  3000
#define ACK_TIMER 1500
#define MAX_SEQ 7

void inc(unsigned char* number)
{
	(*number)++;
	if(*number==MAX_SEQ+1)
	*number=0;
}

struct FRAME { 
    unsigned char kind; /* FRAME_DATA */
    unsigned char ack;
    unsigned char seq;
    unsigned char data[PKT_LEN]; 
    unsigned int  padding;
};

struct ACK_FRAME { 
    unsigned char kind; /* FRAME_DATA */
    unsigned char ack;
    unsigned int  padding;
};

static unsigned char frame_nr = 0;	//next frame to send
static unsigned char ack_expected = 0; 
static unsigned char buffer[MAX_SEQ+1][PKT_LEN];	//
static unsigned char nbuffered = 0;					//缓冲区大小	
static unsigned char frame_expected = 0;
static int phl_ready = 0;


static void put_frame(unsigned char *frame, int len)
{
    *(unsigned int *)(frame + len) = crc32(frame, len);
    send_frame(frame, len + 4);