协议实现c语言

1、中文注释编程实现一个GBN传输协议的发送方和接收方两程序，采用编程语言不限，要求能将发送接收流程以及处理方法表现出来.附源代码及注释源代码：三：GBN-CS.c#include "GBN.h"#include <stdio.h>#include <string.h>#include <stdlib.h>extern int TRACE ; /* 用于跟踪 */ extern int nsim ; /* 当前第5层到第4层的信息数 */ extern int nsimmax; /*"msg"生成数量,直到停止，生成的最大

2、信息数 */extern float time; /时间extern int packet_correct; /包的正确到达数extern int packet_resent; /包的重传数extern struct event *evlist; /事件int main() /主函数struct event *eventptr;/变量，结构体声明struct msg msg2give;struct pkt pkt2give;int i,j;char c; init();/初始化 A_init();/A端初始化 B_init();/B端初始化 while (1) /循环，用于每个包的传送 eve

3、ntptr = evlist; /* 从模拟器得到下一个事件 */ if (eventptr=NULL)goto terminate; evlist = evlist->next;/* 从事件清单改变该事件 */ if (evlist!=NULL)evlist->prev=NULL;if (TRACE >= 2)/打印与事件相关的信息printf("n事件时间: %f,",eventptr->evtime);printf(" 类型: %d",eventptr->evtype);if (eventptr->evtype=

4、0)printf(", 计时器中断： ");else if (eventptr->evtype=1)printf(", 来自第五层 ");elseprintf(", 来自第三层 ");if (eventptr->eventity = A)/打印事件实体printf(" 通信实体: %d A端n",eventptr->eventity); elseprintf(" 通信实体: %d B端n",eventptr->eventity); time = eventptr->

5、evtime; /* 更新下一个事件的时间 */if (nsim=nsimmax)break; /* 当输入包个数等于生成的最大包个数，模拟器停止 */ if (eventptr->evtype = FROM_LAYER5 ) /如果事件调用来自第五层generate_next_arrival(); /* 为将来的包的到达做准备 */ /* 将相同的信息转换为字母字符串 */ j = nsim % 26; for (i=0; i<20; i+)msg2give.datai = 97 + j; if (TRACE>2)printf(" 学生发送的主要数据是: &quo

6、t;);for (i=0; i<20; i+)printf("%c", msg2give.datai);/打印信息printf("n"); nsim+;if (eventptr->eventity = A)/A端向外发送数据A_output(msg2give); else/B端向外发送数据B_output(msg2give);else if (eventptr->evtype = FROM_LAYER3)/如果事件调用来自第三层pkt2give.seqnum = eventptr->pktptr->seqnum; pkt2g

7、ive.acknum = eventptr->pktptr->acknum; pkt2give.checksum = eventptr->pktptr->checksum; for (i=0; i<20; i+) pkt2give.payloadi = eventptr->pktptr->payloadi;if (eventptr->eventity = A) /* A端交付包*/ A_input(pkt2give); /* 适当的实体*/else /* B端交付包*/B_input(pkt2give);free(eventptr->pkt

8、ptr); /* 释放包的缓存 */else if (eventptr->evtype = TIMER_INTERRUPT)/计时器中断情况if (eventptr->eventity = A) A_timerinterrupt();elseB_timerinterrupt();else /校检,防止发生不可预料事件printf("内部警告: 不可预知的事件类型！ n"); free(eventptr); terminate:/终止 printf(" 模拟器停止在： %f s n ，从第五层发送了 %d个包n",time,nsim); pri

9、ntf(" 正确发送包的个数: %d n", packet_correct); printf(" 重发包的个数: %d n", packet_resent); system("pause");/暂停一GBN.h#pragma once#include <stdio.h>/基础功能模块的数据结构声明#define BIDIRECTIONAL 1 /* 改变值1如果你需要写额外的可靠程序或B输出程序(即B端系统)*/* "msg"结构体是由第五层（教师代码）转变成第四层的数据单元（学生代码）*/*它包括了经

10、由第五层向学生层协议通信实体交付的数据（字符）*/struct msg char data20;/* "pkt"结构体是第4层（学生代码）向第3层传送的数据单元（老师代码）。值得注意的是预先定义的包结构,这一切学生必须遵守。*/struct pktint seqnum;/顺序号int acknum;/应答号int checksum;/检查和char payload20;#define WINDOWSIZE 8 /定义滑动窗口大小#define MAXBUFSIZE 50/最大窗口大小#define RTT 15.0/周游时间#define NOTUSED 0/没用到#def

11、ine NACK -1/否定应答#define TRUE 1#define FALSE 0#define A 0#define B 1/网络仿真部分数据结构声明*struct eventfloat evtime; /* 事件时间 */int evtype; /* 事件类型 */int eventity; /* 事件实体*/struct pkt *pktptr; /* 指向这个事件的指针（如果需要） */struct event *prev; /前一事件struct event *next; /后一事件 ;/* possible events: */#define TIMER_INTERRUPT

12、 0 /事件中断#define FROM_LAYER5 1 /来自第五层#define FROM_LAYER3 2 /来自第三层#define OFF 0#define ON 1/基础功能模块的函数声明*void ComputeChecksum(struct pkt *packet);/计算校验和int CheckCorrupted(struct pkt packet);/检查数据是否出错void A_output( struct msg message);/A端向外发送数据void A_input(struct pkt packet);/A端接收数据void A_timerinterrupt

13、();/A计时器超时void A_init();/A端初始化void B_output(struct msg message); void B_input(struct pkt packet);void B_timerinterrupt();void B_init();/网络仿真部分的函数声明*void init(); /初始化仿真器float jimsrand();/随机数发生器0,1/处理事件列表部分的函数声明*void generate_next_arrival();/产生下一个到达的分组void insertevent(struct event *p);/向事件列表中插入一条新的事件v

14、oid printevlist();/打印事件列表/*/*计时器模块*void stoptimer(int);/停止计时器void starttimer(int,float);/启动计时器/*/*网络各层之间传送模块*void tolayer3(int AorB,struct pkt packet);/向第3层发送信息void tolayer5(int AorB,char datasent20);/向第5层发送信息二：#include "GBN.h"#include <stdio.h>#include <string.h>#include <s

15、tdlib.h>extern int TRACE = 1; /*用于跟踪*/extern int nsim = 0; /* 当前第5层到第4层的信息数*/ extern int nsimmax = 0; /* "msg"生成数量,直到停止*/extern float time = 0.000;float lossprob; /* 丢包可能性*/float corruptprob; /* 包的数据位数丢失可能性*/float lambda; /* 从第五层到达的比率 */ int ntolayer3; /* 送往第3层的包数量*/static int nlost = 0

16、; /* 在媒体中丢失的包数量*/static int ncorrupt = 0; /* 在网络中被破坏的包*/static int expectedseqnum = 0; /* 期待接收方发送的序号 */static int nextseqnum; /* 下一次发送方要使用的包序号*/static int base; /* 发送方头窗*/struct pkt winbufWINDOWSIZE; /* 窗口包缓冲区*/static int winfront,winrear; /* 缓冲区的头尾指针*/static int pktnum;/* 缓冲窗口包的数量*/struct msg buffe

17、rMAXBUFSIZE; /* 发送方数据缓冲区*/int buffront,bufrear; /* 缓冲区的头尾指针 */static int msgnum;/* 缓冲窗口包的数量 */关于各种包的类型定义/*int packet_lost =0; /包丢失int packet_corrupt=0; /包破坏int packet_sent =0; /包发送extern int packet_correct=0;/正确包extern int packet_resent =0;/重发包int packet_timeout=0;/超时包extern struct event *evlist = N

18、ULL; /* 事件清单 */相关接口函数的实现/计算校验和,即脚链和1的补码和void ComputeChecksum( struct pkt *packet) int checksum;int i;checksum = packet->seqnum;checksum = checksum + packet->acknum;/求脚链for ( i=0; i<20; i+ ) /取最高位，按位相加checksum = checksum + (int)(packet->payloadi);checksum = 0-checksum;/取反packet->checks

19、um = checksum;/检查是否出错int CheckCorrupted(struct pkt packet)int checksum;int i;checksum = packet.seqnum;checksum = checksum + packet.acknum;for ( i=0; i<20; i+ ) checksum = checksum + (int)(packet.payloadi);if ( (packet.checksum+checksum) = 0 )/检查校检和是否相加为0return (FALSE);elsereturn (TRUE);/A端向外发送数据/

20、* 被第五层调用，向另一端发送数据*/void A_output(struct msg message)int i;struct pkt sendpkt;/* 如果的发送方下次使用序号小于滑动窗口的最大序号，那么补发包*/if ( nextseqnum < base+WINDOWSIZE )printf("-A：新的包到达，发送窗口不满，新的包送往第3层！n");/* 创建包 */sendpkt.seqnum = nextseqnum;sendpkt.acknum = NOTUSED;for ( i=0; i<20 ; i+ ) sendpkt.payloadi

21、 = message.datai;/* 检查是否出错 */ComputeChecksum (&sendpkt); /* 送出包 */ tolayer3 (A, sendpkt); /* 复制这些包到窗口缓冲区 */ winrear = (winrear+1)%WINDOWSIZE; pktnum +; winbufwinrear = sendpkt; for (i=0; i<20; i+) winbufwinrear.payloadi= sendpkt.payloadi; /* 更新状态变量 */ nextseqnum = nextseqnum+1; starttimer(A,R

22、TT); B_input(sendpkt); A_input(sendpkt);/* 如果移动窗口包满*/else printf("-A:新的包到达，发送窗口已满!");/* 如果缓冲区满，放弃并退出*/if ( msgnum = MAXBUFSIZE)printf (" 错误：发送缓冲区已满 ！n"); exit (1); /* 否则，将信息送入缓冲区 */ else printf("信息已送入缓冲区n"); bufrear = (bufrear+1) % MAXBUFSIZE; /拥塞控制,防止拥塞,减小缓冲区 for (i=0;

23、 i<20; i+) bufferbufrear.datai = message.datai; msgnum +; /B端向外发送数据/* 被第五层调用，发送数据到另一方,同A方相似 */void B_output(struct msg message)int i;struct pkt sendpkt;/* 如果发送窗口不满*/if ( nextseqnum < base+WINDOWSIZE )printf("-B：新的包到达，发送窗口不满，新的包送往第3层！!n");/* create packet */sendpkt.seqnum = nextseqnum

24、;sendpkt.acknum = NOTUSED;for ( i=0; i<20 ; i+ ) sendpkt.payloadi = message.datai;/* computer checksum */ComputeChecksum (&sendpkt); /* send out packet */ tolayer3 (A, sendpkt);A_input(sendpkt); /* copy the packet to window packet buffer */ winrear = (winrear+1)%WINDOWSIZE; pktnum +; winbufwi

25、nrear = sendpkt; for (i=0; i<20; i+) winbufwinrear.payloadi= sendpkt.payloadi; /* if it is the first packet in window, start timeout */ /if ( base = nextseqnum ) / /starttimer(A,RTT); /printf("-A: start a new timer!n"); / /* update state variables */ nextseqnum = nextseqnum+1;/* 如果发送窗口满

26、*/else printf("-B:新的包到达，发送窗口已满!,");/* if buffer full, give up and exit*/if ( msgnum = MAXBUFSIZE)printf (" 错误：发送缓冲区已满 ！ n"); exit (1); /* otherwise, buffer the message */ else printf("缓冲区满!n"); bufrear = (bufrear+1) % MAXBUFSIZE; for (i=0; i<20; i+) bufferbufrear.dat

27、ai = message.datai; msgnum +; /A端接收数据void A_input(struct pkt packet)struct pkt sendpkt;int i;/* 如果收到没有被破坏的包并且确认包收到*/ if ( (CheckCorrupted(packet) = FALSE) && (packet.acknum != NACK) )printf("-A: ACK(确认包) %d 被正确的收到,",packet.acknum);packet_correct+; /* 从窗口缓冲区删去被确认的包*/ winfront = (win

28、front+(packet.acknum+1-base) % WINDOWSIZE; pktnum = pktnum - (packet.acknum+1-base); /* 改变窗口最小号确认包 */ base = packet.acknum+1; stoptimer(A); if ( base < nextseqnum) /starttimer(A,RTT); printf ("nnn发送新的包!"); /* 如果缓冲区不空发送新的包*/ while ( (msgnum!=0) && (nextseqnum<base+WINDOWSIZE)

29、)/* 创建包*/ sendpkt.seqnum = nextseqnum; sendpkt.acknum = NOTUSED; buffront = (buffront+1) % MAXBUFSIZE; for ( i=0; i<20 ; i+ ) sendpkt.payloadi = bufferbuffront.datai; /* 和确认*/ ComputeChecksum (&sendpkt); /*如果是滑动窗口的第一个包，开始超时检测*/ if ( base = nextseqnum ) /如果滑动窗口最小的包等于下一次要发送的序号/starttimer(A,RTT)

30、;printf ("发送新的包!n"); /* 送出包 */ tolayer3 (A, sendpkt); /* 复制包到窗口缓冲区 */ winrear = (winrear+1)%WINDOWSIZE; winbufwinrear = sendpkt; pktnum +; /* 更新状态变量 */nextseqnum = nextseqnum+1; /* 删除缓冲区的包 */msgnum -;else printf ("-A: 收到否定应答，什么也没有完成!n");/B端接收数据*一定要调用这个/* 这只是单一的A到B的传送方式，没有B端的数据发出

31、*/* 被第三层调用，但数据到达B端第4层*/void B_input(struct pkt packet) struct pkt sendpkt;int i;/*如果收到没有被破坏的包并且确认包收到 */if ( (CheckCorrupted(packet) = FALSE) && (packet.seqnum = expectedseqnum)printf("n-B: 包正确的到达，发送ACK确认包n",packet.seqnum);/* 发送应答包 */ /* create packet */ sendpkt.seqnum = NOTUSED; se

32、ndpkt.acknum = expectedseqnum; for ( i=0; i<20 ; i+ )sendpkt.payloadi = '0'/* computer checksum */ ComputeChecksum (&sendpkt); /* send out packet */tolayer3 (B, sendpkt);/* update state variables */expectedseqnum = expectedseqnum+1; printf("-B:expectedseqnum (期待下一次的发送序号)= %dn&quo

33、t;,expectedseqnum); /* 发送包到第五层 */ /tolayer5(B,packet.payload); /* 否则，抛弃包，发送否定应答*/ elseprintf("-B: 包 %d 损坏或者不是我所需要的, 发送否定应答!n",packet.seqnum);/* 创建包 */ sendpkt.seqnum = NOTUSED; sendpkt.acknum = NACK; for ( i=0; i<20 ; i+ ) sendpkt.payloadi = '0'/* 校检和检查 */ ComputeChecksum (&

34、sendpkt); /* 发出包 */ tolayer3 (B, sendpkt); /A计时器超时/* A超时被调用 */void A_timerinterrupt()int i;printf("-A:超时！重新发包!n");/* start timer */starttimer(A,RTT);/* 重新发送所有未被确认的包*/for ( i=1; i<=pktnum; i+ )packet_resent+; tolayer3(A,winbuf(winfront+i)%WINDOWSIZE); /B计时器超时/* called when B's timer

35、goes off */void B_timerinterrupt()int i;printf("-B: 超时！重新发包!n");/* start timer */starttimer(B,RTT);/* 重新发送所有未被确认的包 */for ( i=1; i<=pktnum; i+ )packet_resent+; tolayer3(B,winbuf(winfront+i)%WINDOWSIZE); /A端初始化/* entity A routines are called. You can use it to do any initialization */void

36、 A_init()base = 0;nextseqnum = 0;buffront = 0;bufrear = 0;msgnum = 0;winfront = 0;winrear = 0;pktnum = 0;/B端初始化/* entity B routines are called. You can use it to do any initialization */void B_init()expectedseqnum = 0;/初始化仿真器void init() /* initialize the simulator */int i;float sum, avg;float jimsra

37、nd();FILE *fp;fp = fopen ("parameter.txt","r");printf("- Stop and Wait Network Simulator Version 1.1 - nn");printf(" -停止等待网络模拟器版本1.1 - nn");printf("回车输入包的个数给虚拟器: ");/fscanf(fp,"%d",&nsimmax); scanf("%d",&nsimmax);printf(&q

38、uot;n输入包被丢失的可能性输入 0.0 表示不丢失: ");/fscanf(fp, "%f",&lossprob);scanf("%f",&lossprob);printf("n输入包被损坏的可能性输入 0.0 表示不损坏:");/fscanf(fp,"%f",&corruptprob);scanf("%f",&corruptprob); printf("n输入包从发送方第五层到达的平均时间 > 0.0: "); /fsca

39、nf(fp,"%f",&lambda);scanf("%f",&lambda); printf("n输入跟踪: ");/fscanf(fp,"%d",&TRACE);scanf("%d",&TRACE);printf("nn");srand(9999); /* init random number generator */sum = 0.0; /* test random number generator for students */for

40、(i=0; i<1000; i+)sum=sum+jimsrand(); /* jimsrand() should be uniform in 0,1 */avg = sum/1000.0; /*if(avg < 0.25 | avg > 0.75) printf("It is likely that random number generation on your machinen" ); printf("is different from what this emulator expects. Please taken"); pri

41、ntf("a look at the routine jimsrand() in the emulator code. Sorry. n"); exit(0); */ printf("%f",avg);ntolayer3 = 0;nlost = 0;ncorrupt = 0;time=0.0; /* initialize time to 0.0 */ generate_next_arrival(); /* initialize event list */随机数发生器float jimsrand() double mmm = 2147483647; /*

42、largest int - MACHINE DEPENDENT! */float x; /* individual students may need to change mmm */ x = rand()/mmm; /* x should be uniform in 0,1 */return(x); /*/*事件处理部分*void generate_next_arrival()double x,log(),ceil();struct event *evptr;float ttime;int tempint;/if (TRACE>2)/printf("-GENERATE NEX

43、T ARRIVAL: creating new arrivaln");x = lambda*jimsrand()*2; /* x is uniform on 0,2*lambda */ /* having mean of lambda */evptr = (struct event *)malloc(sizeof(struct event);evptr->evtime = time + x; evptr->evtype = FROM_LAYER5;if (jimsrand()<0.5)evptr->eventity = A;elseevptr->even

44、tity = B;insertevent(evptr);/向事件列表中插入一条新的事件void insertevent(struct event *p) struct event *q,*qold;if (TRACE>2)/printf(" INSERTEVENT: time is %lfn",time);/printf(" INSERTEVENT: future time will be %lfn",p->evtime); q = evlist; /* q points to front of list in which p struct

45、inserted q指针指向表前部当p结构被插入*/if (q=NULL)/* 表是空的*/ evlist=p; p->next=NULL; p->prev=NULL; else for (qold = q; q !=NULL && p->evtime > q->evtime; q=q->next)qold=q; if (q=NULL)/* 表尾 */ qold->next = p; p->prev = qold; p->next = NULL;else if (q=evlist)/* front of list */ p-

46、>next=evlist; p->prev=NULL; p->next->prev=p; evlist = p;else /* 表中部 */ p->next=q; p->prev=q->prev; q->prev->next=p; q->prev=p;/打印事件列表void printevlist()struct event *q;int i;printf("-n事件列表如下:n");for(q = evlist; q!=NULL; q=q->next)printf("事件时间: %f, 类型: %

47、d 实体: %dn",q->evtime,q->evtype,q->eventity); printf("-n");/启动计时器void starttimer(int AorB,float increment)struct event *q;struct event *evptr;if (TRACE>2)printf("n-A: 启动计时器: 在 %f 开始定时n",time);/* 友好的：检查计时器是否早已开始计时，如果是，则发出警告*/* for (q=evlist; q!=NULL && q-&g

48、t;next!=NULL; q = q->next) */for (q=evlist; q!=NULL ; q = q->next)if ( (q->evtype=TIMER_INTERRUPT && q->eventity=AorB) ) /printf("Warning: attempt to start a timer that is already startedn");return;/* 创建事件当超时发生 */evptr = (struct event *)malloc(sizeof(struct event);evptr->evtime = time + increment;evptr->evtype