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Selective Repeat.cpp
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Selective Repeat.cpp
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#include "../include/simulator.h"
#include <iostream>
#include <stdio.h>
#include <string.h>
#include <list>
#include <map>
using namespace std;
/* ******************************************************************
SELECTIVE REPEAT NETWORK EMULATOR:
This code shows unidirectional data transfer protocols (from A to B).
Network properties:
- one way network delay averages five time units (longer if there
are other messages in the channel for GBN), but can be larger
- packets can be corrupted (either the header or the data portion)
or lost, according to user-defined probabilities
- packets will be delivered in the order in which they were sent
(although some can be lost).
**********************************************************************/
struct pkt_list
{
int seqnum;
int acknum;
int checksum;
char payload[20];
float time;
};
list <pkt_list> p_l1;
list <pkt_list>::iterator it1;
map <int,pkt_list> p_map;
map <int,pkt_list>:: iterator itm;
struct pmap
{
int seqnum;
char payload[20];
};
map <int,pmap> p_map1;
map <int,pmap>::iterator itm1;
struct pkt p;
struct pkt p2;
int send_base,nextseqnum,rcv_base;
char msg[20];
/* called from layer 5, passed the data to be sent to other side */
void A_output(struct msg message)
{
int s=0,c;
struct pkt_list pl;
memset(p.payload,'\0',20);
strncpy(p.payload,message.data,20);
if(nextseqnum < (send_base+getwinsize()))
{
p.acknum = 0;
for(int i=0;i<20;i++)
{
s+= p.payload[i];
}
p.checksum = s + p.seqnum + p.acknum;
pl.seqnum = p.seqnum;
pl.acknum = p.acknum;
pl.checksum = p.checksum;
memset(pl.payload,'\0',20);
strncpy(pl.payload,p.payload,20);
pl.payload[20] = '\0';
pl.time = get_sim_time();
tolayer3(0,p);
starttimer(0,35.0);
p2.seqnum = pl.seqnum;
p2.acknum = pl.acknum;
p2.checksum = pl.checksum;
memset(p2.payload,'\0',20);
strncpy(p2.payload,pl.payload,20);
p_map[pl.seqnum] = pl;
p.seqnum++;
nextseqnum = p.seqnum;
}
else
{
p.acknum = 0;
for(int i=0;i<strlen(p.payload);i++)
s+= p.payload[i];
p.checksum = s + p.seqnum + p.acknum;
pl.seqnum = p.seqnum;
pl.acknum = p.acknum;
pl.checksum = p.checksum;
memset(pl.payload,'\0',20);
strncpy(pl.payload,p.payload,20);
pl.payload[20] = '\0';
p_l1.push_back(pl);
p.seqnum++;
nextseqnum = p.seqnum;
}
}
/* called from layer 3, when a packet arrives for layer 4 */
void A_input(struct pkt packet)
{
int c,seq;
float t,min,t1;
struct pkt_list pl;
struct pkt pack;
c = packet.seqnum + packet.acknum;
if(c == packet.checksum)
{
if(packet.acknum >= send_base && packet.acknum < send_base+getwinsize())
{
stoptimer(0);
if(!p_map.empty())
{
cout<<"130"<<endl;
int present=0;
for(itm=p_map.begin();itm!=p_map.end();itm++)
{
if(itm->second.seqnum == packet.acknum)
p_map.erase(itm);
}
for(itm=p_map.begin();itm!=p_map.end();itm++)
{
if(itm->second.seqnum < packet.acknum)
present++;
}
if(present == 0)
{
send_base = packet.acknum + 1;
if(!p_l1.empty())
{
it1 = p_l1.begin();
pl.seqnum = it1->seqnum;
pl.acknum = it1->acknum;
pl.checksum = it1->checksum;
memset(pl.payload,'\0',20);
strncpy(pl.payload,it1->payload,20);
pl.payload[20] = '\0';
pack.seqnum = pl.seqnum;
pack.acknum = pl.acknum;
pack.checksum = pl.checksum;
memset(pack.payload,'\0',20);
strncpy(pack.payload,pl.payload,20);
pack.payload[20] = '\0';
pl.time = get_sim_time();
tolayer3(0,pack);
p_map[pl.seqnum] = pl;
p_l1.pop_front();
}
}
}
if(!p_map.empty())
{
itm = p_map.begin();
min = itm->second.time;
for(itm=p_map.begin();itm!=p_map.end();itm++)
{
t = 35.0 - (get_sim_time() - itm->second.time);
if (t <= min)
{
min = t;
seq = itm->second.seqnum;
}
}
for(itm=p_map.begin();itm!=p_map.end();itm++)
{
if(itm->second.seqnum == seq)
{
starttimer(0,min);
p2.seqnum = itm->second.seqnum;
p2.acknum = itm->second.acknum;
p2.checksum = itm->second.checksum;
memset(p2.payload,'\0',20);
strncpy(p2.payload,itm->second.payload,20);
break;
}
}
}
//}
}
}
else
cout<<"Corrupted ACK"<<endl;
}
/* called when A's timer goes off */
void A_timerinterrupt()
{
int seq;
float t,t0,min,t2;
t0 = get_sim_time();
tolayer3(0,p2);
for(itm=p_map.begin();itm!=p_map.end();itm++)
{
if(itm->second.seqnum == p2.seqnum)
{
itm->second.time = get_sim_time();
break;
}
}
if(!p_map.empty())
{
itm = p_map.begin();
min = itm->second.time;
for(itm=p_map.begin();itm!=p_map.end();itm++)
{
t = 35.0 - (t0 - itm->second.time);
if (t <= min)
{
min = t;
seq = itm->second.seqnum;
}
}
itm = p_map.find(seq);
starttimer(0,min);
p2.seqnum = itm->second.seqnum;
p2.acknum = itm->second.acknum;
p2.checksum = itm->second.checksum;
memset(p2.payload,'\0',20);
strncpy(p2.payload,itm->second.payload,20);
}
}
/* the following routine will be called once (only) before any other */
/* entity A routines are called. You can use it to do any initialization */
void A_init()
{
p.seqnum = 1;
p.acknum = 0;
p.checksum = 0;
memset(p.payload,'\0',20);
nextseqnum = p.seqnum;
send_base = 1;
}
/* Note that with simplex transfer from a-to-B, there is no B_output() */
/* called from layer 3, when a packet arrives for layer 4 at B*/
void B_input(struct pkt packet)
{
int s=0,c,present;
memset(msg,'\0',20);
strncpy(msg,packet.payload,20);
msg[20] = '\0';
for(int i=0;i<20;i++)
s+= msg[i];
c = packet.seqnum + packet.acknum + s;
if(c == packet.checksum)
{
if(packet.seqnum >= rcv_base && packet.seqnum < rcv_base+getwinsize()-1)
{
if(packet.seqnum == rcv_base)
{
tolayer5(1,msg);
struct pkt ack;
ack.seqnum = 0;
ack.acknum = packet.seqnum;
ack.checksum = ack.seqnum + ack.acknum;
tolayer3(1,ack);
itm1 = p_map1.begin();
while(!p_map1.empty())
{
if(itm1->second.seqnum == rcv_base+1)
{
char m[20];
memset(m,'\0',20);
strncpy(m,itm1->second.payload,20);
m[20] = '\0';
tolayer5(1,m);
p_map1.erase(itm1);
rcv_base++;
itm1++;
}
else
break;
}
rcv_base++;
}
else
{
struct pmap pt;
pt.seqnum = packet.seqnum;
memset(pt.payload,'\0',20);
strncpy(pt.payload,msg,20);
pt.payload[20] = '\0';
p_map1[pt.seqnum] = pt;
struct pkt ack;
ack.seqnum = 0;
ack.acknum = packet.seqnum;
ack.checksum = ack.seqnum + ack.acknum;
tolayer3(1,ack);
}
}
else if (packet.seqnum >= rcv_base-getwinsize() && packet.seqnum <= rcv_base - 1)
{
struct pkt ack;
ack.seqnum = 0;
ack.acknum = packet.seqnum;
ack.checksum = ack.seqnum + ack.acknum;
tolayer3(1,ack);
}
}
else
{
cout<<"Corrupted pkt"<<endl;
}
}
/* the following rouytine will be called once (only) before any other */
/* entity B routines are called. You can use it to do any initialization */
void B_init()
{
rcv_base = 1;
}