void gen_dismat()
{
int i,j;
float s_obs,s_rand,s_max;
for(i=0;i<200;i++)
for(j=0;j<200;j++)
dismat[i][j] = 0;
for(i=0;i<num_seq;i++)
for(j=i+1;j<num_seq;j++)
{
s_obs=(float)scmat[i][j];
s_max=((float)(scmat[i][i]+scmat[j][j]))/2;
s_rand = s_obs;
while(s_rand>=s_obs || s_rand>=s_max)
s_rand=seq_rand(seq[i],seq[j]);
dismat[i][j]=-log((s_obs-s_rand)/(s_max-s_rand));
}
}
/* The server waits for client to send its initial sequence number,
send its own initial sequence number,
and returns the client's initial sequence number. */
uint16_t handshake(int sockfd, struct sockaddr_in &clientaddr, socklen_t clientlen)
{
unsigned char handshake_buf[HEADERSIZE];
segment syn, ack;
// receive syn
long recv_len;
if ((recv_len = recvfrom(sockfd, handshake_buf, HEADERSIZE, 0,
(struct sockaddr *) &clientaddr, &clientlen)) < 8)
{
cerr << "syn error" << endl;
return USHRT_MAX;
}
syn.decode(handshake_buf, HEADERSIZE);
if (syn.getFlagsyn())
{
server_seq = server_ack = seq_rand(MAX_SEQ_NUM);
bool firstSyn = true;
do {// send syn-ack
segment synack;
synack.setSeqnum(server_seq);
setReplyAck(syn, synack, 1);
client_ack = synack.getAcknum();
synack.setFlagsyn();
synack.setFlagack();
unsigned char *handshake_buf2 = synack.encode(NULL, 0);
sendto(sockfd, handshake_buf2, HEADERSIZE, 0,
(struct sockaddr *) &clientaddr, clientlen);
if (firstSyn)
{
cout << "Sending packet " << server_seq << " " << cwnd << " " << ssthresh
<< " SYN" << endl;
firstSyn = false;
}
else
{
cout << "Sending packet " << server_seq << " " << cwnd << " " << ssthresh
<< " Retransmission SYN" << endl;
}
clock_t clock_begin, clock_end;
clock_begin = clock_end = clock();
double elapsed_secs = 0.0;
// receive ack
while ((recv_len = recvfrom(sockfd, handshake_buf, HEADERSIZE, MSG_DONTWAIT,
(struct sockaddr *) &clientaddr, &clientlen)) == -1)
{
if (errno != EWOULDBLOCK && errno != EAGAIN)
perror("recvfrom");
clock_end = clock();
elapsed_secs = double(clock_end - clock_begin) / CLOCKS_PER_SEC;
if (elapsed_secs >= timeout)
break;
}
if (elapsed_secs < timeout)
{
ack.decode(handshake_buf, HEADERSIZE);
if (ack.getFlagsyn())
continue;
else
break;
}
} while (true);
server_seq = (server_seq + 1) % MAX_SEQ_NUM;
if (ack.getFlagack() && ack.getAcknum() == server_seq)
{
cout << "Receiving packet " << ack.getAcknum() << endl;
server_ack = ack.getAcknum();
return client_ack;
}
else
{
cout << "ACK flag: " << ack.getFlagack() << endl;
cout << "SYN flag: " << ack.getFlagsyn() << endl;
cout << "ack num received: " << ack.getAcknum() << endl;
cout << "global_seq: " << server_seq << endl;
cerr << "ack flag error or acknum error" << endl;
return USHRT_MAX;
}
}
else
{
cerr << "syn flag error" << endl;
return USHRT_MAX;
}
}
