uint8_t create_file(uint32_t file_number)
{
if(!CHECK_FILE_FLAG(file_number))
{
SET_FILE_FLAG(file_number);
return 0x00;
}
else
return 0x11; //file already exists!
}
/* This routine does the first phase of the client-server Setup.
* On successfule return, the out parameter sockfd will have the
* connection socket fd.
* */
int connection_setup(int *sockfd, ifi_t *ifi_array[], int num_ifi,
circ_buffer_t *rcv_buf, client_config_t *config)
{
packet_t *send_pkt;
int n, optval=1;
char in_packet[PACKET_LEN],client_ip[IP_MAX];
struct sockaddr_in serv_addr, cliaddr, tempaddr;
unsigned int ack_seq;
unsigned short curr_win;
bool is_error = FALSE;
packet_info_t *rcv_pkt_info, *send_pkt_info = calloc(1, sizeof(packet_info_t));
*sockfd = Socket(AF_INET, SOCK_DGRAM, 0);
if(server_on_same_subnet(config->server_ip,ifi_array, num_ifi, client_ip))
{
printf("server on same subnet, SO_DONTROUTE set\n");
//printf("client ip set to: %s\n",client_ip);
setsockopt(*sockfd,SOL_SOCKET, SO_DONTROUTE, &optval, sizeof(optval));
}
//update cli_ip after if it's on the same host or n/w
bzero(&cliaddr, sizeof(cliaddr));
cliaddr.sin_family = AF_INET;
cliaddr.sin_port = 0;
inet_pton(AF_INET,client_ip,&cliaddr.sin_addr);
Bind(*sockfd, (SA*) &cliaddr, sizeof(cliaddr));
//cli addr and port using getsockname
int cli_port;
char cli_ip[IP_MAX];
socklen_t len = sizeof(tempaddr);
bzero(&tempaddr, sizeof(tempaddr));
getsockname(*sockfd, (SA*) &tempaddr, &len);
Inet_ntop(AF_INET, &tempaddr.sin_addr, cli_ip, IP_MAX);
printf("[Info]client bound to ip:%s\n",cli_ip);
cli_port = ntohs(tempaddr.sin_port);
//connect
bzero(&serv_addr, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(config->server_port);
Inet_pton(AF_INET, config->server_ip, &serv_addr.sin_addr);
Connect(*sockfd, (SA *)&serv_addr, sizeof(serv_addr));
assert(send_pkt_info);
Signal(SIGALRM, sig_alarm);
rtt_newpack(&rttinfo); /* initialize for this packet */
/* Prepare to send file name */
send_pkt_info->seq = 0;
send_pkt_info->ack = 0;
send_pkt_info->window_size = config->window_size;
SET_FILE_FLAG(send_pkt_info);
send_pkt_info->data = strdup(config->file_name);
send_pkt_info->data_len = strlen(config->file_name) + 1;
printf("[Info] Sending file name %s to server ..\n", send_pkt_info->data);
sendagain:
send_pkt_info->timestamp = rtt_ts(&rttinfo);
send_pkt = build_packet(send_pkt_info);
Write(*sockfd, (char *)send_pkt, send_pkt_info->data_len+HEADER_SIZE);
/* set alarm for RTO seconds using setitimer */
set_alarm(rtt_start(&rttinfo));
if (sigsetjmp(jmpbuf, 1) != 0)
{
if (rtt_timeout(&rttinfo))
{
printf("[Error] Timed out Sending File Name, giving Up\n");
free_pkt_info(send_pkt_info);
free(send_pkt);
errno = ETIMEDOUT;
return -1;
}
printf("[Timeout] Retransmitting file name, next RTO:%d ms\n", rttinfo.rtt_rto);
free(send_pkt);
goto sendagain;
}
/* Now Attempt to read the Port message from the Server */
while (1)
{
if ((n = read(*sockfd, in_packet, PACKET_LEN)) < 0)
{
if (errno == EINTR)
continue;
else
err_sys("[Error] Read Error while waiting for Port number");
}
rcv_pkt_info = get_packet_info(in_packet, n);
if (consume_random_packet(rcv_pkt_info, config->prob_loss, TRUE))
{
free_pkt_info(rcv_pkt_info);
continue;
}
if (IS_ACK(rcv_pkt_info) && (rcv_pkt_info->ack == (send_pkt_info->seq+1)))
{
break;
}
else
{
free_pkt_info(rcv_pkt_info);
continue;
}
}
set_alarm(0); /* Turn off the Alarm */
free_pkt_info(send_pkt_info);
free(send_pkt);
assert(rcv_pkt_info->data_len == sizeof(short));
/* Fetch the new port from the server message */
memcpy(&serv_addr.sin_port, rcv_pkt_info->data, sizeof(short));
printf("[Info] Received new Port number %hu from Server.\n", ntohs(serv_addr.sin_port));
/* Connect to the new port of the server child process */
if (connect(*sockfd, (SA *)&serv_addr, sizeof(serv_addr)) < 0) {
printf("[Error] Connect failure to server child: [%s : %hu]\n", config->server_ip, ntohs(serv_addr.sin_port));
return -1;
}
printf("[Info] Connected to server's child process.\n");
/* Advance the Circular buffer's read/write pointers to rcv_pkt_info->seq+1.
* Basically, we are simulating the producer/consumer behavior here, in that we
* have written and read from the buffer.
* Note: The server has to continue the file transfer starting from rcv_pkt_info->seq+1
* as we will not accept anything lower than this sequence for this session
* This is similar to the SYN+ACK in TCP
*/
rcv_buf->next_read_seq = rcv_buf->next_contig_write_seq = rcv_pkt_info->seq+1;
printf("rcv_buf->next_read_seq = rcv_buf->next_contig_write_seq = %u", rcv_pkt_info->seq+1);
curr_win = window_size(rcv_buf);
ack_seq = NEXT_ACK(rcv_buf);
/* Exit if the file does not exist on the server after sending ACK.
* In the event this ACK is lost, the server ichild timeout mechanism will kick in
* and eventually it will timeout and give up
*/
if(is_error = IS_ERR(rcv_pkt_info))
{
printf("[Info] Received Error message from server [Seq: %u] Responding with [Ack:%u] [Window Size:%hu]\n",
rcv_pkt_info->seq, ack_seq, curr_win);
}
else
{
printf("[Info] Received Port message [Seq: %u] Responding with [Ack:%u] [Window Size:%hu]\n",
rcv_pkt_info->seq, ack_seq, curr_win);
}
/* Simulate Loss On Tx */
if (!consume_random_packet(rcv_pkt_info, config->prob_loss, FALSE))
{
send_ack(*sockfd, curr_win, rcv_pkt_info->seq, ack_seq, rcv_pkt_info->timestamp, config->prob_loss);
}
free_pkt_info(rcv_pkt_info);
if(is_error)
{
printf("[Error] File %s does not exist, terminating..\n", config->file_name);
errno = EBADF;
return -1;
}
printf("[Info] Successful Connection Setup with [%s:%u], ready for file reception\n",
config->server_ip, ntohs(serv_addr.sin_port));
return 0;
}
