Hi everyone,
I'm trying to send data using the booster pack cc3000 by Texas Instruments. Therefore I implemented a TCP server socket on my board. I can accept a pending connection and send and receive data on the given socket successfully. In my protocol the client is responsible for closing the connection after reading the response. But after some transmissions the transmissions becomes slow. If I inspect the WLAN traffic using Wireshark I see there is a problem with the socket close procedure. My client is a java based program. The board uses address 100 and the computer runs under 102.
The TCP stream looks the following:
31 4.696711000 192.168.2.102 192.168.2.100 TCP 66 50721 > http-alt [SYN] Seq=0 Win=8192 Len=0 MSS=1460 WS=4 SACK_PERM=1 32 4.700359000 192.168.2.100 192.168.2.102 TCP 58 http-alt > 50721 [SYN, ACK] Seq=0 Ack=1 Win=1460 Len=0 MSS=1460 33 4.700394000 192.168.2.102 192.168.2.100 TCP 54 50721 > http-alt [ACK] Seq=1 Ack=1 Win=17520 Len=0 34 4.700461000 192.168.2.102 192.168.2.100 HTTP 55 Continuation or non-HTTP traffic 35 4.705454000 192.168.2.100 192.168.2.102 TCP 54 http-alt > 50721 [ACK] Seq=1 Ack=2 Win=1460 Len=0 36 4.705476000 192.168.2.102 192.168.2.100 TCP 57 [TCP segment of a reassembled PDU] 37 4.709035000 192.168.2.100 192.168.2.102 TCP 54 http-alt > 50721 [ACK] Seq=1 Ack=5 Win=1460 Len=0 38 5.194961000 192.168.2.100 192.168.2.102 TCP 58 [TCP segment of a reassembled PDU] 39 5.196220000 192.168.2.100 192.168.2.102 HTTP 154 Continuation or non-HTTP traffic 40 5.196244000 192.168.2.102 192.168.2.100 TCP 54 50721 > http-alt [ACK] Seq=5 Ack=105 Win=17416 Len=0 41 5.196286000 192.168.2.102 192.168.2.100 TCP 54 50721 > http-alt [FIN, ACK] Seq=5 Ack=105 Win=17416 Len=0 42 5.202194000 192.168.2.100 192.168.2.102 TCP 54 http-alt > 50721 [ACK] Seq=105 Ack=6 Win=1460 Len=0 138 24.245036000 192.168.2.100 192.168.2.102 TCP 54 http-alt > 50721 [FIN, ACK] Seq=105 Ack=6 Win=1460 Len=0 139 24.245060000 192.168.2.102 192.168.2.100 TCP 54 50721 > http-alt [ACK] Seq=6 Ack=106 Win=17416 Len=0
After about 10 transmissions I get a FIN/ACK cascade. The last FIN/ACK above is part of this cascade. It looks like if the sockets are not completely closed and the HW module starts now closing all sockets in a row.
My Java - Client does the following:
Socket b = new Socket("192.168.2.100",8080);
OutputStream o = b.getOutputStream();
o.write(10);
o.write(0);
o.write(0);
o.write(0);
o.flush();
InputStream i = b.getInputStream();
int id = i.read();
int gId = i.read();
int lengthA = i.read();
int lengthB = i.read();
int length = (lengthB<<8)|lengthA;
if(length < 0|| length > 1000)
{
b.close();
return;
}
System.out.println(new Date()+" GantryID: "+gId+" Package with id: "+id+" has length: "+length+" payload: ");
DataInputStream ds = new DataInputStream(i);
byte[] buffer = new byte[length];
ds.readFully(buffer);
b.close();
System.out.println(new String(buffer));
The server opens a server port and start non blocking accept to serve pending requests. When a new request is due the communication runs the following:
return recv(handle, data, size, 0); //Read request header
return recv(handle, data, size, 0); //Read request payload
send(handle, data, size, 0); //Write response header
send(handle, data, size, 0); //Write response payload
//No Close only set socket handle to -1
Does anyone have a idea what is going on?
Many thanks,
Jonny
