I've written a fairly simple server app using the TWSocket component. The app listens on port 80 for packets with a particular structure, and sends a reply. I've tested it with up to 12 clients connected, all sending requests as fast as possible, and all works well.
As soon as I connect a real client it works for a while then fails then continues to work again. Having done an Ethereal trace of the packets, when it goes wrong I get the following type of situation (for a given client IP address) Time Remote Port Local Port Flags Notes --- 24997 -> 80 [SYN] Seq=0 Len=0 MSS=1460 0.0 24997 <- 80 [SYN ACK] Seq=0 Ack=1 Len=0 MSS=1460 Win=65535 0.2 24997 -> 80 [RST ACK] Seq=1 Ack=1 Win=0 Len=0 Here my application has seen a client connection and disconnection. 1.4 24998 -> 80 [SYN] Seq=0 Len=0 MSS=1460 1.0 24998 -> 80 [SYN] Seq=0 Len=0 MSS=1460 1.0 24998 -> 80 [SYN] Seq=0 Len=0 MSS=1460 1.0 24998 -> 80 [SYN] Seq=0 Len=0 MSS=1460 1.0 24998 -> 80 [SYN] Seq=0 Len=0 MSS=1460 Here my application has also seen a client connection and disconnection, but the trace shows no connection was established. 2.2 25000 -> 80 [SYN] Seq=0 Len=0 MSS=1460 1.0 25000 -> 80 [SYN] Seq=0 Len=0 MSS=1460 1.0 25000 -> 80 [SYN] Seq=0 Len=0 MSS=1460 1.0 25000 -> 80 [SYN] Seq=0 Len=0 MSS=1460 1.0 25000 -> 80 [SYN] Seq=0 Len=0 MSS=1460 Here my application has also seen a client connection and disconnection, but the trace shows no connection was established. This pattern repeats 8 more times (port numbers 25001-25008) then I get 0.6 25009 -> 80 [SYN] Seq=0 Len=0 MSS=1460 1.0 25009 -> 80 [SYN] Seq=0 Len=0 MSS=1460 1.0 25009 -> 80 [SYN] Seq=0 Len=0 MSS=1460 1.0 25009 -> 80 [SYN] Seq=0 Len=0 MSS=1460 1.0 25009 -> 80 [SYN] Seq=0 Len=0 MSS=1460 My application does *not* see a connection for remote port 2509 10.3 25010 -> 80 [SYN] Seq=0 Len=0 MSS=1460 1.6 25011 -> 80 [SYN] Seq=0 Len=0 MSS=1460 1.0 25011 -> 80 [SYN] Seq=0 Len=0 MSS=1460 0.2 25010 <- 80 [SYN ACK] Seq=0 Ack=1 Len=0 MSS=1460 Win=65535 0.2 25010 -> 80 [RST ACK] Seq=1 Ack=1 Win=0 Len=0 0.2 25011 -> 80 [SYN] Seq=0 Len=0 MSS=1460 0.0 25011 <- 80 [ACK] Seq=0 Ack=1 Len=0 Win=65535 1.0 25011 <- 80 [SYN ACK] Seq=0 Ack=1 Len=0 MSS=1460 Win=65535 0.0 25011 -> 80 [ACK] Seq=0 Ack=1 Len=0 Win=4096 TCP ACKed Lost Segment 0.0 25011 <- 80 [ACK] Seq=0 Ack=1 Len=0 Win=65535 0.2 25011 -> 80 [ACK] Seq=1 Ack=1 Len=0 Win=4096 TCP ACKed Lost Segment 0.0 25011 -> 80 [ACK] Seq=1 Ack=1 Len=0 Win=4096 TCP Dupe ACK 0.0 25011 -> 80 [PSH ACK] Seq=1 Ack=1 Len=66 Win=4096 0.1 25011 <- 80 [PSH ACK] Seq=1 Ack=67 Len=8 Win=65469 0.2 25011 -> 80 [ACK] Seq=67 Ack=9 Len=0 Win=4088 0.0 25011 <- 80 [PSH ACK] Seq=9 Ack=67 Len=16 Win=65469 0.2 25011 -> 80 [ACK] Seq=67 Ack=25 Len=0 Win=4080 My app sees a connect and disconnect for remote port 25010 then a connect from port 25011 which seems to be handled correctly. It then works for a while until a similar pattern is repeated. The times shown are seconds since the previous packet. I'm really puzzled as to what could be going on here, and have no idea how to begin to debug/fix it. The Ethereal trace is from the machine running the app, so no packets could have been lost between the PC upon which the app is running and the machine logging the packets. I really would appreciate any pointers you can give. -- To unsubscribe or change your settings for TWSocket mailing list please goto http://www.elists.org/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
