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Hi,
my setup is as follows: 1. owserver - uncached 2. owfs using owserver 3. "client program" using owserver If only the "client program" is running it communicates with owserver fine. However, when owfs is also running (doing uncached queries @ 1Hz, temp conversion every time on the bus) the "client program" sometimes - seemingly in a random manner - receives interesting data in about 40% of the cases in front of the correct server answer. I use owserver and owsf 2.8p2 - failly recent. The below session shows the client program run twice in a row, the first run succeeds, the second one fails (tries to read payload length nr. of chars from the TCP data) [r...@titan kazan]# ./owcltest TCP data: 000000000000000c0000000c000000000000000c00000000202020202035332e38313235 version: 0 payloadlength: 12 retval: 12 controlflags: 0 size: 12 offset: 0 payload: 53.8125 [r...@titan kazan]# ./owcltest TCP data: 00000000ffffffff00000000000000000000000000000000000000000000000c0000000c000000000000000c00000000202020202035332e38313235 ./owcltest:35:in `[]': bignum too big to convert into `long' (RangeError) from ./owcltest:35 [r...@titan kazan]# The second read fails as the string: "00000000ffffffff00000000000000000000000000000000" Is added to the response by owserver. Looking at: http://owfs.org/index.php?page=tcp-messages "RETURN" message
tells me its a message with a payload length of 4,294,967,295, which causes the client to bail out, and of course is in no way compliant with the above message format. The extra header comes in a different IP frame. Here is the corresponding interface capture - 3 frames (not the same session as above but the same happens here): Frame 12 (90 bytes on wire, 90 bytes captured) Arrival Time: Sep 26, 2010 20:09:39.105727000 [Time delta from previous captured frame: 0.492290000 seconds] [Time delta from previous displayed frame: 0.492290000 seconds] [Time since reference or first frame: 1.186131000 seconds] Frame Number: 12 Frame Length: 90 bytes Capture Length: 90 bytes [Frame is marked: False] [Protocols in frame: eth:ip:tcp:data] Ethernet II, Src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00) Destination: 00:00:00_00:00:00 (00:00:00:00:00:00) Address: 00:00:00_00:00:00 (00:00:00:00:00:00) .... ...0 .... .... .... .... = IG bit: Individual address (unicast) .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default) Source: 00:00:00_00:00:00 (00:00:00:00:00:00) Address: 00:00:00_00:00:00 (00:00:00:00:00:00) .... ...0 .... .... .... .... = IG bit: Individual address (unicast) .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default) Type: IP (0x0800) Internet Protocol, Src: 127.0.0.1 (127.0.0.1), Dst: 127.0.0.1 (127.0.0.1) Version: 4 Header length: 20 bytes Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00) 0000 00.. = Differentiated Services Codepoint: Default (0x00) .... ..0. = ECN-Capable Transport (ECT): 0 .... ...0 = ECN-CE: 0 Total Length: 76 Identification: 0x320a (12810) Flags: 0x04 (Don't Fragment) 0... = Reserved bit: Not set .1.. = Don't fragment: Set ..0. = More fragments: Not set Fragment offset: 0 Time to live: 64 Protocol: TCP (0x06) Header checksum: 0x0aa0 [correct] [Good: True] [Bad : False] Source: 127.0.0.1 (127.0.0.1) Destination: 127.0.0.1 (127.0.0.1) Transmission Control Protocol, Src Port: owserver (4304), Dst Port: 33988 (33988), Seq: 1, Ack: 54, Len: 24 Source port: owserver (4304) Destination port: 33988 (33988) Sequence number: 1 (relative sequence number) [Next sequence number: 25 (relative sequence number)] Acknowledgement number: 54 (relative ack number) Header length: 32 bytes Flags: 0x18 (PSH, ACK) 0... .... = Congestion Window Reduced (CWR): Not set .0.. .... = ECN-Echo: Not set ..0. .... = Urgent: Not set ...1 .... = Acknowledgment: Set .... 1... = Push: Set .... .0.. = Reset: Not set .... ..0. = Syn: Not set .... ...0 = Fin: Not set Window size: 32768 (scaled) Checksum: 0xfe40 [incorrect, should be 0xf9a8 (maybe caused by "TCP checksum offload"?)] [Good Checksum: False] [Bad Checksum: True] Options: (12 bytes) NOP NOP Timestamps: TSval 169128930, TSecr 169127930 Data (24 bytes) 0000 00 00 00 00 ff ff ff ff 00 00 00 00 00 00 00 00 ................ 0010 00 00 00 00 00 00 00 00 ........ Data: 00000000FFFFFFFF00000000000000000000000000000000 Frame 13 (66 bytes on wire, 66 bytes captured) [...Lines removed...] [SEQ/ACK analysis] [This is an ACK to the segment in frame: 12] [The RTT to ACK the segment was: 0.000132000 seconds] Frame 14 (102 bytes on wire, 102 bytes captured) Arrival Time: Sep 26, 2010 20:09:39.298353000 [Time delta from previous captured frame: 0.192494000 seconds] [Time delta from previous displayed frame: 0.192494000 seconds] [Time since reference or first frame: 1.378757000 seconds] Frame Number: 14 Frame Length: 102 bytes Capture Length: 102 bytes [Frame is marked: False] [Protocols in frame: eth:ip:tcp:data] Ethernet II, Src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00) Destination: 00:00:00_00:00:00 (00:00:00:00:00:00) Address: 00:00:00_00:00:00 (00:00:00:00:00:00) .... ...0 .... .... .... .... = IG bit: Individual address (unicast) .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default) Source: 00:00:00_00:00:00 (00:00:00:00:00:00) Address: 00:00:00_00:00:00 (00:00:00:00:00:00) .... ...0 .... .... .... .... = IG bit: Individual address (unicast) .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default) Type: IP (0x0800) Internet Protocol, Src: 127.0.0.1 (127.0.0.1), Dst: 127.0.0.1 (127.0.0.1) Version: 4 Header length: 20 bytes Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00) 0000 00.. = Differentiated Services Codepoint: Default (0x00) .... ..0. = ECN-Capable Transport (ECT): 0 .... ...0 = ECN-CE: 0 Total Length: 88 Identification: 0x320b (12811) Flags: 0x04 (Don't Fragment) 0... = Reserved bit: Not set .1.. = Don't fragment: Set ..0. = More fragments: Not set Fragment offset: 0 Time to live: 64 Protocol: TCP (0x06) Header checksum: 0x0a93 [correct] [Good: True] [Bad : False] Source: 127.0.0.1 (127.0.0.1) Destination: 127.0.0.1 (127.0.0.1) Transmission Control Protocol, Src Port: owserver (4304), Dst Port: 33988 (33988), Seq: 25, Ack: 54, Len: 36 Source port: owserver (4304) Destination port: 33988 (33988) Sequence number: 25 (relative sequence number) [Next sequence number: 61 (relative sequence number)] Acknowledgement number: 54 (relative ack number) Header length: 32 bytes Flags: 0x18 (PSH, ACK) 0... .... = Congestion Window Reduced (CWR): Not set .0.. .... = ECN-Echo: Not set ..0. .... = Urgent: Not set ...1 .... = Acknowledgment: Set .... 1... = Push: Set .... .0.. = Reset: Not set .... ..0. = Syn: Not set .... ...0 = Fin: Not set Window size: 32768 (scaled) Checksum: 0xfe4c [incorrect, should be 0x00bc (maybe caused by "TCP checksum offload"?)] [Good Checksum: False] [Bad Checksum: True] Options: (12 bytes) NOP NOP Timestamps: TSval 169129122, TSecr 169128930 [SEQ/ACK analysis] [This is an ACK to the segment in frame: 13] [The RTT to ACK the segment was: 0.192494000 seconds] Data (36 bytes) 0000 00 00 00 00 00 00 00 0c 00 00 00 0c 00 00 00 00 ................ 0010 00 00 00 0c 00 00 00 00 20 20 20 20 20 20 33 31 ........ 31 0020 2e 36 32 35 .625 Data: 000000000000000C0000000C000000000000000C00000000... Does someone have an idea what's going on here? Thanks, Doma |
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