Corrupted AP file

tedmorgan · 10-16-2004

I have a ~900 AP NS1 file that I can no longer open. It appears the file has been corrupted in some way. I tried looking through the raw file but don't know the spec well enough to figure out what is wrong. Any help would be appreciated.

File Located at:
http://www.quarterscope.com/files/ProblemFile.zip

beakmyn · 10-16-2004

I fixed it. There were a couple bytes in the in the 'header' that were wrong.

upoaded here

tedmorgan · 10-16-2004

You rock. Thanks!!!

streaker69 · 10-17-2004

Quote:

Originally Posted by beakmyn

I fixed it. There were a couple bytes in the in the 'header' that were wrong.

upoaded here

Can I ask what you were using to view the files? I've been looking at the two files here to try and do a comparison between the two so I can figure out how to repair a couple o corrupted files that I have, and so far have not had any luck..

thanks

beakmyn · 10-17-2004

xvi hex editor

ns1 File format

I've also used examdiff to compare files but for the original problem I used xvi

streaker69 · 10-17-2004

thank you sir, I shall play with those things and see if I can figure these things out..

King_Ice_Flash · 10-17-2004

You got some good ones in there

f**kyou, and a classic SST-Page Ranking-1

streaker69 · 10-17-2004

I've mostly figured out the header from the information you've given, but I do have one question..

A standard file header appears as:

4E 65 74 53 0C 00 00 00 1C 00 00 00 0B

# of AP's in the data] 1C 00
What is this? 00 0B

Values that I've seen there are 07, 08, 09, 0A and 0B.

The corrupt file I'm working with, I've gotten it recovered to 239 AP's, but I know there were alot more in there. I think I can figure out the rest of my issues if you can give me some pointers as to what that last bit of data means in the header file. I've read everything that I've found about it, and I'm just not getting it..

Thanks.

beakmyn · 10-18-2004

File header

Code:

4E 65 74 53 0C 00 00 00 1C 00 00 00 0B

Code:

4E 65 74 53
4	dwSignature	char[4]	File Signature ('NetS')

Code:

0c 00 00 00
4	dwFileVer	uint32	File Format Version

Code:

1C 00 00 00
4	ApCount	uint32	Number of APINFO entries that follow

Beginning of 1st apInfo entry

Code:

0B
1	SSIDLength	uint8	Length of SSID

In this case the 0B indicates the number of characters in the following AP name

streaker69 · 10-18-2004

Thank you very much, that was a big help.. Now I can move forward on getting these things fixed..

I appreciate it!!

tedmorgan · 10-18-2004

I continue to have this problem. I can see where the header problem is (thanks for the explanation) but I am not sure how to fix. It appears that it is placing the wrong AP count in the header. How do I figure out which is the correct entry to have in that part of the header. Is it because the AP count doesn't match the actual count of APs in the file so it crashed?

Below are two more files which are corrupted.

http://www.quarterscope.com/files/ProblemFiles2.zip

Any thoughts as to how I am getting myself in this pickle? Have autosave running. Sometimes app apears to lock up so I have to restart.

streaker69 · 10-18-2004

Quote:

Originally Posted by tedmorgan

I continue to have this problem. I can see where the header problem is (thanks for the explanation) but I am not sure how to fix. It appears that it is placing the wrong AP count in the header. How do I figure out which is the correct entry to have in that part of the header. Is it because the AP count doesn't match the actual count of APs in the file so it crashed?

Below are two more files which are corrupted.

http://www.quarterscope.com/files/ProblemFiles2.zip

Any thoughts as to how I am getting myself in this pickle? Have autosave running. Sometimes app apears to lock up so I have to restart.

The only time I've ever had this problem is when I had autosave turned on. That's what corrupted all the files that I just repaired lastnight. I turned it on because I was on a longer trip than I normally make and just wanted to make sure my data was saved.. turns out it was a bad idea.

Anyone else experience Autosave corrupting files? My setup is as follows..

Gateway Solo 5150 P2-300 notebook
Dell 1150 Truemobile card with external antenna.
WinXp sp2
160m RAM..

I'm wondering if maybe there's an issue with Sp2 for XP causing it, as I do not really recall this issue before I installed Sp2.

I can give it a shot at fixing your files though, it'll be good practice for me.. I fixed 5 lastnight..

streaker69 · 10-18-2004

Give these a try. I'm not gonna guarentee they're 100% but it looks like most of them are there. I think the smaller file has some more corruption further down in the file, but at least it's readable now..

http://www.netjunkies.net/streaker/temp/fixed.htm

beakmyn · 10-18-2004

I'm working on a way to compare the APcount to the number of APs actually in the file. My guess is what's happening is that NS is appending the new APs to the file but not updating the AP count correctly which causes the file corruption. If this is the case it should be a simple fix to compare the two and update the AP count.

streaker69 · 10-18-2004

Quote:

Originally Posted by beakmyn

I'm working on a way to compare the APcount to the number of APs actually in the file. My guess is what's happening is that NS is appending the new APs to the file but not updating the AP count correctly which causes the file corruption. If this is the case it should be a simple fix to compare the two and update the AP count.

That would be a very cool tool if you can do it. I think that there is another problem though. If you look at the smaller file of the ones that were just posted by the other user, you'll see that the top AP has bad data listed in it. It's possible there are more AP's past that bad one in the dataset, but because of the bad data, you can't read them.

That might be the problem I was having with one of my files. Without reading through the entire file line by line, it's gonna be really tough to find bad data. Maybe you have another idea how to find and remove bad data?

What I was doing to fix them, was to set to the count to 0 and try opening the file. If it opens, then it will open with no AP's listed. Then based upon the file size, I start setting the count up. I would set it to 200 and see if the file opens. If it does, then I increase it by 20, if not, then decrease it by 20. I keep following this process increasing and decreasing by smaller increments until I get to the exact count. It takes a few minutes, but so far it's worked.

Do you have a faster procedure?

10-16-2004	#1 (permalink)
tedmorgan Registered Member Join Date: Apr 2003 Posts: 7	Corrupted AP file I have a ~900 AP NS1 file that I can no longer open. It appears the file has been corrupted in some way. I tried looking through the raw file but don't know the spec well enough to figure out what is wrong. Any help would be appreciated. File Located at: http://www.quarterscope.com/files/ProblemFile.zip Last edited by tedmorgan : 10-16-2004 at 10:27 AM. Reason: Adding file link

10-16-2004	#2 (permalink)
beakmyn Free Public Wifi Join Date: Aug 2003 Posts: 4,992	I fixed it. There were a couple bytes in the in the 'header' that were wrong. upoaded here Last edited by beakmyn : 10-16-2004 at 11:05 AM.

10-17-2004	#7 (permalink)
King_Ice_Flash Alien Paranoid Stumbler Join Date: May 2003 Location: WI Posts: 2,688	You got some good ones in there f**kyou, and a classic SST-Page Ranking-1 __________________ "Yeah," said a voice from under the table, "you go to pieces so fast people get hit by the shrapnel."

10-17-2004	#8 (permalink)
streaker69 Psychic Amish Stumbler Join Date: Jul 2004 Location: Virginville, BlueBall, Bird In Hand, Intercourse, Paradise, PA Posts: 12,239	I've mostly figured out the header from the information you've given, but I do have one question.. A standard file header appears as: 4E 65 74 53 0C 00 00 00 1C 00 00 00 0B # of AP's in the data] 1C 00 What is this? 00 0B Values that I've seen there are 07, 08, 09, 0A and 0B. The corrupt file I'm working with, I've gotten it recovered to 239 AP's, but I know there were alot more in there. I think I can figure out the rest of my issues if you can give me some pointers as to what that last bit of data means in the header file. I've read everything that I've found about it, and I'm just not getting it.. Thanks. Last edited by streaker69 : 10-17-2004 at 11:26 PM.

10-18-2004	#9 (permalink)
beakmyn Free Public Wifi Join Date: Aug 2003 Posts: 4,992	File header Code: 4E 65 74 53 0C 00 00 00 1C 00 00 00 0B Code: 4E 65 74 53 4 dwSignature char[4] File Signature ('NetS') Code: 0c 00 00 00 4 dwFileVer uint32 File Format Version Code: 1C 00 00 00 4 ApCount uint32 Number of APINFO entries that follow Beginning of 1st apInfo entry Code: 0B 1 SSIDLength uint8 Length of SSID In this case the 0B indicates the number of characters in the following AP name Last edited by beakmyn : 10-18-2004 at 05:52 AM.

10-16-2004	#3 (permalink)
tedmorgan Registered Member Join Date: Apr 2003 Posts: 7	You rock. Thanks!!!

10-17-2004	#5 (permalink)
beakmyn Free Public Wifi Join Date: Aug 2003 Posts: 4,992	xvi hex editor ns1 File format I've also used examdiff to compare files but for the original problem I used xvi

10-17-2004	#6 (permalink)
streaker69 Psychic Amish Stumbler Join Date: Jul 2004 Location: Virginville, BlueBall, Bird In Hand, Intercourse, Paradise, PA Posts: 12,239	thank you sir, I shall play with those things and see if I can figure these things out..

10-18-2004	#10 (permalink)
streaker69 Psychic Amish Stumbler Join Date: Jul 2004 Location: Virginville, BlueBall, Bird In Hand, Intercourse, Paradise, PA Posts: 12,239	Thank you very much, that was a big help.. Now I can move forward on getting these things fixed.. I appreciate it!!

10-18-2004	#11 (permalink)
tedmorgan Registered Member Join Date: Apr 2003 Posts: 7	I continue to have this problem. I can see where the header problem is (thanks for the explanation) but I am not sure how to fix. It appears that it is placing the wrong AP count in the header. How do I figure out which is the correct entry to have in that part of the header. Is it because the AP count doesn't match the actual count of APs in the file so it crashed? Below are two more files which are corrupted. http://www.quarterscope.com/files/ProblemFiles2.zip Any thoughts as to how I am getting myself in this pickle? Have autosave running. Sometimes app apears to lock up so I have to restart.

10-18-2004	#13 (permalink)
streaker69 Psychic Amish Stumbler Join Date: Jul 2004 Location: Virginville, BlueBall, Bird In Hand, Intercourse, Paradise, PA Posts: 12,239	Give these a try. I'm not gonna guarentee they're 100% but it looks like most of them are there. I think the smaller file has some more corruption further down in the file, but at least it's readable now.. http://www.netjunkies.net/streaker/temp/fixed.htm

10-18-2004	#14 (permalink)
beakmyn Free Public Wifi Join Date: Aug 2003 Posts: 4,992	I'm working on a way to compare the APcount to the number of APs actually in the file. My guess is what's happening is that NS is appending the new APs to the file but not updating the AP count correctly which causes the file corruption. If this is the case it should be a simple fix to compare the two and update the AP count.

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