First of all, what I do at the moment:
I sniff a asyncron serial bus with 9 bit protocol and send the data to the PC. At the PC side I receive the data as an endless string, that looks like that: .12_80E886.02_80E894.13. The Software of the PC-side is written with winforms with C#. Now I have the problem that I haven´t a clearly start you can see it in the stream example. The reason for that is, that I start the sniff somewhere in the protocol.
What I want to do:
I think I can use startindex = IndexOf("_"), and set them now as new start. I have to evaluate sign´s in the stream the stream is build: _(timestamp in milliseconds).(addressbyte databyte). The only what I want to display in my RichTextBox is the databyte, also I need a data management method for the timestamp. Because I have in the GUI the function that I can see the time beetween two or more databyte´s, for that I think I make a sql database. The addressbyte need I to collor the byte with an one as address in a special collor.
Question:
How can I evaluate the stream so that i have alternately timestamp,
addressbyte and than databyte as single substring?
The reason why I want them so, is that, I think I can make an easy if elseif else block to realize all what I want to do.
When someone has an better suggestion for my project pls write it as comment.
With friendly wishes sniffi
I think you're trying to solve two problems at the same time. It would be better to separate them and solve them individually.
There is the issue of transporting the data, for this you are using streams. That is a valid solution. There is sending and receiving the data (bits) over the stream.
You have the problem of transforming these bits (after receiving them) into actual objects (dates, strings, etc..). For that you an use a simple parser, tokenizer, a local script that can get the correct parts from the data and convert it, or you can use a serialization framework (like DataContracts).
If you have simple data, I would opt for using a single method that can parse the data. For more complex scenarios I would look into serialization.
Also be ware that you will need to validate your inputs, since you cannot assume that there is always a trusted (non compromised) piece of software that is sending the bits to you.
I think string is bad choice. Propably data is send as bytes. Sniff rather bytes than string. And you need protocol description to understand data.
You need to read bytes form bus and interpret it.
Related
Should data manipulation once data is returned either with TCP or HTTP be received as byte arrays or is it an O.K. practice to receive it as a string? I've been trying to find some professional projects on github to get my answer, but have had no luck. Some examples of HTTPClient from Microsoft on MSDN usually make use of the GetByteArrayAsync(website) method, instead of GetStringAsync(website). Is there any reason why they would use GetByteArrayAsync instead of GetStringAsync, which would make data manipulation much easier right off the bat? Are there any advantages to using GetByteArrayAsync first instead?
What moves "through the wire" are bytes, not strings.
They might be text, but can be pictures, or a zip file.
At TCP/HTTP level this is unknown, and it does not matter.
That decision belongs with a higher level.
HTTP has a bit more info than TCP, so you might have a mimetype to help you decide what those bytes are.
Even if you know it is some kind of text, you will need to know the character set. You might get that info in the HTTP header, or in the document itself, or there might be a standard saying what the encoding is.
Only then you will be able to convert to a string.
I have created an app that retrieves network packets using this example: http://www.codeproject.com/Articles/4217/Packet-Sniffing-with-Winpcap-Functions-Ported-to-a
My intention is to use it in order to obtain the content of specific packets sent to a specific application from a server, I'm not interested in any other packets. The packet I'm interesting is 1 value which updates periodically.
I converted it to VB .Net as that is my preference so I'll be giving my code snippets in VB, though I can understand C# as well so feel free to give examples using C#.
It has an event with the parameter 's' which contains the content of the received packet in a byte array.
I'm converting that array to read with a binary reader like this:
Dim stream As System.IO.MemoryStream = New System.IO.MemoryStream(s)
Dim reader As New System.IO.BinaryReader(stream)
Dim pos As Long = 0
Dim length As Long = reader.BaseStream.Length
I'll then go through a loop with the 'pos' variable as the current position, incremented by the data type of the current bytes. (Like: something = reader.ReadString() pos += something.Length)
My only problem is: I'm not sure what types I should be looking for? What is the 'structure' of a packet? Is it possible to retrieve the server that the packet was sent from, and the application it was sent to?
I've never tried using something like this for packets before, I've only had experience getting data from a custom format database file.
Edit: I've found something a bit more useful which has documentation explaining about source/destination IP and how to filter by them and it looks to be a lot more complete than the above example mentioned earlier.
http://www.codeproject.com/Articles/12458/SharpPcap-A-Packet-Capture-Framework-for-NET
Though it still doesn't give an explanation of how to understand the packet contents itself, but being able to filter the packets is a big help.
There are many different types of possible network packets - most are well documented.
What you'll want to do is download Wireshark (Microsoft also has a similar tool whose name escapes me right now), run some captures with that, and look at the logs.
Wireshark recognizes virtually every existing network packet in existence, so you can use its logs to determine what type of packet you need to be able to recognize and then google for its specification.
I am wondering how should I set up interprocess unified communication in better way than I do now. Client process sends a lot of messages of different sort to the server process. Messages like... I have done some work[what],I started at [time], ended at[time]. or state, progress even command messages.
example message: From:Process1;StartedAt|12:12:12;EndedAt|12:45:56;DoneUnit:51
Server parser split string by semicolon. From first part reads from who was message sent. from second and third part it reads times and from last how much work it did.
When I add another info at the end of message
ex. From:Process1;StartedAt|12:12:12;EndedAt|12:45:56;DoneUnit:51;Source:tableT
I have to rewrite the server parser as well.
Server tries to parse received message using my own parse function. Every message has its own format. So parser know how should message look. But if I change the format on client I have to change it on server as well. It does not seems to be very efficient way.
For that reason I ask you a question.
How should this communication get better or is there any different approach how to store the format for client and server on one place?
I use c# .net 3.5(Must be this version)
Thank you for reply
The obvious solution to your problem would be to not write the parsing code yourself.
If you create a class that can be serialized, you can send the serialized version of the class over the wire and deserialize at the other end. That means the message class can be shared between both applications, and the parsing code is trivial. Depending on your requirements, you can use various serializers: Xml or JSON would be verbose but human-readable, or the binary serializer would be more efficient in terms of bandwidth (but harder to debug or monitor over-the-wire).
i'm developing application that is listening to the data coming to the pc and store it in a db
when i'm trying to use any sniffing software it decode the data and i can read it...
but in my code ....i cant read it at all
it come in a format like that
1822262151622341817118815518211616121520941131921572041519912321413018224510453482062312258624219217426213385792952422362282081777270129716688629114817282188771708157542505055171418651781981425595109572128317191993018793431541418175198551682143218916536118562071014546919618158204181231187237183188160147127165111798312311810419822146114761993113815821216617541542372062129733198212250147199288115346102031191275215728146245198190171121209115149107193226253199151253205183146112072202559697791491441131572351381412278441552554817712614110121823714822712523618924690185291182071331471286244143181469018522814822821118012620321315924832238219115405615512392145202385512115735771691111055935782371281492476567165158924021493139815144225143762294713291762001113814720516216041120169912317914878167571392103510118386589521910621319622274158971538465206168139190127867123282255271781242497522124211517622131122113236255230254211206911242051832545515823012124925217318223920523316923122925514321122343602492471242........
can any one tell me what kind of data is that and any code to solve it out??
To see what a real packet sniffer looks like, check out WireShark. There are many different protocols over TCP, and many of them are binary. Those that aren't may be using unicode characters, which are two-byte characters so an ascii display of them would be meaningless.
Anyway, the data you're displaying is pretty meaningless. It looks like decimal data, are you concatenating a bunch of decimal representations of the binary stream interpreted as byte or integer values? That would explain it. You should start by running the stream through System.TextEncoding.ASCII.Decode You'll probably see some recognizable strings. Then try System.TextEncoding.Unicode.Decode, etc.
No, we cannot. And the reason is simple, we don't know what application you are sniffing.
That stream of data could mean anything.
But, I suggest you print the data in hexadecimal. Maybe the data would make more sense.
First of all i am new to networking so i may say dumb thing in here.
Considering a client-server application using sockets(.net with c# if that matters).
The client sends some data, the
server process it and sends back a
string.
The client sends some other data,
the serve process it, queries the db
and sends back several hundreds of
items from the database
The client sends some other type of
data and the server notifies some
other clients
.
My question is how to set the buffer size correctly for reading/writing operation.
Should i do something like this: byte[] buff = new byte[client.ReceiveBufferSize] ?
I am thinking of something like this:
Client sends data to the server(and the server will follow the same pattern)
byte[] bytesToSend=new byte[2048] //2048 to be standard for any command send by the client
bytes 0..1 ->command type
bytes 1..2047 ->command parameters
byte[] bytesToReceive=new byte[8]/byte[64]/byte[8192] //switch(command type)
But..what is happening when a client is notified by the server without sending data?
What is the correct way to accomplish what i am trying to do?
Thanks for reading.
Doesn't matter what is the size of your buffer, it should be just a temporary storage for the data. Read this about reading from binary streams: http://www.yoda.arachsys.com/csharp/readbinary.html
I don't really understand what you are trying to do, but i try to give some advice. Your byte array and the Socket.ReceiveBufferSize property are two different things. The buffer size doesn't matter. You should use a byte array large enough to store the data you want to send or receive. For the size of the byte array, 2048 is probably ok, unless you want to send images, very large text, etc. I've done some simple client server programming and i found it easier if the receiver knows how much data to receive in advance. So for example you send the length of the string first as 1 or 2 bytes, and then the string using utf8 encoding. Use the Encoding.GetByteCount method for getting the size of the string in bytes for the chosen encoding. You should convert numbers to binary using the methods from Bitconverter. I found those helpful and now i wish, i would have discovered them earlier. To send other more complex data types you should decompose them and send them as strings or numbers one at a time.
When designing client/server communication it is good to introduces some a notion of a communication protocol (basically a set of rules, format that will be sent/received) by the client/server.
Here's an example of exchanging messages of variable size over the network
You can simplest think about XML as a protocol of your communication, then you reading socket until null byte was readed. (This is typicaly marker of end of xml document). You can implement this protocol in two ways.
To parse and generate XML document you can use XMLDocument class. You must to it impelemnt some schema. But if you want clean transform data as XML you can use simplest DataSet.