I am working with a project that includes getting MMS from a mms-gateway and storing the image on disk.
This includes using a received base64encoded string and storing it as a zip to a web server. This zip is then opened, and the image is retrieved.
We have managed to store it as a zip file, but it is corrupted and cannot be opened.
The documentation from the gateway is pretty sparse, and we have only a php example to rely on. I think we have figured out how to "translate" most of it, except for the PHP function stripcslashes(inputvalue). Can anyone shed shed any light on how to do the same thing in c#?
We are thankful for any help!
stripcslashes() looks for "\x" type elements within longer strings (where 'x' could be any character, or perhaps, more than one). If the 'x' is not recognised as meaningful, it just removes the '\' but if it does recognise it as a valid C-style escape sequence (i.e. "\n" is newline; "\t" is tab, etc.), as I understand it, the recognised character is inserted instead: \t will be replaced by a tab character (0x09, I think) in your string.
I'm not aware of any simple way to get the .net framework to do the same thing without building a similar function yourself. This obviously isn't very hard, but you need to know which escape sequences to process.
If you happen to know (or find out by inspecting your base64 text) that the only thing in your input that will need processing is a particular one or two sequences (say, tab characters), it becomes very easy and the following snippet shows use of String.Replace():
string input = #"Some\thing"; // '#' means string stored without processing '\t'
Console.WriteLine(input);
string output = input.Replace(#"\t", "\t");
Console.WriteLine(output);
Of course, if you really do simply want to remove all the slashes:
string output = input.Replace(#"\", "");
Related
Ok, I'm racking my brains over this one. It's pretty simple though (I think).
I'm currently creating a text file as a comma separated string of values.
Later, I read in that file data and then use the .split function to split the data by commas.
I discovered that sometimes one of the description fields in the data conatins an embedded comma, which ends up throwing the split command off.
Is there any special character I could use that could pretty much guarantee wouldn't be in the data, or is there a better way to accomplish this? Thanks!
// Initial Load
fullString = fileName + "," + String.Join(",", fieldValues);
// Access later
String[] valuesArray = myString.Split(',');
Short answer, there's no "simple" way to do it using Split. The best you can hope for is to set the deliminator as something cooky that wouldn't ever get used (but even that's not a guarantee).
The simple method would be to used something like CsvHelper (get it through Nuget) or any of the other dozen or so packages that are designed for parsing CSV.
I'm writing a utility that takes in a .resx file and creates a javascript object containing properties for all the name/value pairs in the .resx file. This is all well and good, until one of the values in the .resx is
This dealer accepts electronic orders.
/r/nClick to order {0} from this dealer.
I'm adding the name/value pairs to the js object like this:
streamWriter.Write(string.Format("\n{0} : \"{1}\"", kvp.Key, kvp.Value));
When kvp.Value = "This dealer accepts electronic orders./r/nClick to order {0} from this dealer."
This causes StreamWriter.Write() to actually place a newline in between 'orders.' and 'Click', which naturally screws up my javascript output.
I've tried different things with # and without using string.Format, but I've had no luck. Any suggestions?
Edit: This application is run during build to get some javascript files deployed later, so at no point is it accessible to / run by anyone but the app developers. So while I obviously need a way to escape characters here, XSS as such is not really a concern.
Your problem has already happened by the time you get to this code. String.Format will not "expand" literal \n and \r in the substituted strings ({0} etc) into newline and CR, so it must have happened at some earlier point, possibly while reading the .resx file.
You have two possible solutions. One, as you discovered in the comments to DonaldRay's answer, is to explicitly reverse this replacement, and replace literal newlines with the two characters \n:
kvp.Value.Replace("\r", // <-- replaced by the C# compiler with a literal CR character
"\\r"); // <-- "\\" replaced by the C# compiler with a single "\",
// leaving the two-char string "\r"
You will need to do the same for every character that could appear in your strings. \n and \r are the most common, and then \t (tab); that's probably enough for most dev tools.
string formatted = kvp.Value.Replace("\r", "\\r")
.Replace("\n", "\\n")
.Replace("\t", "\\t");
Alternatively, you could look upstream at the .resx file reading code, and try to find and remove the part that's explicitly expanding these character sequences. This would be a better general solution, if it's possible.
You need to escape the strings, using Microsoft's Anti-XSS Library.
Just escape the backslashes.
kvp.Value = kvp.Value.Replace(#"\", #"\\");
You may need to do this when you are reading from the resx file.
I have a slight problem with a path:
"D:\\Music\\DJ Ti%C3%ABsto\\Tiesto\\Adagio For Strings (Spirit of London).mp3"
"D:\\Music\\Dj Tiësto\\Tiesto\\Adagio For Strings (Spirit of London).mp3"
Currently, when it sends that path to my Audio Library, it cannot open the path. (the reason for it crashing is trying to assign a -1 to a trackbar...but it's irrelevant).
So I'm wondering, is there anyway to prevent C# from switching special characters with %[code]? I've done a .Replace for "[" and "]", but I rather not have to look up every single special character, and add a line of code to prevent it. Is there anyway around this?
Call Uri.UnescapeDataString.
By the way, when putting paths in strings, you can put an # sign before the string to tell the compiler not to process escape codes, like this: #"D:\Music\DJ Tiësto\Tiesto\Adagio For Strings (Spirit of London).mp3". This way, you don't need to double up every backslash.
How would I accomplish displaying a line as the one below in a console window by writing it into a variable during design time then just calling Console.WriteLine(sDescription) to display it?
Options:
-t Description of -t argument.
-b Description of -b argument.
If I understand your question right, what you need is the # sign in front of your string. This will make the compiler take in your string literally (including newlines etc)
In your case I would write the following:
String sDescription =
#"Options:
-t Description of -t argument.";
So far for your question (I hope), but I would suggest to just use several WriteLines.
The performance loss is next to nothing and it just is more adaptable.
You could work with a format string so you would go for this:
string formatString = "{0:10} {1}";
Console.WriteLine("Options:");
Console.WriteLine(formatString, "-t", "Description of -t argument.");
Console.WriteLine(formatString, "-b", "Description of -b argument.");
the formatstring makes sure your lines are formatted nicely without putting spaces manually and makes sure that if you ever want to make the format different you just need to do it in one place.
Console.Write("Options:\n\tSomething\t\tElse");
produces
Options:
Something Else
\n for next line, \t for tab, for more professional layouts try the field-width setting with format specifiers.
http://msdn.microsoft.com/en-us/library/txafckwd.aspx
If this is a /? screen, I tend to throw the text into a .txt file that I embed via a resx file. Then I just edit the txt file. This then gets exposed as a string property on the generated resx class.
If needed, I embed standard string.Format symbols into my txt for replacement.
Personally I'd normally just write three Console.WriteLine calls. I know that gives extra fluff, but it lines the text up appropriately and it guarantees that it'll use the right line terminator for whatever platform I'm running on. An alternative would be to use a verbatim string literal, but that will "fix" the line terminator at compile-time.
I know C# is mostly used on windows machines, but please, please, please try to write your code as platform neutral. Not all platforms have the same end of line character. To properly retrieve the end of line character for the currently executing platform you should use:
System.Environment.NewLine
Maybe I'm just anal because I am a former java programmer who ran apps on many platforms, but you never know what the platform of the future is.
The "best" answer depends on where the information you're displaying comes from.
If you want to hard code it, using an "#" string is very effective, though you'll find that getting it to display right plays merry hell with your code formatting.
For a more substantial piece of text (more than a couple of lines), embedding a text resources is good.
But, if you need to construct the string on the fly, say by looping over the commandline parameters supported by your application, then you should investigate both StringBuilder and Format Strings.
StringBuilder has methods like AppendFormat() that accept format strings, making it easy to build up lines of format.
Format Strings make it easy to combine multiple items together. Note that Format strings may be used to format things to a specific width.
To quote the MSDN page linked above:
Format Item Syntax
Each format item takes the following
form and consists of the following
components:
{index[,alignment][:formatString]}
The matching braces ("{" and "}") are
required.
Index Component
The mandatory index component, also
called a parameter specifier, is a
number starting from 0 that identifies
a corresponding item in the list of
objects ...
Alignment Component
The optional alignment component is a
signed integer indicating the
preferred formatted field width. If
the value of alignment is less than
the length of the formatted string,
alignment is ignored and the length of
the formatted string is used as the
field width. The formatted data in
the field is right-aligned if
alignment is positive and left-aligned
if alignment is negative. If padding
is necessary, white space is used. The
comma is required if alignment is
specified.
Format String Component
The optional formatString component is
a format string that is appropriate
for the type of object being formatted
...
I'm trying to pass in a Base64 string into a C#.Net web application via the QueryString. When the string arrives the "+" (plus) sign is being replaced by a space. It appears that the automatic URLDecode process is doing this. I have no control over what is being passed via the QueryString. Is there any way to handle this server side?
Example:
http://localhost:3399/Base64.aspx?VLTrap=VkxUcmFwIHNldCB0byAiRkRTQT8+PE0iIHBsdXMgb3IgbWludXMgNSBwZXJjZW50Lg==
Produces:
VkxUcmFwIHNldCB0byAiRkRTQT8 PE0iIHBsdXMgb3IgbWludXMgNSBwZXJjZW50Lg==
People have suggested URLEncoding the querystring:
System.Web.HttpUtility.UrlEncode(yourString)
I can't do that as I have no control over the calling routine (which is working fine with other languages).
There was also the suggestion of replacing spaces with a plus sign:
Request.QueryString["VLTrap"].Replace(" ", "+");
I had though of this but my concern with it, and I should have mentioned this to start, is that I don't know what other characters might be malformed in addition to the plus sign.
My main goal is to intercept the QueryString before it is run through the decoder.
To this end I tried looking at Request.QueryString.toString() but this contained the same malformed information. Is there any way to look at the raw QueryString before it is URLDecoded?
After further testing it appears that .Net expects everything coming in from the QuerString to be URL encoded but the browser does not automatically URL encode GET requests.
The suggested solution:
Request.QueryString["VLTrap"].Replace(" ", "+");
Should work just fine. As for your concern:
I had though of this but my concern with it, and I should have mentioned this to start, is that I don't know what other characters might be malformed in addition to the plus sign.
This is easy to alleviate by reading about base64. The only non alphanumeric characters that are legal in modern base64 are "/", "+" and "=" (which is only used for padding).
Of those, "+" is the only one that has special meaning as an escaped representation in URLs. While the other two have special meaning in URLs (path delimiter and query string separator), they shouldn't pose a problem.
So I think you should be OK.
You could manually replace the value (argument.Replace(' ', '+')) or consult the HttpRequest.ServerVariables["QUERY_STRING"] (even better the HttpRequest.Url.Query) and parse it yourself.
You should however try to solve the problem where the URL is given; a plus sign needs to get encoded as "%2B" in the URL because a plus otherwise represents a space.
If you don't control the inbound URLs, the first option would be preferred as you avoid the most errors this way.
I'm having this exact same issue except I have control over my URL. Even with Server.URLDecode and Server.URLEncode it doesn't convert it back to a + sign, even though my query string looks as follows:
http://localhost/childapp/default.aspx?TokenID=0XU%2fKUTLau%2bnSWR7%2b5Z7DbZrhKZMyeqStyTPonw1OdI%3d
When I perform the following.
string tokenID = Server.UrlDecode(Request.QueryString["TokenID"]);
it still does not convert the %2b back into a + sign. Instead I have to do the following:
string tokenID = Server.UrlDecode(Request.QueryString["TokenID"]);
tokenID = tokenID.Replace(" ", "+");
Then it works correctly. Really odd.
I had similar problem with a parameter that contains Base64 value and when it comes with '+'.
Only Request.QueryString["VLTrap"].Replace(" ", "+"); worked fine for me;
no UrlEncode or other encoding helping because even if you show encoded link on page yourself with '+' encoded as a '%2b' then it's browser that changes it to '+' at first when it showen and when you click it then browser changes it to empty space. So no way to control it as original poster says even if you show links yourself. The same thing with such links even in html emails.
If you use System.Uri.UnescapeDataString(yourString) it will ignore the +. This method should only be used in cases like yours where when the string was encoded using some sort of legacy approach either on the client or server.
See this blog post:
http://blogs.msdn.com/b/yangxind/archive/2006/11/09/don-t-use-net-system-uri-unescapedatastring-in-url-decoding.aspx
If you URLEncode the string before adding it to the URL you will not have any of those problems (the automatic URLDecode will return it to the original state).
Well, obviously you should have the Base64 string URLEncoded before sending it to the server.
If you cannot accomplish that, I would suggest simply replacing any embedded spaces back to +; since b64 strings are not suposed to have spaces, its a legitimate tactic...
System.Web.HttpUtility.UrlEncode(yourString) will do the trick.
As a quick hack you could replace space with plus character before base64-decoding.
I am by no means a C# developer but it looks like you need to url ENCODE your Base64 string before sending it as a url.
Can't you just assume a space is a + and replace it?
Request.QueryString["VLTrap"].Replace(" ", "+");
;)