File-uploading | Using get and post method | Runtime Evironment library
kandi X-RAY | File-uploading Summary
kandi X-RAY | File-uploading Summary
Using get and post method i have learnt how to upload files on a server in nodejs, and learnt how backend is working and where the uploaded file is going.
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QUESTION
My problem is very similar to Similar Question
I tried my level best and at last, I'm posting my query here. Hope to get a solution for the below problem.
Problem I'm trying to upload multiple files through php. But getting one file in $_FILES array.
Other meta data
- php.ini config. file_uploads = On
- php.ini config. upload_max_filesize = 2M
- php.ini config. max_file_uploads = 20
- PHP version 8
- No error in error log
index.html
...ANSWER
Answered 2021-May-12 at 06:01QUESTION
In my Angular8 app, I have a drop zone where I can drag & drop files, such as PDF, MS Word, CSV, etc. I am using the technique found on this blog, but also documented by Mozilla MDN. The code works very well, but the one important thing I can't figure out is how to capture the file bytes being uploaded, so that I can save them to the database.
I placed a screenshot of the Opera browser source debugger below, showing the typescript and resulting fileObj and blobObj values. The debugger complains about readAsBinaryString(blobObj), saying that blobObj is not a Blob. Looking at the blobObj value, I can see it's not a Blob that I've seen before. And, looking at all the values, none stand-out to me as a Blob. Also, the file bytes aren't obvious either. Looking at the html, below, I can't think of a change that would reveal the bytes.
I'm hoping someone with drag and drop experience can explain how it's done.
Thanks!
HTML
...ANSWER
Answered 2021-Feb-17 at 15:29const reader = new FileReader();
// FileReader has an onload event that you handle when it has loaded data
reader.onload = (e: any) => {
const data = e.target.result as any;
console.log({type: 'GalleryComponent prepareFilesList - data:', data});
};
// this will kick off the onload handler above
reader.readAsDataURL(file);
QUESTION
I followed this tutorial for impementing an file upload into my reactive form: https://netbasal.com/how-to-implement-file-uploading-in-angular-reactive-forms-89a3fffa1a03 but I'm Having a problem: "this.onChange is not a function" my Component:
...ANSWER
Answered 2020-Oct-12 at 07:18@MikeOne was right, i needed to separate component that contains all the controlValueAccessor.
QUESTION
I'm curious if anyone could fill me in on how safe it is to use toDataURL on a user provided image. The basic idea is that User A would upload an image in their browser and it would be converted to an URL, and then ignoring steps in between, eventually User B (as well as other users) would retrieve the URL format where it would be converted back into an image and displayed in User B's browser.
So my question revolves around whether someone could abuse the system to inject code into User B's browser, or otherwise cause havoc. In general, what security considerations are there that must be taken when using toDataURL and then later converting it back?
I'm aware that cross origin images taint a canvas which disallows any methods that involve the data, but I'm not aware of how much of a blanket solution this is. I've read that some browsers don't have this restriction while other's (and even other versions of the same browser) implement this restriction differently depending on the content of the cross origin image.
What I've found in my research so far:
- this question where the answer pointed to a great article that looked at it from the perspective of storing the uploaded image on a server.
- this question where the answer points out an interesting way to hide a script in an image I'd never seen before, but I'm not sure what vulnerability it creates if I'm not trying to extract a script from that image and run it.
- and this link which details a great reason why browser's choose to restrict access to image data for cross origin images. I always assumed it was just about protecting against malicious images, but now realize it also protects against much more.
None of the above have sufficiently approached it from the perspective of one user attacking another user through uploading an image (that doesn't stay as uploaded but instead gets converted to data url) that another user later downloads and views (with img src set to data url, not the malicious user's original upload). 2 is close to answering my question, but as I understand it, the detailed methods wouldn't work without the malicious user also having injected some script into the viewing user's browser.
To go along with this question is an example of what I would like to do including the file uploading/conversion to data url along with a sample data url to try out the importing (this sample url is safe to import and small so it imports quickly):
...ANSWER
Answered 2020-Mar-17 at 06:10There seems to be some confusion here, and given how misleading your links are I can understand.
Tainted canvas"Tainting the canvas" is a security operation which blocks .toDataURL() and any other exporting method like .toBlob(), .captureStream() or 2D context's .getImageData().
There are only a few cases where this operation is done:
Cross-origin resources: That's the most common on the web. Site A drew a resource like an image from Site B on a canvas. If Site B didn't tell the browser that it allows Site A to read this content by passing an appropriate Allow-Origin headers, then the browser has to "taint" the canvas.
This only protects the resource. There is no real security added to Site A in that case.Information leakage: That's more of an exception, but still it's a thing. Browsers may decide on their own that some actions could leak privacy information about their user. For instance the most common case is to "taint" the canvas when an SVG image containing a is painted on the canvas. Since this tag can render HTML, it can also leak what link has been visited for instance. Browsers should take care of anonymizing these resources, but nevertheless, Safari still does taint any such SVG image, Chrome buggily still does taint the ones served from a
blob:URI, IE did taint any SVG image (not only the ones with ), and all did at some point taint the canvas when using some externalsfilter.Information leakage II: There is also something that no browser can fight against when reading a canvas generated bitmap. Every hardware and software will produce slightly different results when asked to perform the same drawing operations. This can be used to finger-print the current browser. Some browser extensions will thus block these methods too, or make it return dummy results.
Now, none of this really protects from malicious images.
Images embedding malicious codeThe kind of images that can embed malicious code are generally exploiting vulnerabilities in the image parsers and renderers. I don't think any up to date such parser or renderer is still vulnerable to such attacks, but even though there was one, which would be used by a web browser, then when it's been drawn to the canvas, it's already too late. Tainting the canvas would not protect anything.
One thing you may have heard about is stegosploit. This consists in hiding malicious code in the image, but the HTML canvas there was used to decode that malicious code. So if you don't have the script to extract and execute the malicious script embedded, it doesn't represent much a risk, and actually, if you do reexport it, there are good chances that this embedded data gets lost.
Risks inherent with uploading content to a serverThere are many risks when uploading anything to your server. I can't stress it out enough but Read OWASP recommendations carefully.
Particular risks when uploading adata: URL
data: URLs are a good vector for XSS attacks. Indeed, it is very likely that you will build HTML code directly using that data: URL. If you didn't apply the correct sanitization steps, you may very well load an attacker's script instead of an image:
QUESTION
I would upload the file in Angular using upload component
Here's my HTML:
...ANSWER
Answered 2018-Sep-13 at 10:01In the official documentation you have an example:
QUESTION
I am using WebdriverIO to run a file-uploading .exe created with AutoIt.
I am running the script inside a browser.execute command. The file needs to run from the local drive and execute wd in Chrome browser.
Here is the code :
ANSWER
Answered 2019-Oct-17 at 08:07I remember doing something like this in the past and I used NodeJS's child_process.execFile command. The documentation is heavy on child_process, so read carefully.
You should end up with something along the lines of:
QUESTION
My question is similar to this one: webapi-file-uploading-without-writing-files-to-disk
However, this and most of the other similar questions stop at reading the file data. I have made that bit work fine, but I am also wanting to read the rest of the form data in the form which has other elements for the upload such as 'Title' etc. This comes from the solution in the aforementioned question:
...ANSWER
Answered 2019-Oct-12 at 18:01Now that it is sorted out in the comments I shall post this answer to help others maybe.
form multipart content sends a data back to server like this"
QUESTION
With my Error Handling, It throws the Error as expected, even though it uploads some files(till reaches the limit) and then the Error is thrown. how to throw this error before uploading some chunk files?
How to throw error before uploading, when it exceeds the limit no of files uploaded? Thanks in advance!
Which I tried:
...ANSWER
Answered 2019-Sep-25 at 08:57Since you are uploading multiple files it should be multer array. You can specify the file limit like so:
QUESTION
I have express-oriented sample code for receiving multi-part form data from a provider:
ANSWER
Answered 2019-Aug-12 at 07:26Here's the answer, via coagmano on the Meteor forum:
Note: in case it may be useful to others, the provider is HelloSign. Here's my completed code.
QUESTION
This morning I wrote a custom server in Java. Eventually, I want to use it as the backend for a react-native app, and so I was working on implementing file-uploading. I've been testing this with a simple HTML form that submits its data to my local machine. When I parse the HTTP request headers, I extract the Content-Length of the data section of the request (hereafter refered to as the "message body" of the request). Sometimes, the message body of the HTTP request contains the file name and contents, but more often than not it is empty, even if the Content-Length and Content-Type (including the form boundary) are set correctly (non-zero length, "--WebKitBoundary..." boundary). I can detect this and timeout (and no, increasing my timeout does not let me read more data), but the fact that the HTTP request seems to indicate that there should be data when none is received seems like a significant issue.
The post here seems to be exactly what I am seeing, but as of this posting it has not been answered.
This is the class I use to read data from the InputStream of the established Socket connection:
...ANSWER
Answered 2019-Jun-09 at 02:02There are two problems in your code.
The first one is the most likely to cause your problem:
Scanner isn't a good choice here, since it will not stop reading your InputStream at "\r\n\r\n". Scanner only works well when it's the only thing reading your InputStream, not when you want to read it directly as well. Scanner will try to fill its internal buffer first and then search in its buffer for \r\n\r\n. So it will invariably read beyond that. And those bytes will not be available in the InputStream anymore in the second part of your function.
So you can't use Scanner - you need to read directly from the InputStream until you have seen \r\n\r\n; only then an you be sure that you have read the request correctly without reading any of the request body yet.
The second problem is that using InputStream.available() is a brittle way to read data. You are very much depending on networking timing and that could be off by quite a bit. If the data is coming in quickly, you are waiting to long since you do a Thread.sleep for every read. And if it doesn't come in fast enough, you may timeout too quickly.
A much more reliable way to read is this:
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