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Forum Discussion
HairyWombat
2 years agoHelpful | Level 6
Problem downloading file using Dropbox-provided URL
Hi 1. I'm developing an app for iOS and Android. Users can enter the url of a file they would like to download. They might choose a Dropbox url like https://www.dropbox.com/s/fzv989hz5mazhqw/Repl...
- 2 years ago
Hi Greg-DB
Hey I really appreciate the effort you and the team have put in.
What I found was:
1. Yes, curl works with the url - I switched from Mac to Windows and curl worked. Bash both times.
2. Fiddler also works with the URL.
3. My published code fails using automatic redirect. It works for you - the difference may be that I'm using Microsoft Xamarin on Mac.
4. In the second redirect, Dropbox proposes https://uc012d2e25383f12de25c9db8029.dl.dropboxusercontent.com/cd/0/get/B-Dfp2veRgmAiBVuB2GBdOb2SPrjBQh9t0CkeebfBm8SdzO4_8rntEJaHCvdDqpc6-v3DZF5AGyupcRw9SOyfq8l_wlZmj63OWNOQpPgmBUcisawx6C0OptaJHDM9IoDPKvPtxaegRX8av8D36sJb1hcObvW7harZlcWcGjIqXz0aw/file?dl=1# -- which strictly speaking is not a valid url because of the trailing #.
5. I solved the problem by handling the redirects myself and url-encoding the #.
So, Xamarin could do better. But also, Dropbox really should not be sending invalid urls. 🙂
Code below fyi.
Cheers
Bill
----------------------
httpClientHandler = new HttpClientHandler{AllowAutoRedirect = false};----------------------
try{// Here change ?dl=0 to ?dl=1 *****// webUrl = "https://www.howsmyssl.com/a/check"; // Debug - to check TLS version. It is TLS 1.2. (June 2023)HttpResponseMessage response = await httpClient.GetAsync ( webUrl );int redirectCount = 0;while ( redirectCount < 20 ){if ( response.StatusCode == HttpStatusCode.Redirect ){string redirectUrl;if ( response.Headers != null && response.Headers.Location != null ){if ( response.Headers.Location.IsAbsoluteUri )redirectUrl = response.Headers.Location.AbsoluteUri;else{string[] splits = webUrl.Split ('/' );redirectUrl = "https://" + splits [2] + response.Headers.Location.OriginalString;}redirectUrl = redirectUrl.Replace ( "#", "#".UrlEncode () );response = await httpClient.GetAsync ( redirectUrl );if ( response.StatusCode != HttpStatusCode.Redirect )break;}redirectCount++;}}using ( MemoryStream memoryStream = new MemoryStream () ){using ( Stream stream = await response.Content.ReadAsStreamAsync () ){stream.CopyTo ( memoryStream );}memoryStream.Seek ( 0, SeekOrigin.Begin );bytes = memoryStream.ToArray ();}return bytes;}catch ( Exception ex ){// ...}}----------------------
HairyWombat
2 years agoHelpful | Level 6
I mean, when the path to the file is unknown.
- DB-Des2 years agoDropbox Engineer
Yes, you should be able to download with ?dl=1.
I was unable to reproduce the reported issue, by using cURL.
Could you provide detailed steps on how to reproduce the issue you are experiencing? For example, the code snippet you are using to reproduce the issue.
- HairyWombat2 years agoHelpful | Level 6
Thanks, iMonkia, for the very prompt and helpful response! Love your wolf icon btw.
When I use curl -L, I get 'no matches found'. However this same url downloads correctly in a web browser. You might try it yourself with my sample url https://www.dropbox.com/s/fzv989hz5mazhqw/ReplacementDatabase.dbf?dl=1
The command line transcript is below. I've also attached my C# .NET 7.0.1 code. It is allowing redirection as best I can see.
My test file ReplacementDatabase.dbf is in a Dropbox subdirectory, not at top level, if that matters. Any suggestion appreciated. 🙂
Cheers
Bill
---------------------------------
Last login: Tue Jun 13 11:14:00 on ttys000
bill@Bills-MBP-10 ~ % cd desktop
bill@Bills-MBP-10 desktop % ls Test.dbf
ls: Test.dbf: No such file or directory
bill@Bills-MBP-10 desktop % curl https://billfulton.github.io/ReplacementDatabase.dbf > Test.dbf
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 671k 100 671k 0 0 1045k 0 --:--:-- --:--:-- --:--:-- 1064k
bill@Bills-MBP-10 desktop % ls -l Test.dbf
-rw-r--r-- 1 bill staff 687752 13 Jun 11:31 Test.dbf
bill@Bills-MBP-10 desktop %
bill@Bills-MBP-10 desktop %
bill@Bills-MBP-10 desktop % curl -L https://www.dropbox.com/s/fzv989hz5mazhqw/ReplacementDatabase.dbf?dl=1 > Test1.dbf
zsh: no matches found: https://www.dropbox.com/s/fzv989hz5mazhqw/ReplacementDatabase.dbf?dl=1
bill@Bills-MBP-10 desktop % curl -L https://www.dropbox.com/s/fzv989hz5mazhqw/ReplacementDatabase.dbf?dl=1
zsh: no matches found: https://www.dropbox.com/s/fzv989hz5mazhqw/ReplacementDatabase.dbf?dl=1
bill@Bills-MBP-10 desktop % curl https://www.dropbox.com/s/fzv989hz5mazhqw/ReplacementDatabase.dbf?dl=1
zsh: no matches found: https://www.dropbox.com/s/fzv989hz5mazhqw/ReplacementDatabase.dbf?dl=1
bill@Bills-MBP-10 desktop % curl -L --max-redirs 20 https://www.dropbox.com/s/fzv989hz5mazhqw/ReplacementDatabase.dbf?dl=1 > Test2.dbf
zsh: no matches found: https://www.dropbox.com/s/fzv989hz5mazhqw/ReplacementDatabase.dbf?dl=1
bill@Bills-MBP-10 desktop %
---------------------------------
// Initialise httpClienthttpClientHandler = new HttpClientHandler{AllowAutoRedirect = true,// Allegedly the default, but to make sureMaxAutomaticRedirections = 20};httpClient = new HttpClient ( httpClientHandler );httpClient.Timeout = TimeSpan.FromSeconds ( 60 );// Accept all languageshttpClient.DefaultRequestHeaders.AcceptLanguage.Clear();httpClient.DefaultRequestHeaders.AcceptLanguage.Add ( new System.Net.Http.Headers.StringWithQualityHeaderValue ( "*" ) );// Accept binary datahttpClient.DefaultRequestHeaders.Accept.Add ( new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue ( "application/octet-stream" ) );---------------------------------
public static async Task<byte []> ReadWebFileBinaryAsync ( HttpClient httpClient, string webUrl )// Returns byte array from given file URL{byte [] bytes;try{// Force Dropbox url for testing purposes - to be removedHttpResponseMessage response = await httpClient.GetAsync ( webUrl );using ( MemoryStream memoryStream = new MemoryStream () ){using ( Stream stream = await response.Content.ReadAsStreamAsync () ){stream.CopyTo ( memoryStream );}memoryStream.Seek ( 0, SeekOrigin.Begin );bytes = memoryStream.ToArray ();}return bytes;}catch ( Exception ex ){// ...}}---------------------------------
- HairyWombat2 years agoHelpful | Level 6
Further info:
I tried with a file that sin the Dropbox root folder, but it didn't help.
Here is the html string that I am receiving (Error 400):
<!DOCTYPE html>
<html>
<head><meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1" />
<title>Dropbox - 400</title>
<link href="https://cfl.dropboxstatic.com/static/metaserver/static/css/error.css" rel="stylesheet" type="text/css"/>
<link rel="shortcut icon" href="https://cfl.dropboxstatic.com/static/images/favicon.ico"/>
</head>
<body>
<div class="figure">
<img src="https://assets.dropbox.com/www/en-us/illustrations/spot/target-miss.svg" alt="Error: 400"/>
</div>
<div id="errorbox">
<h1>Error (400)</h1>Something went wrong. Don't worry, your files are still safe and the Dropbox team has been notified. Check out our <a href="https://status.dropbox.com">Status Page</a> to see if there is a known incident, our <a href="https://www.dropbox.com/help">Help Center</a> and <a href="https://forums.dropbox.com">forums</a> for help, or head back to <a href="https://www.dropbox.com/home">home</a>.
</div></body>
</html>- Здравко2 years agoLegendary | Level 20
Hi HairyWombat,
On my side it works as expected:
curl -L https://www.dropbox.com/s/fzv989hz5mazhqw/ReplacementDatabase.dbf?dl=1 > Test1.dbf % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 100 17 0 17 0 0 2 0 --:--:-- 0:00:06 --:--:-- 4 100 363 100 363 0 0 52 0 0:00:06 0:00:06 --:--:-- 52 100 671k 100 671k 0 0 68064 0 0:00:10 0:00:10 --:--:-- 267k
As expected, there are 3 transactions - 2 redirections and the last one is actual download. You can try verbose output (flag v) for more info:
curl -Lv https://www.dropbox.com/s/fzv989hz5mazhqw/ReplacementDatabase.dbf?dl=1 > Test1.dbf
Here - in the detailed output, you should be able see what's going wrong on your side.
Good luck.
Add: A trick code that works for me:
namespace Dropbox { using System; using System.IO; using System.Net; internal class Program { static void Main(string[] args) { if (args.Length != 1) { Console.WriteLine( "Expected one Dropbox URL as a single command parameter!"); return; } //"https://www.dropbox.com/s/fzv989hz5mazhqw/ReplacementDatabase.dbf?dl=1"; string webUrl = args[0]; var request = WebRequest.Create(webUrl); var response = request.GetResponse(); var ContentDisposition = response.Headers["Content-Disposition"]; var dispositions = ContentDisposition.Split(';'); string fileName = "Test.bin"; // default name string disposeName = "filename"; var disposeLength = disposeName.Length; for(int i = 0; i < dispositions.Length; ++i) { var disposition = dispositions[i].Trim(); if (string.Compare(disposition, 0, disposeName, 0, disposeLength, true) == 0) { if (string.Compare(disposition, disposeLength, "=\"", 0, 2) == 0 && disposition[disposition.Length-1] == '"') fileName = disposition.Substring(disposeLength + 2, disposition.Length - disposeLength - 3); else if (string.Compare(disposition, disposeLength, "*=UTF-8''", 0, 9) == 0) fileName = disposition.Substring(disposeLength + 9); } } Console.WriteLine("fileName: " + fileName); var ContentLength = response.ContentLength; Console.WriteLine("ContentLength: " + ContentLength); FileStream fs = new FileStream(fileName, FileMode.Create, FileAccess.Write); int bufLength = Math.Min((int)ContentLength, 0x10000); var buffer = new byte[bufLength]; var readStream = response.GetResponseStream(); int readed = readStream.Read(buffer, 0, bufLength); int consumed = 0; while(readed > 0) { consumed += readed; fs.Write(buffer, 0, readed); readed = readStream.Read(buffer, 0, bufLength); } readStream.Close(); fs.Close(); Console.WriteLine("Downloaded: " + consumed); } } }
- Greg-DB2 years agoDropbox Staff
HairyWombat The "zsh: no matches found" error you're getting is because the URL contains the "?" character which has a special meaning in that shell. To avoid that, quote the URL, like this:
curl -L "https://www.dropbox.com/s/fzv989hz5mazhqw/ReplacementDatabase.dbf?dl=1" > Test1.dbf
I also put together your C# code and tried downloading the file from the shared link with that, and I did successfully get the expected 687752 bytes of the file back.
If you're getting back that HTML 400 error page, that may indicate that the HTTP request was malformed, causing the Dropbox servers to be unable to understand the request. Is there anything on your .NET environment or your network connection itself, such as a proxy, VPN, firewall, etc., that may be interfering with or modifying these requests?
- HairyWombat2 years agoHelpful | Level 6
Hi Greg-DB
Hey I really appreciate the effort you and the team have put in.
What I found was:
1. Yes, curl works with the url - I switched from Mac to Windows and curl worked. Bash both times.
2. Fiddler also works with the URL.
3. My published code fails using automatic redirect. It works for you - the difference may be that I'm using Microsoft Xamarin on Mac.
4. In the second redirect, Dropbox proposes https://uc012d2e25383f12de25c9db8029.dl.dropboxusercontent.com/cd/0/get/B-Dfp2veRgmAiBVuB2GBdOb2SPrjBQh9t0CkeebfBm8SdzO4_8rntEJaHCvdDqpc6-v3DZF5AGyupcRw9SOyfq8l_wlZmj63OWNOQpPgmBUcisawx6C0OptaJHDM9IoDPKvPtxaegRX8av8D36sJb1hcObvW7harZlcWcGjIqXz0aw/file?dl=1# -- which strictly speaking is not a valid url because of the trailing #.
5. I solved the problem by handling the redirects myself and url-encoding the #.
So, Xamarin could do better. But also, Dropbox really should not be sending invalid urls. 🙂
Code below fyi.
Cheers
Bill
----------------------
httpClientHandler = new HttpClientHandler{AllowAutoRedirect = false};----------------------
try{// Here change ?dl=0 to ?dl=1 *****// webUrl = "https://www.howsmyssl.com/a/check"; // Debug - to check TLS version. It is TLS 1.2. (June 2023)HttpResponseMessage response = await httpClient.GetAsync ( webUrl );int redirectCount = 0;while ( redirectCount < 20 ){if ( response.StatusCode == HttpStatusCode.Redirect ){string redirectUrl;if ( response.Headers != null && response.Headers.Location != null ){if ( response.Headers.Location.IsAbsoluteUri )redirectUrl = response.Headers.Location.AbsoluteUri;else{string[] splits = webUrl.Split ('/' );redirectUrl = "https://" + splits [2] + response.Headers.Location.OriginalString;}redirectUrl = redirectUrl.Replace ( "#", "#".UrlEncode () );response = await httpClient.GetAsync ( redirectUrl );if ( response.StatusCode != HttpStatusCode.Redirect )break;}redirectCount++;}}using ( MemoryStream memoryStream = new MemoryStream () ){using ( Stream stream = await response.Content.ReadAsStreamAsync () ){stream.CopyTo ( memoryStream );}memoryStream.Seek ( 0, SeekOrigin.Begin );bytes = memoryStream.ToArray ();}return bytes;}catch ( Exception ex ){// ...}}----------------------
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