Dropbox - uploading files from url doesn't work consistently - php

Question

I have a PHP script that uploads files into Dropbox. When I run it from command-line as a standalone script, it works perfectly.
However, when I incorporate my code into the larger project, the file fails to upload, cURL returns "errno" 0 (meaning, no cURL errors), and there's no output from Dropbox's API.
Here is the code that works:
$token = '<token>';
$url = "https://content.dropboxapi.com/2/files/upload";
$post_body = file_get_contents("/other/server/url/test.txt");
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Authorization: Bearer ' . $token,
'Content-Type: application/octet-stream',
'Dropbox-API-Arg: {"path": "/Dropbox/path/subfolder/test.txt","mode": "add", "autorename": true, "mute": false}'));
curl_setopt($ch,CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_body);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$data = json_decode(curl_exec($ch), true);
curl_close($ch);
print_r($data);
.... and here is the broken code:
private function dropbox_uploadFile( $path, $file_source, $file_name = "test1.txt") {
echo "<br /><br />PATH: ". $path . '/' . $file_name . "<br /><br />";
echo "<br /><br />SOURCE: ". $file_source . "<br /><br />";
$token = '<token>';
$url = "https://content.dropboxapi.com/2/files/upload";
$post_body = file_get_contents( $file_source );
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Authorization: Bearer ' . $token,
'Content-Type: application/octet-stream',
'Dropbox-API-Arg: {"path": ' . $path.'/'.$file_name. '","mode": "add", "autorename": true, "mute": false}'));
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_body);
curl_setopt($ch,CURLOPT_SSL_VERIFYPEER, false); // to prevent cURL error #60
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$data = json_decode(curl_exec($ch), true);
if( ! $data ) {
echo "<pre>";
print_r(curl_getinfo($ch));
echo "</pre>";
echo "ERROR: " . curl_errno( $ch ) . "<br /><br />";
}
curl_close($ch);
print_r($data);
}

Answer 1

I broke out the API call itself, like this:
$res = curl_exec($ch);
print_r($res);
$data = json_decode($res, true);
That showed me the actual error from the API:
Error in call to API function "files/upload": HTTP header "Dropbox-API-Arg": could not decode input as JSON
For different types of errors, the API will return either plain text or JSON, with the response Content-Type header telling you which. In your code, you were only handling JSON, and json_decode apparently silently fails when it isn't supplied valid JSON.
Anyway, that error indicates the supplied JSON for the upload arguments is itself invalid. The problem seems to be a missing quote at the beginning of the path value, fixed here:
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Authorization: Bearer ' . $token,
'Content-Type: application/octet-stream',
'Dropbox-API-Arg: {"path": "' . $path.'/'.$file_name. '","mode": "add", "autorename": true, "mute": false}'));

Answer 2

I went here trying some tips, and I ma using SWIFT.
Hope can help OTHERS.
After some (hard) mailing with dropbox support...
Error in my case was due to unescaping special chars in path.
If You want to upload:
let unescapedFileName = "αβγ.jpg"
You have to escape:
let unescapedFileName = "αβγ.jpg"
let escapedFileName = DB_asciiEscape(unescapedFileName)
Here an Unit test:
func testUtf8Decode(){
let unescapedFileName = "αβγ.jpg"
let escapedFileName = DB_asciiEscape(unescapedFileName)
print(escapedFileName)
let contains = escapedFileName.contains("\\u03b1\\u03b2\\u03b3")
XCTAssert(contains, "not escaped")
}
where function is:
func DB_asciiEscape(_ s: String) -> String {
let out = s.unicodeScalars.reduce("", { (partialResult: String, char: UnicodeScalar) -> String in
if !char.isASCII {
return partialResult + String(format:"\\u%04x", char.value)
} else {
if (char == "\u{7F}") {
return partialResult + "\\u007f"
} else {
return partialResult + "\(char)"
}
}
})
return out
}