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I'm trying to develop a file updater for some files in a folder, to Sync an FTP server with a local folder, using Java on the client and PHP on the server side.

On the server side, I'm calculating the md5_file($filename) for the file and returning every of them on a JSON.

On Java, I'm checking first if the file exists in the local folder. If the file exists, then I check for the MD5 checksum to see if the file is exactly the same as the online one.

The MD5 is not matching when checking .txt or .lua files. It's ok when checking other file types, as .dds texture files.

The MD5 I'm using on Java is this:

private String md5(File f) throws FileNotFoundException, NoSuchAlgorithmException {
    MessageDigest digest = MessageDigest.getInstance("MD5");
    InputStream is = new FileInputStream(f);                
    byte[] buffer = new byte[8192];
    int read = 0;
    try {
        while( (read = is.read(buffer)) > 0) {
            digest.update(buffer, 0, read);
        }       
        byte[] md5sum = digest.digest();
        BigInteger bigInt = new BigInteger(1, md5sum);
        String output = bigInt.toString(16);
        return output;
    }
    catch(IOException e) {
        throw new RuntimeException("Unable to process file for MD5", e);
    }
    finally {
        try {
            is.close();
        }
        catch(IOException e) {
            throw new RuntimeException("Unable to close input stream for MD5 calculation", e);
        }
    }
}

As an example, for a description.lua file, with the following contents:

livery = {
{"KC-130_fusel", 0 ,"KC-130_map_fus",false};
{"KC-130_wing", 0 ,"KC-130_map_wingS",false};
{"KC-130_wing_2", 0 ,"KC-130_map_wings_2",false};
{"KC-130_notes", 0 ,"KC-130_notes_empty",true};
{"KC-130_FPod", 0 ,"kc-130_map_drg",false};
}
name = "Spain ALA 31 TK.10-06"
countries = {"SPN"} -- and any others you want to add

PHP md5_file($filename) = d0c32f9e38cc6e1bb8b54a6aca4a0190

JAVA md5(File) = 08bf57441b904c69e9ce3ca02a9257c7

I've been trying to find a relation between those two codes to see what's making the difference, but have not find any. I have checked like 10 md5 scripts for Java and all of them give the same result.

Is there any way I can fix this?

EDIT: Solution given on first comment: Change the Transfer type on the FTP Client to Binary to avoid changing txt files to ASCII encoding, changing their length and md5.

Dani Aguado
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    Does your FTP client perhaps perform newline conversion (`\r\n` to `\n` or vice versa) when you upload text-y files? Perhaps try forcing it to use binary transfer on all file types. – zenzelezz Jul 12 '18 at 07:40
  • @zenzelezz Looks like this was the problem: Filezilla was uploading the files on ASCII. When changing to Binary now it match. Although PHP is adding a leading 0 and Java is not doing it, but that's an easy fix. Thank you! – Dani Aguado Jul 12 '18 at 07:46
  • I just want to say I'm somehow amazed with the solution you've come up with to serialize a byte array as hexadecimal. Though as you pointed out, this won't display the leading zeroes. – kumesana Jul 12 '18 at 07:56
  • @kumesana I found this code on a Stackoverflow or a website, I don't remember now. It's not my code. – Dani Aguado Jul 12 '18 at 07:58

0 Answers0