Skip to content

ungzipping buffer with trailing garbage throws error #7502

Closed
@horpto

Description

One site sends a gzipped html page and I try to ungzip page for further processing but zlib throws error incorrect header check. Error happens due to extra data after gzipped page. Yes, gzipped data is not valid, since have trailing data, but in other hand, browser eat that normally.

Minimal example:

var zlib = require('zlib')

// from test-zlib-from-gzip-with-trailing-garbage.js
bufOk = Buffer.concat([
    zlib.gzipSync("abc"),
    Buffer(10).fill(0)
]);

bufWrong = Buffer.concat([
    zlib.gzipSync("abc"),
    Buffer("\n \n\n\n\n \n")
]);

// wil not raise Error
console.log("bufOk:", zlib.gunzipSync(bufOk).toString());

// will raise Error('incorrect header check')
console.log("bufWrong:", zlib.gunzipSync(bufWrong).toString());

Also live example:

var req = require('request')
req.get('http://irsural.ru', {gzip: true}, (err, res, body) => {
    if (err != null) {
        console.log('Error:', err);
        return 
    }
    console.log(body);
});

In other languages (for example, python - requests) I can set windowBits to 16 + zlib.Z_MAX_WINDOWBITS but node strictly restricted windowBits from 0 to 15 even in addon.

  • Version: v6.2.2
  • Platform: linux, x86_64
  • Subsystem: zlib

Activity

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Metadata

Assignees

No one assigned

    Labels

    zlibIssues and PRs related to the zlib subsystem.

    Type

    No type

    Projects

    No projects

    Milestone

    No milestone

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions