go (original) (raw)

What version of Go are you using (go version)? go version go1.5.1 solaris/amd64
What operating system and processor architecture are you using? SunOS 5.11 joyent_20141030T081701Z i86pc i386 i86pc Solaris, SunOS 5.11 joyent_20151002T091442Z i86pc i386 i86pc Solaris
What did you do? Retrieved a >250K file over http from a golang server
What did you expect to see? The correct contents of the file
What did you see instead? A file with the correct size, but the first ~25% of the file repeated to fill the file.

If I access the file through localhost, the file is served correctly. If I send it over any network interface, the bug appears. Different lengths of the file are repeated to fill the space in each case. All smaller files come through without error.

I attempted to step through using godebug but ran into mailgun/godebug#12, since the issue is clearly somewhere in the standard library. So I have setup a temporary fileserver to demonstrate the issue. text.text.2 contains the beginning of Sherlock Holmes from Project Gutenberg (thanks Norvig).

Control: python -m SimpleHTTPServer
http://165.225.174.156:8000/
http://165.225.174.156:8000/test.txt.2
Serves correct contents of file.

Bug: gohttp (itang/gohttp)
http://165.225.174.156:8080/
http://165.225.174.156:8080/test.txt.2
Serves garbled file, every time.

Localhost: gohttp with a barebones nginx proxy from localhost
http://165.225.174.156/
http://165.225.174.156/test.txt.2
Serves correct contents of file.

I discovered this bug because we just recently have hashicorp/consul building on SmartOS (hashicorp/consul#159), and the Consul UI contains a ~750K minified JS file. Consul uses gorilla/mux and http.FileServer, but I am able to reproduce with the much simpler case of gohttp.

The test suite for the http response methods doesn't have tests from a remote machine, or use large files, so this bug can slip through in most cases unnoticed. Please let me know if I can provide more details. We really need a way to step through and debug the standard libs!