Invalid HTTP request form (expected: authority or absolute, got: relative) from Burp

Steps to reproduce the problem:

1. I used mitmproxy as forwarding proxy from Burp but I keep getting these error.

2. And this is error I get from console

mitmdump -p 8779 -s proxy.py

Proxy server listening at http://*:8779
127.0.0.1:56560: clientconnect
 << Invalid HTTP request form (expected: authority or absolute, got: relative)
127.0.0.1:56560: HTTP protocol error in client request: Invalid HTTP request form (expected: authority or absolute, got: relative)

1. I only get this error when use mitmproxy as upstream proxy on burp in Repeater tab from Burp

System information

Mitmproxy: 3.0.2 Python: 3.7.0 OpenSSL: OpenSSL 1.0.2p 14 Aug 2018 Platform: Darwin-18.0.0-x86_64-i386-64bit

[jkryanchou]

@patrickjahns it turns out that you should use absolute paths rather than relative paths. Do it like

GET https://xxx.google.com/foo/bar
hostname: xxx.google.com
... ...

instead of

GET /foo/bar
hostname: xxx.google.com
... ...

[mhils]

I’m not sure how Burp’s forwarding proxy is supposed to work, but this looks like a configuration issue. Please take a look at https://docs.mitmproxy.org/stable/concepts-modes/.