abique / hefur

The parsing of HTTP headers is broken for certain value of Accept-Encoding when Hefur is behind a reverse proxy.

Apache config:

<VirtualHost *:443>
        ServerName tracker.domain.com
        (...)
        <Location />
                ProxyPass http://localhost:6969/
                ProxyPassReverse http://localhost:6969/
                ProxyPreserveHost On
        </Location>
</VirtualHost>

Hefur is launched like this:
$ hefurd -torrent-dir /srv/tracker -bind-addr 127.0.0.1 -reverse-proxy-from 127.0.0.1 -reverse-proxy-header X-Forwarded-For

The problem arise here:

hefur/hefur/log-handler.cc

Lines 24 to 25 in 5136250

    
           auto headers = request.unparsedHeaders(); 
        
           auto header = headers.find(REVERSE_PROXY_HEADER);

With qBittorrent, Apache sends the following request to Hefur:

Host: tracker.domain.com
User-Agent: qBittorrent/4.3.9
Accept-Encoding: gzip
X-Forwarded-For: 42.42.42.42
(...)

request.unparsedHeaders() returns all headers and X-Forwarded-For is found.

With Transmission, Apache sends the following request to Hefur:

Host: tracker.domain.com
User-Agent: Transmission/3.00
Accept: */*
Accept-Encoding: deflate, gzip, br, zstd
X-Forwarded-For: 42.42.42.42
(...)

request.unparsedHeaders() returns only Accept: */*

If I remove Accept-Encoding from the request sent by Apache (with RequestHeader unset Accept-Encoding in <Location />), then the request is parsed correctly and the real IP is found, but Hefur crash soon after with:

hefurd[28911]: hefurd: hefur/address.cc:133: hefur::Address& hefur::Address::operator=(const sockaddr*): Assertion 'false' failed.

So an announce request from Transmission seems totally broken: the real IP is not found, the response is bad (wrong values of seeders/leechers) and Transmission try to announce again every 8 seconds in a loop.
Everything is working fine with qBittorrent.

OS: Arch Linux
Hefur: 1.0
Apache: 2.4.51
qBittorrent: 4.3.9
Transmission: 3.00

Thank you very much!
I'll look into it soon.

I think the problem in https://github.com/abique/mimosa/blob/42c0041b570b55a24c606a7da79c70c9933c07d4/mimosa/http/request-parser.y#L98
abouvier, can you test it please?

--- request-parser.y	2021-02-01 20:32:00.000000000 +0300
+++ request-parser.y	2022-06-07 13:22:20.739899488 +0300
@@ -95,8 +95,8 @@
 kvs: kv kvs | /* epsilon */ ;
 
 kv:
-  KEY VALUE { rq.addHeader(*$1, *$2); delete $1; delete $2; }
-| KEY_ACCEPT_ENCODING accept_encodings
+  KEY_ACCEPT_ENCODING accept_encodings
+| KEY VALUE { rq.addHeader(*$1, *$2); delete $1; delete $2; }
 | KEY_CONNECTION VALUE_CONNECTION { rq.setKeepAlive($2); }
 | KEY_COOKIE cookies
 | KEY_CONTENT_LENGTH VAL64 { rq.setContentLength($2); }

KEY_ACCEPT_ENCODING shows up first in the lexer, but does not hurt to move it down.
Then maybe I could move the KEY VALUE option at the end.

I've added a unit test with your example, and updated mimosa.
@abouvier does it fixes it for you?
PS: sorry for the long delay...

The new commit of mimosa submodule is non existent. Did you forget to push something on the mimosa repository?

Super strange I get timeout to push and pull to mimosa...

You can try again now.

hefur now crashes immediately when I try to load https://tracker.domain.com/stat, with the same error:

hefurd: hefur/address.cc:133: hefur::Address& hefur::Address::operator=(const sockaddr*): Assertion 'false' failed.

I've pushed some changes, that assertion wasn't correct.

It's better. The client's public address is correctly registered in hefur, but the response sent by hefur to Transmission is still bogus, with nonsensical values. File sharing with other peers works though.

Yeah something must have gone wrong, because it is a strange error to have a inet addr that isn't ipv4 or ipv6.
I'll have to take a deeper look I suppose.

It may be because hefur and Transmission are on the same host?

Still it should be using ipv4/6

	auto headers = request.unparsedHeaders();
	auto header = headers.find(REVERSE_PROXY_HEADER);

Broken parsing of HTTP headers