When calling cowboy_req:reply/4 with a body a crash will occur
resulting in a 500 response. When calling cowboy_req:stream_reply/2,3
and then attempting to send a body a crash will occur.
To avoid intermittent test failures. We only want to make
sure the function eventually returns so we don't need to
use timeouts in the test itself, or check exactly what was
read.
This resulted in a badarith error due to the current flow being
set to infinity when the body has been fully read. A test case
has been added reproducing the issue.
The flow control is now only set to infinity when we are
skipping the request body of the stream that is being
terminated. This fixes a bug where it was set to infinity
while reading a subsequent request's body, leading to a
crash.
The timeout is no longer reset on stream termination.
Timeout handling is already done when receiving data
from the socket and doing a reset on stream termination
was leading to the wrong timeout being set or the right
timeout being reset needlessly.
While the protocol does not allow sending data before
receiving a successful Websocket upgrade response, we
do not want to discard that data if it does come in.
Now both HTTP/1.1 and HTTP/2 follow the documented format.
HTTP/1.1 was including an extra element containing the
StreamID before, which was unnecessary because it is also
given as argument to the callback.
HTTP/2 early_error will now include headers in its PartialReq.
This allows giving custom metadata to the metrics stream handler.
This can be useful to for example provide the name of the
module handling the request which is only known after routing.
But any user data is allowed.
When called multiple times the user data maps are merged.
Fix a case where Cowboy was waiting for more data that simply
did not come. Now Cowboy will generate an error immediately
when a header line has no colon separator.
These test cases come from known request smuggling attack
vectors. Cowboy was not vulnerable to any of them.
A number of HTTP/2 CVEs were documented recently:
https://www.kb.cert.org/vuls/id/605641/
This commit, along with a few changes and additions in Cowlib,
fix or improve protection against all of them.
For CVE-2019-9511, also known as Data Dribble, the new option
stream_window_data_threshold can be used to control how little
the DATA frames that Cowboy sends can get.
For CVE-2019-9516, also known as 0-Length Headers Leak, Cowboy
will now simply reject streams containing 0-length header names.
For CVE-2019-9517, also known as Internal Data Buffering, the
backpressure changes were already pretty good at preventing this
issue, but a new option max_connection_buffer_size was added for
even better control over how much memory we are willing to allocate.
For CVE-2019-9512, also known as Ping Flood; CVE-2019-9515, also
known as Settings Flood; CVE-2019-9518, also known as Empty Frame
Flooding; and similar undocumented scenarios, a frame rate limiting
mechanism was added. By default Cowboy will now allow 1000 frames
every 10 seconds. This can be configured via max_received_frame_rate.
For CVE-2019-9514, also known as Reset Flood, another rate limiting
mechanism was added and can be configured via max_reset_stream_rate.
By default Cowboy will do up to 10 stream resets every 10 seconds.
Finally, nothing was done for CVE-2019-9513, also known as Resource
Loop, because Cowboy does not currently implement the HTTP/2
priority mechanism (in parts because these issues were well known
from the start).
Tests were added for all cases except Internal Data Buffering,
which I'm not sure how to test, and Resource Loop, which is not
currently relevant.
