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puma--puma/test/test_rack_server.rb
Blake Williams b2283d8f25
Fix rack.after_reply exceptions breaking connections (#2861)
* Fix rack.after_reply exceptions breaking connections

Currently, when a `rack.after_reply` callable raises an exception we
attempt to handle it like other client errors by responding with an HTTP
500 response. This however doesn't work because `rack.after_reply`
callbacks are called after the response body has already been written to
the client.

This can cause issues with re-used connections. This is because 2 HTTP
responses are being returned for a single request. If a second HTTP
request is made before the error handling logic completes the timing can
line up causing the second HTTP response to be served a 500 from the
first HTTP requests `rack.after_reply` callbacks raising.

That may look roughly like:

1. Request 1 starts, opening a reusable TCP connection
2. Request 1 is written to and "completed"
3. Request 1 `rack.after_reply` callables are called
4. Request 2 starts, reusing the same TCP connection as request 1
5. `rack.after_reply` raises, calls `client_error` and serves a 500
   response
6. Request 2 receives the 500 response.

This is somewhat difficult to reproduce using HTTP clients since it's a
race condition whether or not the 500 is written at the "correct" time
or not.

To prevent this issue the `rack.after_reply` callables are now wrapped
in a begin/rescue/end block that rescues from `StandardError` and logs
instead of attempting to serve a 500 response.

* Assert against less specific exception
2022-04-17 10:21:36 -06:00

172 lines
3.5 KiB
Ruby

# frozen_string_literal: true
require_relative "helper"
require "net/http"
require "rack"
class TestRackServer < Minitest::Test
parallelize_me!
class ErrorChecker
def initialize(app)
@app = app
@exception = nil
end
attr_reader :exception, :env
def call(env)
begin
@app.call(env)
rescue Exception => e
@exception = e
[ 500, {}, ["Error detected"] ]
end
end
end
class ServerLint < Rack::Lint
def call(env)
check_env env
@app.call(env)
end
end
def setup
@simple = lambda { |env| [200, { "X-Header" => "Works" }, ["Hello"]] }
@server = Puma::Server.new @simple
@port = (@server.add_tcp_listener "127.0.0.1", 0).addr[1]
@tcp = "http://127.0.0.1:#{@port}"
@stopped = false
end
def stop
@server.stop(true)
@stopped = true
end
def teardown
@server.stop(true) unless @stopped
end
def test_lint
@checker = ErrorChecker.new ServerLint.new(@simple)
@server.app = @checker
@server.run
hit(["#{@tcp}/test"])
stop
refute @checker.exception, "Checker raised exception"
end
def test_large_post_body
@checker = ErrorChecker.new ServerLint.new(@simple)
@server.app = @checker
@server.run
big = "x" * (1024 * 16)
Net::HTTP.post_form URI.parse("#{@tcp}/test"),
{ "big" => big }
stop
refute @checker.exception, "Checker raised exception"
end
def test_path_info
input = nil
@server.app = lambda { |env| input = env; @simple.call(env) }
@server.run
hit(["#{@tcp}/test/a/b/c"])
stop
assert_equal "/test/a/b/c", input['PATH_INFO']
end
def test_after_reply
closed = false
@server.app = lambda do |env|
env['rack.after_reply'] << lambda { closed = true }
@simple.call(env)
end
@server.run
hit(["#{@tcp}/test"])
stop
assert_equal true, closed
end
def test_after_reply_exception
@server.app = lambda do |env|
env['rack.after_reply'] << lambda { raise ArgumentError, "oops" }
@simple.call(env)
end
@server.run
socket = TCPSocket.open "127.0.0.1", @port
socket.puts "GET /test HTTP/1.1\r\n"
socket.puts "Connection: Keep-Alive\r\n"
socket.puts "\r\n"
headers = socket.readline("\r\n\r\n")
.split("\r\n")
.drop(1)
.map { |line| line.split(/:\s?/) }
.to_h
content_length = headers["Content-Length"].to_i
real_response_body = socket.read(content_length)
assert_equal "Hello", real_response_body
# When after_reply breaks the connection it will write the expected HTTP
# response followed by a second HTTP response: HTTP/1.1 500
#
# This sleeps to give the server time to write the invalid/extra HTTP
# response.
#
# * If we can read from the socket, we know that extra content has been
# written to the connection and assert that it's our erroneous 500
# response.
# * If we would block trying to read from the socket, we can assume that
# the erroneous 500 response wasn't/won't be written.
sleep 0.1
assert_raises IO::WaitReadable do
content = socket.read_nonblock(12)
refute_includes content, "500"
end
socket.close
stop
end
def test_common_logger
log = StringIO.new
logger = Rack::CommonLogger.new(@simple, log)
@server.app = logger
@server.run
hit(["#{@tcp}/test"])
stop
assert_match %r!GET /test HTTP/1\.1!, log.string
end
end