webrick: do not hang acceptor on slow TLS connections

OpenSSL::SSL::SSLSocket#accept may block indefinitely on clients
which negotiate the TCP connection, but fail (or are slow) to
negotiate the subsequent TLS handshake.  This prevents the
multi-threaded WEBrick server from accepting other connections.

Since the TLS handshake (via OpenSSL::SSL::SSLSocket#accept)
consists of normal read/write traffic over TCP, handle it in the
per-client thread, instead.

Furthermore, using non-blocking accept() is useful for non-TLS
sockets anyways because spurious wakeups are possible from
select(2).

* lib/webrick/server.rb (accept_client): use TCPServer#accept_nonblock
  and remove OpenSSL::SSL::SSLSocket#accept call
* lib/webrick/server.rb (start_thread): call OpenSSL::SSL::SSLSocket#accept
* test/webrick/test_ssl_server.rb (test_slow_connect): new test
  [ruby-core:83221] [Bug #14005]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60172 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 24 insertions, 10 deletions

diff --git a/lib/webrick/server.rb b/lib/webrick/server.rb
index 5e83b692db..52a09f5186 100644
--- a/lib/webrick/server.rb
+++ b/lib/webrick/server.rb
@@ -251,17 +251,26 @@ module WEBrick
     # the client socket.
 
     def accept_client(svr)
-      sock = nil
-      begin
-        sock = svr.accept
-        Utils::set_non_blocking(sock)
-      rescue Errno::ECONNRESET, Errno::ECONNABORTED,
-             Errno::EPROTO, Errno::EINVAL
-      rescue StandardError => ex
-        msg = "#{ex.class}: #{ex.message}\n\t#{ex.backtrace[0]}"
-        @logger.error msg
+      case sock = svr.to_io.accept_nonblock(exception: false)
+      when :wait_readable
+        nil
+      else
+        if svr.respond_to?(:start_immediately)
+          sock = OpenSSL::SSL::SSLSocket.new(sock, ssl_context)
+          sock.sync_close = true
+          # we cannot do OpenSSL::SSL::SSLSocket#accept here because
+          # a slow client can prevent us from accepting connections
+          # from other clients
+        end
+        sock
       end
-      return sock
+    rescue Errno::ECONNRESET, Errno::ECONNABORTED,
+           Errno::EPROTO, Errno::EINVAL
+      nil
+    rescue StandardError => ex
+      msg = "#{ex.class}: #{ex.message}\n\t#{ex.backtrace[0]}"
+      @logger.error msg
+      nil
     end
 
     ##
@@ -284,6 +293,11 @@ module WEBrick
             @logger.debug "accept: <address unknown>"
             raise
           end
+          if sock.respond_to?(:sync_close=) && @config[:SSLStartImmediately]
+            WEBrick::Utils.timeout(@config[:RequestTimeout]) do
+              sock.accept # OpenSSL::SSL::SSLSocket#accept
+            end
+          end
           call_callback(:AcceptCallback, sock)
           block ? block.call(sock) : run(sock)
         rescue Errno::ENOTCONN