[HTTPCORE-397] HttpClient 4.4.1 may perform multiple requests on the same connection despite having "Connection: close" header.

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 4.4.1
• Fix Version/s: 5.0-alpha1
• Component/s: HttpCore
• Assignee: Unassigned
• Reporter: Alan Silva
• Created: 10/Apr/15 20:26
• Updated: 17/May/17 15:32
• Resolved: 13/Apr/15 18:33

Description

Question originally posted in Stack Overflow here. Answered by olegk.

The quick summary of the question and its resolution:

My use case involved a request to a server whose response back was a 302 redirect using non-persistence on the connection.

The current implementation of the HttpClient on version 4.4.1 GA will implicitly launch a follow-up request to the path specified in the "location" header path from the 302 response. The problem is, when the httpclient is sent with the "Connection: close" header, it is not aware of having done so. The result is that, if the server responds WITHOUT a corresponding "Connection: close", the client will assume the connection must be kept alive, and perform the next request for the redirect path on the same connection. This obviously leads to a problem since the server will have closed the socket on its end of the connection by now.

The problem was ultimately fixed by forcing the server to send a "Connection: close" header in response to the HttpClient's "Connection:close". However, according to the HTTP 1.1 spec, the server is not obliged to do this, although, it should. http://tools.ietf.org/html/rfc2616#section-8:

An HTTP/1.1 server MAY assume that a HTTP/1.1 client intends to
   maintain a persistent connection unless a Connection header including
   the connection-token "close" was sent in the request. If the server
   chooses to close the connection immediately after sending the
   response, it SHOULD send a Connection header including the
   connection-token close.

However, on the client side, the rules on the matter are stricter.

Persistent connections provide a mechanism by which a client and a
   server can signal the close of a TCP connection. This signaling takes
   place using the Connection header field (section 14.10). Once a close
   has been signaled, the client MUST NOT send any more requests on that
   connection.

Ideally, there should be a way for the HttpClient to realize it has announced its intention to close the connection via the "Connection: close" header, and stop itself from sending any more requests on the connection, without outside intervention from the server it's communicating with.

This issue was not observed in HttpClient 4.2.6

Issue Links

• links to: GitHub Pull Request #19