From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by passt.top (Postfix, from userid 1000) id C081E5A027F; Fri, 15 Aug 2025 18:10:42 +0200 (CEST) From: Stefano Brivio To: passt-dev@passt.top Subject: [PATCH 4/6] tcp: Fix closing logic for half-closed connections Date: Fri, 15 Aug 2025 18:10:40 +0200 Message-ID: <20250815161042.3606244-5-sbrivio@redhat.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250815161042.3606244-1-sbrivio@redhat.com> References: <20250815161042.3606244-1-sbrivio@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-ID-Hash: WUEK5LEAYQ5ZUWLADH6ROZ3LW3MEBJUL X-Message-ID-Hash: WUEK5LEAYQ5ZUWLADH6ROZ3LW3MEBJUL X-MailFrom: sbrivio@passt.top X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: Jon Maloy , Paul Holzinger X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: First off, don't close connections half-closed by the guest before our own FIN is acknowledged by the guest itself. That is, after we receive a FIN from the guest (TAP_FIN_RCVD), if we don't have any data left to send from the socket (SOCK_FIN_RCVD, or EPOLLHUP), we send a FIN segment to the guest (TAP_FIN_SENT), but we need to actually have it acknowledged (and have no pending retransmissions) before we can close the connection: check for TAP_FIN_ACKED, first. Then, if we set TAP_FIN_SENT, and we receive an ACK segment from the guest, set TAP_FIN_ACKED. This was entirely missing for the TAP_FIN_RCVD case, and as we fix the problem described above, this becomes relevant as well. Signed-off-by: Stefano Brivio --- tcp.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/tcp.c b/tcp.c index dda0a2e..aed25a9 100644 --- a/tcp.c +++ b/tcp.c @@ -2081,9 +2081,14 @@ int tcp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af, tcp_tap_window_update(c, conn, ntohs(th->window)); tcp_data_from_sock(c, conn); - if (conn->events & SOCK_FIN_RCVD && - conn->seq_ack_from_tap == conn->seq_to_tap) - conn_event(c, conn, CLOSED); + if (conn->seq_ack_from_tap == conn->seq_to_tap) { + if (th->ack && conn->events & TAP_FIN_SENT) + conn_event(c, conn, TAP_FIN_ACKED); + + if (conn->events & SOCK_FIN_RCVD && + conn->events & TAP_FIN_ACKED) + conn_event(c, conn, CLOSED); + } return 1; } @@ -2363,7 +2368,7 @@ void tcp_sock_handler(const struct ctx *c, union epoll_ref ref, return; } - if ((conn->events & TAP_FIN_SENT) && (events & EPOLLHUP)) { + if ((conn->events & TAP_FIN_ACKED) && (events & EPOLLHUP)) { conn_event(c, conn, CLOSED); return; } -- 2.43.0