tcp: Refactor to use events instead of states, split out spliced implementation

Using events and flags instead of states makes the implementation
much more straightforward: actions are mostly centered on events
that occurred on the connection rather than states.

An example is given by the ESTABLISHED_SOCK_FIN_SENT and
FIN_WAIT_1_SOCK_FIN abominations: we don't actually care about
which side started closing the connection to handle closing of
connection halves.

Split out the spliced implementation, as it has very little in
common with the "regular" TCP path.

Refactor things here and there to improve clarity. Add helpers
to trace where resets and flag settings come from.

No functional changes intended.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/tcp_splice.h b/tcp_splice.h
new file mode 100644
index 0000000..45ab1ca
--- /dev/null
+++ b/tcp_splice.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: AGPL-3.0-or-later
+ * Copyright (c) 2022 Red Hat GmbH
+ * Author: Stefano Brivio <sbrivio@redhat.com>
+ */
+
+#define TCP_SPLICE_MAX_CONNS			(128 * 1024)
+
+struct tcp_splice_conn;
+
+void tcp_sock_handler_splice(struct ctx *c, union epoll_ref ref,
+			     uint32_t events);
+void tcp_splice_destroy(struct ctx *c, struct tcp_splice_conn *conn);
+void tcp_splice_init(struct ctx *c);
+void tcp_splice_timer(struct ctx *c, struct timespec *now);