We can splice TCP connections in pasta mode if and only if they
originate from localhost. Currently we separate the two cases by
having separate listening sockets: one listens on the host address for
non-spliceable connections, the other listens on the loopback address
for spliceable connections.
As well as requiring twice as many listening sockets, this has the
drawback of meaning that passt and pasta behaviour differ subtley but
surprisingly: by default passt inbound port forwards will listen on
the unspecified address, but for pasta they will be changed to listen
on the host's interface address.
In fact we don't need to do this. We can defer the decision about
whether to splice a connection until after we've accepted it, by
testing the peer address to see if it is local.
At least, in principle we can. This series deals with a number of
complications on the way to accomplishing that.
CAVEAT: The current draft increases the size of tcp_conn above its
current 64 bytes, which is likely to push it into a second cache line
on some machines. This is fixable, but doing so is fiddly, and I'm
still working on it.
David Gibson (14):
style: Minor corrections to function comments
tcp: Remove unused TCP_MAX_SOCKS constant
tcp: Better helpers for converting between connection pointer and
index
tcp_splice: Helpers for converting from index to/from tcp_splice_conn
tcp: Move connection state structures into a shared header
tcp: Add connection union type
tcp: Improved helpers to update connections after moving
tcp: Unify spliced and non-spliced connection tables
tcp: Unify tcp_defer_handler and tcp_splice_defer_handler()
tcp: Partially unify tcp_timer() and tcp_splice_timer()
tcp: Unify the IN_EPOLL flag
tcp: Separate helpers to create ns listening sockets
tcp: Unify part of spliced and non-spliced conn_from_sock path
tcp: Use the same sockets to listen for spliced and non-spliced
connections
Makefile | 3 +-
conf.c | 12 +-
tap.c | 6 +-
tcp.c | 661 +++++++++++++++++++++++----------------------------
tcp.h | 7 +-
tcp_conn.h | 208 ++++++++++++++++
tcp_splice.c | 292 +++++++++--------------
tcp_splice.h | 4 +-
8 files changed, 625 insertions(+), 568 deletions(-)
create mode 100644 tcp_conn.h
--
2.38.1