[PATCH v4 00/16] RFC: Unified flow table

[David Gibson <david@gibson.dropbear.id.au>]

This is a fourth draft of the first steps in implementing more general
"connection" tracking, as described at:
    https://pad.passt.top/p/NewForwardingModel

This series changes the TCP connection table and hash table into a
more general flow table that can track other protocols as well.  Each
flow uniformly keeps track of all the relevant addresses and ports,
which will allow for more robust control of NAT and port forwarding.

ICMP is converted to use the new flow table.

This doesn't include UDP, but I'm working on it right now and making
progress.  I'm posting this to give a head start on the review :)

Caveats:
 * We significantly increase the size of a connection/flow entry
   - Can probably be mitigated, but I haven't investigated much yet
 * We perform a number of extra getsockname() calls to know some of
   the socket endpoints
    - Haven't yet measured how much performance impact that has
    - Can be mitigated in at least some cases, but again, haven't
      tried yet

Changes since v4:
 * Complex rebase on top of the many things that have happened
   upstream since v3.
 * Assorted other changes.

Changes since v3:
 * Replace TAPFSIDE() and SOCKFSIDE() macros with local variables.

Changes since v2:
 * Cosmetic fixes based on review
 * Extra doc comments for enum flow_type
 * Rename flowside to flowaddrs which turns out to make more sense in
   light of future changes
 * Fix bug where the socket flowaddrs for tap initiated connections
   wasn't initialised to match the socket address we were using in the
   case of map-gw NAT
 * New flowaddrs_from_sock() helper used in most cases which is cleaner
   and should avoid bugs like the above
 * Using newer centralised workarounds for clang-tidy issue 58992
 * Remove duplicate definition of FLOW_MAX as maximum flow type and
   maximum number of tracked flows
 * Rebased on newer versions of preliminary work (ICMP, flow based
   dispatch and allocation, bind/address cleanups)
 * Unified hash table as well as base flow table
 * Integrated ICMP

Changes since v1:
 * Terminology changes
   - "Endpoint" address/port instead of "correspondent" address/port
   - "flowside" instead of "demiflow"
 * Actually move the connection table to a new flow table structure in
   new files
 * Significant rearrangement of earlier patchs on top of that new
   table, to reduce churn

David Gibson (16):
  flow: Common data structures for tracking flow addresses
  tcp: Maintain flowside information for "tap" connections
  tcp_splice: Maintain flowside information for spliced connections
  tcp: Obtain guest address from flowside
  tcp: Simplify endpoint validation using flowside information
  tcp, tcp_splice: Construct sockaddrs for connect() from flowside
  tcp_splice: Eliminate SPLICE_V6 flag
  tcp, flow: Replace TCP specific hash function with general flow hash
  flow, tcp: Generalise TCP hash table to general flow hash table
  tcp: Re-use flow hash for initial sequence number generation
  icmp: Populate flowside information
  icmp: Use flowsides as the source of truth wherever possible
  icmp: Look up ping flows using flow hash
  icmp: Eliminate icmp_id_map
  flow, tcp: flow based NAT and port forwarding for TCP
  flow, icmp: Use general flow forwarding rules for ICMP

 flow.c       | 199 ++++++++++++++++++++-
 flow.h       |  97 +++++++++++
 fwd.c        | 139 +++++++++++++++
 fwd.h        |   5 +
 icmp.c       |  83 +++++----
 icmp_flow.h  |   1 -
 inany.h      |  29 +++-
 passt.h      |   3 +
 pif.h        |   1 -
 tap.c        |  11 --
 tap.h        |   1 -
 tcp.c        | 475 +++++++++++++--------------------------------------
 tcp_conn.h   |  20 +--
 tcp_splice.c |  93 ++--------
 tcp_splice.h |   5 +-
 15 files changed, 649 insertions(+), 513 deletions(-)

-- 
2.44.0