diff options
| author | Matthieu Baerts <matthieu.baerts@tessares.net> | 2022-02-02 17:03:39 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2022-02-03 11:44:08 +0000 |
| commit | 8cca39e251718baec13a5999bf3d18c05af865be (patch) | |
| tree | db6fa9c3cd5d4cb98d49d712fce44eb64aea77d8 /net/mptcp/options.c | |
| parent | 902c8f8648828c9293533cc54393f163fb594d06 (diff) | |
mptcp: clarify when options can be used
RFC8684 doesn't seem to clearly specify which MPTCP options can be used
together.
Some options are mutually exclusive -- e.g. MP_CAPABLE and MP_JOIN --,
some can be used together -- e.g. DSS + MP_PRIO --, some can but we
prefer not to -- e.g. DSS + ADD_ADDR -- and some have to be used
together at some points -- e.g. MP_FAIL and DSS.
We need to clarify this as a base before allowing other modifications.
For example, does it make sense to send a RM_ADDR with an MPC or MPJ?
This remains open for possible future discussions.
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/mptcp/options.c')
| -rw-r--r-- | net/mptcp/options.c | 23 |
1 files changed, 21 insertions, 2 deletions
diff --git a/net/mptcp/options.c b/net/mptcp/options.c index ab054c389a5f..7345f28f3de1 100644 --- a/net/mptcp/options.c +++ b/net/mptcp/options.c @@ -1267,8 +1267,27 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp, const struct sock *ssk = (const struct sock *)tp; struct mptcp_subflow_context *subflow; - /* DSS, MPC, MPJ, ADD_ADDR, FASTCLOSE and RST are mutually exclusive, - * see mptcp_established_options*() + /* Which options can be used together? + * + * X: mutually exclusive + * O: often used together + * C: can be used together in some cases + * P: could be used together but we prefer not to (optimisations) + * + * Opt: | MPC | MPJ | DSS | ADD | RM | PRIO | FAIL | FC | + * ------|------|------|------|------|------|------|------|------| + * MPC |------|------|------|------|------|------|------|------| + * MPJ | X |------|------|------|------|------|------|------| + * DSS | X | X |------|------|------|------|------|------| + * ADD | X | X | P |------|------|------|------|------| + * RM | C | C | C | P |------|------|------|------| + * PRIO | X | C | C | C | C |------|------|------| + * FAIL | X | X | C | X | X | X |------|------| + * FC | X | X | X | X | X | X | X |------| + * RST | X | X | X | X | X | X | O | O | + * ------|------|------|------|------|------|------|------|------| + * + * The same applies in mptcp_established_options() function. */ if (likely(OPTION_MPTCP_DSS & opts->suboptions)) { struct mptcp_ext *mpext = &opts->ext_copy; |