From 163a339214dd34696ce485930f35ed21c86057f0 Mon Sep 17 00:00:00 2001 From: David Gibson Date: Thu, 18 Jul 2024 15:26:34 +1000 Subject: tcp, flow: Replace TCP specific hash function with general flow hash Currently we match TCP packets received on the tap connection to a TCP connection via a hash table based on the forwarding address and both ports. We hope in future to allow for multiple guest side addresses, or for multiple interfaces which means we may need to distinguish based on the endpoint address and pif as well. We also want a unified hash table to cover multiple protocols, not just TCP. Replace the TCP specific hash function with one suitable for general flows, or rather for one side of a general flow. This includes all the information from struct flowside, plus the pif and the L4 protocol number. Signed-off-by: David Gibson Signed-off-by: Stefano Brivio --- flow.c | 35 ++++++++++++++++++++++++++++++++--- 1 file changed, 32 insertions(+), 3 deletions(-) (limited to 'flow.c') diff --git a/flow.c b/flow.c index 71c44d2..e70e3cb 100644 --- a/flow.c +++ b/flow.c @@ -116,9 +116,9 @@ static struct timespec flow_timer_run; * @faddr: Forwarding address (pointer to in_addr or in6_addr) * @fport: Forwarding port */ -static void flowside_from_af(struct flowside *side, sa_family_t af, - const void *eaddr, in_port_t eport, - const void *faddr, in_port_t fport) +void flowside_from_af(struct flowside *side, sa_family_t af, + const void *eaddr, in_port_t eport, + const void *faddr, in_port_t fport) { if (faddr) inany_from_af(&side->faddr, af, faddr); @@ -401,6 +401,35 @@ void flow_alloc_cancel(union flow *flow) flow_new_entry = NULL; } +/** + * flow_hash() - Calculate hash value for one side of a flow + * @c: Execution context + * @proto: Protocol of this flow (IP L4 protocol number) + * @pif: pif of the side to hash + * @side: Flowside (must not have unspecified parts) + * + * Return: hash value + */ +uint64_t flow_hash(const struct ctx *c, uint8_t proto, uint8_t pif, + const struct flowside *side) +{ + struct siphash_state state = SIPHASH_INIT(c->hash_secret); + + /* For the hash table to work, we need complete endpoint information, + * and at least a forwarding port. + */ + ASSERT(pif != PIF_NONE && !inany_is_unspecified(&side->eaddr) && + side->eport != 0 && side->fport != 0); + + inany_siphash_feed(&state, &side->faddr); + inany_siphash_feed(&state, &side->eaddr); + + return siphash_final(&state, 38, (uint64_t)proto << 40 | + (uint64_t)pif << 32 | + (uint64_t)side->fport << 16 | + (uint64_t)side->eport); +} + /** * flow_defer_handler() - Handler for per-flow deferred and timed tasks * @c: Execution context -- cgit v1.2.3