Unlike TCP, UDP has no in-band signalling for the end of a flow. So the only way we remove flows is on a timer if they have no activity for 180s. However, we've started to investigate some error conditions in which we want to prematurely abort / abandon a UDP flow. We can call udp_flow_close(), which will make the flow inert (sockets closed, no epoll events, can't be looked up in hash). However it will still wait 3 minutes to clear away the stale entry. Clean this up by adding an explicit 'closed' flag which will cause a flow to be more promptly cleaned up. We also publish udp_flow_close() so it can be called from other places to abort UDP flows(). Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> --- flow.c | 3 ++- udp_flow.c | 18 +++++++++++++++++- udp_flow.h | 4 ++++ 3 files changed, 23 insertions(+), 2 deletions(-) diff --git a/flow.c b/flow.c index a00e01d1..f2de0414 100644 --- a/flow.c +++ b/flow.c @@ -832,7 +832,8 @@ void flow_defer_handler(const struct ctx *c, const struct timespec *now) closed = icmp_ping_timer(c, &flow->ping, now); break; case FLOW_UDP: - if (timer) + closed = udp_flow_defer(&flow->udp); + if (!closed && timer) closed = udp_flow_timer(c, &flow->udp, now); break; default: diff --git a/udp_flow.c b/udp_flow.c index 1ff59a9b..b81be2cf 100644 --- a/udp_flow.c +++ b/udp_flow.c @@ -39,8 +39,11 @@ struct udp_flow *udp_at_sidx(flow_sidx_t sidx) * @c: Execution context * @uflow: UDP flow */ -static void udp_flow_close(const struct ctx *c, struct udp_flow *uflow) +void udp_flow_close(const struct ctx *c, struct udp_flow *uflow) { + if (uflow->closed) + return; /* Nothing to do */ + if (uflow->s[INISIDE] >= 0) { /* The listening socket needs to stay in epoll */ close(uflow->s[INISIDE]); @@ -56,6 +59,8 @@ static void udp_flow_close(const struct ctx *c, struct udp_flow *uflow) flow_hash_remove(c, FLOW_SIDX(uflow, INISIDE)); if (!pif_is_socket(uflow->f.pif[TGTSIDE])) flow_hash_remove(c, FLOW_SIDX(uflow, TGTSIDE)); + + uflow->closed = true; } /** @@ -256,6 +261,17 @@ flow_sidx_t udp_flow_from_tap(const struct ctx *c, return udp_flow_new(c, flow, -1, now); } +/** + * udp_flow_defer() - Deferred per-flow handling (clean up aborted flows) + * @uflow: Flow to handle + * + * Return: true if the connection is ready to free, false otherwise + */ +bool udp_flow_defer(const struct udp_flow *uflow) +{ + return uflow->closed; +} + /** * udp_flow_timer() - Handler for timed events related to a given flow * @c: Execution context diff --git a/udp_flow.h b/udp_flow.h index 12ddf039..9a1b059c 100644 --- a/udp_flow.h +++ b/udp_flow.h @@ -10,6 +10,7 @@ /** * struct udp - Descriptor for a flow of UDP packets * @f: Generic flow information + * @closed: Flow is already closed * @ts: Activity timestamp * @s: Socket fd (or -1) for each side of the flow */ @@ -17,6 +18,7 @@ struct udp_flow { /* Must be first element */ struct flow_common f; + bool closed :1; time_t ts; int s[SIDES]; }; @@ -30,6 +32,8 @@ flow_sidx_t udp_flow_from_tap(const struct ctx *c, const void *saddr, const void *daddr, in_port_t srcport, in_port_t dstport, const struct timespec *now); +void udp_flow_close(const struct ctx *c, struct udp_flow *uflow); +bool udp_flow_defer(const struct udp_flow *uflow); bool udp_flow_timer(const struct ctx *c, struct udp_flow *uflow, const struct timespec *now); -- 2.46.0