path: root/net/ipv4/igmp.c
diff options
authorMichal Tesar <mtesar@redhat.com>2017-01-02 14:38:36 +0100
committerDavid S. Miller <davem@davemloft.net>2017-01-02 13:01:03 -0500
commit7ababb782690e03b78657e27bd051e20163af2d6 (patch)
tree877788cd46dc059970fc32b847c5d15888324969 /net/ipv4/igmp.c
parentflow_dissector: Update pptp handling to avoid null pointer deref. (diff)
igmp: Make igmp group member RFC 3376 compliant
5.2. Action on Reception of a Query When a system receives a Query, it does not respond immediately. Instead, it delays its response by a random amount of time, bounded by the Max Resp Time value derived from the Max Resp Code in the received Query message. A system may receive a variety of Queries on different interfaces and of different kinds (e.g., General Queries, Group-Specific Queries, and Group-and-Source-Specific Queries), each of which may require its own delayed response. Before scheduling a response to a Query, the system must first consider previously scheduled pending responses and in many cases schedule a combined response. Therefore, the system must be able to maintain the following state: o A timer per interface for scheduling responses to General Queries. o A per-group and interface timer for scheduling responses to Group- Specific and Group-and-Source-Specific Queries. o A per-group and interface list of sources to be reported in the response to a Group-and-Source-Specific Query. When a new Query with the Router-Alert option arrives on an interface, provided the system has state to report, a delay for a response is randomly selected in the range (0, [Max Resp Time]) where Max Resp Time is derived from Max Resp Code in the received Query message. The following rules are then used to determine if a Report needs to be scheduled and the type of Report to schedule. The rules are considered in order and only the first matching rule is applied. 1. If there is a pending response to a previous General Query scheduled sooner than the selected delay, no additional response needs to be scheduled. 2. If the received Query is a General Query, the interface timer is used to schedule a response to the General Query after the selected delay. Any previously pending response to a General Query is canceled. --8<-- Currently the timer is rearmed with new random expiration time for every incoming query regardless of possibly already pending report. Which is not aligned with the above RFE. It also might happen that higher rate of incoming queries can postpone the report after the expiration time of the first query causing group membership loss. Now the per interface general query timer is rearmed only when there is no pending report already scheduled on that interface or the newly selected expiration time is before the already pending scheduled report. Signed-off-by: Michal Tesar <mtesar@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/igmp.c')
1 files changed, 6 insertions, 1 deletions
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 68d622133f53..5b15459955f8 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -219,9 +219,14 @@ static void igmp_start_timer(struct ip_mc_list *im, int max_delay)
static void igmp_gq_start_timer(struct in_device *in_dev)
int tv = prandom_u32() % in_dev->mr_maxdelay;
+ unsigned long exp = jiffies + tv + 2;
+ if (in_dev->mr_gq_running &&
+ time_after_eq(exp, (in_dev->mr_gq_timer).expires))
+ return;
in_dev->mr_gq_running = 1;
- if (!mod_timer(&in_dev->mr_gq_timer, jiffies+tv+2))
+ if (!mod_timer(&in_dev->mr_gq_timer, exp))