|
|
- commit 7bd7a8d2b8889f604b807c21190d2e70328d6674
- Author: Christopher Faulet <cfaulet@haproxy.com>
- Date: Tue Apr 30 12:17:13 2019 +0200
-
- BUG/MEDIUM: listener: Fix how unlimited number of consecutive accepts is handled
-
- There is a bug when global.tune.maxaccept is set to -1 (no limit). It is pretty
- visible with one process (nbproc sets to 1). The functions listener_accept() and
- accept_queue_process() don't expect to handle negative maxaccept values. So
- instead of accepting incoming connections without any limit, none are never
- accepted and HAProxy loop infinitly in the scheduler.
-
- When there are 2 or more processes, the bug is a bit more subtile. The limit for
- a listener is set to 1. So only one connection is accepted at a time by a given
- listener. This happens because the listener's maxaccept value is an unsigned
- integer. In check_config_validity(), it is first set to UINT_MAX (-1 casted in
- an unsigned integer), and then some calculations on it leads to an integer
- overflow.
-
- To fix the bug, the listener's maxaccept value is now a signed integer. So, if a
- negative value is set for global.tune.maxaccept, we keep it untouched for the
- listener and no calculation is made on it. Then, in the listener code, this
- signed value is casted to a unsigned one. It simplifies all tests instead of
- dealing with negative values. So, it limits the number of connections accepted
- at a time to UINT_MAX at most. But, honestly, it not an issue.
-
- This patch must be backported to 1.9 and 1.8.
-
- (cherry picked from commit 102854cbbaa4d22466dddec9035d411db244082f)
- Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
- (cherry picked from commit bca4fb2d9d7f2966d9f8270fa1796fdc0dfc866d)
- Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
-
- diff --git a/include/types/listener.h b/include/types/listener.h
- index ea2eadb5..16ef6d7a 100644
- --- a/include/types/listener.h
- +++ b/include/types/listener.h
- @@ -196,7 +196,7 @@ struct listener {
- int nbconn; /* current number of connections on this listener */
- int maxconn; /* maximum connections allowed on this listener */
- unsigned int backlog; /* if set, listen backlog */
- - unsigned int maxaccept; /* if set, max number of connections accepted at once */
- + int maxaccept; /* if set, max number of connections accepted at once (-1 when disabled) */
- struct list proto_list; /* list in the protocol header */
- int (*accept)(struct listener *l, int fd, struct sockaddr_storage *addr); /* upper layer's accept() */
- enum obj_type *default_target; /* default target to use for accepted sessions or NULL */
- diff --git a/src/listener.c b/src/listener.c
- index 821c931a..74990c45 100644
- --- a/src/listener.c
- +++ b/src/listener.c
- @@ -406,7 +406,7 @@ void listener_accept(int fd)
- {
- struct listener *l = fdtab[fd].owner;
- struct proxy *p;
- - int max_accept;
- + unsigned int max_accept;
- int next_conn = 0;
- int next_feconn = 0;
- int next_actconn = 0;
- @@ -420,6 +420,10 @@ void listener_accept(int fd)
- if (!l)
- return;
- p = l->bind_conf->frontend;
- +
- + /* if l->maxaccept is -1, then max_accept is UINT_MAX. It is not really
- + * illimited, but it is probably enough.
- + */
- max_accept = l->maxaccept ? l->maxaccept : 1;
-
- if (!(l->options & LI_O_UNLIMITED) && global.sps_lim) {
- @@ -480,7 +484,7 @@ void listener_accept(int fd)
- * worst case. If we fail due to system limits or temporary resource
- * shortage, we try again 100ms later in the worst case.
- */
- - for (; max_accept-- > 0; next_conn = next_feconn = next_actconn = 0) {
- + for (; max_accept; next_conn = next_feconn = next_actconn = 0, max_accept--) {
- struct sockaddr_storage addr;
- socklen_t laddr = sizeof(addr);
- unsigned int count;
|
