[tor-commits] [tor/master] Stub out connection_handle_oos() and call it from places we can change the socket count or thresholds
nickm at torproject.org
nickm at torproject.org
Thu Aug 25 18:32:16 UTC 2016
commit 34d9d02150fc41107887c27900a62c4552578789
Author: Andrea Shepard <andrea at torproject.org>
Date: Thu Jun 30 10:43:44 2016 +0000
Stub out connection_handle_oos() and call it from places we can change the socket count or thresholds
---
src/or/config.c | 3 ++
src/or/connection.c | 108 +++++++++++++++++++++++++++++++++++++++++++++++++++-
src/or/connection.h | 2 +
3 files changed, 112 insertions(+), 1 deletion(-)
diff --git a/src/or/config.c b/src/or/config.c
index 33c80e5..f7a7a53 100644
--- a/src/or/config.c
+++ b/src/or/config.c
@@ -1358,6 +1358,9 @@ options_act_reversible(const or_options_t *old_options, char **msg)
options->ConnLimit, options->ConnLimit_,
options->ConnLimit_high_thresh,
options->ConnLimit_low_thresh);
+
+ /* Give the OOS handler a chance with the new thresholds */
+ connection_handle_oos(get_n_open_sockets(), 0);
}
goto done;
diff --git a/src/or/connection.c b/src/or/connection.c
index 68e442d..3939531 100644
--- a/src/or/connection.c
+++ b/src/or/connection.c
@@ -1090,6 +1090,7 @@ connection_listener_new(const struct sockaddr *listensockaddr,
int start_reading = 0;
static int global_next_session_group = SESSION_GROUP_FIRST_AUTO;
tor_addr_t addr;
+ int exhaustion = 0;
if (listensockaddr->sa_family == AF_INET ||
listensockaddr->sa_family == AF_INET6) {
@@ -1108,6 +1109,11 @@ connection_listener_new(const struct sockaddr *listensockaddr,
int e = tor_socket_errno(s);
if (ERRNO_IS_RESOURCE_LIMIT(e)) {
warn_too_many_conns();
+ /*
+ * We'll call the OOS handler at the error exit, so set the
+ * exhaustion flag for it.
+ */
+ exhaustion = 1;
} else {
log_warn(LD_NET, "Socket creation failed: %s",
tor_socket_strerror(e));
@@ -1226,6 +1232,11 @@ connection_listener_new(const struct sockaddr *listensockaddr,
int e = tor_socket_errno(s);
if (ERRNO_IS_RESOURCE_LIMIT(e)) {
warn_too_many_conns();
+ /*
+ * We'll call the OOS handler at the error exit, so set the
+ * exhaustion flag for it.
+ */
+ exhaustion = 1;
} else {
log_warn(LD_NET,"Socket creation failed: %s.", strerror(e));
}
@@ -1344,6 +1355,12 @@ connection_listener_new(const struct sockaddr *listensockaddr,
dnsserv_configure_listener(conn);
}
+ /*
+ * Normal exit; call the OOS handler since connection count just changed;
+ * the exhaustion flag will always be zero here though.
+ */
+ connection_handle_oos(get_n_open_sockets(), 0);
+
return conn;
err:
@@ -1352,6 +1369,9 @@ connection_listener_new(const struct sockaddr *listensockaddr,
if (conn)
connection_free(conn);
+ /* Call the OOS handler, indicate if we saw an exhaustion-related error */
+ connection_handle_oos(get_n_open_sockets(), exhaustion);
+
return NULL;
}
@@ -1442,21 +1462,34 @@ connection_handle_listener_read(connection_t *conn, int new_type)
if (!SOCKET_OK(news)) { /* accept() error */
int e = tor_socket_errno(conn->s);
if (ERRNO_IS_ACCEPT_EAGAIN(e)) {
- return 0; /* they hung up before we could accept(). that's fine. */
+ /*
+ * they hung up before we could accept(). that's fine.
+ *
+ * give the OOS handler a chance to run though
+ */
+ connection_handle_oos(get_n_open_sockets(), 0);
+ return 0;
} else if (ERRNO_IS_RESOURCE_LIMIT(e)) {
warn_too_many_conns();
+ /* Exhaustion; tell the OOS handler */
+ connection_handle_oos(get_n_open_sockets(), 1);
return 0;
}
/* else there was a real error. */
log_warn(LD_NET,"accept() failed: %s. Closing listener.",
tor_socket_strerror(e));
connection_mark_for_close(conn);
+ /* Tell the OOS handler about this too */
+ connection_handle_oos(get_n_open_sockets(), 0);
return -1;
}
log_debug(LD_NET,
"Connection accepted on socket %d (child of fd %d).",
(int)news,(int)conn->s);
+ /* We accepted a new conn; run OOS handler */
+ connection_handle_oos(get_n_open_sockets(), 0);
+
if (make_socket_reuseable(news) < 0) {
if (tor_socket_errno(news) == EINVAL) {
/* This can happen on OSX if we get a badly timed shutdown. */
@@ -1661,12 +1694,18 @@ connection_connect_sockaddr,(connection_t *conn,
s = tor_open_socket_nonblocking(protocol_family, SOCK_STREAM, proto);
if (! SOCKET_OK(s)) {
+ /*
+ * Early OOS handler calls; it matters if it's an exhaustion-related
+ * error or not.
+ */
*socket_error = tor_socket_errno(s);
if (ERRNO_IS_RESOURCE_LIMIT(*socket_error)) {
warn_too_many_conns();
+ connection_handle_oos(get_n_open_sockets(), 1);
} else {
log_warn(LD_NET,"Error creating network socket: %s",
tor_socket_strerror(*socket_error));
+ connection_handle_oos(get_n_open_sockets(), 0);
}
return -1;
}
@@ -1676,6 +1715,13 @@ connection_connect_sockaddr,(connection_t *conn,
tor_socket_strerror(errno));
}
+ /*
+ * We've got the socket open; give the OOS handler a chance to check
+ * against configuured maximum socket number, but tell it no exhaustion
+ * failure.
+ */
+ connection_handle_oos(get_n_open_sockets(), 0);
+
if (bindaddr && bind(s, bindaddr, bindaddr_len) < 0) {
*socket_error = tor_socket_errno(s);
log_warn(LD_NET,"Error binding network socket: %s",
@@ -4454,6 +4500,66 @@ connection_reached_eof(connection_t *conn)
}
}
+/** Out-of-Sockets handler; n_socks is the current number of open
+ * sockets, and failed is non-zero if a socket exhaustion related
+ * error immediately preceded this call. This is where to do
+ * circuit-killing heuristics as needed.
+ */
+void
+connection_handle_oos(int n_socks, int failed)
+{
+ int target_n_socks = 0;
+
+ /* Sanity-check args */
+ tor_assert(n_socks >= 0);
+
+ /*
+ * Make some log noise; keep it at debug level since this gets a chance
+ * to run on every connection attempt.
+ */
+ log_debug(LD_NET,
+ "Running the OOS handler (%d open sockets, %s)",
+ n_socks, (failed != 0) ? "exhaustion seen" : "no exhaustion");
+
+ /*
+ * Check if we're really handling an OOS condition, and if so decide how
+ * many sockets we want to get down to.
+ */
+ if (n_socks > get_options()->ConnLimit_high_thresh) {
+ /* Try to get down to the low threshold */
+ target_n_socks = get_options()->ConnLimit_low_thresh;
+ log_notice(LD_NET,
+ "Current number of sockets %d is greater than configured "
+ "limit %d; OOS handler trying to get down to %d",
+ n_socks, get_options()->ConnLimit_high_thresh,
+ target_n_socks);
+ } else if (failed) {
+ /*
+ * If we're not at the limit but we hit a socket exhaustion error, try to
+ * drop some (but not as aggressively as ConnLimit_low_threshold, which is
+ * 3/4 of ConnLimit_)
+ */
+ target_n_socks = (n_socks * 9) / 10;
+ log_notice(LD_NET,
+ "We saw socket exhaustion at %d open sockets; OOS handler "
+ "trying to get down to %d",
+ n_socks, target_n_socks);
+ }
+
+ if (target_n_socks > 0) {
+ /*
+ * It's an OOS!
+ *
+ * TODO count moribund sockets; it'll be important that anything we decide
+ * to get rid of here but don't immediately close get counted as moribund
+ * on subsequent invocations so we don't try to kill too many things if
+ * this gets called multiple times.
+ */
+
+ /* TODO pick what to try to close */
+ }
+}
+
/** Log how many bytes are used by buffers of different kinds and sizes. */
void
connection_dump_buffer_mem_stats(int severity)
diff --git a/src/or/connection.h b/src/or/connection.h
index f8e0f73..4e8a740 100644
--- a/src/or/connection.h
+++ b/src/or/connection.h
@@ -247,6 +247,8 @@ void clock_skew_warning(const connection_t *conn, long apparent_skew,
int trusted, log_domain_mask_t domain,
const char *received, const char *source);
+void connection_handle_oos(int n_socks, int failed);
+
#ifdef CONNECTION_PRIVATE
STATIC void connection_free_(connection_t *conn);
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