details: https://hg.nginx.org/nginx/rev/c5840ca2063d
branches:
changeset: 7673:c5840ca2063d
user: Ruslan Ermilov <ru@nginx.com>
date: Fri Jul 03 16:16:47 2020 +0300
description:
HTTP/2: lingering close after GOAWAY.

After sending the GOAWAY frame, a connection is now closed using
the lingering close mechanism.

This allows for the reliable delivery of the GOAWAY frames, while
also fixing connection resets observed when http2_max_requests is
reached (ticket #1250), or with graceful shutdown (ticket #1544),
when some additional data from the client is received on a fully
closed connection.

For HTTP/2, the settings lingering_close, lingering_timeout, and
lingering_time are taken from the "server" level.

diffstat:

src/http/v2/ngx_http_v2.c | 128 +++++++++++++++++++++++++++++++++++++++++++--
src/http/v2/ngx_http_v2.h | 2 +
2 files changed, 124 insertions(+), 6 deletions(-)

diffs (187 lines):

diff -r 3dcb1aba894a -r c5840ca2063d src/http/v2/ngx_http_v2.c
--- a/src/http/v2/ngx_http_v2.c Mon Jun 29 17:15:51 2020 +0300
+++ b/src/http/v2/ngx_http_v2.c Fri Jul 03 16:16:47 2020 +0300
@@ -60,6 +60,8 @@ typedef struct {
static void ngx_http_v2_read_handler(ngx_event_t *rev);
static void ngx_http_v2_write_handler(ngx_event_t *wev);
static void ngx_http_v2_handle_connection(ngx_http_v2_connection_t *h2c);
+static void ngx_http_v2_lingering_close(ngx_http_v2_connection_t *h2c);
+static void ngx_http_v2_lingering_close_handler(ngx_event_t *rev);

static u_char *ngx_http_v2_state_proxy_protocol(ngx_http_v2_connection_t *h2c,
u_char *pos, u_char *end);
@@ -661,7 +663,7 @@ ngx_http_v2_handle_connection(ngx_http_v
}

if (h2c->goaway) {
- ngx_http_close_connection(c);
+ ngx_http_v2_lingering_close(h2c);
return;
}

@@ -699,6 +701,113 @@ ngx_http_v2_handle_connection(ngx_http_v
}


+static void
+ngx_http_v2_lingering_close(ngx_http_v2_connection_t *h2c)
+{
+ ngx_event_t *rev, *wev;
+ ngx_connection_t *c;
+ ngx_http_core_loc_conf_t *clcf;
+
+ c = h2c->connection;
+
+ clcf = ngx_http_get_module_loc_conf(h2c->http_connection->conf_ctx,
+ ngx_http_core_module);
+
+ if (clcf->lingering_close == NGX_HTTP_LINGERING_OFF) {
+ ngx_http_close_connection(c);
+ return;
+ }
+
+ rev = c->read;
+ rev->handler = ngx_http_v2_lingering_close_handler;
+
+ h2c->lingering_time = ngx_time() + (time_t) (clcf->lingering_time / 1000);
+ ngx_add_timer(rev, clcf->lingering_timeout);
+
+ if (ngx_handle_read_event(rev, 0) != NGX_OK) {
+ ngx_http_close_connection(c);
+ return;
+ }
+
+ wev = c->write;
+ wev->handler = ngx_http_empty_handler;
+
+ if (wev->active && (ngx_event_flags & NGX_USE_LEVEL_EVENT)) {
+ if (ngx_del_event(wev, NGX_WRITE_EVENT, 0) != NGX_OK) {
+ ngx_http_close_connection(c);
+ return;
+ }
+ }
+
+ if (ngx_shutdown_socket(c->fd, NGX_WRITE_SHUTDOWN) == -1) {
+ ngx_connection_error(c, ngx_socket_errno,
+ ngx_shutdown_socket_n " failed");
+ ngx_http_close_connection(c);
+ return;
+ }
+
+ if (rev->ready) {
+ ngx_http_v2_lingering_close_handler(rev);
+ }
+}
+
+
+static void
+ngx_http_v2_lingering_close_handler(ngx_event_t *rev)
+{
+ ssize_t n;
+ ngx_msec_t timer;
+ ngx_connection_t *c;
+ ngx_http_core_loc_conf_t *clcf;
+ ngx_http_v2_connection_t *h2c;
+ u_char buffer[NGX_HTTP_LINGERING_BUFFER_SIZE];
+
+ c = rev->data;
+ h2c = c->data;
+
+ ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
+ "http2 lingering close handler");
+
+ if (rev->timedout) {
+ ngx_http_close_connection(c);
+ return;
+ }
+
+ timer = (ngx_msec_t) h2c->lingering_time - (ngx_msec_t) ngx_time();
+ if ((ngx_msec_int_t) timer <= 0) {
+ ngx_http_close_connection(c);
+ return;
+ }
+
+ do {
+ n = c->recv(c, buffer, NGX_HTTP_LINGERING_BUFFER_SIZE);
+
+ ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0, "lingering read: %z", n);
+
+ if (n == NGX_ERROR || n == 0) {
+ ngx_http_close_connection(c);
+ return;
+ }
+
+ } while (rev->ready);
+
+ if (ngx_handle_read_event(rev, 0) != NGX_OK) {
+ ngx_http_close_connection(c);
+ return;
+ }
+
+ clcf = ngx_http_get_module_loc_conf(h2c->http_connection->conf_ctx,
+ ngx_http_core_module);
+ timer *= 1000;
+
+ if (timer > clcf->lingering_timeout) {
+ timer = clcf->lingering_timeout;
+ }
+
+ ngx_add_timer(rev, timer);
+}
+
+
static u_char *
ngx_http_v2_state_proxy_protocol(ngx_http_v2_connection_t *h2c, u_char *pos,
u_char *end)
@@ -4541,16 +4650,15 @@ ngx_http_v2_finalize_connection(ngx_http
h2c->blocked = 1;

if (!c->error && !h2c->goaway) {
+ h2c->goaway = 1;
+
if (ngx_http_v2_send_goaway(h2c, status) != NGX_ERROR) {
(void) ngx_http_v2_send_output_queue(h2c);
}
}

- c->error = 1;
-
if (!h2c->processing && !h2c->pushing) {
- ngx_http_close_connection(c);
- return;
+ goto done;
}

c->read->handler = ngx_http_empty_handler;
@@ -4598,10 +4706,18 @@ ngx_http_v2_finalize_connection(ngx_http
h2c->blocked = 0;

if (h2c->processing || h2c->pushing) {
+ c->error = 1;
return;
}

- ngx_http_close_connection(c);
+done:
+
+ if (c->error) {
+ ngx_http_close_connection(c);
+ return;
+ }
+
+ ngx_http_v2_lingering_close(h2c);
}


diff -r 3dcb1aba894a -r c5840ca2063d src/http/v2/ngx_http_v2.h
--- a/src/http/v2/ngx_http_v2.h Mon Jun 29 17:15:51 2020 +0300
+++ b/src/http/v2/ngx_http_v2.h Fri Jul 03 16:16:47 2020 +0300
@@ -157,6 +157,8 @@ struct ngx_http_v2_connection_s {
ngx_uint_t last_sid;
ngx_uint_t last_push;

+ time_t lingering_time;
+
unsigned closed_nodes:8;
unsigned settings_ack:1;
unsigned table_update:1;
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