commit 517de5a9ff52a51ea773fb3b48e78b7df3d06672
author Vladimir Homutov <vl@nginx.com> Wed Sep 22 10:20:00 2021 +0300
committer Vladimir Homutov <vl@nginx.com> Wed Sep 22 10:20:00 2021 +0300
tree 100e8c1244711933931875c1cdca5f1615ad3f3a
parent fa8712a283f4526ba417ec5a6fa98caaf1b313f6

Stream: added half-close support.

The "proxy_half_close" directive enables handling of TCP half close.  If
enabled, connection to proxied server is kept open until both read ends get
EOF.  Write end shutdown is properly transmitted via proxy.

src/stream/ngx_stream_proxy_module.c

diff --git a/src/stream/ngx_stream_proxy_module.c b/src/stream/ngx_stream_proxy_module.c
index 1275cf2..934e7d8 100644
--- a/src/stream/ngx_stream_proxy_module.c
+++ b/src/stream/ngx_stream_proxy_module.c
@@ -31,6 +31,7 @@
     ngx_uint_t                       next_upstream_tries;
     ngx_flag_t                       next_upstream;
     ngx_flag_t                       proxy_protocol;
+    ngx_flag_t                       half_close;
     ngx_stream_upstream_local_t     *local;
     ngx_flag_t                       socket_keepalive;
 
@@ -245,6 +246,13 @@
       offsetof(ngx_stream_proxy_srv_conf_t, proxy_protocol),
       NULL },
 
+    { ngx_string("proxy_half_close"),
+      NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_FLAG,
+      ngx_conf_set_flag_slot,
+      NGX_STREAM_SRV_CONF_OFFSET,
+      offsetof(ngx_stream_proxy_srv_conf_t, half_close),
+      NULL },
+
 #if (NGX_STREAM_SSL)
 
     { ngx_string("proxy_ssl"),
@@ -1755,6 +1763,24 @@
     }
 
     if (dst) {
+
+        if (dst->type == SOCK_STREAM && pscf->half_close
+            && src->read->eof && !u->half_closed && !dst->buffered)
+        {
+            if (ngx_shutdown_socket(dst->fd, NGX_WRITE_SHUTDOWN) == -1) {
+                ngx_connection_error(c, ngx_socket_errno,
+                                     ngx_shutdown_socket_n " failed");
+
+                ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
+                return;
+            }
+
+            u->half_closed = 1;
+            ngx_log_debug1(NGX_LOG_DEBUG_STREAM, s->connection->log, 0,
+                           "stream proxy %s socket shutdown",
+                           from_upstream ? "client" : "upstream");
+        }
+
         if (ngx_handle_write_event(dst->write, 0) != NGX_OK) {
             ngx_stream_proxy_finalize(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
             return;
@@ -1833,6 +1859,13 @@
         return NGX_DECLINED;
     }
 
+    if (pscf->half_close) {
+        /* avoid closing live connections until both read ends get EOF */
+        if (!(c->read->eof && pc->read->eof && !c->buffered && !pc->buffered)) {
+             return NGX_DECLINED;
+        }
+    }
+
     handler = c->log->handler;
     c->log->handler = NULL;
 
@@ -2052,6 +2085,7 @@
     conf->proxy_protocol = NGX_CONF_UNSET;
     conf->local = NGX_CONF_UNSET_PTR;
     conf->socket_keepalive = NGX_CONF_UNSET;
+    conf->half_close = NGX_CONF_UNSET;
 
 #if (NGX_STREAM_SSL)
     conf->ssl_enable = NGX_CONF_UNSET;
@@ -2110,6 +2144,8 @@
     ngx_conf_merge_value(conf->socket_keepalive,
                               prev->socket_keepalive, 0);
 
+    ngx_conf_merge_value(conf->half_close, prev->half_close, 0);
+
 #if (NGX_STREAM_SSL)
 
     ngx_conf_merge_value(conf->ssl_enable, prev->ssl_enable, 0);

src/stream/ngx_stream_upstream.h

diff --git a/src/stream/ngx_stream_upstream.h b/src/stream/ngx_stream_upstream.h
index 9857e0b..f561779 100644
--- a/src/stream/ngx_stream_upstream.h
+++ b/src/stream/ngx_stream_upstream.h
@@ -142,6 +142,7 @@
     ngx_stream_upstream_state_t       *state;
     unsigned                           connected:1;
     unsigned                           proxy_protocol:1;
+    unsigned                           half_closed:1;
 } ngx_stream_upstream_t;