From 22a2a225ba87029f0e7bbc09a80ff7cdad23399d Mon Sep 17 00:00:00 2001 From: Roman Arutyunyan Date: Wed, 15 Jan 2025 12:42:39 +0400 Subject: Added "keepalive_min_timeout" directive. The directive sets a timeout during which a keepalive connection will not be closed by nginx for connection reuse or graceful shutdown. The change allows clients that send multiple requests over the same connection without delay or with a small delay between them, to avoid receiving a TCP RST in response to one of them. This excludes network issues and non-graceful shutdown. As a side-effect, it also addresses the TCP reset problem described in RFC 9112, Section 9.6, when the last sent HTTP response could be damaged by a followup TCP RST. It is important for non-idempotent requests, which cannot be retried by client. It is not recommended to set keepalive_min_timeout to large values as this can introduce an additional delay during graceful shutdown and may restrict nginx from effective connection reuse. --- src/http/ngx_http_request.c | 50 ++++++++++++++++++++++++++++++++++++++------- 1 file changed, 43 insertions(+), 7 deletions(-) (limited to 'src/http/ngx_http_request.c') diff --git a/src/http/ngx_http_request.c b/src/http/ngx_http_request.c index f44c9e79b..0be9da95e 100644 --- a/src/http/ngx_http_request.c +++ b/src/http/ngx_http_request.c @@ -2799,6 +2799,13 @@ ngx_http_finalize_connection(ngx_http_request_t *r) r->lingering_close = 1; } + if (r->keepalive + && clcf->keepalive_min_timeout > 0) + { + ngx_http_set_keepalive(r); + return; + } + if (!ngx_terminate && !ngx_exiting && r->keepalive @@ -3301,10 +3308,22 @@ ngx_http_set_keepalive(ngx_http_request_t *r) r->http_state = NGX_HTTP_KEEPALIVE_STATE; #endif - c->idle = 1; - ngx_reusable_connection(c, 1); + if (clcf->keepalive_min_timeout == 0) { + c->idle = 1; + ngx_reusable_connection(c, 1); + } + + if (clcf->keepalive_min_timeout > 0 + && clcf->keepalive_timeout > clcf->keepalive_min_timeout) + { + hc->keepalive_timeout = clcf->keepalive_timeout + - clcf->keepalive_min_timeout; + + } else { + hc->keepalive_timeout = 0; + } - ngx_add_timer(rev, clcf->keepalive_timeout); + ngx_add_timer(rev, clcf->keepalive_timeout - hc->keepalive_timeout); if (rev->ready) { ngx_post_event(rev, &ngx_posted_events); @@ -3315,15 +3334,32 @@ ngx_http_set_keepalive(ngx_http_request_t *r) static void ngx_http_keepalive_handler(ngx_event_t *rev) { - size_t size; - ssize_t n; - ngx_buf_t *b; - ngx_connection_t *c; + size_t size; + ssize_t n; + ngx_buf_t *b; + ngx_connection_t *c; + ngx_http_connection_t *hc; c = rev->data; + hc = c->data; ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http keepalive handler"); + if (!ngx_terminate + && !ngx_exiting + && rev->timedout + && hc->keepalive_timeout > 0) + { + c->idle = 1; + ngx_reusable_connection(c, 1); + + ngx_add_timer(rev, hc->keepalive_timeout); + + hc->keepalive_timeout = 0; + rev->timedout = 0; + return; + } + if (rev->timedout || c->close) { ngx_http_close_connection(c); return; -- cgit v1.2.3