[nginx] Request body: explicit handling of NGX_AGAIN.

[Maxim Dounin]

details:   http://freenginx.org/hg/nginx/rev/392e8e2fd22a
branches:  
changeset: 9238:392e8e2fd22a
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Sat Mar 30 05:06:59 2024 +0300
description:
Request body: explicit handling of NGX_AGAIN.

Request body reading indirectly uses the "do { c->recv() } while
(c->read->ready)" form, which is not really correct, as for example
with SSL c->read->ready may be still set when c->recv() returns NGX_AGAIN
due to SSL_ERROR_WANT_WRITE (see 7351:2b5528023f6b), and therefore this
form might be an infinite loop.

Added explicit NGX_AGAIN handling for the sake of correctness.

diffstat:

 src/http/ngx_http_request_body.c |  3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diffs (20 lines):

diff --git a/src/http/ngx_http_request_body.c b/src/http/ngx_http_request_body.c
--- a/src/http/ngx_http_request_body.c
+++ b/src/http/ngx_http_request_body.c
@@ -307,6 +307,7 @@ ngx_http_do_read_client_request_body(ngx
     c = r->connection;
     rb = r->request_body;
     flush = 1;
+    n = NGX_AGAIN;
 
     ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                    "http read client request body");
@@ -432,7 +433,7 @@ ngx_http_do_read_client_request_body(ngx
             break;
         }
 
-        if (!c->read->ready || rb->rest == 0) {
+        if (n == NGX_AGAIN || !c->read->ready || rb->rest == 0) {
 
             clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
             ngx_add_timer(c->read, clcf->client_body_timeout);