Fixed socket leak with "return 444" in error_page (ticket #274).

Socket leak was observed in the following configuration:

    error_page 400 = /close;

    location = /close {
        return 444;
    }

The problem is that "return 444" triggers termination of the request,
and due to error_page termination thinks that it needs to use a posted
request to clear stack.  But at the early request processing where 400
errors are generated there are no ngx_http_run_posted_requests() calls,
so the request is only terminated after an external event.

Variants of the problem include "error_page 497" instead (ticket #695)
and various other errors generated during early request processing
(405, 414, 421, 494, 495, 496, 501, 505).

The same problem can be also triggered with "return 499" and "return 408"
as both codes trigger ngx_http_terminate_request(), much like "return 444".

To fix this, the patch adds ngx_http_run_posted_requests() calls to
ngx_http_process_request_line() and ngx_http_process_request_headers()
functions, and to ngx_http_v2_run_request() and ngx_http_v2_push_stream()
functions in HTTP/2.

Since the ngx_http_process_request() function is now only called via
other functions which call ngx_http_run_posted_requests(), the call
there is no longer needed and was removed.

1 files changed, 26 insertions, 24 deletions

diff --git a/src/http/ngx_http_request.c b/src/http/ngx_http_request.c
index d7e4d69f1..c80df6e66 100644
--- a/src/http/ngx_http_request.c
+++ b/src/http/ngx_http_request.c
@@ -959,7 +959,7 @@ ngx_http_process_request_line(ngx_event_t *rev)
             n = ngx_http_read_request_header(r);
 
             if (n == NGX_AGAIN || n == NGX_ERROR) {
-                return;
+                break;
             }
         }
 
@@ -984,7 +984,7 @@ ngx_http_process_request_line(ngx_event_t *rev)
             }
 
             if (ngx_http_process_request_uri(r) != NGX_OK) {
-                return;
+                break;
             }
 
             if (r->schema_end) {
@@ -1003,16 +1003,16 @@ ngx_http_process_request_line(ngx_event_t *rev)
                     ngx_log_error(NGX_LOG_INFO, c->log, 0,
                                   "client sent invalid host in request line");
                     ngx_http_finalize_request(r, NGX_HTTP_BAD_REQUEST);
-                    return;
+                    break;
                 }
 
                 if (rc == NGX_ERROR) {
                     ngx_http_close_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
-                    return;
+                    break;
                 }
 
                 if (ngx_http_set_virtual_server(r, &host) == NGX_ERROR) {
-                    return;
+                    break;
                 }
 
                 r->headers_in.server = host;
@@ -1024,11 +1024,11 @@ ngx_http_process_request_line(ngx_event_t *rev)
                     && ngx_http_set_virtual_server(r, &r->headers_in.server)
                        == NGX_ERROR)
                 {
-                    return;
+                    break;
                 }
 
                 ngx_http_process_request(r);
-                return;
+                break;
             }
 
 
@@ -1037,7 +1037,7 @@ ngx_http_process_request_line(ngx_event_t *rev)
                 != NGX_OK)
             {
                 ngx_http_close_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
-                return;
+                break;
             }
 
             c->log->action = "reading client request headers";
@@ -1045,7 +1045,7 @@ ngx_http_process_request_line(ngx_event_t *rev)
             rev->handler = ngx_http_process_request_headers;
             ngx_http_process_request_headers(rev);
 
-            return;
+            break;
         }
 
         if (rc != NGX_AGAIN) {
@@ -1062,7 +1062,7 @@ ngx_http_process_request_line(ngx_event_t *rev)
                 ngx_http_finalize_request(r, NGX_HTTP_BAD_REQUEST);
             }
 
-            return;
+            break;
         }
 
         /* NGX_AGAIN: a request line parsing is still incomplete */
@@ -1073,7 +1073,7 @@ ngx_http_process_request_line(ngx_event_t *rev)
 
             if (rv == NGX_ERROR) {
                 ngx_http_close_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
-                return;
+                break;
             }
 
             if (rv == NGX_DECLINED) {
@@ -1083,10 +1083,12 @@ ngx_http_process_request_line(ngx_event_t *rev)
                 ngx_log_error(NGX_LOG_INFO, c->log, 0,
                               "client sent too long URI");
                 ngx_http_finalize_request(r, NGX_HTTP_REQUEST_URI_TOO_LARGE);
-                return;
+                break;
             }
         }
     }
+
+    ngx_http_run_posted_requests(c);
 }
 
 
@@ -1248,7 +1250,7 @@ ngx_http_process_request_headers(ngx_event_t *rev)
 
                 if (rv == NGX_ERROR) {
                     ngx_http_close_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
-                    return;
+                    break;
                 }
 
                 if (rv == NGX_DECLINED) {
@@ -1261,7 +1263,7 @@ ngx_http_process_request_headers(ngx_event_t *rev)
                                       "client sent too large request");
                         ngx_http_finalize_request(r,
                                             NGX_HTTP_REQUEST_HEADER_TOO_LARGE);
-                        return;
+                        break;
                     }
 
                     len = r->header_in->end - p;
@@ -1276,14 +1278,14 @@ ngx_http_process_request_headers(ngx_event_t *rev)
 
                     ngx_http_finalize_request(r,
                                             NGX_HTTP_REQUEST_HEADER_TOO_LARGE);
-                    return;
+                    break;
                 }
             }
 
             n = ngx_http_read_request_header(r);
 
             if (n == NGX_AGAIN || n == NGX_ERROR) {
-                return;
+                break;
             }
         }
 
@@ -1313,7 +1315,7 @@ ngx_http_process_request_headers(ngx_event_t *rev)
             h = ngx_list_push(&r->headers_in.headers);
             if (h == NULL) {
                 ngx_http_close_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
-                return;
+                break;
             }
 
             h->hash = r->header_hash;
@@ -1329,7 +1331,7 @@ ngx_http_process_request_headers(ngx_event_t *rev)
             h->lowcase_key = ngx_pnalloc(r->pool, h->key.len);
             if (h->lowcase_key == NULL) {
                 ngx_http_close_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
-                return;
+                break;
             }
 
             if (h->key.len == r->lowcase_index) {
@@ -1343,7 +1345,7 @@ ngx_http_process_request_headers(ngx_event_t *rev)
                                h->lowcase_key, h->key.len);
 
             if (hh && hh->handler(r, h, hh->offset) != NGX_OK) {
-                return;
+                break;
             }
 
             ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
@@ -1367,12 +1369,12 @@ ngx_http_process_request_headers(ngx_event_t *rev)
             rc = ngx_http_process_request_header(r);
 
             if (rc != NGX_OK) {
-                return;
+                break;
             }
 
             ngx_http_process_request(r);
 
-            return;
+            break;
         }
 
         if (rc == NGX_AGAIN) {
@@ -1388,8 +1390,10 @@ ngx_http_process_request_headers(ngx_event_t *rev)
                       "client sent invalid header line");
 
         ngx_http_finalize_request(r, NGX_HTTP_BAD_REQUEST);
-        return;
+        break;
     }
+
+    ngx_http_run_posted_requests(c);
 }
 
 
@@ -1944,8 +1948,6 @@ ngx_http_process_request(ngx_http_request_t *r)
     r->read_event_handler = ngx_http_block_reading;
 
     ngx_http_handler(r);
-
-    ngx_http_run_posted_requests(c);
 }