HTTP/2: always use temporary pool for processing headers.

This is required for implementing per request timeouts.

Previously, the temporary pool was used only during skipping of
headers and the request pool was used otherwise.  That required
switching of pools if the request was closed while parsing.

It wasn't a problem since the request could be closed only after
the validation of the fully parsed header.  With the per request
timeouts, the request can be closed at any moment, and switching
of pools in the middle of parsing header name or value becomes a
problem.

To overcome this, the temporary pool is now always created and
used.  Special checks are added to keep it when either the stream
is being processed or until header block is fully parsed.

2 files changed, 37 insertions, 25 deletions

diff --git a/src/http/v2/ngx_http_v2.c b/src/http/v2/ngx_http_v2.c
index 0447534e7..e4f824cfe 100644
--- a/src/http/v2/ngx_http_v2.c
+++ b/src/http/v2/ngx_http_v2.c
@@ -112,8 +112,6 @@ static u_char *ngx_http_v2_state_skip_padded(ngx_http_v2_connection_t *h2c,
     u_char *pos, u_char *end);
 static u_char *ngx_http_v2_state_skip(ngx_http_v2_connection_t *h2c,
     u_char *pos, u_char *end);
-static u_char *ngx_http_v2_state_skip_headers(ngx_http_v2_connection_t *h2c,
-    u_char *pos, u_char *end);
 static u_char *ngx_http_v2_state_save(ngx_http_v2_connection_t *h2c,
     u_char *pos, u_char *end, ngx_http_v2_handler_pt handler);
 static u_char *ngx_http_v2_connection_error(ngx_http_v2_connection_t *h2c,
@@ -1133,6 +1131,11 @@ ngx_http_v2_state_headers(ngx_http_v2_connection_t *h2c, u_char *pos,
 
     h2c->last_sid = h2c->state.sid;
 
+    h2c->state.pool = ngx_create_pool(1024, h2c->connection->log);
+    if (h2c->state.pool == NULL) {
+        return ngx_http_v2_connection_error(h2c, NGX_HTTP_V2_INTERNAL_ERROR);
+    }
+
     if (depend == h2c->state.sid) {
         ngx_log_error(NGX_LOG_INFO, h2c->connection->log, 0,
                       "client sent HEADERS frame for stream %ui "
@@ -1146,7 +1149,7 @@ ngx_http_v2_state_headers(ngx_http_v2_connection_t *h2c, u_char *pos,
                                                 NGX_HTTP_V2_INTERNAL_ERROR);
         }
 
-        return ngx_http_v2_state_skip_headers(h2c, pos, end);
+        return ngx_http_v2_state_header_block(h2c, pos, end);
     }
 
     h2scf = ngx_http_get_module_srv_conf(h2c->http_connection->conf_ctx,
@@ -1166,7 +1169,7 @@ ngx_http_v2_state_headers(ngx_http_v2_connection_t *h2c, u_char *pos,
                                                 NGX_HTTP_V2_INTERNAL_ERROR);
         }
 
-        return ngx_http_v2_state_skip_headers(h2c, pos, end);
+        return ngx_http_v2_state_header_block(h2c, pos, end);
     }
 
     node = ngx_http_v2_get_node_by_id(h2c, h2c->state.sid, 1);
@@ -1185,6 +1188,11 @@ ngx_http_v2_state_headers(ngx_http_v2_connection_t *h2c, u_char *pos,
         return ngx_http_v2_connection_error(h2c, NGX_HTTP_V2_INTERNAL_ERROR);
     }
 
+    h2c->state.stream = stream;
+
+    stream->pool = h2c->state.pool;
+    h2c->state.keep_pool = 1;
+
     stream->request->request_length = h2c->state.length;
 
     stream->in_closed = h2c->state.flags & NGX_HTTP_V2_END_STREAM_FLAG;
@@ -1192,9 +1200,6 @@ ngx_http_v2_state_headers(ngx_http_v2_connection_t *h2c, u_char *pos,
 
     node->stream = stream;
 
-    h2c->state.stream = stream;
-    h2c->state.pool = stream->request->pool;
-
     if (priority || node->parent == NULL) {
         node->weight = weight;
         ngx_http_v2_set_dependency(h2c, node, depend, excl);
@@ -1686,7 +1691,6 @@ ngx_http_v2_state_process_header(ngx_http_v2_connection_t *h2c, u_char *pos,
 error:
 
     h2c->state.stream = NULL;
-    h2c->state.pool = NULL;
 
     return ngx_http_v2_state_header_complete(h2c, pos, end);
 }
@@ -1699,8 +1703,7 @@ ngx_http_v2_state_header_complete(ngx_http_v2_connection_t *h2c, u_char *pos,
     ngx_http_v2_stream_t  *stream;
 
     if (h2c->state.length) {
-        h2c->state.handler = h2c->state.pool ? ngx_http_v2_state_header_block
-                                             : ngx_http_v2_state_skip_headers;
+        h2c->state.handler = ngx_http_v2_state_header_block;
         return pos;
     }
 
@@ -1713,12 +1716,14 @@ ngx_http_v2_state_header_complete(ngx_http_v2_connection_t *h2c, u_char *pos,
 
     if (stream) {
         ngx_http_v2_run_request(stream->request);
+    }
 
-    } else if (h2c->state.pool) {
+    if (!h2c->state.keep_pool) {
         ngx_destroy_pool(h2c->state.pool);
     }
 
     h2c->state.pool = NULL;
+    h2c->state.keep_pool = 0;
 
     if (h2c->state.padding) {
         return ngx_http_v2_state_skip_padded(h2c, pos, end);
@@ -2337,19 +2342,6 @@ ngx_http_v2_state_skip(ngx_http_v2_connection_t *h2c, u_char *pos, u_char *end)
 
 
 static u_char *
-ngx_http_v2_state_skip_headers(ngx_http_v2_connection_t *h2c, u_char *pos,
-    u_char *end)
-{
-    h2c->state.pool = ngx_create_pool(1024, h2c->connection->log);
-    if (h2c->state.pool == NULL) {
-        return ngx_http_v2_connection_error(h2c, NGX_HTTP_V2_INTERNAL_ERROR);
-    }
-
-    return ngx_http_v2_state_header_block(h2c, pos, end);
-}
-
-
-static u_char *
 ngx_http_v2_state_save(ngx_http_v2_connection_t *h2c, u_char *pos, u_char *end,
     ngx_http_v2_handler_pt handler)
 {
@@ -3633,6 +3625,7 @@ ngx_http_v2_terminate_stream(ngx_http_v2_connection_t *h2c,
 void
 ngx_http_v2_close_stream(ngx_http_v2_stream_t *stream, ngx_int_t rc)
 {
+    ngx_pool_t                *pool;
     ngx_event_t               *ev;
     ngx_connection_t          *fc;
     ngx_http_v2_node_t        *node;
@@ -3670,8 +3663,25 @@ ngx_http_v2_close_stream(ngx_http_v2_stream_t *stream, ngx_int_t rc)
     ngx_queue_insert_tail(&h2c->closed, &node->reuse);
     h2c->closed_nodes++;
 
+    /*
+     * This pool keeps decoded request headers which can be used by log phase
+     * handlers in ngx_http_free_request().
+     *
+     * The pointer is stored into local variable because the stream object
+     * will be destroyed after a call to ngx_http_free_request().
+     */
+    pool = stream->pool;
+
     ngx_http_free_request(stream->request, rc);
 
+    if (pool != h2c->state.pool) {
+        ngx_destroy_pool(pool);
+
+    } else {
+        /* pool will be destroyed when the complete header is parsed */
+        h2c->state.keep_pool = 0;
+    }
+
     ev = fc->read;
 
     if (ev->active || ev->disabled) {
@@ -3825,7 +3835,6 @@ ngx_http_v2_finalize_connection(ngx_http_v2_connection_t *h2c,
 
     if (h2c->state.stream) {
         h2c->state.stream->out_closed = 1;
-        h2c->state.pool = NULL;
         ngx_http_v2_close_stream(h2c->state.stream, NGX_HTTP_BAD_REQUEST);
     }
 
diff --git a/src/http/v2/ngx_http_v2.h b/src/http/v2/ngx_http_v2.h
index 070aa435a..5a791e626 100644
--- a/src/http/v2/ngx_http_v2.h
+++ b/src/http/v2/ngx_http_v2.h
@@ -73,6 +73,7 @@ typedef struct {
     unsigned                         flags:8;
 
     unsigned                         incomplete:1;
+    unsigned                         keep_pool:1;
 
     /* HPACK */
     unsigned                         parse_name:1;
@@ -186,6 +187,8 @@ struct ngx_http_v2_stream_s {
 
     size_t                           header_limit;
 
+    ngx_pool_t                      *pool;
+
     unsigned                         handled:1;
     unsigned                         blocked:1;
     unsigned                         exhausted:1;