fix(proxy-wasm) free dispatch calls during resume edge-case

Fix a Valgrind memory leak and an unrelated suppression.

Dispatch resume invoking on_request_headers for subsequent filters may
yield themselves (NGX_AGAIN). In this case, also ensure the dispatch
call is destroyed.

Fix the suppression for headers-more-nginx-module which can happen with
other stacktraces on builtin headers (e.g. Content-Length).

src/http/proxy_wasm/ngx_http_proxy_wasm_dispatch.c

@@ -425,6 +425,8 @@ ngx_http_proxy_wasm_dispatch_destroy(ngx_http_proxy_wasm_dispatch_t *call)
     sock = &call->sock;
     rctx = call->rctx;
 
+    dd("enter");
+
     ngx_wasm_socket_tcp_destroy(sock);
 
     if (call->host.data) {
@@ -842,10 +844,7 @@ ngx_http_proxy_wasm_dispatch_resume_handler(ngx_wasm_socket_tcp_t *sock)
             /* resume current step if unfinished */
             rc = ngx_proxy_wasm_resume(pwexec->parent, pwexec->parent->phase,
                                        step);
-            if (rc == NGX_AGAIN) {
-                goto done;
-
-            } else if (rc != NGX_OK) {
+            if (rc != NGX_OK && rc != NGX_AGAIN) {
                 goto error;
             }
 

valgrind.suppress

@@ -25,10 +25,9 @@
    <headers-more-nginx-module: set_header_helper>
    Memcheck:Cond
    fun:ngx_http_set_header_helper
+   ...
    fun:ngx_http_headers_more_exec_cmd
    fun:ngx_http_headers_more_filter
-   ...
-   fun:main
 }
 {
    <wasmer 3.1.1: parse>