Fix handling of keepalive HTTP requests/responses

Clean the HTTP connection state when ia request/response has been fully
buffered and handler invoked.

Fixes https://github.com/cesanta/mongoose/issues/971

CL: mg: Fix handling of keepalive HTTP requests/responses

PUBLISHED_FROM=70c854aa306aacb9161f6ee48841f38dc0312e6b

mongoose.c

@@ -6616,6 +6616,7 @@ void mg_http_handler(struct mg_connection *nc, int ev,
       }
     } else {
       /* We did receive all HTTP body. */
+      int request_done = 1;
       int trigger_ev = nc->listener ? MG_EV_HTTP_REQUEST : MG_EV_HTTP_REPLY;
       char addr[32];
       mg_sock_addr_to_str(&nc->sa, addr, sizeof(addr),
@@ -6627,11 +6628,31 @@ void mg_http_handler(struct mg_connection *nc, int ev,
       mg_http_call_endpoint_handler(nc, trigger_ev, hm);
       mbuf_remove(io, hm->message.len);
       pd->rcvd -= hm->message.len;
+#if MG_ENABLE_FILESYSTEM
+      /* We don't have a generic mechanism of communicating that we are done
+       * responding to a request (should probably add one). But if we are
+       * serving
+       * a file, we are definitely not done. */
+      if (pd->file.fp != NULL) request_done = 0;
+#endif
+#if MG_ENABLE_HTTP_CGI
+      /* If this is a CGI request, we are not done either. */
+      if (pd->cgi.cgi_nc != NULL) request_done = 0;
+#endif
+      if (request_done) {
+        /* This request is done but we may receive another on this connection.
+         */
+        mg_http_conn_destructor(pd);
+        nc->proto_data = NULL;
         if (io->len > 0) {
+          /* We already have data for the next one, restart parsing. */
+          pd = mg_http_get_proto_data(nc);
+          pd->rcvd = io->len;
           goto again;
         }
       }
     }
+  }
 }
 
 static size_t mg_get_line_len(const char *buf, size_t buf_len) {

src/mg_http.c

@@ -869,6 +869,7 @@ void mg_http_handler(struct mg_connection *nc, int ev,
       }
     } else {
       /* We did receive all HTTP body. */
+      int request_done = 1;
       int trigger_ev = nc->listener ? MG_EV_HTTP_REQUEST : MG_EV_HTTP_REPLY;
       char addr[32];
       mg_sock_addr_to_str(&nc->sa, addr, sizeof(addr),
@@ -880,11 +881,31 @@ void mg_http_handler(struct mg_connection *nc, int ev,
       mg_http_call_endpoint_handler(nc, trigger_ev, hm);
       mbuf_remove(io, hm->message.len);
       pd->rcvd -= hm->message.len;
+#if MG_ENABLE_FILESYSTEM
+      /* We don't have a generic mechanism of communicating that we are done
+       * responding to a request (should probably add one). But if we are
+       * serving
+       * a file, we are definitely not done. */
+      if (pd->file.fp != NULL) request_done = 0;
+#endif
+#if MG_ENABLE_HTTP_CGI
+      /* If this is a CGI request, we are not done either. */
+      if (pd->cgi.cgi_nc != NULL) request_done = 0;
+#endif
+      if (request_done) {
+        /* This request is done but we may receive another on this connection.
+         */
+        mg_http_conn_destructor(pd);
+        nc->proto_data = NULL;
         if (io->len > 0) {
+          /* We already have data for the next one, restart parsing. */
+          pd = mg_http_get_proto_data(nc);
+          pd->rcvd = io->len;
           goto again;
         }
       }
     }
+  }
 }
 
 static size_t mg_get_line_len(const char *buf, size_t buf_len) {

test/unit_test.c

@@ -2069,7 +2069,7 @@ static const char *test_http(void) {
   nc->user_data = mime2;
 
   /* Run event loop. Use more cycles to let file download complete. */
-  poll_until(&mgr, 5, c_str_ne, status, (void *) "");
+  poll_until(&mgr, 15, c_str_ne, status, (void *) "");
   mg_mgr_free(&mgr);
 
   /* Check that test buffer has been filled by the callback properly. */