From ea955e1efc9b1259467b55946a421a3950e6059f Mon Sep 17 00:00:00 2001
From: David Cermak <cermak@espressif.com>
Date: Thu, 22 Aug 2019 17:39:20 +0200
Subject: [PATCH] ws_client: fix ping-pong mechanism to use mask, support
 reception of zero-payload PONG and sending non-zero-payload PING

Closes https://github.com/espressif/esp-idf/issues/3890
Closes https://github.com/espressif/esp-idf/issues/4138
---
 .../tcp_transport/include/esp_transport_ws.h  |  1 -
 components/tcp_transport/transport_ws.c       | 21 +++++++++----------
 2 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/components/tcp_transport/include/esp_transport_ws.h b/components/tcp_transport/include/esp_transport_ws.h
index f47fd049c..bb4f0bc01 100644
--- a/components/tcp_transport/include/esp_transport_ws.h
+++ b/components/tcp_transport/include/esp_transport_ws.h
@@ -43,7 +43,6 @@ void esp_transport_ws_set_path(esp_transport_handle_t t, const char *path);
  */
 esp_err_t esp_transport_ws_set_subprotocol(esp_transport_handle_t t, const char *sub_protocol);
 
-
 #ifdef __cplusplus
 }
 #endif
diff --git a/components/tcp_transport/transport_ws.c b/components/tcp_transport/transport_ws.c
index 886f2a31e..c8f3da31c 100644
--- a/components/tcp_transport/transport_ws.c
+++ b/components/tcp_transport/transport_ws.c
@@ -188,18 +188,17 @@ static int _ws_write(esp_transport_handle_t t, int opcode, int mask_flag, const
         ws_header[header_len++] = (uint8_t)((len >> 8) & 0xFF);
         ws_header[header_len++] = (uint8_t)((len >> 0) & 0xFF);
     }
-    if (len) {
-        if (mask_flag) {
-            mask = &ws_header[header_len];
-            getrandom(ws_header + header_len, 4, 0);
-            header_len += 4;
 
-            for (i = 0; i < len; ++i) {
-                buffer[i] = (buffer[i] ^ mask[i % 4]);
-            }
+    if (mask_flag) {
+        mask = &ws_header[header_len];
+        getrandom(ws_header + header_len, 4, 0);
+        header_len += 4;
+
+        for (i = 0; i < len; ++i) {
+            buffer[i] = (buffer[i] ^ mask[i % 4]);
         }
-
     }
+
     if (esp_transport_write(ws->parent, ws_header, header_len, timeout_ms) != header_len) {
         ESP_LOGE(TAG, "Error write header");
         return -1;
@@ -224,7 +223,7 @@ static int ws_write(esp_transport_handle_t t, const char *b, int len, int timeou
 {
     if (len == 0) {
         ESP_LOGD(TAG, "Write PING message");
-        return _ws_write(t, WS_OPCODE_PING | WS_FIN, 0, NULL, 0, timeout_ms);
+        return _ws_write(t, WS_OPCODE_PING | WS_FIN, WS_MASK, NULL, 0, timeout_ms);
     }
     return _ws_write(t, WS_OPCODE_BINARY | WS_FIN, WS_MASK, b, len, timeout_ms);
 }
@@ -282,7 +281,7 @@ static int ws_read(esp_transport_handle_t t, char *buffer, int len, int timeout_
     }
 
     // Then receive and process payload
-    if ((rlen = esp_transport_read(ws->parent, buffer, payload_len, timeout_ms)) <= 0) {
+    if (payload_len != 0 && (rlen = esp_transport_read(ws->parent, buffer, payload_len, timeout_ms)) <= 0) {
         ESP_LOGE(TAG, "Error read data");
         return rlen;
     }