tcp: add uv_tcp_close_reset method

It resets a TCP connection by sending a RST packet. Due to some platform
inconsistencies, mixing of `uv_shutdown` and `uv_tcp_close_reset` calls
is not allowed.

Fixes: https://github.com/libuv/libuv/issues/1991
PR-URL: https://github.com/libuv/libuv/pull/2425
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Saúl Ibarra Corretgé <saghul@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

CMakeLists.txt

@@ -128,6 +128,7 @@ set(uv_test_sources
     test/test-tcp-close-accept.c
     test/test-tcp-close-while-connecting.c
     test/test-tcp-close.c
+    test/test-tcp-close-reset.c
     test/test-tcp-connect-error-after-write.c
     test/test-tcp-connect-error.c
     test/test-tcp-connect-timeout.c

Makefile.am

@@ -260,6 +260,7 @@ test_run_tests_SOURCES = test/blackhole-server.c \
                          test/test-tcp-close-accept.c \
                          test/test-tcp-close-while-connecting.c \
                          test/test-tcp-close.c \
+                         test/test-tcp-close-reset.c \
                          test/test-tcp-create-socket-early.c \
                          test/test-tcp-connect-error-after-write.c \
                          test/test-tcp-connect-error.c \

docs/src/tcp.rst

@@ -113,3 +113,13 @@ API
         mapping
 
 .. seealso:: The :c:type:`uv_stream_t` API functions also apply.
+
+.. c:function:: int uv_tcp_close_reset(uv_tcp_t* handle, uv_close_cb close_cb)
+
+    Resets a TCP connection by sending a RST packet. This is accomplished by
+    setting the `SO_LINGER` socket option with a linger interval of zero and
+    then calling :c:func:`uv_close`.
+    Due to some platform inconsistencies, mixing of :c:func:`uv_shutdown` and
+    :c:func:`uv_tcp_close_reset` calls is not allowed.
+
+    .. versionadded:: 1.32.0

include/uv.h

@@ -559,6 +559,7 @@ UV_EXTERN int uv_tcp_getsockname(const uv_tcp_t* handle,
 UV_EXTERN int uv_tcp_getpeername(const uv_tcp_t* handle,
                                  struct sockaddr* name,
                                  int* namelen);
+UV_EXTERN int uv_tcp_close_reset(uv_tcp_t* handle, uv_close_cb close_cb);
 UV_EXTERN int uv_tcp_connect(uv_connect_t* req,
                              uv_tcp_t* handle,
                              const struct sockaddr* addr,

src/unix/tcp.c

@@ -308,6 +308,23 @@ int uv_tcp_getpeername(const uv_tcp_t* handle,
 }
 
 
+int uv_tcp_close_reset(uv_tcp_t* handle, uv_close_cb close_cb) {
+  int fd;
+  struct linger l = { 1, 0 };
+
+  /* Disallow setting SO_LINGER to zero due to some platform inconsistencies */
+  if (handle->flags & UV_HANDLE_SHUTTING)
+    return UV_EINVAL;
+
+  fd = uv__stream_fd(handle);
+  if (0 != setsockopt(fd, SOL_SOCKET, SO_LINGER, &l, sizeof(l)))
+    return UV__ERR(errno);
+
+  uv_close((uv_handle_t*) handle, close_cb);
+  return 0;
+}
+
+
 int uv_tcp_listen(uv_tcp_t* tcp, int backlog, uv_connection_cb cb) {
   static int single_accept = -1;
   unsigned long flags;

src/win/stream.c

@@ -198,8 +198,10 @@ int uv_try_write(uv_stream_t* stream,
 int uv_shutdown(uv_shutdown_t* req, uv_stream_t* handle, uv_shutdown_cb cb) {
   uv_loop_t* loop = handle->loop;
 
-  if (!(handle->flags & UV_HANDLE_WRITABLE)) {
-    return UV_EPIPE;
+  if (!(handle->flags & UV_HANDLE_WRITABLE) ||
+      handle->flags & UV_HANDLE_SHUTTING ||
+      uv__is_closing(handle)) {
+    return UV_ENOTCONN;
   }
 
   UV_REQ_INIT(req, UV_SHUTDOWN);
@@ -207,6 +209,7 @@ int uv_shutdown(uv_shutdown_t* req, uv_stream_t* handle, uv_shutdown_cb cb) {
   req->cb = cb;
 
   handle->flags &= ~UV_HANDLE_WRITABLE;
+  handle->flags |= UV_HANDLE_SHUTTING;
   handle->stream.conn.shutdown_req = req;
   handle->reqs_pending++;
   REGISTER_HANDLE_REQ(loop, handle, req);

src/win/tcp.c

@@ -549,6 +549,21 @@ static void uv_tcp_queue_read(uv_loop_t* loop, uv_tcp_t* handle) {
 }
 
 
+int uv_tcp_close_reset(uv_tcp_t* handle, uv_close_cb close_cb) {
+  struct linger l = { 1, 0 };
+
+  /* Disallow setting SO_LINGER to zero due to some platform inconsistencies */
+  if (handle->flags & UV_HANDLE_SHUTTING)
+    return UV_EINVAL;
+
+  if (0 != setsockopt(handle->socket, SOL_SOCKET, SO_LINGER, &l, sizeof(l)))
+    return uv_translate_sys_error(WSAGetLastError());
+
+  uv_close((uv_handle_t*) handle, close_cb);
+  return 0;
+}
+
+
 int uv_tcp_listen(uv_tcp_t* handle, int backlog, uv_connection_cb cb) {
   unsigned int i, simultaneous_accepts;
   uv_tcp_accept_t* req;

test/test-list.h

@@ -112,6 +112,10 @@ TEST_DECLARE   (tcp_connect_error_fault)
 TEST_DECLARE   (tcp_connect_timeout)
 TEST_DECLARE   (tcp_close_while_connecting)
 TEST_DECLARE   (tcp_close)
+TEST_DECLARE   (tcp_close_reset_accepted)
+TEST_DECLARE   (tcp_close_reset_accepted_after_shutdown)
+TEST_DECLARE   (tcp_close_reset_client)
+TEST_DECLARE   (tcp_close_reset_client_after_shutdown)
 TEST_DECLARE   (tcp_create_early)
 TEST_DECLARE   (tcp_create_early_bad_bind)
 TEST_DECLARE   (tcp_create_early_bad_domain)
@@ -624,6 +628,10 @@ TASK_LIST_START
   TEST_ENTRY  (tcp_connect_timeout)
   TEST_ENTRY  (tcp_close_while_connecting)
   TEST_ENTRY  (tcp_close)
+  TEST_ENTRY  (tcp_close_reset_accepted)
+  TEST_ENTRY  (tcp_close_reset_accepted_after_shutdown)
+  TEST_ENTRY  (tcp_close_reset_client)
+  TEST_ENTRY  (tcp_close_reset_client_after_shutdown)
   TEST_ENTRY  (tcp_create_early)
   TEST_ENTRY  (tcp_create_early_bad_bind)
   TEST_ENTRY  (tcp_create_early_bad_domain)

test/test-tcp-bind-error.c

@@ -239,11 +239,7 @@ TEST_IMPL(tcp_bind_writable_flags) {
   r = uv_write(&write_req, (uv_stream_t*) &server, &buf, 1, NULL);
   ASSERT(r == UV_EPIPE);
   r = uv_shutdown(&shutdown_req, (uv_stream_t*) &server, NULL);
-#ifdef _WIN32
-  ASSERT(r == UV_EPIPE);
-#else
   ASSERT(r == UV_ENOTCONN);
-#endif
   r = uv_read_start((uv_stream_t*) &server, NULL, NULL);
   ASSERT(r == UV_ENOTCONN);
 

test/test-tcp-close-reset.c

@@ -0,0 +1,289 @@
+/* Copyright libuv project contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "uv.h"
+#include "task.h"
+
+#include <errno.h>
+#include <string.h> /* memset */
+
+static uv_loop_t* loop;
+static uv_tcp_t tcp_server;
+static uv_tcp_t tcp_client;
+static uv_tcp_t tcp_accepted;
+static uv_connect_t connect_req;
+static uv_shutdown_t shutdown_req;
+static uv_write_t write_reqs[4];
+
+static int client_close;
+static int shutdown_before_close;
+
+static int write_cb_called;
+static int close_cb_called;
+static int shutdown_cb_called;
+
+static void connect_cb(uv_connect_t* req, int status);
+static void write_cb(uv_write_t* req, int status);
+static void close_cb(uv_handle_t* handle);
+static void shutdown_cb(uv_shutdown_t* req, int status);
+
+static int read_size;
+
+
+static void do_write(uv_tcp_t* handle) {
+  uv_buf_t buf;
+  int i, r;
+
+  buf = uv_buf_init("PING", 4);
+  for (i = 0; i < ARRAY_SIZE(write_reqs); i++) {
+    r = uv_write(&write_reqs[i], (uv_stream_t*) handle, &buf, 1, write_cb);
+    ASSERT(r == 0);
+  }
+}
+
+
+static void do_close(uv_tcp_t* handle) {
+  if (shutdown_before_close == 1) {
+    ASSERT(0 == uv_shutdown(&shutdown_req, (uv_stream_t*) handle, shutdown_cb));
+    ASSERT(UV_EINVAL == uv_tcp_close_reset(handle, close_cb));
+  } else {
+    ASSERT(0 == uv_tcp_close_reset(handle, close_cb));
+    ASSERT(UV_ENOTCONN == uv_shutdown(&shutdown_req, (uv_stream_t*) handle, shutdown_cb));
+  }
+
+  uv_close((uv_handle_t*) &tcp_server, NULL);
+}
+
+static void alloc_cb(uv_handle_t* handle, size_t size, uv_buf_t* buf) {
+  static char slab[1024];
+  buf->base = slab;
+  buf->len = sizeof(slab);
+}
+
+static void read_cb2(uv_stream_t* stream, ssize_t nread, const uv_buf_t* buf) {
+  ASSERT((uv_tcp_t*)stream == &tcp_client);
+  if (nread == UV_EOF)
+    uv_close((uv_handle_t*) stream, NULL);
+}
+
+
+static void connect_cb(uv_connect_t* conn_req, int status) {
+  ASSERT(conn_req == &connect_req);
+  uv_read_start((uv_stream_t*) &tcp_client, alloc_cb, read_cb2);
+  do_write(&tcp_client);
+  if (client_close)
+    do_close(&tcp_client);
+}
+
+
+static void write_cb(uv_write_t* req, int status) {
+  /* write callbacks should run before the close callback */
+  ASSERT(close_cb_called == 0);
+  ASSERT(req->handle == (uv_stream_t*)&tcp_client);
+  write_cb_called++;
+}
+
+
+static void close_cb(uv_handle_t* handle) {
+  if (client_close)
+    ASSERT(handle == (uv_handle_t*) &tcp_client);
+  else
+    ASSERT(handle == (uv_handle_t*) &tcp_accepted);
+
+  close_cb_called++;
+}
+
+static void shutdown_cb(uv_shutdown_t* req, int status) {
+  if (client_close)
+    ASSERT(req->handle == (uv_stream_t*) &tcp_client);
+  else
+    ASSERT(req->handle == (uv_stream_t*) &tcp_accepted);
+
+  shutdown_cb_called++;
+}
+
+
+static void read_cb(uv_stream_t* stream, ssize_t nread, const uv_buf_t* buf) {
+  ASSERT((uv_tcp_t*)stream == &tcp_accepted);
+  if (nread < 0) {
+    uv_close((uv_handle_t*) stream, NULL);
+  } else {
+    read_size += nread;
+    if (read_size == 16 && client_close == 0)
+      do_close(&tcp_accepted);
+  }
+}
+
+
+static void connection_cb(uv_stream_t* server, int status) {
+  ASSERT(status == 0);
+
+  ASSERT(0 == uv_tcp_init(loop, &tcp_accepted));
+  ASSERT(0 == uv_accept(server, (uv_stream_t*) &tcp_accepted));
+
+  uv_read_start((uv_stream_t*) &tcp_accepted, alloc_cb, read_cb);
+}
+
+
+static void start_server(uv_loop_t* loop, uv_tcp_t* handle) {
+  struct sockaddr_in addr;
+  int r;
+
+  ASSERT(0 == uv_ip4_addr("127.0.0.1", TEST_PORT, &addr));
+
+  r = uv_tcp_init(loop, handle);
+  ASSERT(r == 0);
+
+  r = uv_tcp_bind(handle, (const struct sockaddr*) &addr, 0);
+  ASSERT(r == 0);
+
+  r = uv_listen((uv_stream_t*)handle, 128, connection_cb);
+  ASSERT(r == 0);
+}
+
+
+static void do_connect(uv_loop_t* loop, uv_tcp_t* tcp_client) {
+  struct sockaddr_in addr;
+  int r;
+
+  ASSERT(0 == uv_ip4_addr("127.0.0.1", TEST_PORT, &addr));
+
+  r = uv_tcp_init(loop, tcp_client);
+  ASSERT(r == 0);
+
+  r = uv_tcp_connect(&connect_req,
+                     tcp_client,
+                     (const struct sockaddr*) &addr,
+                     connect_cb);
+  ASSERT(r == 0);
+}
+
+
+/* Check that pending write requests have their callbacks
+ * invoked when the handle is closed.
+ */
+TEST_IMPL(tcp_close_reset_client) {
+  int r;
+
+  loop = uv_default_loop();
+
+  start_server(loop, &tcp_server);
+
+  client_close = 1;
+  shutdown_before_close = 0;
+
+  do_connect(loop, &tcp_client);
+
+  ASSERT(write_cb_called == 0);
+  ASSERT(close_cb_called == 0);
+  ASSERT(shutdown_cb_called == 0);
+
+  r = uv_run(loop, UV_RUN_DEFAULT);
+  ASSERT(r == 0);
+
+  ASSERT(write_cb_called == 4);
+  ASSERT(close_cb_called == 1);
+  ASSERT(shutdown_cb_called == 0);
+
+  MAKE_VALGRIND_HAPPY();
+  return 0;
+}
+
+TEST_IMPL(tcp_close_reset_client_after_shutdown) {
+  int r;
+
+  loop = uv_default_loop();
+
+  start_server(loop, &tcp_server);
+
+  client_close = 1;
+  shutdown_before_close = 1;
+
+  do_connect(loop, &tcp_client);
+
+  ASSERT(write_cb_called == 0);
+  ASSERT(close_cb_called == 0);
+  ASSERT(shutdown_cb_called == 0);
+
+  r = uv_run(loop, UV_RUN_DEFAULT);
+  ASSERT(r == 0);
+
+  ASSERT(write_cb_called == 4);
+  ASSERT(close_cb_called == 0);
+  ASSERT(shutdown_cb_called == 1);
+
+  MAKE_VALGRIND_HAPPY();
+  return 0;
+}
+
+TEST_IMPL(tcp_close_reset_accepted) {
+  int r;
+
+  loop = uv_default_loop();
+
+  start_server(loop, &tcp_server);
+
+  client_close = 0;
+  shutdown_before_close = 0;
+
+  do_connect(loop, &tcp_client);
+
+  ASSERT(write_cb_called == 0);
+  ASSERT(close_cb_called == 0);
+  ASSERT(shutdown_cb_called == 0);
+
+  r = uv_run(loop, UV_RUN_DEFAULT);
+  ASSERT(r == 0);
+
+  ASSERT(write_cb_called == 4);
+  ASSERT(close_cb_called == 1);
+  ASSERT(shutdown_cb_called == 0);
+
+  MAKE_VALGRIND_HAPPY();
+  return 0;
+}
+
+TEST_IMPL(tcp_close_reset_accepted_after_shutdown) {
+  int r;
+
+  loop = uv_default_loop();
+
+  start_server(loop, &tcp_server);
+
+  client_close = 0;
+  shutdown_before_close = 1;
+
+  do_connect(loop, &tcp_client);
+
+  ASSERT(write_cb_called == 0);
+  ASSERT(close_cb_called == 0);
+  ASSERT(shutdown_cb_called == 0);
+
+  r = uv_run(loop, UV_RUN_DEFAULT);
+  ASSERT(r == 0);
+
+  ASSERT(write_cb_called == 4);
+  ASSERT(close_cb_called == 0);
+  ASSERT(shutdown_cb_called == 1);
+
+  MAKE_VALGRIND_HAPPY();
+  return 0;
+}

test/test.gyp

@@ -109,6 +109,7 @@
         'test-tcp-bind6-error.c',
         'test-tcp-close.c',
         'test-tcp-close-accept.c',
+        'test-tcp-close-reset.c',
         'test-tcp-close-while-connecting.c',
         'test-tcp-create-socket-early.c',
         'test-tcp-connect-error-after-write.c',