1 2.. _tcp: 3 4:c:type:`uv_tcp_t` --- TCP handle 5================================= 6 7TCP handles are used to represent both TCP streams and servers. 8 9:c:type:`uv_tcp_t` is a 'subclass' of :c:type:`uv_stream_t`. 10 11 12Data types 13---------- 14 15.. c:type:: uv_tcp_t 16 17 TCP handle type. 18 19.. c:enum:: uv_tcp_flags 20 21 Flags used in :c:func:`uv_tcp_bind`. 22 23 :: 24 25 enum uv_tcp_flags { 26 /* Used with uv_tcp_bind, when an IPv6 address is used. */ 27 UV_TCP_IPV6ONLY = 1, 28 29 /* Enable SO_REUSEPORT socket option when binding the handle. 30 * This allows completely duplicate bindings by multiple processes 31 * or threads if they all set SO_REUSEPORT before binding the port. 32 * Incoming connections are distributed across the participating 33 * listener sockets. 34 * 35 * This flag is available only on Linux 3.9+, DragonFlyBSD 3.6+, 36 * FreeBSD 12.0+, Solaris 11.4, and AIX 7.2.5+ for now. 37 */ 38 UV_TCP_REUSEPORT = 2, 39 }; 40 41 42Public members 43^^^^^^^^^^^^^^ 44 45N/A 46 47.. seealso:: The :c:type:`uv_stream_t` members also apply. 48 49 50API 51--- 52 53.. c:function:: int uv_tcp_init(uv_loop_t* loop, uv_tcp_t* handle) 54 55 Initialize the handle. No socket is created as of yet. 56 57.. c:function:: int uv_tcp_init_ex(uv_loop_t* loop, uv_tcp_t* handle, unsigned int flags) 58 59 Initialize the handle with the specified flags. At the moment only the lower 8 bits 60 of the `flags` parameter are used as the socket domain. A socket will be created 61 for the given domain. If the specified domain is ``AF_UNSPEC`` no socket is created, 62 just like :c:func:`uv_tcp_init`. 63 64 .. versionadded:: 1.7.0 65 66.. c:function:: int uv_tcp_open(uv_tcp_t* handle, uv_os_sock_t sock) 67 68 Open an existing file descriptor or SOCKET as a TCP handle. 69 70 .. versionchanged:: 1.2.1 the file descriptor is set to non-blocking mode. 71 72 .. note:: 73 The passed file descriptor or SOCKET is not checked for its type, but 74 it's required that it represents a valid stream socket. 75 76.. c:function:: int uv_tcp_nodelay(uv_tcp_t* handle, int enable) 77 78 Enable `TCP_NODELAY`, which disables Nagle's algorithm. 79 80.. c:function:: int uv_tcp_keepalive(uv_tcp_t* handle, int enable, unsigned int delay) 81 82 Enable / disable TCP keep-alive. `delay` is the initial delay in seconds, 83 ignored when `enable` is zero. 84 85 After `delay` has been reached, 10 successive probes, each spaced 1 second 86 from the previous one, will still happen. If the connection is still lost 87 at the end of this procedure, then the handle is destroyed with a 88 ``UV_ETIMEDOUT`` error passed to the corresponding callback. 89 90 If `delay` is less than 1 then ``UV_EINVAL`` is returned. 91 92 .. versionchanged:: 1.49.0 If `delay` is less than 1 then ``UV_EINVAL``` is returned. 93 94.. c:function:: int uv_tcp_simultaneous_accepts(uv_tcp_t* handle, int enable) 95 96 Enable / disable simultaneous asynchronous accept requests that are 97 queued by the operating system when listening for new TCP connections. 98 99 This setting is used to tune a TCP server for the desired performance. 100 Having simultaneous accepts can significantly improve the rate of accepting 101 connections (which is why it is enabled by default) but may lead to uneven 102 load distribution in multi-process setups. 103 104.. c:function:: int uv_tcp_bind(uv_tcp_t* handle, const struct sockaddr* addr, unsigned int flags) 105 106 Bind the handle to an address and port. 107 108 When the port is already taken, you can expect to see an ``UV_EADDRINUSE`` 109 error from :c:func:`uv_listen` or :c:func:`uv_tcp_connect` unless you specify 110 ``UV_TCP_REUSEPORT`` in `flags` for all the binding sockets. That is, a successful 111 call to this function does not guarantee that the call to :c:func:`uv_listen` or 112 :c:func:`uv_tcp_connect` will succeed as well. 113 114 :param handle: TCP handle. It should have been initialized with :c:func:`uv_tcp_init`. 115 116 :param addr: Address to bind to. It should point to an initialized ``struct sockaddr_in`` 117 or ``struct sockaddr_in6``. 118 119 :param flags: Flags that control the behavior of binding the socket. 120 ``UV_TCP_IPV6ONLY`` can be contained in `flags` to disable dual-stack 121 support and only use IPv6. 122 ``UV_TCP_REUSEPORT`` can be contained in `flags` to enable the socket option 123 `SO_REUSEPORT` with the capability of load balancing that distribute incoming 124 connections across all listening sockets in multiple processes or threads. 125 126 :returns: 0 on success, or an error code < 0 on failure. 127 128 .. versionchanged:: 1.49.0 added the ``UV_TCP_REUSEPORT`` flag. 129 130 .. note:: 131 ``UV_TCP_REUSEPORT`` flag is available only on Linux 3.9+, DragonFlyBSD 3.6+, 132 FreeBSD 12.0+, Solaris 11.4, and AIX 7.2.5+ at the moment. On other platforms 133 this function will return an UV_ENOTSUP error. 134 135.. c:function:: int uv_tcp_getsockname(const uv_tcp_t* handle, struct sockaddr* name, int* namelen) 136 137 Get the current address to which the handle is bound. `name` must point to 138 a valid and big enough chunk of memory, ``struct sockaddr_storage`` is 139 recommended for IPv4 and IPv6 support. 140 141.. c:function:: int uv_tcp_getpeername(const uv_tcp_t* handle, struct sockaddr* name, int* namelen) 142 143 Get the address of the peer connected to the handle. `name` must point to 144 a valid and big enough chunk of memory, ``struct sockaddr_storage`` is 145 recommended for IPv4 and IPv6 support. 146 147.. c:function:: int uv_tcp_connect(uv_connect_t* req, uv_tcp_t* handle, const struct sockaddr* addr, uv_connect_cb cb) 148 149 Establish an IPv4 or IPv6 TCP connection. Provide an initialized TCP handle 150 and an uninitialized :c:type:`uv_connect_t`. `addr` should point to an 151 initialized ``struct sockaddr_in`` or ``struct sockaddr_in6``. 152 153 On Windows if the `addr` is initialized to point to an unspecified address 154 (``0.0.0.0`` or ``::``) it will be changed to point to ``localhost``. 155 This is done to match the behavior of Linux systems. 156 157 The callback is made when the connection has been established or when a 158 connection error happened. 159 160 .. versionchanged:: 1.19.0 added ``0.0.0.0`` and ``::`` to ``localhost`` 161 mapping 162 163.. seealso:: The :c:type:`uv_stream_t` API functions also apply. 164 165.. c:function:: int uv_tcp_close_reset(uv_tcp_t* handle, uv_close_cb close_cb) 166 167 Resets a TCP connection by sending a RST packet. This is accomplished by 168 setting the `SO_LINGER` socket option with a linger interval of zero and 169 then calling :c:func:`uv_close`. 170 Due to some platform inconsistencies, mixing of :c:func:`uv_shutdown` and 171 :c:func:`uv_tcp_close_reset` calls is not allowed. 172 173 .. versionadded:: 1.32.0 174 175.. c:function:: int uv_socketpair(int type, int protocol, uv_os_sock_t socket_vector[2], int flags0, int flags1) 176 177 Create a pair of connected sockets with the specified properties. 178 The resulting handles can be passed to `uv_tcp_open`, used with `uv_spawn`, 179 or for any other purpose. 180 181 Valid values for `flags0` and `flags1` are: 182 183 - UV_NONBLOCK_PIPE: Opens the specified socket handle for `OVERLAPPED` 184 or `FIONBIO`/`O_NONBLOCK` I/O usage. 185 This is recommended for handles that will be used by libuv, 186 and not usually recommended otherwise. 187 188 Equivalent to :man:`socketpair(2)` with a domain of AF_UNIX. 189 190 .. versionadded:: 1.41.0 191
