客户端必须在它发送到服务器的全部帧中添加掩码（Mask）

 

在WebSocket协议中，数据是经过一系列数据帧来进行传输的。为了不因为网络中介（例如一些拦截代理）或者一些在第10.3节讨论的安全缘由，客户端必须在它发送到服务器的全部帧中添加掩码（Mask）（具体细节见5.3节）。（注意：不管WebSocket协议是否使用了TLS，帧都须要添加掩码）。服务端收到没有添加掩码的数据帧之后，必须当即关闭链接。在这种状况下，服务端能够发送一个在7.4.1节定义的状态码为1002（协议错误）的关闭帧。服务端禁止在发送数据帧给客户端时添加掩码。客户端若是收到了一个添加了掩码的帧，必须当即关闭链接。在这种状况下，它可使用第7.4.1节定义的1002（协议错误）状态码。（这些规则可能会在未来的规范中放开）。

基础的数据帧协议使用操做码、有效负载长度和在“有效负载数据”中定义的放置“扩展数据”与“引用数据”的指定位置来定义帧类型。特定的bit位和操做码为未来的协议扩展作了保留。

一个数据帧能够在开始握手完成以后和终端发送了一个关闭帧以前的任意一个时间经过客户端或者服务端进行传输（第5.5.1节）。

 

 

5. Data Framing

5.1. Overview

 In the WebSocket Protocol, data is transmitted using a sequence of frames. To avoid confusing network intermediaries (such as intercepting proxies) and for security reasons that are further discussed in Section 10.3, a client MUST mask all frames that it sends to the server (see Section 5.3 for further details). (Note that masking is done whether or not the WebSocket Protocol is running over TLS.) The server MUST close the connection upon receiving a frame that is not masked. In this case, a server MAY send a Close frame with a status code of 1002 (protocol error) as defined in Section 7.4.1. A server MUST NOT mask any frames that it sends to the client. A client MUST close a connection if it detects a masked frame. In this case, it MAY use the status code 1002 (protocol error) as defined in Section 7.4.1. (These rules might be relaxed in a future specification.) The base framing protocol defines a frame type with an opcode, a payload length, and designated locations for "Extension data" and "Application data", which together define the "Payload data". Certain bits and opcodes are reserved for future expansion of the protocol. Fette & Melnikov Standards Track [Page 27]

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RFC 6455                 The WebSocket Protocol            December 2011


   A data frame MAY be transmitted by either the client or the server at
   any time after opening handshake completion and before that endpoint
   has sent a Close frame (Section 5.5.1).

 

RFC 6455 - The WebSocket Protocol https://tools.ietf.org/html/rfc6455#section-5.1