Request Pseudo-Header Fields / 请求的伪首部字段

The following pseudo-header fields are defined for HTTP/2 requests:

• The :method pseudo-header field includes the HTTP method ([RFC7231], Section 4).

• The :scheme pseudo-header field includes the scheme portion of the target URI ([RFC3986], Section 3.1).

  :scheme is not restricted to http and https schemed URIs. A proxy or gateway can translate requests for non-HTTP schemes, enabling the use of HTTP to interact with non-HTTP services.

• The :authority pseudo-header field includes the authority portion of the target URI ([RFC3986], Section 3.2). The authority MUST NOT include the deprecated userinfo subcomponent for http or https schemed URIs.

  To ensure that the HTTP/1.1 request line can be reproduced accurately, this pseudo-header field MUST be omitted when translating from an HTTP/1.1 request that has a request target in origin or asterisk form (see [RFC7230], Section 5.3). Clients that generate HTTP/2 requests directly SHOULD use the :authority pseudo-header field instead of the Host header field. An intermediary that converts an HTTP/2 request to HTTP/1.1 MUST create a Host header field if one is not present in a request by copying the value of the :authority pseudo-header field.

• The :path pseudo-header field includes the path and query parts of the target URI (the path-absolute production and optionally a '?' character followed by the query production (see Sections 3.3 and 3.4 of [RFC3986]). A request in asterisk form includes the value '*' for the :path pseudo-header field.

  This pseudo-header field MUST NOT be empty for http or https URIs; http or https URIs that do not contain a path component MUST include a value of '/'. The exception to this rule is an OPTIONS request for an http or https URI that does not include a path component; these MUST include a :path pseudo-header field with a value of '*' (see [RFC7230], Section 5.3.4).

HTTP/2请求定义了如下伪首部字段：

• :method 伪首部字段包含HTTP方法( [RFC7231]，第4章 )。

• :scheme 伪首部字段包含目标URI( [RFC3986]，3.1节 )的方案部分。

  :scheme并不局限于http和https URIs方案。代理或网关可以转化非HTTP方案的请求，从而可以使用HTTP和非HTTP的服务进行交互。

• :authority伪首部字段包含目标URI( [RFC3986]，3.2节 )的authority部分。authority不能包含http或https URIs方案废弃的用户信息的子组件。

  为了确保HTTP/1.1请求队列可以被精确地复制，当转换具有源或星号形式(参见 [RFC7230], 5.3节 )请求目标的HTTP/1.1请求时，该伪首部字段必须被忽略。直接生成HTTP/2请求的客户端应该使用:authority伪首部字段代替Host首部字段。中介将HTTP/2请求转换为HTTP/1.1请求时，如果通过拷贝:authority伪首部字段的值，请求里没有出现Host首部字段，就必须创建一个Host首部字段。

• :path伪首部字段包含目标URI的path和query部分(绝对路径部分和一个后跟query部分的可选的'?'字符(参见 [RFC3986] 的 3.3节 和 3.4节 ))。星号形式的请求包含:path伪首部字段的'*'值。

  对于http或者https URIs，该伪首部字段不能为空。不包含path组件的http或https URIs必须包含一个'/'值。该规则的例外情况是OPTIONS请求，其http或https URI不包含path组件，此时必须包含一个值为'*'的:path伪首部字段(参见 [RFC7230]， 5.3.4节 )。

All HTTP/2 requests MUST include exactly one valid value for the :method, :scheme, and :path pseudo-header fields, unless it is a CONNECT request (Section 8.3). An HTTP request that omits mandatory pseudo-header fields is malformed (Section 8.1.2.6).

除非是CONNECT请求( 8.3节 )，否则对于:method、:scheme和:path伪首部字段，所有的HTTP/2请求都必须只包含一个有效值。忽略了强制的伪首部字段的HTTP请求是有缺陷的( 8.1.2.6节 )。

HTTP/2 does not define a way to carry the version identifier that is included in the HTTP/1.1 request line.

HTTP/2没有定义携带HTTP/1.1请求行里包含的版本号的方法。