网络协议 - ABNF表示的http协议

桃扇骨 2022-11-14 14:41 213阅读 0赞

## ABNF ##

使用ABNF描述http的请求和响应，需要几个要素：

1.  start-line
2.  `*`
3.  header-filed
4.  CRLF
5.  SP
6.  message-body
7.  \[\]
8.  OWS

1. start-line: request-line / status-line
    2. * 代表一个或者多个
    3. header-field 代表请求头/响应头字段
    4. CRLF 代表换行/回车 在mac系统中，CR代表换行，linux系统中LF代表换行，在windows中CRLF代表换行
    5. SP 代表空格
    6. message-body 代表请求/响应内容
    7. [] 代表可选，即可有可无
    8. OWS 代表空格或者制表符

表现http的ABNF

HTTP-message = start-line*(head-field CRLF)CRLF[message-body]
    * start-line = request-line/status-line
    	* request-line = method SP request-target SP HTTP-version CRLF
    	* status-line = HTTP-version SP status-code SP reason-phrase CRLF
    * header-field = field-name:OWS field-value OWS
    	* OWS = (SP / HTAB)
    	* field-name = token
    	* field-value = *(field-content / obs-fold)
    * message-body = *OCTET
    
    // 
    OCTET 代表二进制数据

## http request ##

// http request使用ABNF的表示方式
    request-line *(head-field CRLF)CRLF [message-body]
    
    // 示例
    GET www.baidu.com HTTP/1.1
    Remote Address: 182.61.200.7:443
    Referrer Policy: unsafe-url

## http response ##

// http response使用ABNF的表示形式
    status-line *(head-field CRLF)CRLF [message-body]
    
    // 示例
    HTTP/1.1 400 Bad Request
    Server: openresty/1.19.3.1
    Date: Mon, 29 Mar 2021 15:09:39 GMT
    Content-Type: text/html
    Content-Length: 163
    Connection: close
    
    <html>
    <head><title>400 Bad Request</title></head>
    <body>
    <center><h1>400 Bad Request</h1></center>
    <hr><center>openresty/1.19.3.1</center>
    </body>
    </html>