http协议：request 和 response包组成

Request = Request-Line;

                 *((general-header|request-header|entity-header)CRLF);

                  CRLF

                 [message-body];

解析：（正则表达式语法结构）

1、request请求包的起始为请求行（Request-Line）

2、接着可以出现0个或者多个的general-header,request-header,entity-header。

顺序无关，但一般都按照以上顺序组成。

3、http的header都是键值对，以CRLF（回车换行）结束

4、三个header的区域以一个空行即CRLF结束

5、接着就是可选的message-body了

 

example:

GET /index.html HTTP/1.1
Accept:*?*
Accept-Language: zh-cn
User-Agent: Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)
Host:192.168.0.119
Connection: Keep-Alive

 

 

Response = Status-Line;

                    *((general-header|response-header|entity-header)CRLF);

                    CRLF

                 [message-body];

解析：同上

 以上就是request和response的组成结构了，下面解析其各个元素，

general-header = Cache-Control; |Connection; |Date; |Pragma; |Triler; |Transfe-Encoding; |Upgrade; |Via; |Warning; entity-header = Allow; |Content-Encoding; |Content-Language; |Content-Lenght; |Content-Location; |Content-MD5; |Content-Range; |Content-Type; |Expires; |Last_Modified; |extension-header; request-header = Accept |Accept-Charset |Accept-Encoding; |Accept-Language; |Authorization; |Expect; |From; |Host; |If-Match; |If-Modified-Since; ... |User-Agent; Request-Line = Method SP Request-URI SP HTTP-Version CRLF response-header = Accept-Ranges; |Age; |ETag; |Location; |Roxy-Authenticate; |Retry-After; |Server; |Vary; |WWW/Authenticate; Status-Line = HTTP-Version SP Status-Code SP Reason-Phrase CRLF