request message: request method, request URI, protocol version, optional request header fields and content entities
Method URI Protocol Version POST /form/entry HTTP/1.1 request header fields Host: hacke.jp Connection: keep-live Content-type:application/x-www-form-urlencoded Content-Length: 16 content entity name=ueno&age=37
Response message: protocol version, status code, reason phrase to explain the status, optional response header fields, entity body
2, Http stateless protocol, requests or responses sent by Du Yu are not persistent.
3. Three-way handshake The
sender first sends a data packet with the SYN flag to the other party.
After receiving it, the receiver sends back a data packet with the SYN/ACK flag to convey confirmation information.
The sender sends back a data packet with an ACK flag, which means the end of the "handshake".
4. Status code category
1XX Informational status code The received request is being processed
2XX Sucess success status code The request is processed normally
3XX Redirection redirection status code requires additional operations to complete the request
4XX Client Error Client error status code The server cannot process the request
5XX Server Error Server Error Status Code Server processing request error
301 Permanent redirect
302 Temporary redirect
5. HTTP header field type:
common header field The header used by both request and response messages.
The request header field is the field used in the request message sent from the client to the server, and is used to supplement the additional information of the request, the new client, and the priority related to the response content.
The response header field is the field used in the response message returned by the server to the client, and is used to supplement the additional information of the response, the server information, and the additional requirements of the client.
The entity header field contains the headers used by the entity part in the request message and the response message, and is used to supplement the update time of the content and other entity-related information.
6. Inadequacy of http: The
communication uses clear text (not encrypted), and the content may be viewed.
The identity of the communication defense is not verified, so it may be spoofed.
The integrity of the message cannot be proven, so it may have been tampered with.
7. HTTP + encryption + authentication + integrity protection = HTTPS
HTTP
http: application (HTTP) TCP IP
https: application (HTTP) SSL TCP IP