04 MU class Network "Attack on node. JS Foundation (i)" HTTP explanation

HTTP: Communication protocol

Process Overview:

HTTP client originating request, creating port default 8080

HTTP server listens for client requests on port

HTTP server returns status and content to client

A little more detailed analysis:

1. Domain Name resolution: Browser Search for its own DNS buffer, to see if there is a requested domain name defined by the IP, buffer 1 minutes

# # Google Browser input:
Chrome://net-internals/#dns

2. Search for DNS buffering of the operating system itself (no browser buffering or invalidation)

3. Read the local Host file

C:\Windows\System32\drivers\etc

4. Browser initiates a DNS call to the system

-Broadband carrier server view itself cache

-The carrier server initiates a request for DNS resolution from an iteration (starting with the IP corresponding to the domain name)

The carrier server caches the resulting IP back to the operating system core

The operating system kernel sends IP back to the browser

The final browser gets the IP address of the domain name

5. After the browser obtains the domain name corresponding IP, initiates the HTTP " three times Handshake "

-the browser's random port (8080) sends a TCP connection request to the server,

The request passes through the routing device, the network card, the TCP/IP protocol stack of the kernel, and the firewall eventually arrives at the Web server

After the 6.TCP/IP connection is established, the browser sends an HTTP request to the server

-for example, use the Get method of HTTP to request the domain name of a root domain, rest can use HTTP 1.0 protocol

7. The server side receives the request, according to the path parameter, passes through the backend processing, returns the result data to the browser;

-If the page is the full HTML page code will be returned to the browser

8. The browser gets the HTML page code and starts parsing and rendering

-HTML page of JS, CSS, pictures and other static resources also need to go through a HTTP request to repeat the above steps to obtain

9. The browser combines HTML and static resources to render the full page

Requests and responses

The entire process of HTTP can be summed up as a request and response two parts

Both will send HTTP headers and body information

HTTP Header

Additional Information: Content type, Server send response date, HTTP status code

Body Information

User-submitted form data, or the returned data

Request method for HTTP

Get: GET, read data

POST: Submitting data to a specified resource

PUT: Update

Delete: Remove

HEAD: Similar to get, the server does not return all data

Status code

1xx	The identity request is accepted
2xx	The request was successfully accepted and disposed of
3xx	redirect
4xx	Client Error
5xx	Server-side Error

Common Status Codes

200	Client request succeeded
400	Client request has syntax and other errors, server side does not understand
60s	Request not authorized
403	Server-side deny, due to permissions and other reasons
404	Resource not Found
500	Unexpected error on server side
503	The server is currently unable to process, maybe sometime

04 MU class Network "Attack on node. JS Foundation (i)" HTTP explanation