dabreadman/go-web-proxy

A simple web proxy in Go

go-web-proxy

A simple web proxy server implemented in Golang.

Features

• HTTP Caching
  The proxy caches HTTP response to save time and bandwidth. Expires every 90 seconds.
  This is usually done on your browser.
• Blocklist
  The proxy maintains a blocklist to stop requests to specified URLs.

Read more about the proxy here.

Flowchart

Use

^{Please make sure Go is present.}

1. Clone go-web-proxy git clone https://github.com/dabreadman/go-web-proxy.git.
2. Run go run proxy.go. This will serve the proxy server on 127.0.0.1:8080.

These are several commands to use for the proxy CLI.

• list
  This command lists all the domains that is in the blocklist.
• block <domain>
  This blocks any request to domain as host. E.g. domain, or domain/some/url
• unblock <domain>
  This remove entry of domain from the blocklist, unblocking requests to domain.
• saved
  This command lists the bandwidth and time saved from using the HTTP cache.

Development

What's important to understand is that go <func> creates a thread of func, making it non-blocking.

The program is mainly consisted in proxy.go.

The program starts from main.

networkHandler := http.HandlerFunc(networkHandler)
http.ListenAndServe(":8080", networkHandler)

This serves a listener to port 8080, and assign a networkHandler for every connection to the port.

networkHandler handles blocking, and calls to httpHandler or httpsHandler depending on the request method. A HTTPS request has a CONNECT method.

httpsHandler establish a connection to both the client and the server, and forward connections, forming a HTTPS tunnel.

httpHandler checks if a HTTP request is cached, If it is cached, a request with If-Modified-Since header is sent to the server.

• A 200 (OK) will indicate that the cache is now unusable, and new response will be pass to the proxy, which will pass to the client and cache the response. A cache killer is hired to kill the cache in CACHE_EXPIRY time if it was not updated, indicated by the date property.

• A 304 (Not Modified) will be returned if cache is still usable, in which the cached response will be forwarded to the client. As a 304 response does not carry body, it saves bandwidth and time as connection between intranet (proxy to client) is significantly faster than connection between internet (proxy to server).

CLIhandler reads input from os.Stdin, and parse it to perform operations based on the input arguments.
I removed \r\n from input as this was developed on Windows environment. For Linux, remove \n instead.

colorOutput colors the terminal output by surrounding strings with special characters.
Read more here
\e is replaced with \033 in this program.
Read more about the difference between the two here.

_{Unit test is still in shambles}