This is a simple proxy, which gave me the excuse of embedding lua in a Rust. This, by no means, is production ready, and it is under heavy development.

The simple idea behind the proxy is to kind of act as a middle man, which can inspect and change the Request from the client and the Response from the server.

git clone "https://github.com/omer-biz/amica.git"
cd amica
cargo run

cargo run -- --help

Usage: amica [OPTIONS]

Options:
  -f, --filter-script <lua script>  Optional lua script to run on the the intermediate request and response
  -a, --address <ip:port>           Address to bind to
  -p, --pool-number <pool number>   Number of Proxy pools to spawn. By default it's 1
  -v, --verbose                     Verbosity. if turned on shows the request and response as they are happening for `http` requests
  -h, --help                        Print help

The lua file must contain two functions with exactly the following signature

function on_http_request(req)
  -- getters
  req:uri() 
  req:method() 
  req:body() 
  req:headers() -- request headers as lua tables.

  -- setters
  req:set_uri("http://duckduckgo.com") -- https doesn't work.
  req:set_method("POST")

  -- updates the header value`Content-Length` automatically.
  req:set_body("<h1>Hello from Amica</h1>" .. req:body()) 
  req:set_header("Host", "duckduckgo.com")

  return req
end

function on_http_response(res)
  -- getters
  res:body() -- string
  res:headers() -- table
  res:status() -- number

  -- setters
  res:set_status(500)
  -- updates the header value`Content-Length` automatically.
  res:set_body("<h1>Hello from Amica</h1>" .. req:body()) 
  res:set_header("location", "duckduckgo.com")

  return res
end

The method defined on req and res are provided by amica and can be used to inspect and change the Request from the client with req, and Response from the server with res.

• on_http_request is called on the client's Request, and
• 'on_http_response' is called on the server's Response.

Assume you want every request that is targeted at google.com to be redirected to duckduckgo.com. To do that first we create a script, let's call it no_google.lua, in the current directory with the following content.

function on_http_request(req)
  -- TODO: regex
  if req:uri() == "http://google.com/" then
    req:set_uri("http://duckduckgo.com")
  end

  return req
end

Second run the app like this.

cargo run -- -v --filter-script no_google.lua
Listening on 127.0.0.1:9001

Finally direct your clients to this address for example with curl.

curl -vv google.com --proxy 127.0.0.1:9001
...
> location: https://duckduckgo.com/
...

you can see the response is trying to redirect us to duckduckgo.com as well as making us use https.

Any help is appreciated, just submit a PR or open an issue.