Proxy SOCKS support

[linkdd]

Problem to solve

ssh -D8080 user@host

curl --socks5 localhost:8080 https://httpbin.org/anything

Proposal

~In the [Options] section, the proxy field should be a URL, such as:~

• http://localhost:8012
• socks5://localhost:8012
• ...

~The scheme of the URL could then be used to determine the type of proxy (no scheme would default to HTTP for backward compatibility) we want to connect to.~

~Then, we should be able to connect to SOCKS proxy as demonstrated with cURL above.~

EDIT: Let's add instead a sock5 request option with the host and port of the SOCKS proxy to use.

Additional context and resources

We are using Hurl to implement the test suite of a Reverse Proxy service we provide in our infrastructure. Its configuration is pulled from Netbox. One feature is the Access Control Lists, which translates to the following NGINX configuration:

server {
  # ...

  location / {
    # ...

    deny 192.168.2.0/24;
    allow all;

    # ...
  }

  # ...
}

The test we want to execute is the following:

# Rejection when coming from 192.168.2.0/24
GET https://example.com

HTTP 403

# No rejection when coming from 127.0.0.1/8
GET https://example.com
[Options]
socks5: localhost:8012

HTTP 200

Tasks to complete

• [x] ~Support URLs in proxy request option~
• [ ] Add socks5 request option
• [ ] Support Proxy SOCKS protocol

[jcamiel]

Hi @linkdd

I think I prefer to have a dedicated socks5 option to match exactly the curl option name

GET https://example.com
[Options]
socks5: localhost:8012
HTTP 200

[linkdd]

Sounds good to me. But what would be the behavior when we define both proxy and socks5 fields then? Should it be an error?

[jcamiel]

Yes we can check what is the behavior of curl in this case and try to match it.

[linkdd]

Ok, I updated the issue description accordingly.

It seems the curl crate you use already provides everything needed, the Easy2::proxy() function (docs) seems to accept URLs of the form socks5://host:port, which correspond to the CURLOPT_PROXY option.

[jcamiel]

@linkdd Reviewing the code, I see that we have no restriction on urls passed to proxy option.

Could you try this syntax ?

# Rejection when coming from 192.168.2.0/24
GET https://example.com
HTTP 403

# No rejection when coming from 127.0.0.1/8
GET https://example.com
[Options]
proxy: socks5://localhost:8012
HTTP 200

[linkdd]

Indeed, it works 🙂

Another case of PEBKAC.

I'm closing the issue.