About Transparent Proxy

First of all, I am very grateful to the [AdguardTeam](https://github.com/AdguardTeam) team for giving so many excellent open source projects, from which I have learned a lot. Recently, I have been fascinated by the **[gomitmproxy](https://github.com/AdguardTeam/gomitmproxy)** project. The code of this project is very elegant, but I want to enter gomitmproxy through iptables traffic on Openwrt, but Encountered many setbacks.

So, I would like to ask you to help me, now I will describe the problem in detail:

First of all, there is no problem with HTTP proxying, it works fine. But I wanted to use a transparent proxy, so I replaced `&net.TCPAddr` with `net.ResolveTCPAddr`:

```
//addr := &net.TCPAddr{IP: listenIP, Port: options.ListenPort}
addr, err := net.ResolveTCPAddr("tcp", ":12345")

config.ProxyConfig = gomitmproxy.Config{
ListenAddr: addr,

MITMConfig: mitmConfig,
MITMExceptions: []string{"example.com"},
}
```

```
sudo iptables -t nat -A PREROUTING -p tcp --dport 80 -j DNAT --to 10.20.1.1:12345
sudo iptables -t nat -A PREROUTING -p tcp --dport 443 -j DNAT --to 10.20.1.1:12345
```

It seems that the code does not report an error, but when it is actually run, a huge problem occurs. First of all, if you access the content of port 80, there seems to be no big problem, and you can access it normally:

```
2022/04/07 08:12:41 9756#56 [debug] id=100004-1: handle request GET http://local.local.wooc.org/cart
2022/04/07 08:12:41 9756#56 [debug] urlfilter: id=100004-1: saving session
2022/04/07 08:12:41 9756#56 [debug] id=100004-1: request was overridden by: http://local.wooc.org/cart
2022/04/07 08:12:41 9756#56 [debug] id=100004-1: response was overridden by: 200 OK
2022/04/07 08:12:41 9756#56 [debug] id=100004: waiting for request
2022/04/07 08:12:42 9756#51 [debug] id=100005: accepted connection from 10.20.1.92:54267
```

But when accessing the link to 443, it cannot be accessed, and a bunch of garbled characters are prompted:

```
2022/04/07 08:12:42 9756#35 [debug] id=100005: failed to read request: malformed HTTP request "\x16\x03\x01\x02\x00\x01\x00\x01\xfc\x03\x03**\xa41\x92\x963K\x84\xb5\xe6f{>W\xb9\xcbVL\xe5\xc1[\xa2I\xeb#\x96xH\u0094\xe7 \xd2=\xa27\x1a\xb83\xa7?[\x83s(\xcfy\xeeʞ\xcfJ\x97`\xeb\x03\xb2;v\xfaJO\xf65\x006\xca\xca\x13\x01\x13\x02\x13\x03\xc0,\xc0+̩\xc00\xc0/̨\xc0$\xc0#\xc0"
2022/04/07 08:12:42 9756#61 [debug] id=100005: closing connection due to: malformed HTTP request "\x16\x03\x01\x02\x00\x01\x00\x01\xfc\x03\x03**\xa41\x92\x963K\x84\xb5\xe6f{>W\xb9\xcbVL\xe5\xc1[\xa2I\xeb#\x96xH\u0094\xe7 \xd2=\xa27\x1a\xb83\xa7?[\x83s(\xcfy\xeeʞ\xcfJ\x97`\xeb\x03\xb2;v\xfaJO\xf65\x006\xca\xca\x13\x01\x13\x02\x13\x03\xc0,\xc0+̩\xc00\xc0/̨\xc0$\xc0#\xc0"
2022/04/07 08:12:42 9756#51 [debug] id=100006: accepted connection from 10.20.1.92:54268
```

It should be a CONNECT request, but the above is not.

I have been troubled by this problem for a long time. I hope the official can help me when I see my post, and I will continue to support you with more and better products.