From cdd3d4b8d8814137e16116002e5bf6aad38b794f Mon Sep 17 00:00:00 2001 From: idk Date: Mon, 24 Jul 2023 03:18:17 -0400 Subject: [PATCH] Allow the use of alternative net.Listener implementations by downstreams (#25855) This is a simple PR which moves the `GetListener` function to a `DefaultGetListener` function, and changes `GetListener` to be a variable which by default points to the `DefaultGetListener` function. This allows people who may exist quasi-downstream of Gitea to create alternate "GetListener" functions, with identical signatures, which return different implementations of the `net.Listener` interface. This approach is expressly intended to be non-invasive and have the least possible impact on the gitea codebase. A previous version of this idea was rejected before: https://github.com/go-gitea/gitea/issues/15544 but because of issues like: https://github.com/go-gitea/gitea/issues/22335 I **really** think that recommending people configure proxies by hand is exactly the wrong way to do things(This is why there is a Tor Browser.). This tiny change lets me put proper hidden service configuration into single `i2p.go` file which lives in `modules/graceful/` and which never has to be checked in to your codebase or affect your dependencies or bloat your project in any way, it can live on a branch in my fork and I'll fast-forward every release and never the twain shall meet. The main use-case for this is to listen on Peer-to-Peer networks and Hidden Services directly without error-prone and cumbersome port-forwarding configuration. For instance, I might implement an "I2PGetListener" as follows: ```Go // adapted from i2p.go which is unchecked-in in my modules/graceful/ directory import "github.com/eyedeekay/onramp" var garlic = &onramp.Garlic{} func I2PGetListener(network, address string) (net.Listener, error) { // Add a deferral to say that we've tried to grab a listener defer GetManager().InformCleanup() switch network { case "tcp", "tcp4", "tcp6", "i2p", "i2pt": return garlic.Listen() case "unix", "unixpacket": // I2P isn't really a replacement for the stuff you use Unix sockets for and it's also not an anonymity risk, so treat them normally unixAddr, err := net.ResolveUnixAddr(network, address) if err != nil { return nil, err } return GetListenerUnix(network, unixAddr) default: return nil, net.UnknownNetworkError(network) } } ``` I could then substitute that GetListener function and be 50% of the way to having a fully-functioning gitea-over-hidden-services instance without any additional configuration(The other 50% doesn't require any code-changes on gitea's part). There are 2 advantages here, one being convenience, first this turns hidden services into a zero-configuration option for self-hosting gitea, and second safety, these Go libraries are passing around hidden-service-only versions of the net.Addr struct, they're using hidden-service-only versions of the sockets, which are both expressly designed to never require access to any information outside the hidden service network, manipulating the application so it reveals information about the host becomes much more difficult, and some attacks become nearly impossible. It also opens up TLS-over-Hidden Services support which is niche right now, of course, but in a future where gitea instances federate if hidden services want to be part of the federation they're probably going to need TLS certificates. They don't need to be painful to set up. This doesn't fix an open issue, but it might affect: - https://github.com/go-gitea/gitea/issues/22335 - my `i2p.go` file actually has a mod that fixes this but it requires adding a handful of new dependencies to gitea and isn't compatible with the normal way you guys recommend using a proxy so I don't think it's ready to send to you as a PR, but if I can find a non-invasive way to fix it I will. - https://github.com/go-gitea/gitea/issues/18240 I hereby agree to the Code of Conduct published here: https://github.com/go-gitea/gitea/blob/8b89563bf1031089a218e6d05dc61047281b35ee/CODE_OF_CONDUCT.md I have read and understood the recommendations published here: https://github.com/go-gitea/gitea/blob/8b89563bf1031089a218e6d05dc61047281b35ee/CONTRIBUTING.md Thank you for your consideration. --------- Co-authored-by: eyedeekay Co-authored-by: wxiaoguang --- modules/graceful/net_unix.go | 8 +++++--- modules/graceful/net_windows.go | 8 +++++--- modules/graceful/server.go | 8 ++++++++ 3 files changed, 18 insertions(+), 6 deletions(-) diff --git a/modules/graceful/net_unix.go b/modules/graceful/net_unix.go index e9c1285123..f5af1e3937 100644 --- a/modules/graceful/net_unix.go +++ b/modules/graceful/net_unix.go @@ -150,11 +150,13 @@ func CloseProvidedListeners() error { return returnableError } -// GetListener obtains a listener for the local network address. The network must be +// DefaultGetListener obtains a listener for the local network address. The network must be // a stream-oriented network: "tcp", "tcp4", "tcp6", "unix" or "unixpacket". It // returns an provided net.Listener for the matching network and address, or -// creates a new one using net.Listen. -func GetListener(network, address string) (net.Listener, error) { +// creates a new one using net.Listen. This function can be replaced by changing the +// GetListener variable at the top of this file, for example to listen on an onion service using +// github.com/cretz/bine +func DefaultGetListener(network, address string) (net.Listener, error) { // Add a deferral to say that we've tried to grab a listener defer GetManager().InformCleanup() switch network { diff --git a/modules/graceful/net_windows.go b/modules/graceful/net_windows.go index a2f58e224a..15d228d6b6 100644 --- a/modules/graceful/net_windows.go +++ b/modules/graceful/net_windows.go @@ -9,9 +9,11 @@ package graceful import "net" -// GetListener obtains a listener for the local network address. -// On windows this is basically just a shim around net.Listen. -func GetListener(network, address string) (net.Listener, error) { +// DefaultGetListener obtains a listener for the local network address. +// On windows this is basically just a shim around net.Listen. This function +// can be replaced by changing the GetListener variable at the top of this file, +// for example to listen on an onion service using github.com/cretz/bine +func DefaultGetListener(network, address string) (net.Listener, error) { // Add a deferral to say that we've tried to grab a listener defer GetManager().InformCleanup() diff --git a/modules/graceful/server.go b/modules/graceful/server.go index e42d35cd49..bd917828bc 100644 --- a/modules/graceful/server.go +++ b/modules/graceful/server.go @@ -33,6 +33,14 @@ var ( PerWriteWriteTimeoutKbTime = 10 * time.Second ) +// GetListener returns a listener from a GetListener function, which must have the +// signature: `func FunctioName(network, address string) (net.Listener, error)`. +// This determines the implementation of net.Listener which the server will use.` +// It is implemented in this way so that downstreams may specify the type of listener +// they want to provide Gitea on by default, such as with a hidden service or a p2p network +// No need to worry about "breaking" if there would be a refactoring for the Listeners. No compatibility-guarantee for this mechanism +var GetListener = DefaultGetListener + func init() { DefaultMaxHeaderBytes = 0 // use http.DefaultMaxHeaderBytes - which currently is 1 << 20 (1MB) }