From 8bc4f9badd3faa44e245fd3fb1e4cebdd215bc9c Mon Sep 17 00:00:00 2001
From: jwijenbergh <jeroenwijenbergh@protonmail.com>
Date: Mon, 22 Apr 2024 16:24:21 +0200
Subject: Client: Cancel ProxyGuard in Cleanup function

Clients like Android currently do not cleanup ProxyGuard, whilst they
should, it makes sense to just cancel it for them. Cleanup should be
called if possible by the client anyways.
---
 client/proxy.go | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 70 insertions(+), 2 deletions(-)

(limited to 'client/proxy.go')

diff --git a/client/proxy.go b/client/proxy.go
index e7757ca..849b524 100644
--- a/client/proxy.go
+++ b/client/proxy.go
@@ -1,7 +1,10 @@
 package client
 
 import (
+	"context"
 	"encoding/json"
+	"errors"
+	"sync"
 
 	"codeberg.org/eduVPN/proxyguard"
 
@@ -23,6 +26,70 @@ func (pl *ProxyLogger) Log(msg string) {
 	log.Logger.Infof("[Proxyguard] %s", msg)
 }
 
+// Proxy is a wrapper around ProxyGuard
+// that has the client
+// and a cancel for cancellation by common
+// and a mutex to protect against race conditions
+type Proxy struct {
+	c      *proxyguard.Client
+	mu     sync.Mutex
+	cancel context.CancelFunc
+}
+
+// NewClient creates a new ProxyGuard wrapper from client `c`
+func (p *Proxy) NewClient(c *proxyguard.Client) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	p.c = c
+}
+
+// Delete sets the inner client to nil
+func (p *Proxy) Delete() {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	p.c = nil
+}
+
+// ErrNoProxyGuardCancel indicates that no ProxyGuard cancel function
+// was ever defined. You probably forgot to call `Tunnel`
+var ErrNoProxyGuardCancel = errors.New("no ProxyGuard cancel function")
+
+// Cancel cancels a running ProxyGuard tunnel
+// it returns an error if it cannot be canceled
+func (p *Proxy) Cancel() error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if p.cancel == nil {
+		return ErrNoProxyGuardCancel
+	}
+	p.cancel()
+	p.cancel = nil
+	return nil
+}
+
+// ErrNoProxyGuardClient is an error that is returned when no ProxyGuard client is created
+var ErrNoProxyGuardClient = errors.New("no ProxyGuard client created")
+
+// Tunnel is a wrapper around ProxyGuard tunnel that
+// that creates a new context that can be canceled
+func (p *Proxy) Tunnel(ctx context.Context, peer string) error {
+	p.mu.Lock()
+	if p.c == nil {
+		p.mu.Unlock()
+		return ErrNoProxyGuardClient
+	}
+	cctx, cf := context.WithCancel(ctx)
+	p.cancel = cf
+	p.mu.Unlock()
+	defer func() {
+		p.mu.Lock()
+		p.cancel = nil
+		p.mu.Unlock()
+	}()
+	// we set peer IPs to nil here as proxyguard already does a DNS request for us
+	return p.c.Tunnel(cctx, peer, nil)
+}
+
 // StartProxyguard starts proxyguard for proxied WireGuard connections
 func (c *Client) StartProxyguard(ck *cookie.Cookie, listen string, tcpsp int, peer string, gotFD func(fd int, pips string), ready func()) error {
 	var err error
@@ -45,8 +112,9 @@ func (c *Client) StartProxyguard(ck *cookie.Cookie, listen string, tcpsp int, pe
 		Ready: ready,
 	}
 
-	// we set peer IPs to nil here as proxyguard already does a DNS request for us
-	err = proxyc.Tunnel(ck.Context(), peer, nil)
+	c.proxy.NewClient(&proxyc)
+	defer c.proxy.Delete()
+	err = c.proxy.Tunnel(ck.Context(), peer)
 	if err != nil {
 		return i18nerr.Wrap(err, "The VPN proxy exited")
 	}
-- 
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