Fix linter issues

.golangci.yml

@@ -4,6 +4,7 @@ run:
 linters:
   default: all
   disable:
+    - errcheck
     - gomodguard
     - wsl
     - revive

LICENSE

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2026 Vladimir "hdkv" Hodakov
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -0,0 +1,3 @@
+# deconnect
+
+A tool to make sure your super-duper-enterprise proxy accepts your requests.

internal/application/application.go

@@ -29,9 +29,9 @@ func (a *App) Logger() *logrus.Entry {
 }
 
 func New(ctx context.Context) *App {
-	var m runtime.MemStats
+	var memStats runtime.MemStats
 
-	runtime.ReadMemStats(&m)
+	runtime.ReadMemStats(&memStats)
 
 	app := new(App)
 
@@ -43,9 +43,9 @@ func New(ctx context.Context) *App {
 	})
 
 	app.logger = logger.WithContext(ctx).WithFields(logrus.Fields{
-		"memalloc": fmt.Sprintf("%dMB", m.Alloc/1024/1024),
-		"memsys":   fmt.Sprintf("%dMB", m.Sys/1024/1024),
-		"numgc":    strconv.FormatUint(uint64(m.NumGC), 10),
+		"memalloc": fmt.Sprintf("%dMB", memStats.Alloc/1024/1024),
+		"memsys":   fmt.Sprintf("%dMB", memStats.Sys/1024/1024),
+		"numgc":    strconv.FormatUint(uint64(memStats.NumGC), 10),
 	})
 
 	app.domains = make(map[string]domains.Domain)

internal/domains/deconnector.go

@@ -1,11 +1,12 @@
 package domains
 
 import (
+	"context"
 	"net"
 )
 
 const DomainNameDeconnector = "deconnector"
 
 type Deconnector interface {
-	Handle(clientConn net.Conn)
+	Handle(ctx context.Context, clientConn net.Conn)
 }

internal/domains/deconnector/connect.go

@@ -2,15 +2,15 @@ package deconnector
 
 import (
 	"bufio"
+	"context"
 	"fmt"
 	"net"
 	"net/http"
-	"net/url"
 )
 
-func (d *Deconnector) handleDeconnect(clientConn net.Conn, connectReq *http.Request, upstreamURL *url.URL) {
+func (d *Deconnector) handleDeconnect(ctx context.Context, clientConn net.Conn, connectReq *http.Request) {
 	// Tell client the tunnel is open
-	fmt.Fprintf(clientConn, "HTTP/1.1 200 Connection established\r\n\r\n")
+	_, _ = fmt.Fprintf(clientConn, "HTTP/1.1 200 Connection established\r\n\r\n")
 
 	// Read the real HTTP request the client sends through the tunnel
 	innerReq, err := http.ReadRequest(bufio.NewReader(clientConn))
@@ -30,5 +30,5 @@ func (d *Deconnector) handleDeconnect(clientConn net.Conn, connectReq *http.Requ
 		WithField("url", innerReq.URL).
 		Info("Handling de-CONNECT request")
 
-	d.forwardHTTP(clientConn, innerReq, upstreamURL)
+	d.forwardHTTP(ctx, clientConn, innerReq)
 }

internal/domains/deconnector/forward.go

@@ -2,14 +2,14 @@ package deconnector
 
 import (
 	"bufio"
+	"context"
 	"fmt"
 	"net"
 	"net/http"
-	"net/url"
 )
 
-func (d *Deconnector) forwardHTTP(clientConn net.Conn, req *http.Request, upstreamURL *url.URL) {
-	upstreamConn, err := d.dialer.Dial()
+func (d *Deconnector) forwardHTTP(ctx context.Context, clientConn net.Conn, req *http.Request) {
+	upstreamConn, err := d.dialer.Dial(ctx)
 	if err != nil {
 		d.app.Logger().WithError(err).Error("upstream dial failed")
 		fmt.Fprintf(clientConn, "HTTP/1.1 502 Bad Gateway\r\n\r\n")
@@ -18,6 +18,10 @@ func (d *Deconnector) forwardHTTP(clientConn net.Conn, req *http.Request, upstre
 	}
 	defer upstreamConn.Close()
 
+	if authHeader, ok := d.dialer.Auth(); ok {
+		req.Header.Set("Proxy-Authorization", "Basic "+authHeader)
+	}
+
 	if err := req.WriteProxy(upstreamConn); err != nil {
 		d.app.Logger().WithError(err).Error("failed to write request")
 
@@ -33,5 +37,8 @@ func (d *Deconnector) forwardHTTP(clientConn net.Conn, req *http.Request, upstre
 
 	defer resp.Body.Close()
 
-	resp.Write(clientConn)
+	err = resp.Write(clientConn)
+	if err != nil {
+		d.app.Logger().WithError(err).Error("failed to write response")
+	}
 }

internal/domains/deconnector/handle.go

@@ -2,18 +2,12 @@ package deconnector
 
 import (
 	"bufio"
+	"context"
 	"net"
 	"net/http"
 )
 
-func (d *Deconnector) Handle(clientConn net.Conn) {
-	upstreamURL, err := d.dialer.UpstreamURL()
-	if err != nil {
-		d.app.Logger().WithError(err).Error("failed to get upstream URL")
-
-		return
-	}
-
+func (d *Deconnector) Handle(ctx context.Context, clientConn net.Conn) {
 	defer clientConn.Close()
 
 	req, err := http.ReadRequest(bufio.NewReader(clientConn))
@@ -26,9 +20,9 @@ func (d *Deconnector) Handle(clientConn net.Conn) {
 	if req.Method == http.MethodConnect {
 		_, port, _ := net.SplitHostPort(req.Host)
 		if port == "443" {
-			d.handleTunnel(clientConn, req.Host, upstreamURL)
+			d.handleTunnel(ctx, clientConn, req.Host)
 		} else {
-			d.handleDeconnect(clientConn, req, upstreamURL)
+			d.handleDeconnect(ctx, clientConn, req)
 		}
 	} else {
 		req.RequestURI = ""
@@ -42,6 +36,6 @@ func (d *Deconnector) Handle(clientConn net.Conn) {
 			WithField("url", req.URL).
 			Info("Forwarding HTTP request")
 
-		d.forwardHTTP(clientConn, req, upstreamURL)
+		d.forwardHTTP(ctx, clientConn, req)
 	}
 }

internal/domains/deconnector/tunnel.go

@@ -2,17 +2,18 @@ package deconnector
 
 import (
 	"bufio"
+	"context"
 	"fmt"
 	"io"
 	"net"
 	"net/http"
-	"net/url"
 )
 
-func (d *Deconnector) handleTunnel(clientConn net.Conn, host string, upstreamURL *url.URL) {
+//nolint:funlen
+func (d *Deconnector) handleTunnel(ctx context.Context, clientConn net.Conn, host string) {
 	d.app.Logger().WithField("host", host).Info("Handling CONNECT tunnel")
 
-	upstreamConn, err := d.dialer.Dial()
+	upstreamConn, err := d.dialer.Dial(ctx)
 	if err != nil {
 		d.app.Logger().WithError(err).Error("upstream dial failed")
 		fmt.Fprintf(clientConn, "HTTP/1.1 502 Bad Gateway\r\n\r\n")
@@ -24,6 +25,10 @@ func (d *Deconnector) handleTunnel(clientConn net.Conn, host string, upstreamURL
 	connectLine := fmt.Sprintf(
 		"CONNECT %s HTTP/1.1\r\nHost: %s\r\n\r\n", host, host,
 	)
+	if authHeader, ok := d.dialer.Auth(); ok {
+		connectLine += fmt.Sprintf("Proxy-Authorization: Basic %s\r\n", authHeader)
+	}
+
 	fmt.Fprint(upstreamConn, connectLine)
 
 	resp, err := http.ReadResponse(bufio.NewReader(upstreamConn), nil)
@@ -33,13 +38,40 @@ func (d *Deconnector) handleTunnel(clientConn net.Conn, host string, upstreamURL
 
 		return
 	}
+	defer resp.Body.Close()
 
 	fmt.Fprintf(clientConn, "HTTP/1.1 200 Connection established\r\n\r\n")
 
 	done := make(chan struct{}, 2)
 
-	go func() { io.Copy(upstreamConn, clientConn); done <- struct{}{} }()
-	go func() { io.Copy(clientConn, upstreamConn); done <- struct{}{} }()
+	go func() {
+		defer func() {
+			_ = upstreamConn.Close()
+			_ = clientConn.Close()
+
+			done <- struct{}{}
+		}()
+
+		if _, err := io.Copy(upstreamConn, clientConn); err != nil {
+			d.app.Logger().
+				WithError(err).
+				Debug("client -> upstream copy stopped")
+		}
+	}()
+	go func() {
+		defer func() {
+			_ = upstreamConn.Close()
+			_ = clientConn.Close()
+
+			done <- struct{}{}
+		}()
+
+		if _, err := io.Copy(clientConn, upstreamConn); err != nil {
+			d.app.Logger().
+				WithError(err).
+				Debug("upstream -> client copy stopped")
+		}
+	}()
 
 	<-done
 }

internal/domains/dialer.go

@@ -1,6 +1,7 @@
 package domains
 
 import (
+	"context"
 	"net"
 	"net/url"
 )
@@ -8,6 +9,7 @@ import (
 const DomainNameDialer = "dialer"
 
 type Dialer interface {
-	Dial() (net.Conn, error)
+	Auth() (string, bool)
+	Dial(ctx context.Context) (net.Conn, error)
 	UpstreamURL() (*url.URL, error)
 }

internal/domains/dialer/dial.go

@@ -1,21 +1,52 @@
 package dialer
 
 import (
+	"context"
 	"crypto/tls"
+	"encoding/base64"
 	"fmt"
 	"net"
 	"net/url"
 )
 
-func (d *Dialer) Dial() (net.Conn, error) {
-	if d.dialURL.Scheme == "https" {
-		return tls.Dial("tcp", d.dialURL.Host, &tls.Config{
-			ServerName:         d.dialURL.Hostname(),
-			InsecureSkipVerify: d.app.Config().Upstream.InsecureTLS,
-		})
+func (d *Dialer) Auth() (string, bool) {
+	url, _ := d.UpstreamURL()
+	if url.User == nil {
+		return "", false
 	}
 
-	return net.Dial("tcp", d.dialURL.Host)
+	username := url.User.Username()
+	password, _ := url.User.Password()
+
+	return base64.StdEncoding.EncodeToString(
+		[]byte(username + ":" + password),
+	), true
+}
+
+func (d *Dialer) Dial(ctx context.Context) (net.Conn, error) {
+	dialer := &net.Dialer{}
+
+	conn, err := dialer.DialContext(ctx, "tcp", d.dialURL.Host)
+	if err != nil {
+		return nil, fmt.Errorf("%w: %w (%w)", ErrDialer, ErrDial, err)
+	}
+
+	if d.dialURL.Scheme != "https" {
+		return conn, nil
+	}
+
+	tlsConn := tls.Client(conn, &tls.Config{
+		ServerName: d.dialURL.Hostname(),
+		//nolint:gosec
+		InsecureSkipVerify: d.app.Config().Upstream.InsecureTLS,
+	})
+	if err := tlsConn.HandshakeContext(ctx); err != nil {
+		_ = conn.Close()
+
+		return nil, fmt.Errorf("%w: %w (%w)", ErrDialer, ErrDial, err)
+	}
+
+	return tlsConn, nil
 }
 
 func (d *Dialer) UpstreamURL() (*url.URL, error) {
@@ -26,12 +57,12 @@ func (d *Dialer) UpstreamURL() (*url.URL, error) {
 		)
 	}
 
-	u, err := url.Parse(d.app.Config().Upstream.URL)
+	upstreamURL, err := url.Parse(d.app.Config().Upstream.URL)
 	if err != nil {
 		return nil, fmt.Errorf(
 			"%w: %w (%w)", ErrDialer, ErrUpstreamURL, err,
 		)
 	}
 
-	return u, nil
+	return upstreamURL, nil
 }

internal/domains/dialer/errors.go

@@ -5,5 +5,6 @@ import "errors"
 var (
 	ErrDialer              = errors.New("dialer")
 	ErrConnectDependencies = errors.New("function ConnectDependencies()")
+	ErrDial                = errors.New("function Dial()")
 	ErrUpstreamURL         = errors.New("function UpstreamURL()")
 )

internal/domains/listener/listen.go

@@ -7,9 +7,15 @@ import (
 )
 
 func (l *Listener) Listen(ctx context.Context) error {
-	ln, err := net.Listen(
+	listenerConfig := new(net.ListenConfig)
+
+	listener, err := listenerConfig.Listen(
+		ctx,
 		"tcp",
-		l.app.Config().Deconnect.Host+":"+l.app.Config().Deconnect.Port,
+		net.JoinHostPort(
+			l.app.Config().Deconnect.Host,
+			l.app.Config().Deconnect.Port,
+		),
 	)
 	if err != nil {
 		return fmt.Errorf("%w: %w (%w)", ErrListener, ErrListen, err)
@@ -24,16 +30,16 @@ func (l *Listener) Listen(ctx context.Context) error {
 
 		l.app.Logger().Info("Shutting down listener")
 
-		if err := ln.Close(); err != nil {
+		if err := listener.Close(); err != nil {
 			l.app.Logger().WithError(err).Error("listener close error")
 		}
 	}()
 
 	for {
-		conn, err := ln.Accept()
+		conn, err := listener.Accept()
 		if err != nil {
 			if ctx.Err() != nil {
-				return nil
+				return fmt.Errorf("%w: %w (%w)", ErrListener, ErrListen, err)
 			}
 
 			l.app.Logger().WithError(err).Error("accept error")
@@ -41,6 +47,6 @@ func (l *Listener) Listen(ctx context.Context) error {
 			continue
 		}
 
-		go l.deconnector.Handle(conn)
+		go l.deconnector.Handle(ctx, conn)
 	}
 }