feat(GODT-2538): implement smart picking of default IMAP/SMTP ports

internal/vault/types_settings.go

@@ -22,6 +22,7 @@ import (
 	"runtime"
 
 	"github.com/ProtonMail/proton-bridge/v3/internal/updater"
+	"github.com/ProtonMail/proton-bridge/v3/pkg/ports"
 )
 
 type Settings struct {
@@ -70,12 +71,14 @@ func GetDefaultSyncWorkerCount() int {
 
 func newDefaultSettings(gluonDir string) Settings {
 	syncWorkers := GetDefaultSyncWorkerCount()
+	imapPort := ports.FindFreePortFrom(1143)
+	smtpPort := ports.FindFreePortFrom(1025, imapPort)
 
 	return Settings{
 		GluonDir: gluonDir,
 
-		IMAPPort: 1143,
+		IMAPPort: imapPort,
-		SMTPPort: 1025,
+		SMTPPort: smtpPort,
 		IMAPSSL:  false,
 		SMTPSSL:  false,
 

pkg/ports/ports.go

@@ -22,6 +22,7 @@ import (
 	"net"
 
 	"github.com/ProtonMail/proton-bridge/v3/internal/constants"
+	"golang.org/x/exp/slices"
 )
 
 const (
@@ -43,19 +44,19 @@ func IsPortFree(port int) bool {
 
 func isOccupied(port string) bool {
 	// Try to create server at port.
-	dummyserver, err := net.Listen("tcp", port)
+	dummyServer, err := net.Listen("tcp", port)
 	if err != nil {
 		return true
 	}
-	_ = dummyserver.Close()
+	_ = dummyServer.Close()
 	return false
 }
 
-// FindFreePortFrom finds first empty port, starting with `startPort`.
+// FindFreePortFrom finds first empty port, starting with `startPort`, and excluding ports listed in exclude.
-func FindFreePortFrom(startPort int) int {
+func FindFreePortFrom(startPort int, exclude ...int) int {
 	loopedOnce := false
 	freePort := startPort
-	for !IsPortFree(freePort) {
+	for slices.Contains(exclude, freePort) || !IsPortFree(freePort) {
 		freePort++
 		if freePort >= maxPortNumber {
 			freePort = 1

pkg/ports/ports_test.go

@@ -32,12 +32,12 @@ func TestFreePort(t *testing.T) {
 }
 
 func TestOccupiedPort(t *testing.T) {
-	dummyserver, err := net.Listen("tcp", ":"+strconv.Itoa(testPort))
+	dummyServer, err := net.Listen("tcp", ":"+strconv.Itoa(testPort))
 	require.NoError(t, err)
 
 	require.True(t, !IsPortFree(testPort), "port should be occupied")
 
-	_ = dummyserver.Close()
+	_ = dummyServer.Close()
 }
 
 func TestFindFreePortFromDirectly(t *testing.T) {
@@ -46,11 +46,21 @@ func TestFindFreePortFromDirectly(t *testing.T) {
 }
 
 func TestFindFreePortFromNextOne(t *testing.T) {
-	dummyserver, err := net.Listen("tcp", ":"+strconv.Itoa(testPort))
+	dummyServer, err := net.Listen("tcp", ":"+strconv.Itoa(testPort))
 	require.NoError(t, err)
 
 	foundPort := FindFreePortFrom(testPort)
 	require.Equal(t, testPort+1, foundPort)
 
-	_ = dummyserver.Close()
+	_ = dummyServer.Close()
+}
+
+func TestFindFreePortExcluding(t *testing.T) {
+	dummyServer, err := net.Listen("tcp", ":"+strconv.Itoa(testPort))
+	require.NoError(t, err)
+
+	foundPort := FindFreePortFrom(testPort, testPort+1, testPort+2)
+	require.Equal(t, testPort+3, foundPort)
+
+	_ = dummyServer.Close()
 }

tests/bdd_test.go

@@ -107,7 +107,10 @@ func TestFeatures(testingT *testing.T) {
 			ctx.Step(`^the header in the "([^"]*)" request to "([^"]*)" has "([^"]*)" set to "([^"]*)"$`, s.theHeaderInTheRequestToHasSetTo)
 			ctx.Step(`^the body in the "([^"]*)" request to "([^"]*)" is:$`, s.theBodyInTheRequestToIs)
 			ctx.Step(`^the API requires bridge version at least "([^"]*)"$`, s.theAPIRequiresBridgeVersion)
-
+			ctx.Step(`^the network port (\d+) is busy$`, s.networkPortIsBusy)
+			ctx.Step(`^the network port range (\d+)-(\d+) is busy$`, s.networkPortRangeIsBusy)
+			ctx.Step(`^bridge IMAP port is (\d+)`, s.bridgeIMAPPortIs)
+			ctx.Step(`^bridge SMTP port is (\d+)`, s.bridgeSMTPPortIs)
 			// ==== SETUP ====
 			ctx.Step(`^there exists an account with username "([^"]*)" and password "([^"]*)"$`, s.thereExistsAnAccountWithUsernameAndPassword)
 			ctx.Step(`^there exists a disabled account with username "([^"]*)" and password "([^"]*)"$`, s.thereExistsAnAccountWithUsernameAndPasswordWithDisablePrimary)

tests/bridge_test.go

@@ -21,7 +21,9 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"net"
 	"os"
+	"strconv"
 	"time"
 
 	"github.com/Masterminds/semver/v3"
@@ -307,3 +309,37 @@ func (s *scenario) theUserHidesAllMail() error {
 func (s *scenario) theUserShowsAllMail() error {
 	return s.t.bridge.SetShowAllMail(true)
 }
+
+func (s *scenario) networkPortIsBusy(port int) {
+	if listener, err := net.Listen("tcp", "127.0.0.1:"+strconv.Itoa(port)); err == nil { // we ignore errors. Most likely port is already busy.
+		s.t.dummyListeners = append(s.t.dummyListeners, listener)
+	}
+}
+
+func (s *scenario) networkPortRangeIsBusy(startPort, endPort int) {
+	if startPort > endPort {
+		startPort, endPort = endPort, startPort
+	}
+
+	for port := startPort; port <= endPort; port++ {
+		s.networkPortIsBusy(port)
+	}
+}
+
+func (s *scenario) bridgeIMAPPortIs(expectedPort int) error {
+	actualPort := s.t.bridge.GetIMAPPort()
+	if actualPort != expectedPort {
+		return fmt.Errorf("expected IMAP port to be %v but got %v", expectedPort, actualPort)
+	}
+
+	return nil
+}
+
+func (s *scenario) bridgeSMTPPortIs(expectedPort int) error {
+	actualPort := s.t.bridge.GetSMTPPort()
+	if actualPort != expectedPort {
+		return fmt.Errorf("expected SMTP port to be %v but got %v", expectedPort, actualPort)
+	}
+
+	return nil
+}

tests/ctx_test.go

@@ -20,6 +20,7 @@ package tests
 import (
 	"context"
 	"fmt"
+	"net"
 	"net/smtp"
 	"net/url"
 	"regexp"
@@ -160,6 +161,9 @@ type testCtx struct {
 	// errors holds test-related errors encountered while running test steps.
 	errors     [][]error
 	errorsLock sync.RWMutex
+
+	// This slice contains the dummy listeners that are intended to block network ports.
+	dummyListeners []net.Listener
 }
 
 type imapClient struct {
@@ -437,6 +441,12 @@ func (t *testCtx) close(ctx context.Context) {
 		}
 	}
 
+	for _, listener := range t.dummyListeners {
+		if err := listener.Close(); err != nil {
+			logrus.WithError(err).Errorf("Failed to close dummy listener %v", listener.Addr())
+		}
+	}
+
 	t.api.Close()
 	t.events.close()
 	t.reporter.close()

tests/features/bridge/default_ports.feature

@@ -0,0 +1,24 @@
+Feature: Bridge picks default ports wisely
+
+  Scenario: bridge picks ports for IMAP and SMTP using default values.
+    When bridge starts
+    Then bridge IMAP port is 1143
+    Then bridge SMTP port is 1025
+
+  Scenario: bridge picks ports for IMAP wisely when default port is busy.
+    When the network port 1143 is busy
+    And bridge starts
+    Then bridge IMAP port is 1144
+    Then bridge SMTP port is 1025
+
+  Scenario: bridge picks ports for SMTP wisely when default port is busy.
+    When the network port range 1025-1030 is busy
+    And bridge starts
+    Then bridge IMAP port is 1143
+    Then bridge SMTP port is 1031
+
+  Scenario: bridge picks ports for IMAP SMTP wisely when default ports are busy.
+    When the network port range 1025-1200 is busy
+    And bridge starts
+    Then bridge IMAP port is 1201
+    Then bridge SMTP port is 1202

utils/port-blocker/port-blocker.go

@@ -0,0 +1,83 @@
+// Copyright (c) 2023 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
+
+// port-blocker is a command-line that ensure a port or range of ports is occupied by creating listeners.
+package main
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"strconv"
+)
+
+func main() {
+	argCount := len(os.Args)
+	if (len(os.Args) < 2) || (argCount > 3) {
+		exitWithUsage("Invalid number of arguments.")
+	}
+
+	startPort := parsePort(os.Args[1])
+	endPort := startPort
+	if argCount == 3 {
+		endPort = parsePort(os.Args[2])
+	}
+
+	runBlocker(startPort, endPort)
+}
+
+func parsePort(portString string) int {
+	result, err := strconv.Atoi(portString)
+	if err != nil {
+		exitWithUsage(fmt.Sprintf("Invalid port '%v'.", portString))
+	}
+
+	if (result < 1024) || (result > 65535) { // ports below 1024 are reserved.
+		exitWithUsage("Ports must be in the range [1024-65535].")
+	}
+
+	return result
+}
+
+func exitWithUsage(message string) {
+	fmt.Printf("Usage: port-blocker <startPort> [<endPort>]\n")
+	if len(message) > 0 {
+		fmt.Println(message)
+	}
+	os.Exit(1)
+}
+
+func runBlocker(startPort, endPort int) {
+	if endPort < startPort {
+		exitWithUsage("startPort must be less than or equal to endPort.")
+	}
+
+	for port := startPort; port <= endPort; port++ {
+		listener, err := net.Listen("tcp", "127.0.0.1:"+strconv.Itoa(port))
+		if err != nil {
+			fmt.Printf("Port %v is already blocked. Skipping.\n", port)
+		} else {
+			//goland:noinspection GoDeferInLoop
+			defer func() {
+				_ = listener.Close()
+			}()
+		}
+	}
+
+	fmt.Println("Blocking requested ports. Press enter to exit.")
+	_, _ = fmt.Scanln()
+}