Gg/connection reset status check

.github/workflows/go.yml

@@ -19,7 +19,7 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@v3
       with:
-        go-version: 1.19
+        go-version: 1.25
 
     - name: Build
       run: go build -v ./...

README.md

@@ -1,4 +1,4 @@
 # go-lprlib
 ![Test](https://github.com/documatrix/go-lprlib/actions/workflows/go.yml/badge.svg)
 
-This repository contains an implementation of the LPR protocol (send & receive) in go
+This repository contains an implementation of the [LPR protocol](https://datatracker.ietf.org/doc/html/rfc1179) (send & receive) in go

go.mod

@@ -1,10 +1,10 @@
 module github.com/documatrix/go-lprlib
 
-go 1.18
+go 1.25
 
 require (
 	github.com/stretchr/testify v1.8.0
-	golang.org/x/text v0.3.8
+	golang.org/x/text v0.31.0
 )
 
 require (

go.sum

@@ -8,8 +8,8 @@ github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSS
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
-golang.org/x/text v0.3.8 h1:nAL+RVCQ9uMn3vJZbV+MRnydTJFPf8qqY42YiA6MrqY=
-golang.org/x/text v0.3.8/go.mod h1:E6s5w1FMmriuDzIBO73fBruAKo1PCIq6d2Q6DHfQ8WQ=
+golang.org/x/text v0.31.0 h1:aC8ghyu4JhP8VojJ2lEHBnochRno1sgL6nEi9WGFGMM=
+golang.org/x/text v0.31.0/go.mod h1:tKRAlv61yKIjGGHX/4tP1LTbc13YSec1pxVEWXzfoeM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

lpr_daemon.go

@@ -1,7 +1,6 @@
 package lprlib
 
 import (
-	"context"
 	"errors"
 	"fmt"
 	"io"
@@ -33,10 +32,6 @@ type QueueState func(queue string, list string, long bool) string
 
 type ExternalIDCallbackFunc func() uint64
 
-func init() {
-	rand.Seed(time.Now().UnixMicro())
-}
-
 // LprDaemon structure
 type LprDaemon struct {
 	finishedConns chan *LprConnection
@@ -287,10 +282,6 @@ type LprConnection struct {
 	// SaveName The File name of the new file
 	SaveName string
 
-	// ctx is the lpr daemon's context.
-	// The connection must be closed once the context is canceled.
-	ctx context.Context
-
 	// daemon contains a reference to the LprDaemon
 	daemon *LprDaemon
 
@@ -374,22 +365,51 @@ func (lpr *LprConnection) RunConnection() {
 		if err != nil {
 			logErrorf("failed to create trace file: %v", err)
 		}
-		defer traceFile.Close()
+
+		defer func() {
+			err := traceFile.Close()
+			if err != nil {
+				logErrorf("failed to close trace file %s: %v", traceFile.Name(), err)
+			}
+		}()
+
 		logDebugf("Created trace file %s", traceFile.Name())
-		traceFile.WriteString(fmt.Sprintf("LPR connection trace %s\n", time.Now()))
+
+		_, err = fmt.Fprintf(traceFile, "LPR connection trace %s\n", time.Now())
+		if err != nil {
+			logErrorf("failed to write to trace file %s: %v", traceFile.Name(), err)
+		}
 	}
 
 	for lpr.Status != Error && lpr.Status != End {
 		command, err := lpr.ReadCommand()
 
 		if traceFile != nil {
-			traceFile.WriteString(fmt.Sprintf("received message %d:\n", len(command)))
+			_, traceErr := fmt.Fprintf(traceFile, "received message %d:\n", len(command))
+			if traceErr != nil {
+				logErrorf("failed to write to trace file %s: %v", traceFile.Name(), traceErr)
+			}
+
 			if err != nil {
-				traceFile.WriteString(fmt.Sprintf("error: %v\n", err))
+				_, traceErr = fmt.Fprintf(traceFile, "error: %v\n", err)
+				if traceErr != nil {
+					logErrorf("failed to write to trace file %s: %v", traceFile.Name(), traceErr)
+				}
 			} else {
-				traceFile.WriteString("-----\n")
-				traceFile.Write(command)
-				traceFile.WriteString("\n-----\n")
+				_, traceErr = traceFile.WriteString("-----\n")
+				if traceErr != nil {
+					logErrorf("failed to write to trace file %s: %v", traceFile.Name(), traceErr)
+				}
+
+				_, traceErr = traceFile.Write(command)
+				if traceErr != nil {
+					logErrorf("failed to write to trace file %s: %v", traceFile.Name(), traceErr)
+				}
+
+				_, traceErr = traceFile.WriteString("\n-----\n")
+				if traceErr != nil {
+					logErrorf("failed to write to trace file %s: %v", traceFile.Name(), traceErr)
+				}
 			}
 		}
 

lpr_daemon_test.go

@@ -156,7 +156,7 @@ func TestDaemonLargeFileConnection(t *testing.T) {
 
 	conn := <-lprd.FinishedConnections()
 
-	out, err = ioutil.ReadFile(conn.SaveName)
+	out, err = os.ReadFile(conn.SaveName)
 	if err != nil {
 		t.Error(err)
 	} else {
@@ -243,7 +243,7 @@ func TestDaemonMultipleConnection(t *testing.T) {
 
 	i := 0
 	for conn := range lprd.FinishedConnections() {
-		out, err = ioutil.ReadFile(conn.SaveName)
+		out, err = os.ReadFile(conn.SaveName)
 		if err != nil {
 			t.Error(err)
 		} else {
@@ -288,7 +288,7 @@ func generateTempFile(dir, prefix, text string) (string, error) {
 	var err error
 	var file *os.File
 
-	file, err = ioutil.TempFile(dir, prefix)
+	file, err = os.CreateTemp(dir, prefix)
 	if err != nil {
 		return "", err
 	}
@@ -413,6 +413,9 @@ func TestDaemonClose(t *testing.T) {
 	conn := <-lprd.FinishedConnections()
 	require.Equal(t, End, conn.Status)
 
+	err = os.Remove(conn.SaveName)
+	require.Nil(t, err)
+
 	// no new connection may be opened
 	lprs = LprSend{}
 	err = lprs.Init("127.0.0.1", name, port, "raw", "TestUser", time.Minute)
@@ -457,7 +460,7 @@ func TestDaemonFileSize(t *testing.T) {
 
 	con := <-lprd.FinishedConnections()
 	require.Equal(t, End, con.Status)
-	out, err = ioutil.ReadFile(con.SaveName)
+	out, err = os.ReadFile(con.SaveName)
 	require.Nil(t, err)
 	err = os.Remove(con.SaveName)
 	require.Nil(t, err)
@@ -501,7 +504,7 @@ func TestDaemonFileSize(t *testing.T) {
 
 	con = <-lprd.FinishedConnections()
 	require.Equal(t, End, con.Status)
-	out, err = ioutil.ReadFile(con.SaveName)
+	out, err = os.ReadFile(con.SaveName)
 	require.Nil(t, err)
 	err = os.Remove(con.SaveName)
 	require.Nil(t, err)

lpr_status.go

@@ -1,15 +1,21 @@
 package lprlib
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"net"
 	"time"
 )
 
-// GetStatus Reads the Status from the printer
-func GetStatus(hostname string, port uint16, queue string, long bool, timeout time.Duration) (string, error) {
-
+// GetStatus Reads the status of the given queue on the given host (and port).
+// The timeout parameter specifies the maximum time to wait for the connection
+// and for each read/write operation. If timeout is 0, a default of 2 seconds
+// is used. The long parameter specifies whether to request a long listing
+// (true) or a short listing (false). The ignoreForcefulClose parameter controls
+// if the read-status should ignore forceful connection closures by the server (which
+// sometimes happens).
+func GetStatus(hostname string, port uint16, queue string, long bool, timeout time.Duration, ignoreForcefulClose bool) (string, error) {
 	// Set default Port
 	if port == 0 {
 		port = 515
@@ -88,6 +94,20 @@ func GetStatus(hostname string, port uint16, queue string, long bool, timeout ti
 			if err == io.EOF {
 				break
 			} else {
+				if ignoreForcefulClose {
+					opErr := &net.OpError{}
+
+					if errors.As(err, &opErr) {
+						// Check for connection reset errors at the syscall level
+						// This works cross-platform: ECONNRESET on Unix-like systems,
+						// WSAECONNRESET on Windows
+						if isConnResetErr(opErr) {
+							logDebugf("Ignoring forceful connection closure by server")
+							break
+						}
+					}
+				}
+
 				return "", &LprError{"Error while reading status: " + err.Error()}
 			}
 		}

lpr_status_other.go

@@ -0,0 +1,14 @@
+//go:build !windows
+// +build !windows
+
+package lprlib
+
+import (
+	"errors"
+	"net"
+	"syscall"
+)
+
+func isConnResetErr(err *net.OpError) bool {
+	return errors.Is(err.Err, syscall.ECONNRESET)
+}

lpr_status_test.go

@@ -2,6 +2,7 @@ package lprlib
 
 import (
 	"log"
+	"net"
 	"testing"
 	"time"
 
@@ -34,19 +35,19 @@ func TestGetStatus(t *testing.T) {
 
 	time.Sleep(1 * time.Second)
 
-	status, err := GetStatus("127.0.0.1", port, rawQueue, false, 2*time.Second)
+	status, err := GetStatus("127.0.0.1", port, rawQueue, false, 2*time.Second, false)
 	require.Nil(t, err)
 	require.NotEmpty(t, status)
 
 	lprd.GetQueueState = getShortQueueState
 
-	status, err = GetStatus("127.0.0.1", port, rawQueue, false, 2*time.Second)
+	status, err = GetStatus("127.0.0.1", port, rawQueue, false, 2*time.Second, false)
 	require.Nil(t, err)
 	require.Equal(t, shortQueueState, status)
 
 	lprd.GetQueueState = getLongQueueState
 
-	status, err = GetStatus("127.0.0.1", port, rawQueue, true, 2*time.Second)
+	status, err = GetStatus("127.0.0.1", port, rawQueue, true, 2*time.Second, false)
 	require.Nil(t, err)
 	require.Equal(t, longQueueState, status)
 
@@ -63,3 +64,33 @@ func TestGetStatus(t *testing.T) {
 
 	lprd.Close()
 }
+
+func TestGetStatus_ServerClosesImmediatelyAfterCommand(t *testing.T) {
+	listener, err := net.Listen("tcp", net.JoinHostPort("localhost", "0"))
+	require.NoError(t, err)
+
+	defer listener.Close()
+
+	go func() {
+		conn, err := listener.Accept()
+		require.NoError(t, err)
+
+		defer conn.Close()
+
+		// Read command byte
+		buf := make([]byte, 1024)
+		_, err = conn.Read(buf)
+		require.NoError(t, err)
+
+		// Close connection immediately
+		err = conn.(*net.TCPConn).SetLinger(0)
+		require.NoError(t, err)
+	}()
+
+	status, err := GetStatus("localhost", uint16(listener.Addr().(*net.TCPAddr).Port), "raw", false, 2*time.Second, true)
+	require.NoError(t, err)
+	require.Empty(t, status)
+
+	_, err = GetStatus("localhost", uint16(listener.Addr().(*net.TCPAddr).Port), "raw", false, 2*time.Second, false)
+	require.Error(t, err)
+}

lpr_status_windows.go

@@ -0,0 +1,11 @@
+package lprlib
+
+import (
+	"errors"
+	"net"
+	"syscall"
+)
+
+func isConnResetErr(err *net.OpError) bool {
+	return errors.Is(err.Err, syscall.ECONNRESET) || errors.Is(err.Err, syscall.WSAECONNRESET)
+}